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Recognition memory of retrieved sequences of words
Acta Psychologica 0 North-Holland
47 (1981) 207-228 Publishing Company
RECOGNITION OF WORDS *
MEMORY OF RETRIEVED
SEQUENCES
Tarow INDOW and Hiroko TAKADA University of California, Irvine, U.S.A. and Keio University, Tokyo, Japan
Accepted
August
1980
The subject was asked to retrieve words belonging to a given category, natural or artificially created. After n words were retrieved, a recognition task was given either immediately after or after a delay (4 hours, 7, 14, or 28 days). Several probe words were presented and the subject had to decide whether each had been retrieved or not. The length of retrieval sequence, n, was systematically varied. Results of three experiments showed that, in general, mean decision time was almost independent of n. Namely, recognition regarding self-generated lists of words seems to be due to a different information processing than recognition regarding lists of words presented by the experimenter to memorize. Implications of the findings for retrieval from long term memory were discussed.
The present experiments stemmed from two previous studies; one concerned retrieval from long-term memory (Indow and Togano 1970) and the other concerned scanning in short-term memory (Indow and Murase 1973). In the former study, as in the original experiment by Bousfield and Sedgewick (1944), the subject was required to retrieve all words from a given category, e.g., flower. While retrieving, the subject never reproduces words which do not belong to the category, and hence the search in long term memory (LTM) must have an efficient monitor system to exclude irrelevant items. Furthermore, the subject rarely reproduces the same word more than once, which implies two possibilities. * All the experiments were carried out at the Department of Psychology, Keio University. The study was partially supported by a grant (3362) from the Electrical Communication Laboratories, NTT in Japan. Experiments 2 and 3 were conducted by A. Sakamaki in 1974 and by N. Wakita in 1976 respectively. The authors are grateful to these collaborators and all the subjects who participated. Requests for reprints should be made to T. Indow, School of Social Sciences, University of California, Irvine, CA 92717, U.S.A.
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Either that once retrieved words are automatically excluded as targets from the subsequent search or that some kind of monitoring process is in operation during the retrieval. The task of the monitor is to check, whenever a word is picked up by the search, whether it has already been reproduced (old) or not (new) (Indow 1980). In the latter study, the subject memorized a long list of words all belonging to the same category to the first perfect recitation and then probe words were given one by one. The subject was required to judge whether each probe word was in the list or not. The number of words in a list, 12, varied from 6 to 26. As discovered by Sternberg (1966, 1969) with short lists within the immediate memory span, the response time (RT) as a function of y1 suggested that the memory scanning under discussion was serial rather than parallel and exhaustive rather than self-terminating. If the monitor system is in operation during the retrieval in the first study on LTM, a possible way of the continuous recognition (Juola et al. 1974) in determining each word is old or new would be to scan through the list of already retrieved words in memory. This monitoring method can not be said efficient and probably seems not very plausible. If this is the case, however, the situation is similar to that of the second study on recognition memory except that the list to be scanned is generated by the subject in the retrieval rather than given by the experimenter to memorize. Three experiments were conducted to test whether the monitoring during retrieval is made in this way or not. In the first experiment, the monitoring was deliberately called for during a retrieval sequence. On the basis of the results of this experiment, two more studies were added in which recognition experiments of self-generated lists were carried out at various time intervals after retrievals.
Experiment
1: recognition
during and immediately
after retrieval
Method The S was asked to retrieve items in a specified category, e.g., flower, in the order of their occurrence. The S wrote each retrieved name on a card and handed the cards to the experimenter (I?), one by one. As soon as the cumulative number of retrieved items, n(t), reached the first predetermined integer nr at time t, the retrieving process was halted and the time t was recorded. Then, a recognition task was inserted in the following way. Several probe words were visually presented, one at a time. Each probe word was to elicit a response, either Y or N or N’, if correctly responded.
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Y: a word which had already been retrieved. N: a word in the given category which had not yet been retrieved. N’: an irrelevant word which seems to be entirely irrelevant to the given category (e.g., “fish” to the category flower). The S was instructed to press one key for Y and the other key for N and N’. To the S, there was no distinction between N and N’. When 5 to 7 probe words had been responded to, then the retrieving task was resumed and continued until n(t) reached the next predetermined integer na. Then, the second recognition task was inserted in the way as stated above. The experiment was continued in this way until it became almost impossible for the S to retrieve new word. Hence the total number of words retrieved, n(max), as well as the number of the recognition tasks inserted, differed among Ss. The values of ni were about 10, 20, . . . . The probes consisted of 3 Y, 1 or 2 N, and 1 or 2 N’ words on each recognition task. When a probe word to elicit response was unfamiliar, the S was asked to report it and the response was discarded. The S was allowed, if he or she liked, to include names which had been presented as N probes in subsequent retrievals. Immediately after the whole retrieving process was terminated, the last recognition task was given in which 20 Y, 10 N, and 10 N’ probes were used. The experiment was made with two categories, flower and mammal, with each S. Each probe word was written by black ink in 2 to 7 Japanese phonetic letters in the center of a 15.2 X 10.2 cm white card. The card was inserted in the dark window at the eye level of the S. When the E pressed a key, the window was illuminated by a rapid-start fluorescent lamp (4 W) and the word became visible. At the same time a counter was triggered. The viewing distance was about 30 cm and each letter was clearly seen. When the S responded, the fluorescent lamp was turned off and the RT was measured by the counter. Cards with 553 flower names and 179 mammal names, and two sets of N’ cards for the two categories were prepared in advance. Whenever the S retrieved a name, the E chose the corresponding card. From these cards, Y probes were chosen, and at the start of each recognition task the E had to quickly prepare Y, N and N’ cards as probes. Probes were not repeated in subsequent recognition tasks; thus RT was never measured twice for the same word. Furthermore, Y probes at time t were selected with an approximately equal probability from all parts of the retrieved sequence of length n(t). Two additional experiments were carried out: simple judgment on belongingness and sorting according to familiarity. In. the former, words were visually presented one at a time and the S pressed one key or the other one according to whether the stimulus word was an item of a specified category (Y) or not (N’); thus RTs were measured. The category was flower in one case and mammal in the other, The words consisted of 45 Y, 15 N’ in each case. There was no N stimulus word in this experiment. Of the 45 Y targets, 30 were very popular names and 15 were less popular ones. When the S did not know a presented name, the response was discarded. The same apparatus and the same stimulus cards as in experiment 1 were used. In the second experiment, a set of 55 flower names and a set of 43 mammal names were sorted by the S according to familiarity to the S. Each name was written on a card and the S made
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6 piles of cards ranging from 0 (have never heard of) to 5 (very familiar). The S was allowed to move cards freely from one pile to another until satisfied, and there was no time limit. There was one more additional experiment of which no report is made in this paper. All four experiments were run in a random order according to S. Which category, flower or mammal, came first within each experiment was also randomized. All the experiments were carried out individually. The Ss were 14 university students and their equivalents, 7 male and 7 female. In experiments in which RT was measured, half the Ss used their right index finger to press the Y key and their left index finger to press the key for N and N’; this was reversed for the other half of Ss. Some practice in pressing keys was given prior to the experiments. Results 1.1. In the retrieval experiment, the cumulative exhibited exactly the same pattern as described Togano 1970):
n(t) = n(m)( 1 - eeht),
totals n(t) as a function of time t, in the previous article (Indow and
(1)
which was originally suggested by Bousfield and Sedgewick (1944). The time consumed by the recognition tasks was not included in t. The data were analyzed individually and the results of a S are shown in fig. 1 as examples. Contrary to the previous article, points are equally spaced along the ordinate n(t), not along the abscissa t. It will be clear that the intervening recognition task did not ‘disturb the retrieving process.
Fig. 1. Two examples of retrieval sequence of a subject with insertions of recognition tasks.
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Table 1
SD. of Q
S.D. of0
Flower Y N N’
i(n) = 1009 - 3.3n t(n) = 683 + 2.6n iin) = 714 - 0.9n
440 232 152
7.6 10.8 2.3
Mammal Y N N’
i(n) = 935 - 2.8n i(n) = 705 + 5.ln t(n) = 748 - 0.3n
298 293 184
5.2 6.3 3.6
1.2. The value of h tends to be smaller in the present experiment. This is not surprising since A is related to the velocity by which n(t) increases. The S wrote each retrieved word on a card and had to hand it to the E in the present experiment, which is more time consuming than a verbal response in the previous study. 1.3 Mean RTs in recognition tasks during retrieval are shown in fig. 2 as a function of the number of retrieved names n at which the test was inserted. The number of Ss denoted by N(n) decreases as n becomes larger, because the retrieval was satiated for some Ss at a level lower than n. Fig. 2 only presents data where N(n) > 5. Error responses, e.g., pressing the Y key for an N probe word, were extremely rare and were not included in the calculation of RT at n, f(n). First, a linear equation, a!+ /3n, was fitted by the method of least squares to each type of response for each S, and then the same fit was made to mean RTs, T(n) over Ss, which are plotted in fig. 2. The results in msec for the group data and the standard deviations of the two constants over 14 individual fits are given in table 1. The means of individual constants are the same with those for mean RT. 1.4. The overall mean RTs, i(n), for the three kinds of responses (Y, N, and N’) exhibit approximately one and the same trend: the slope /3 is close to zero and the RTs are almost independent of n. However, several points should be noted. First, the mean RT for Y was a slightly decreasing function of n in both categories, which was unanimously observed with individual data also. Second, the mean RT for N was a slightly increasing function of n, in both cases. The trend was not completely unanimous. There were two Ss with whom more or less clear positive slopes for N were observed both in flower and mammal. Third, the slope fl for N’ was almost zero but negative in direction in both categories. 1.5. The results of the last recognition task immediately after the retrieval are as follows. Mean RTs in msec as a function of the total number of retrieved items, n(max), are fitted by CY+ /3n(max) in each case: Flower:
Y N’
t[n(max)] t[n(max)]
= =
Mammal:
Y N’
t[n(max)] t [n(max)]
= 1108 - 6.4n(max) = 859 - O.dn(max)
840 - O.gn(max) 814 + 0.4n(max)
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jY=OXlO
SW
1. 0
.E
1. 0
set
O
I-
8
X_---
r4
3 mammal
0 Q
0
X X
X _--x
X
number
for three decisions
P
_---
_---
_---
Y@
”
fi =-2.8
n : Fig. 2. Mean latencies
memory
_--NX
=5.1
of retrieved during
words
retrieval
with values of slope p and the number
of subjects N(n). As in 1.3, error responses were very rare and were excluded from the data. In this case, as in the experiment on belongingness, there was no probe words corresponding to N response, because unretrieved items may have been words that the S did not know. When plotted in one graph, points are widely scattered around the respective linear equations because of individual differences in overall level of RT. No curvilinear trend was observed, however. Furthermore, the values of constants are not very different from those for the recognitions during retrieval given in 1.3. 1.6. Fig. 3 shows the relation between the mean RT, i, for Y responses in the last recognition task immediately after the retrieval and k, the position that the probe word was retrieved in each individual sequence. The number of Ss over which qk) was defined, N(k), is also given. None of the following tendencies are observed
I 1
10
I
10
M
I
12.5
I
I
39
40
32
047
27
flower
-x 45
2.5
I 11
11 12 I
4 10 I
9
10
I 31
8
9 9 I 41
I
10
8
10
I
7
10
k : position of item in retrieved
1 21
5 11 I
sequence
61
I
I 51
5
3
7
6
7
5
I
6
4
I
I 71
2
1
5
1
81
I
2
I
I
91
2
3
29 I
24
18
22.5
I
19
24
16
32. 5
I
16
k 1 position
I
18
x---x
of
item
I
10
15 14
I
6
14
in retrieved
42.5
L
11
mammal
I
9
11
sequence
52.5
I
11
7
62.5
L
13
5
1
2
5
72.5
1
4
6
I
1
2
82. 5
I
1
1
1
1
1
Fig. 3. Mean latencies for Y responses in the recognition task immediately after retrieval with the number of cases I.
012
N(k:
x
N(k)
_
InamIna~
1 I
1 92.5
I
2
Fig. 4. Mean latencies for Y responses in belongingness judgments with the number of cases N(k) where k represents position at which stimulus word is retrieved.
.2
.4
F(k)
.6
sec.
,2
.4 -
x---x
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Table 2
Flower Mammal
Yl
Y2
N’
556 558
874 1004
821 770
in the case of mammal; items retrieved at the early stage of retrieval are elicit Y response or items retrieved at the last stage have recency effect the case of flower, though slight, the tendencies seem to be pointed whole, however, RT remains constant across retrieved position of word straight lines were fitted, the results in msec were as follows: t(k) = 822.7 - 0.97~ t(k) = 612.8 + 0.8k
quicker to on RT. In out. As a and, when
for flowers for mammals
1.7. Of the belongingness judgments, three overall mean RTs are given in table 2; for 30 very popular names (Yl) of the category, for 15 less popular names (Y2), and for 15 words irrelevant to the category (N’). Error responses were very infrequent and were excluded from the data, In both categories, RT increases in the order of Y 1. N’ and Y2. 1.8. In fig. 4, mean RT, t, for Y response in the belongingness judgments, is plotted against k, the position that the stimulus word was retrieved in each individual sequence, provided the stimulus word was reproduced by the S in the retrieval experiment. The number of Ss over which?(k) was defined,‘&‘(k), is also given. There was no appreciable relationship between retrieval position and RT, but the RTs were generally faster than in recognition tasks after the retrieval (fig. 3). 1.9. It will be of interest to compare overall mean RTs given in 1.7 with corresponding ones in recognition tests during the retrieval (1.3). In the latter, the results were as shown in table 3. In both categories, the overall mean RT for Y in recognition tasks was larger than that for Yl in belongingness judgments. In order to generate a response Y, it was necessary in the latter only to decide whether a given stimulus word belonged to the specified category whereas in the former, in addition to this decision, to determine whether or not a given probe was a name having already been retrieved. 1.10. In the experiment on familiarity, 55 flower names and 43 mammal names
Table 3
Flower Mammal
Y
N’
991 807
699 854
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__X_----xx\ /-
,x---
.--
XC-
1
8
.4
36
386
26
386
Exp. X---X
.6
6 14
flower
M
c
T(fl
6 20
I
U
mammal XI
---
N(f) 2
22
18
26
318
10
I
I
3 I
I
23 I
317 I
0
1
2
3
4
5
.2-X 0
f
1 degree
of
familiarity
Fig. 5. Mean latencies for Y responses in belongingness judgments and mean positions of stimulus words in retrieval sequences plotted against results of sorting, with the number of cases.
were sorted respectively into 6 classes as shown in fig. 5. The distribution was very skewed; most words were identified as most familiar (5) with few being categorized as unfamiliar (0 and 1). Fig. 5 shows the relations between familiarity grade f and results of the two other experiments. The lower plot shows the relation with the mean RT for Y responses in the belongingness judgments whereas the upper plot shows the relation with k, the mean position in individual retrieval sequences. The number of cases, N(fl, over which mean,:(j) or %(fl, was defined is also given. Generally, both i(f) and Em are almost independent of f. If the classes up to f = 4 are pooled, t in set is slightly smaller for the classf= 5 than the classesf= 0 to 4; 0.55 vs. 0.60 for flower and 0.54 vs. 0.56 for mammal_ On the other hand, ku> slightly increases from k(O) to k(4) and then k(4) > k(5) for mammal, whereas K(fl increases up to f= 5 for flower, though slightly. Con elusion
Decision time, RT, in recognition experiment as a function of list length n was found to behave differently according to whether the list is given by the E for memorizing or generated by the S in a retrieval process. In the previous experiment (Indow and Murase 1973), in which lists of n words (n = 6 to 26) were repeatedly presented to one perfect recitation, RT’s for Y and N responses increased with n with the same rate 0, which suggests that the recognition is based upon serial and exhaustive scanning through the list in memory. Though the result was of the same pattern with that of the recognition experiment by Sternberg in which lists of only
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up to 6 digits were used, the value of /3 was 4 to 10 times smaller than his. Burrows and Okada (1975) reported fl of the same small value with their long lists (n = 8 to 20). If the present recognition experiment with self-generated lists is considered as lying in the same spectrum with those with lists given by the experimenter, it would be said that j3 was even smaller. In other words, RT for N was not an increasing function of n, the length of self-generated list (1.3 and 1.6), and furthermore, 0 for Y was even negative for both categories; flower and mammal (1.3). With self-generated lists, the length n can be controlled by the E by terminating the retrieval process and inserting the recognition experiment. However, there may be some extraneous factors with these lists which are beyond control of the E. For example, Y probes at the recognition task at ni have to be words having been retrieved by the S in the sequence k f n,. Consequently, if there is a tendency that the S tends to retrieve familiar words more in the early phase of retrieval, then Y probes in recognition tasks inserted at early stages are apt to consist of more familiar words than in the recognition tasks at later stages. However, the findings described in 1.8 and 1.10 seem to exclude the possibility that the independence of RT on n is ascribed to some extraneous factors being confounded with the order in retrieval sequence. Familiar words in a given category are concerned, RT of Y response in the present recognition experiment was larger than RT of Y response in the simple belongingness judgment (1.9). Deciding whether a probe word is one having already been retrieved or not seems to need something more than recognizing the word as such. For making N’ response to an irrelevant probe word, it is not necessary for the S to scan in memory: RT for N’ was independent of n, both in the present recognition experiment ( 1.3, 1.5, and 1.9) and in the previous one. In both cases, it was of the same level with RT of no-reponse (N’) in the belongingness experiment (1.8 and 1.9). The result of experiment 1 casts doubts on ,whether decision of Y or N in the present recognition experiment is based upon scanning through the list in memory of retrieved words. It may well be possible that the decision is supported by an entirely different information processing. The problem will be discussed in the last section and two experiments will be reported in the subsequent sections in which an interval of time, from 4 hours to 28 days, was inserted between retrieval and recognition task. The problem was to determine whether the difference between self-generated lists and memorized lists persists over these intervals of time.
Experiment 2: recognition at 4 hours or 2 days after retrieval Method
Retrieval
(FL), Japanese
family
i, and Japanese
experiment was made with each of four categories;flowevs (FN), Japanese adjectives (AD) ending with the sound nouns (NO) to which the sound o or go can be added in the polite sion. Each retrieval process was terminated after either 4 or 8 min. task was given either at 4 hours or about 2 days after each retrieval. consisted of three sessions. In the first sessions, two retrievals were names
way of expresThe recognition The experiment conducted with
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two categories, one being terminated when t = 4 and the other when t = 8. In the second session taking place either 4 hours or 2 days later, the recognition tasks were made with the two categories and also two retrievals were conducted with the remaining categories, one until t = 4 and the other until t = 8. In the third session, which took place 4 hours later when the previous interval was 2 days or 2 days later when the previous interval was 4 hours, the recognition tasks were carried out with the latter two categories. The schedule was designed so that all the factors involved, as well as the temporal order of the two retrievals and the two recognition tasks in a session, were balanced over Ss. Combination of two categories in a session was also balanced. In order to satisfy the balanced design, 24 Ss were needed. They were university students and each made one retrieval and one recognition task with each of the four categories during three sessions. Between the first and second recognition tasks, the key for Y responses and the other key for N and N’ responses were reversed. In each recognition task, 3 or 4 Y words, 3 or 4 N words, and 6 N’ words were presented. The same set of words were used as 6 N’ targets for all Ss, and care was taken in selecting Y and N target words individually so that all had approximately equal popularity, at least to the impression of the E, and also so that Y words were distributed uniformly over the retrieved sequence. During the retrieval, the S wrote words on a sheet of paper in the order of their occurrence. Every 30 set, the S was asked to make a mark on the sheet, which made it possible to count the cumulative number n(t). To practice retrieval, the category “fish” was first given to all the Ss, and some practice was provided in the recognition task with categories different from the four used in the experiment. The same apparatus as in experiment 1 was used. Results 2.1. Two out of the four categories in this experiment, AD and NO, are rather artificial in that they are not ordinarily grouped into an organized unity. As discussed in another article (Indow 1980), time course curve of retrieval in these cases usually exhibits the same form as equation (1). As an example, averages over Ss for AD are shown in fig. 6. As a matter of course, n(8) is always larger than n(4) for the same category. 2.2. The results of the recognition task-- are summarized in fig. 7. For each category, only two points, (t(n), $4)) and (t(n), K(8)), are available where each term represents the mean over 12 5’s and 4 or 8 in the parenthesis represents the duration of retrieval in min. As is usually the case, Ss sometimes make one or two extraordinarily long RT’s. All RT’s longer than 1.5 set [ 1] were discarded in the present analysis. First, two points were directly connected to give the values of intercept and slope, (Y and p, for each category. Then, the means of these values across the four categories were defined to be CYand fl for the response. These values and straight lines (Y + fln are given in fig. 7 with the data points. The general pattern was
[l] This is above the level of 3 standard deviations higher than the mean, and this procedure was equivalent to disregarding “not confident” responses in experiment 3 (3.3).
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n(t)
40
memory
=6411-e
n(t) 30
AD
1 Japanese ending
X
up
to
4 min
@
Up to
8 min
adjectives with
A-= 10
0
1
2
3
4
12
each
5
t
i
6
7
8
min
Fig. 6. Two examples of mean retrieval sequences over subjects, one terminated at 4 min and the other at 8 min: an artificial category.
similar to that in experiment 1 described in 1.3 and 1.5. In short, no systematic tendency of RT for Y and N responses to increase with the length of self-generated list was observed. 2.3. The overall slope /.I was as follows. For N response, fl< 0 in both time intervals (-1.8 and -1.4 msec) in contrast to that fl> 0 in experiment 1 (2.6 and 5.1 msec). For Y response, 0 < 0 at 4 hour interval and 0 > 0 at 2 day interval (-2.3 and 1.3 msec), whereas, for N’ response, fl< 0 in both intervals (-2.4 and -1.3 msec). All were of the same order of magnitude in their absolute values, suggesting that these were random variations around zero. Conclusion
As there were only two points for each category in this experiment, the result was not stable if considered separately. However, the overall pattern of results across categories was unequivocal. In spite of the intervening time interval T up to 2 days between retrieval and recognition, RT does not increase with the length of self-generated list and the interval had no appreciable effect in changing the result to the ordinary pattern to be observed with lists given by the E for memorizing (2.2). If we go into comparison between categories, there was a noticeable phenomenon; the difference of behavior between natural categories and artificial categories when T = 2 days. In the upper plot of fig. 7, the sign of fl for N was different according to the type of category: fl> 0 for the two natural categories (circles and triangles) and /.I< 0 for the two artificial categories (two crosses). In the case of Y, the difference was not so systematic, but still 0 > 0 for the two artificial categories in contrast to
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2 DAYS
SS
+-*50-.X-.-.0
FLOWERS
d
FAMt
10
SEC
n ....... .............. .......~........ ................. . ..- - 1.4 (855)
. ......~...~x
:
-3
B
(a)
1974
.-._.
x
ADJECTIVES
+
NOUNS
_._._._..5_._,.3
ENDING
(678)
WITH’)’
‘; LY
NAMES
..
PREFIXED
WITH OR
‘ 0’ ’ GO’
-
2.3
( eao)
A
*--..*.*..-.-..~.~..................._*_.*_~* - 1.8 n (932)
2
3 “:
4
5
NUMBER
OF
6 RETRIEVED
7
8
9
WORDS
Fig. 7. Mean latencies for three responses in recognition after 4 hours and 2 days after retrieval of 4 or 8 min duration with values of slope p and of intercept (Y.
that fl< 0 for flower and/_3 + 0 for mammal. As it was not clear whether these results were meaningful or not, it was felt necessary to add another experiment and to see whether the results are consistent.
Experiment
3: recognition
at longer intervals after retireval
Method The general scheme of this experiment was the same as that for experiment 2, but retrieval was terminated after 2, 4, 7, or 11 min and the interval T between the retrieval and recognition ‘task was varied in four steps; 4 hours, 7, 14, and ,28 days.
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Each S was scheduled to participate in a half of 16 combinations of n(t) and 2”. As the same category could not be assigned to the same S more than once, the following 8 categories were used, 4 natural and 4 artificial: fZower (FL), cities in foreign countries (CI), sports (SP), musical instruments (MI), Japanese adjectives (AD) ending with the sound “i”, Japanese nouns (NE) having “mu” or “fu” in order to indicate negative, Japanese family names (FN) ending with “ta” or “da”, and Japanese verbs (VE) ending with the sound “ru”. The experiment consisted of five sessions. In the first session, retrievals of two categories were performed. In the second session, recognition tasks of these two categories and retrievals of two other categories were made. The situation was the same in the third and fourth sessions and, in the fifth session, recognition tasks of the last two categories were conducted. Each session lasted 10 to 30 min. Two retrievals in each session were always with one natural category and one artificially created category to minimize possible confusion between the two in memory. Intervals between sessions T and their order in experimentation were varied from S to S. In order to have a well balanced experiTable 4 Slopes p and intercepts 01in msec of fitted straight lines in experiment 3.
4 hours P FL
Cl
SP
MI
AD
NE
FN
VE
14 days
1 days (Y
P
cx
P
28 days 01
P
Q!
Y N N Y N N’ Y N N’ Y N N’
-6.3 5.6 4.2 -4.5 6.8 1.0 9.4 25.5 4.0 2.5 6.3 -12.1
1111 818 599 1042 125 675 753 432 713 831 837 1028
-6.9 -5.0 -0.5 -6.5 -11.9 3.8 -3.3 12.4 2.3 8.5 9.1 8.3
1138 1244 801 1319 1603 713 1059 906 730 773 854 543
-14.5 -5.1 0.3 -11.5 -0.9 -3.4 17.4 36.2 8.2 -22.3 -25.2 -4.5
1334 1323 768 1549 1283 959 486 122 597 1560 1899 907
9.1 26.3 5.0 8.2 1.9 8.5 3.1 74.7 10.2 16.8 61.6 10.8
778 446 694 1058 1335 671 827 -513 520 501 -466 565
Y N N’ Y N N’ Y N N’ Y N N’
-3.6 -5.3 -3.1 -3.8 4.9 -3.1 0 15.6 2.8 -5.4 8.8 -3.3
1050 1388 917 1118 1146 895 891 574 644 1258 890 916
-5.3 -3.2 -3.3 -1.5 -10.0 -6.7 -2.3 24.9 3.1 -4.7 0.8 -2.0
1141 1444 943 1232 1457 957 1098 905 764 1249 1140 841
-7.1 -4.7 -1.9 6.4 1.4 -1.7 -11.5 -8.2 -2.4 -3.4 -0.2 0.5
1440 1380 987 824 1151 822 1262 1227 762 1234 1277 874
-16.2 -6.5 0.1 13.1 15.6 5.3 -11.3 -12.5 -3.1 -23.4 -12.8 -3.8
1523 1409 829 850 1705 803 1360 1510 935 2028 1746 1069
T. Indow, H. Takada /Recognition
memory
221
mental design, 48 Ss were necessary. All were university students and participated in the five sessions to complete 8 combinations of n(t) and T with 8 categories. The procedures for retrieval and recognition tasks were the same as in experiment 2. The same care was taken in selecting Y or N probe words as stated in the preceeding section. The S was encouraged in the recognition task to report, after having responded to each probe word, whether the response was made with confidence or not. Results 3.1.
As there were four points (t(n), F(t)), instead of two in fig. 7, straight lines were fitted by the least square method to the respective three responses in each category. Since the results differed for each category, values of slope p and intercept LYare all given in table 4. Incorrect responses and those for which the S was “not confident” were not included in the data. Fig. 8 shows grand means over the 8 categories and straight lines fitted to these values. According to fig. 8, for all intervals T, t(n) for Y has a consistently negative slope whereast(n) for N is almost horizontal for T of 7 and 14 days and exhibits a positive slope for T of 4 hours and 28 days. However, the results in table 4 make it difficult to regard these results as general tendencies. Even after 28 days, no tendency was observed that t(n) has the same positive slope fl for both Y and N responses as is the case in ordinary recognition experiments. 3.2. Compared with Y and N responses, N’ responses were consistently faster and almost independent of n, which is common to all the results in experiments 1, 2 and in the previous study (Indow and Murase 1973). 3.3. Error response in the recognition task will be expected to have some relation with the time interval T between retrieval and recognition. As some systematic differences were observed between natural categories and artificial categories in this respect, means were taken separately for these two groups. As a function of T, the upper part of fig. 9 gives the error rates for miss (N to words in retrieved sequence) and for false recognition (Y to words not in retrieved sequence). The lower part represents, for each category group, two geometric means of ratios, RTs of error Y responses (false recognition) to RTs of correct Y responses and RTs of error N responses (miss) to RTs of correct N responses, by the same S in the same category. The results were based upon all responses without regard to S’s confidence. The miss rate was consistently about 0.1 for both types of categories, and the rate of false recognition increased as the interval T increased, more rapidly for the artificial categories. At 28 days, the rate exceeded 0.5 for the artificial categories and amounted to 0.4 for the natural categories. The ratio of RT did not so much depend upon 7’, and there was not a large difference between the two types of categories. The ratio for false recognition remained almost constant at unity. In other words, Y responses to probe words, no matter whether words were in retrieved sequences or not, were made throughout with about the same latency. The ratio for misses was far above unity suggesting that N responses were made with longer latency to probe words that had actually been in the retrieved sequence than to probe words that had not been retrieved. The S must have felt something
T. Indow, H. Takada /Recognition
222
AVERAGES 8
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7,14,
and 28 days after
when he eventually committed errors to miss. This phenomenon became slightly less marked as T got longer. It may also be pointed out that up to 7 days, the miss rate was smaller and the ratio of RT was larger for the natural categories than for the artificial categories but the relation was reversed for T > 14 days. 3.4. The overall mean RT of correct Y response is plotted in fig. 10 against the position k of probe words in individual retrieved sequences of t = 11 min, the
T. Indow, H. Takada /Recognition
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224
T. Indow, H. Takada / Recognitioiz memory
longest. For k > 35, the size of some blocks of k over which t(k) was defined was made larger than the regular size of 5 since the number of responses became smaller as some Ss ceased retrieving before t = 11 min. As was the case in 1.6, and in fig. 6 of the previous article (Indow and Murase 1973), there was no marked change of RT as a function of k. The grand mean of RT was shorter for 7’ = 4 hours than for the remaining three conditions, which is also observed in fig. 8. Conclusion Again, intervening intervals between retrieval and recognition, up to 28 days, had no systematic effect in changing RT’s to be increasing functions of the number of retrieved words. It is impressive to see that /3 for Y response was consistently negative in all the time interval T. The same tendency was obtained in experiments 1 and 2 with one exception (T = 2 days). The behavior of RT for N response in this experiment was puzzling: fl5 0 for T = 7 and 14 days as is the case in experiments 1 and 2, but 0 > 0 for the smallest and the largest of 7’. It will be easy to find a statistical test by which the null hypothesis fl= 0 is rejected in these cases. The problem is not whether the result is statistically significant compared with an appropriately defined amount of random errors but whether the result is consistent and hence meaningful. Throughout the three experiments, the following conclusion will be inevitable. The relation typical in the recognition decision with lists given by the E that
where 0 is a positive constant same for Y and N responses, does not hold in the present experiments for all the range of intervening time intervals between retrieval and recognition (T = 0 to 28 days).
Discussion It became clear from the pattern of t(n), RT as a function of the length of list, that the recognition decision in the present three experiments is different from the recognition decision in the previous study (Indow and Murase 1973). There are several similarities and differences between the two experimental paradigms. Features common to both cases are as follows: (a) Positive set in the sense of Sternberg (1969, 1975) consisted of meaningful words belonging to a category, natural or artificial. (b) The size of set was larger than in most recognition experiments. (c) What was dealt with was episodic memory (Tulving 1972) because judgment was made on whether a probe word happened to be there or not. (d) The recognition task was made by a fixed-set
T. Indow, H. Takada /Recognition
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225
procedure (Sternberg 1969, 1975) and several probe words were presented in succession to a fixed positive set. (e) Presentation probabilities of the three kinds of probe word (for Y, N, and N’ responses) were appropriately controlled. On the other hand, differences between the two are as follows: (f) In the previous case, a positive set was given by the experimenter and the subject memorized it to one perfect recitation. The recognition task was given immediately after memorization. (g) In the present case, a positive set was always generated by the subject as a retrieving process and the recognition task was given either immediately after the retrieval (experiment 1) or after an interval T of 4 hours to 28 days (experiments 2 and 3). In the previous study, if words are stored as a list in memory and scanned at the moment when a probe word is given, it would be in STM and the results are in accordance with what is expected from serial and exhaustive scanning. In the present experiments, if retrieved words are kept in memory as a list, it would be in STM when T = 0,but it cannot be in STM when T > 0.It may be in a part of LTM, the temporal storage which is different from that part of LTM where respective words are permanently kept as semantic memory. The latter was called as “archival memory” (Nickerson 1977) or “lexical memory” (Atkinson and Juola 1974). Atkinson and Juola named the temporal storage as “E/K store”. No matter where the memory of self-generated list is and no matter when the recognition task is given, the results of the present experiments made the hypothesis untenable that the recognition under discussion is based on serial and exhaustive scanning through the list in memory. Then, on what basis is the recognition made in the present case? When a probe word is given, the subject understands the word and, in addition, makes the recognition decision. Hence, the memory of that word in the permanent store of LTM must be reached anyway, and each word must have a list or network of attributes corresponding to its meaning. As assumed by Anderson and Bower in ordinary recognition (1972), suppose that once a word is retrieved, a tag indicating that fact is added to the list of attributes. Then, the recognition decision can be made according to whether or not the tag exists in the list of attributes and the scanning through the list of words in STM or E/K store is not necessary, even if the words are stored there as a list. The same mechanism may underlie the monitoring system of discriminating “new” words from “old” ones in retrieval from long-term memory
226
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(semantic) which was referred to in the beginning of the article. The situation may not be very different also in the previous case (Indow and Murase 1973). In this case, when a list of words is presented by the experimenter, the subject understands each word and memorizes the list. Suppose a tag indicating that the word is in the list (episodic) is created in the list of attributes, then the recognition can be made, not by scanning the list in STM, but by means of the tag, provided it is clear enough. When a list is self-generated through retrieval, the tag on each retrieved word is strong enough to make it almost unnecessary to scan the list in memory even if the list is in memory. Besides, the tag is persistent as mentioned in 3.3. For example, the miss rate did not increase over 28 days, and RT was longer for miss responses than for correct N responses, suggesting that the tag existed even when it was missed. When a list presented by the experimenter is memorized, the tag seems to be not so powerful and more fragile. In order to make the recognition decision with the list, whenever the tag is not clear enough, the subject has to rely upon the list in memory. The finding that /3, slope of t(n), was much smaller in the previous experiment (Indow and Murase 1973) than in the Sternberg’s case may be understood if scanning through STM occurred with a probability p and recognition through the tag in the list of attributes in LTM occurred in the rest of cases. The same idea was proposed by Atkinson and Juola (1974). The values of p in our case were about 8 msec and if0 for the scanning through STM is about 40 msec (Sternberg 1975: fig. 9), then p = 0.2 [21.It is of interest to reconsider from this point of view the forgetting or retention curve; a traditional study on human memory (Sternberg 1975). If lists of meaningful words are used rather than nonsense syllables and retention is tested by recognition, as in a study by Strong (1913), again what is dealt with is episodic memory and it is questionable whether forgetting is due to decay of the internal representation of the list in a part of LTM, “E/K store”, or due to fading of the tag in the list of attributes of each word in “archival memory” or “lexical memory”. In the discussion above, it was assumed that, whenever a word is [2] Of recognition decision, Y or N, in the present experiment, a possibility of accounting for p < 0 will be to assume that the S occasionally scan the complementary set in semantic memory; the set of words in a given category which have not yet been retrieved. According to whether the word is found therein or not, the response should be N or Y. The size of the set linearly decreases as the retrieval proceeds. The complementary set may exist for natural categories, but it is hard to imagine how it is formed for artificial categories.
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given, its list of attributes in LTM, its semantic memory, is directly accessed. To assume the direct access is analogous to assume “action at a distance” in physics. Both are processes mysterious to human mind. As effort of physicists has been devoted to convert it to “action in direct contact or through medium”, someday our effort must be focused upon how to understand the apparent direct access, how to reduce it to a result of scanning or resonnance, etc. There is another problem which has been left untouched; how the assumed tag in a list of attributes is detected. It may be by scanning through the list or by direct access. If the former is the case and the scanning is serial and exhaustive, then the detection time has to increase lineraly with the length of attribute list, ie., complexity of the word. In the aforementioned discussion, both processes were assumed to be completed instantaneously; the direct access and the detection of the tag. There will be no doubt that each process is extremely fast even if it takes time.
References Anderson, J.R. and G.H. Bower, 1972. Recognition and retrieval Review 79, 79-132. Atkinson, R.C. and J.F. Juola, 1974. ‘Search and decision processes In: D.H. Krantz, R.D. Lute, R.C. Atkinson and P. Suppes (eds.), ments in mathematical psychology I. San Francisco: W.H. Freeman. Boustield, W.A. and H.W. Sedgewick, 1944. An analysis of sequences
processes.
Psychological
in recognition Contemporary pp. 243-293. of restricted
memory’. developassociative
responses. Journal of General Psychology 30,149-165. Burrows, D. and R. Okada, 1975. Memory retrieval from long and short lists. Science 188, 1031-1033. Indow, T., 1980. ‘Some characteristics of word sequence retrieved from a given category’. In: R.S. Nickerson (ed.), Attention and performance VIII. Hillsdale, NJ: Lawrence Erlbaum Associates Inc. pp. 621-636. Indow, T. and A. Murase, 1973. Experiments on memory and visual scannings. Japanese Psychological Research 15, 136-146. Indow, T. and K. Togano, 1970. On retrieving sequence from long-term memory. Psychological Review 77,317-331. Juola, J.F., G.A. Taylor and M.E. Young, 1974. Stimulus encoding and decision processes in recognition memory. Journal of Experimental Psychology 102, 1108-1115. Nickerson, R.D., 1977. ‘Some comments on human archival memory as a large data base’. In: Proceedings, very large data bases, Third International Conference on Very Large Data Bases. Tokyo, Japan. pp. 159-168. Sternberg, S., 1966. High-speed scanning in human memory. Science 153,652-654. Sternberg, S., 1969. Memory scanning: mental processes revealed by reaction-time experiments. American Scientist 57,421-457. Stemberg, S., 1975. Memory scannings: new findings and current controversies. Quarterly Jour-
228
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memory
nal of Experimental Psychology 27, l-32. Strong, E.K., Jr., 1913. The effect of time-interval upon recognition memory. Psychological Review 20,339-372. (eds.), Tulving, E., 1972. ‘Episodic and semantic memory’. In: E. Tulving and W. Donaldson Organization of memory. New York: Academic Press. pp. 381-403.
47 (1981) 207-228 Publishing Company
RECOGNITION OF WORDS *
MEMORY OF RETRIEVED
SEQUENCES
Tarow INDOW and Hiroko TAKADA University of California, Irvine, U.S.A. and Keio University, Tokyo, Japan
Accepted
August
1980
The subject was asked to retrieve words belonging to a given category, natural or artificially created. After n words were retrieved, a recognition task was given either immediately after or after a delay (4 hours, 7, 14, or 28 days). Several probe words were presented and the subject had to decide whether each had been retrieved or not. The length of retrieval sequence, n, was systematically varied. Results of three experiments showed that, in general, mean decision time was almost independent of n. Namely, recognition regarding self-generated lists of words seems to be due to a different information processing than recognition regarding lists of words presented by the experimenter to memorize. Implications of the findings for retrieval from long term memory were discussed.
The present experiments stemmed from two previous studies; one concerned retrieval from long-term memory (Indow and Togano 1970) and the other concerned scanning in short-term memory (Indow and Murase 1973). In the former study, as in the original experiment by Bousfield and Sedgewick (1944), the subject was required to retrieve all words from a given category, e.g., flower. While retrieving, the subject never reproduces words which do not belong to the category, and hence the search in long term memory (LTM) must have an efficient monitor system to exclude irrelevant items. Furthermore, the subject rarely reproduces the same word more than once, which implies two possibilities. * All the experiments were carried out at the Department of Psychology, Keio University. The study was partially supported by a grant (3362) from the Electrical Communication Laboratories, NTT in Japan. Experiments 2 and 3 were conducted by A. Sakamaki in 1974 and by N. Wakita in 1976 respectively. The authors are grateful to these collaborators and all the subjects who participated. Requests for reprints should be made to T. Indow, School of Social Sciences, University of California, Irvine, CA 92717, U.S.A.
207
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memory
Either that once retrieved words are automatically excluded as targets from the subsequent search or that some kind of monitoring process is in operation during the retrieval. The task of the monitor is to check, whenever a word is picked up by the search, whether it has already been reproduced (old) or not (new) (Indow 1980). In the latter study, the subject memorized a long list of words all belonging to the same category to the first perfect recitation and then probe words were given one by one. The subject was required to judge whether each probe word was in the list or not. The number of words in a list, 12, varied from 6 to 26. As discovered by Sternberg (1966, 1969) with short lists within the immediate memory span, the response time (RT) as a function of y1 suggested that the memory scanning under discussion was serial rather than parallel and exhaustive rather than self-terminating. If the monitor system is in operation during the retrieval in the first study on LTM, a possible way of the continuous recognition (Juola et al. 1974) in determining each word is old or new would be to scan through the list of already retrieved words in memory. This monitoring method can not be said efficient and probably seems not very plausible. If this is the case, however, the situation is similar to that of the second study on recognition memory except that the list to be scanned is generated by the subject in the retrieval rather than given by the experimenter to memorize. Three experiments were conducted to test whether the monitoring during retrieval is made in this way or not. In the first experiment, the monitoring was deliberately called for during a retrieval sequence. On the basis of the results of this experiment, two more studies were added in which recognition experiments of self-generated lists were carried out at various time intervals after retrievals.
Experiment
1: recognition
during and immediately
after retrieval
Method The S was asked to retrieve items in a specified category, e.g., flower, in the order of their occurrence. The S wrote each retrieved name on a card and handed the cards to the experimenter (I?), one by one. As soon as the cumulative number of retrieved items, n(t), reached the first predetermined integer nr at time t, the retrieving process was halted and the time t was recorded. Then, a recognition task was inserted in the following way. Several probe words were visually presented, one at a time. Each probe word was to elicit a response, either Y or N or N’, if correctly responded.
T. Indow, H. Takada /Recognition
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Y: a word which had already been retrieved. N: a word in the given category which had not yet been retrieved. N’: an irrelevant word which seems to be entirely irrelevant to the given category (e.g., “fish” to the category flower). The S was instructed to press one key for Y and the other key for N and N’. To the S, there was no distinction between N and N’. When 5 to 7 probe words had been responded to, then the retrieving task was resumed and continued until n(t) reached the next predetermined integer na. Then, the second recognition task was inserted in the way as stated above. The experiment was continued in this way until it became almost impossible for the S to retrieve new word. Hence the total number of words retrieved, n(max), as well as the number of the recognition tasks inserted, differed among Ss. The values of ni were about 10, 20, . . . . The probes consisted of 3 Y, 1 or 2 N, and 1 or 2 N’ words on each recognition task. When a probe word to elicit response was unfamiliar, the S was asked to report it and the response was discarded. The S was allowed, if he or she liked, to include names which had been presented as N probes in subsequent retrievals. Immediately after the whole retrieving process was terminated, the last recognition task was given in which 20 Y, 10 N, and 10 N’ probes were used. The experiment was made with two categories, flower and mammal, with each S. Each probe word was written by black ink in 2 to 7 Japanese phonetic letters in the center of a 15.2 X 10.2 cm white card. The card was inserted in the dark window at the eye level of the S. When the E pressed a key, the window was illuminated by a rapid-start fluorescent lamp (4 W) and the word became visible. At the same time a counter was triggered. The viewing distance was about 30 cm and each letter was clearly seen. When the S responded, the fluorescent lamp was turned off and the RT was measured by the counter. Cards with 553 flower names and 179 mammal names, and two sets of N’ cards for the two categories were prepared in advance. Whenever the S retrieved a name, the E chose the corresponding card. From these cards, Y probes were chosen, and at the start of each recognition task the E had to quickly prepare Y, N and N’ cards as probes. Probes were not repeated in subsequent recognition tasks; thus RT was never measured twice for the same word. Furthermore, Y probes at time t were selected with an approximately equal probability from all parts of the retrieved sequence of length n(t). Two additional experiments were carried out: simple judgment on belongingness and sorting according to familiarity. In. the former, words were visually presented one at a time and the S pressed one key or the other one according to whether the stimulus word was an item of a specified category (Y) or not (N’); thus RTs were measured. The category was flower in one case and mammal in the other, The words consisted of 45 Y, 15 N’ in each case. There was no N stimulus word in this experiment. Of the 45 Y targets, 30 were very popular names and 15 were less popular ones. When the S did not know a presented name, the response was discarded. The same apparatus and the same stimulus cards as in experiment 1 were used. In the second experiment, a set of 55 flower names and a set of 43 mammal names were sorted by the S according to familiarity to the S. Each name was written on a card and the S made
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6 piles of cards ranging from 0 (have never heard of) to 5 (very familiar). The S was allowed to move cards freely from one pile to another until satisfied, and there was no time limit. There was one more additional experiment of which no report is made in this paper. All four experiments were run in a random order according to S. Which category, flower or mammal, came first within each experiment was also randomized. All the experiments were carried out individually. The Ss were 14 university students and their equivalents, 7 male and 7 female. In experiments in which RT was measured, half the Ss used their right index finger to press the Y key and their left index finger to press the key for N and N’; this was reversed for the other half of Ss. Some practice in pressing keys was given prior to the experiments. Results 1.1. In the retrieval experiment, the cumulative exhibited exactly the same pattern as described Togano 1970):
n(t) = n(m)( 1 - eeht),
totals n(t) as a function of time t, in the previous article (Indow and
(1)
which was originally suggested by Bousfield and Sedgewick (1944). The time consumed by the recognition tasks was not included in t. The data were analyzed individually and the results of a S are shown in fig. 1 as examples. Contrary to the previous article, points are equally spaced along the ordinate n(t), not along the abscissa t. It will be clear that the intervening recognition task did not ‘disturb the retrieving process.
Fig. 1. Two examples of retrieval sequence of a subject with insertions of recognition tasks.
T. Indow, H. Takada /Recognition
211
memory
Table 1
SD. of Q
S.D. of0
Flower Y N N’
i(n) = 1009 - 3.3n t(n) = 683 + 2.6n iin) = 714 - 0.9n
440 232 152
7.6 10.8 2.3
Mammal Y N N’
i(n) = 935 - 2.8n i(n) = 705 + 5.ln t(n) = 748 - 0.3n
298 293 184
5.2 6.3 3.6
1.2. The value of h tends to be smaller in the present experiment. This is not surprising since A is related to the velocity by which n(t) increases. The S wrote each retrieved word on a card and had to hand it to the E in the present experiment, which is more time consuming than a verbal response in the previous study. 1.3 Mean RTs in recognition tasks during retrieval are shown in fig. 2 as a function of the number of retrieved names n at which the test was inserted. The number of Ss denoted by N(n) decreases as n becomes larger, because the retrieval was satiated for some Ss at a level lower than n. Fig. 2 only presents data where N(n) > 5. Error responses, e.g., pressing the Y key for an N probe word, were extremely rare and were not included in the calculation of RT at n, f(n). First, a linear equation, a!+ /3n, was fitted by the method of least squares to each type of response for each S, and then the same fit was made to mean RTs, T(n) over Ss, which are plotted in fig. 2. The results in msec for the group data and the standard deviations of the two constants over 14 individual fits are given in table 1. The means of individual constants are the same with those for mean RT. 1.4. The overall mean RTs, i(n), for the three kinds of responses (Y, N, and N’) exhibit approximately one and the same trend: the slope /3 is close to zero and the RTs are almost independent of n. However, several points should be noted. First, the mean RT for Y was a slightly decreasing function of n in both categories, which was unanimously observed with individual data also. Second, the mean RT for N was a slightly increasing function of n, in both cases. The trend was not completely unanimous. There were two Ss with whom more or less clear positive slopes for N were observed both in flower and mammal. Third, the slope fl for N’ was almost zero but negative in direction in both categories. 1.5. The results of the last recognition task immediately after the retrieval are as follows. Mean RTs in msec as a function of the total number of retrieved items, n(max), are fitted by CY+ /3n(max) in each case: Flower:
Y N’
t[n(max)] t[n(max)]
= =
Mammal:
Y N’
t[n(max)] t [n(max)]
= 1108 - 6.4n(max) = 859 - O.dn(max)
840 - O.gn(max) 814 + 0.4n(max)
T. Indow, H. Takada /Recognition
212
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of subjects N(n). As in 1.3, error responses were very rare and were excluded from the data. In this case, as in the experiment on belongingness, there was no probe words corresponding to N response, because unretrieved items may have been words that the S did not know. When plotted in one graph, points are widely scattered around the respective linear equations because of individual differences in overall level of RT. No curvilinear trend was observed, however. Furthermore, the values of constants are not very different from those for the recognitions during retrieval given in 1.3. 1.6. Fig. 3 shows the relation between the mean RT, i, for Y responses in the last recognition task immediately after the retrieval and k, the position that the probe word was retrieved in each individual sequence. The number of Ss over which qk) was defined, N(k), is also given. None of the following tendencies are observed
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4 10 I
9
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1 21
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sequence
61
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in retrieved
42.5
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mammal
I
9
11
sequence
52.5
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7
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13
5
1
2
5
72.5
1
4
6
I
1
2
82. 5
I
1
1
1
1
1
Fig. 3. Mean latencies for Y responses in the recognition task immediately after retrieval with the number of cases I.
012
N(k:
x
N(k)
_
InamIna~
1 I
1 92.5
I
2
Fig. 4. Mean latencies for Y responses in belongingness judgments with the number of cases N(k) where k represents position at which stimulus word is retrieved.
.2
.4
F(k)
.6
sec.
,2
.4 -
x---x
T. Indow, H. Takada /Recognition
214
memory
Table 2
Flower Mammal
Yl
Y2
N’
556 558
874 1004
821 770
in the case of mammal; items retrieved at the early stage of retrieval are elicit Y response or items retrieved at the last stage have recency effect the case of flower, though slight, the tendencies seem to be pointed whole, however, RT remains constant across retrieved position of word straight lines were fitted, the results in msec were as follows: t(k) = 822.7 - 0.97~ t(k) = 612.8 + 0.8k
quicker to on RT. In out. As a and, when
for flowers for mammals
1.7. Of the belongingness judgments, three overall mean RTs are given in table 2; for 30 very popular names (Yl) of the category, for 15 less popular names (Y2), and for 15 words irrelevant to the category (N’). Error responses were very infrequent and were excluded from the data, In both categories, RT increases in the order of Y 1. N’ and Y2. 1.8. In fig. 4, mean RT, t, for Y response in the belongingness judgments, is plotted against k, the position that the stimulus word was retrieved in each individual sequence, provided the stimulus word was reproduced by the S in the retrieval experiment. The number of Ss over which?(k) was defined,‘&‘(k), is also given. There was no appreciable relationship between retrieval position and RT, but the RTs were generally faster than in recognition tasks after the retrieval (fig. 3). 1.9. It will be of interest to compare overall mean RTs given in 1.7 with corresponding ones in recognition tests during the retrieval (1.3). In the latter, the results were as shown in table 3. In both categories, the overall mean RT for Y in recognition tasks was larger than that for Yl in belongingness judgments. In order to generate a response Y, it was necessary in the latter only to decide whether a given stimulus word belonged to the specified category whereas in the former, in addition to this decision, to determine whether or not a given probe was a name having already been retrieved. 1.10. In the experiment on familiarity, 55 flower names and 43 mammal names
Table 3
Flower Mammal
Y
N’
991 807
699 854
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memory
__X_----xx\ /-
,x---
.--
XC-
1
8
.4
36
386
26
386
Exp. X---X
.6
6 14
flower
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mammal XI
---
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22
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318
10
I
I
3 I
I
23 I
317 I
0
1
2
3
4
5
.2-X 0
f
1 degree
of
familiarity
Fig. 5. Mean latencies for Y responses in belongingness judgments and mean positions of stimulus words in retrieval sequences plotted against results of sorting, with the number of cases.
were sorted respectively into 6 classes as shown in fig. 5. The distribution was very skewed; most words were identified as most familiar (5) with few being categorized as unfamiliar (0 and 1). Fig. 5 shows the relations between familiarity grade f and results of the two other experiments. The lower plot shows the relation with the mean RT for Y responses in the belongingness judgments whereas the upper plot shows the relation with k, the mean position in individual retrieval sequences. The number of cases, N(fl, over which mean,:(j) or %(fl, was defined is also given. Generally, both i(f) and Em are almost independent of f. If the classes up to f = 4 are pooled, t in set is slightly smaller for the classf= 5 than the classesf= 0 to 4; 0.55 vs. 0.60 for flower and 0.54 vs. 0.56 for mammal_ On the other hand, ku> slightly increases from k(O) to k(4) and then k(4) > k(5) for mammal, whereas K(fl increases up to f= 5 for flower, though slightly. Con elusion
Decision time, RT, in recognition experiment as a function of list length n was found to behave differently according to whether the list is given by the E for memorizing or generated by the S in a retrieval process. In the previous experiment (Indow and Murase 1973), in which lists of n words (n = 6 to 26) were repeatedly presented to one perfect recitation, RT’s for Y and N responses increased with n with the same rate 0, which suggests that the recognition is based upon serial and exhaustive scanning through the list in memory. Though the result was of the same pattern with that of the recognition experiment by Sternberg in which lists of only
216
T. Indow, H. Takada /Recognition
memory
up to 6 digits were used, the value of /3 was 4 to 10 times smaller than his. Burrows and Okada (1975) reported fl of the same small value with their long lists (n = 8 to 20). If the present recognition experiment with self-generated lists is considered as lying in the same spectrum with those with lists given by the experimenter, it would be said that j3 was even smaller. In other words, RT for N was not an increasing function of n, the length of self-generated list (1.3 and 1.6), and furthermore, 0 for Y was even negative for both categories; flower and mammal (1.3). With self-generated lists, the length n can be controlled by the E by terminating the retrieval process and inserting the recognition experiment. However, there may be some extraneous factors with these lists which are beyond control of the E. For example, Y probes at the recognition task at ni have to be words having been retrieved by the S in the sequence k f n,. Consequently, if there is a tendency that the S tends to retrieve familiar words more in the early phase of retrieval, then Y probes in recognition tasks inserted at early stages are apt to consist of more familiar words than in the recognition tasks at later stages. However, the findings described in 1.8 and 1.10 seem to exclude the possibility that the independence of RT on n is ascribed to some extraneous factors being confounded with the order in retrieval sequence. Familiar words in a given category are concerned, RT of Y response in the present recognition experiment was larger than RT of Y response in the simple belongingness judgment (1.9). Deciding whether a probe word is one having already been retrieved or not seems to need something more than recognizing the word as such. For making N’ response to an irrelevant probe word, it is not necessary for the S to scan in memory: RT for N’ was independent of n, both in the present recognition experiment ( 1.3, 1.5, and 1.9) and in the previous one. In both cases, it was of the same level with RT of no-reponse (N’) in the belongingness experiment (1.8 and 1.9). The result of experiment 1 casts doubts on ,whether decision of Y or N in the present recognition experiment is based upon scanning through the list in memory of retrieved words. It may well be possible that the decision is supported by an entirely different information processing. The problem will be discussed in the last section and two experiments will be reported in the subsequent sections in which an interval of time, from 4 hours to 28 days, was inserted between retrieval and recognition task. The problem was to determine whether the difference between self-generated lists and memorized lists persists over these intervals of time.
Experiment 2: recognition at 4 hours or 2 days after retrieval Method
Retrieval
(FL), Japanese
family
i, and Japanese
experiment was made with each of four categories;flowevs (FN), Japanese adjectives (AD) ending with the sound nouns (NO) to which the sound o or go can be added in the polite sion. Each retrieval process was terminated after either 4 or 8 min. task was given either at 4 hours or about 2 days after each retrieval. consisted of three sessions. In the first sessions, two retrievals were names
way of expresThe recognition The experiment conducted with
T. Indow, H. Takada /Recognition
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211
two categories, one being terminated when t = 4 and the other when t = 8. In the second session taking place either 4 hours or 2 days later, the recognition tasks were made with the two categories and also two retrievals were conducted with the remaining categories, one until t = 4 and the other until t = 8. In the third session, which took place 4 hours later when the previous interval was 2 days or 2 days later when the previous interval was 4 hours, the recognition tasks were carried out with the latter two categories. The schedule was designed so that all the factors involved, as well as the temporal order of the two retrievals and the two recognition tasks in a session, were balanced over Ss. Combination of two categories in a session was also balanced. In order to satisfy the balanced design, 24 Ss were needed. They were university students and each made one retrieval and one recognition task with each of the four categories during three sessions. Between the first and second recognition tasks, the key for Y responses and the other key for N and N’ responses were reversed. In each recognition task, 3 or 4 Y words, 3 or 4 N words, and 6 N’ words were presented. The same set of words were used as 6 N’ targets for all Ss, and care was taken in selecting Y and N target words individually so that all had approximately equal popularity, at least to the impression of the E, and also so that Y words were distributed uniformly over the retrieved sequence. During the retrieval, the S wrote words on a sheet of paper in the order of their occurrence. Every 30 set, the S was asked to make a mark on the sheet, which made it possible to count the cumulative number n(t). To practice retrieval, the category “fish” was first given to all the Ss, and some practice was provided in the recognition task with categories different from the four used in the experiment. The same apparatus as in experiment 1 was used. Results 2.1. Two out of the four categories in this experiment, AD and NO, are rather artificial in that they are not ordinarily grouped into an organized unity. As discussed in another article (Indow 1980), time course curve of retrieval in these cases usually exhibits the same form as equation (1). As an example, averages over Ss for AD are shown in fig. 6. As a matter of course, n(8) is always larger than n(4) for the same category. 2.2. The results of the recognition task-- are summarized in fig. 7. For each category, only two points, (t(n), $4)) and (t(n), K(8)), are available where each term represents the mean over 12 5’s and 4 or 8 in the parenthesis represents the duration of retrieval in min. As is usually the case, Ss sometimes make one or two extraordinarily long RT’s. All RT’s longer than 1.5 set [ 1] were discarded in the present analysis. First, two points were directly connected to give the values of intercept and slope, (Y and p, for each category. Then, the means of these values across the four categories were defined to be CYand fl for the response. These values and straight lines (Y + fln are given in fig. 7 with the data points. The general pattern was
[l] This is above the level of 3 standard deviations higher than the mean, and this procedure was equivalent to disregarding “not confident” responses in experiment 3 (3.3).
T. Indow, H. Takada /Recognition
218
n(t)
40
memory
=6411-e
n(t) 30
AD
1 Japanese ending
X
up
to
4 min
@
Up to
8 min
adjectives with
A-= 10
0
1
2
3
4
12
each
5
t
i
6
7
8
min
Fig. 6. Two examples of mean retrieval sequences over subjects, one terminated at 4 min and the other at 8 min: an artificial category.
similar to that in experiment 1 described in 1.3 and 1.5. In short, no systematic tendency of RT for Y and N responses to increase with the length of self-generated list was observed. 2.3. The overall slope /.I was as follows. For N response, fl< 0 in both time intervals (-1.8 and -1.4 msec) in contrast to that fl> 0 in experiment 1 (2.6 and 5.1 msec). For Y response, 0 < 0 at 4 hour interval and 0 > 0 at 2 day interval (-2.3 and 1.3 msec), whereas, for N’ response, fl< 0 in both intervals (-2.4 and -1.3 msec). All were of the same order of magnitude in their absolute values, suggesting that these were random variations around zero. Conclusion
As there were only two points for each category in this experiment, the result was not stable if considered separately. However, the overall pattern of results across categories was unequivocal. In spite of the intervening time interval T up to 2 days between retrieval and recognition, RT does not increase with the length of self-generated list and the interval had no appreciable effect in changing the result to the ordinary pattern to be observed with lists given by the E for memorizing (2.2). If we go into comparison between categories, there was a noticeable phenomenon; the difference of behavior between natural categories and artificial categories when T = 2 days. In the upper plot of fig. 7, the sign of fl for N was different according to the type of category: fl> 0 for the two natural categories (circles and triangles) and /.I< 0 for the two artificial categories (two crosses). In the case of Y, the difference was not so systematic, but still 0 > 0 for the two artificial categories in contrast to
219
T. Indow, H. Takada /Recognition memory 24
2 DAYS
SS
+-*50-.X-.-.0
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d
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SEC
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Fig. 7. Mean latencies for three responses in recognition after 4 hours and 2 days after retrieval of 4 or 8 min duration with values of slope p and of intercept (Y.
that fl< 0 for flower and/_3 + 0 for mammal. As it was not clear whether these results were meaningful or not, it was felt necessary to add another experiment and to see whether the results are consistent.
Experiment
3: recognition
at longer intervals after retireval
Method The general scheme of this experiment was the same as that for experiment 2, but retrieval was terminated after 2, 4, 7, or 11 min and the interval T between the retrieval and recognition ‘task was varied in four steps; 4 hours, 7, 14, and ,28 days.
T. Indow, H. Takada /Recognition
220
memory
Each S was scheduled to participate in a half of 16 combinations of n(t) and 2”. As the same category could not be assigned to the same S more than once, the following 8 categories were used, 4 natural and 4 artificial: fZower (FL), cities in foreign countries (CI), sports (SP), musical instruments (MI), Japanese adjectives (AD) ending with the sound “i”, Japanese nouns (NE) having “mu” or “fu” in order to indicate negative, Japanese family names (FN) ending with “ta” or “da”, and Japanese verbs (VE) ending with the sound “ru”. The experiment consisted of five sessions. In the first session, retrievals of two categories were performed. In the second session, recognition tasks of these two categories and retrievals of two other categories were made. The situation was the same in the third and fourth sessions and, in the fifth session, recognition tasks of the last two categories were conducted. Each session lasted 10 to 30 min. Two retrievals in each session were always with one natural category and one artificially created category to minimize possible confusion between the two in memory. Intervals between sessions T and their order in experimentation were varied from S to S. In order to have a well balanced experiTable 4 Slopes p and intercepts 01in msec of fitted straight lines in experiment 3.
4 hours P FL
Cl
SP
MI
AD
NE
FN
VE
14 days
1 days (Y
P
cx
P
28 days 01
P
Q!
Y N N Y N N’ Y N N’ Y N N’
-6.3 5.6 4.2 -4.5 6.8 1.0 9.4 25.5 4.0 2.5 6.3 -12.1
1111 818 599 1042 125 675 753 432 713 831 837 1028
-6.9 -5.0 -0.5 -6.5 -11.9 3.8 -3.3 12.4 2.3 8.5 9.1 8.3
1138 1244 801 1319 1603 713 1059 906 730 773 854 543
-14.5 -5.1 0.3 -11.5 -0.9 -3.4 17.4 36.2 8.2 -22.3 -25.2 -4.5
1334 1323 768 1549 1283 959 486 122 597 1560 1899 907
9.1 26.3 5.0 8.2 1.9 8.5 3.1 74.7 10.2 16.8 61.6 10.8
778 446 694 1058 1335 671 827 -513 520 501 -466 565
Y N N’ Y N N’ Y N N’ Y N N’
-3.6 -5.3 -3.1 -3.8 4.9 -3.1 0 15.6 2.8 -5.4 8.8 -3.3
1050 1388 917 1118 1146 895 891 574 644 1258 890 916
-5.3 -3.2 -3.3 -1.5 -10.0 -6.7 -2.3 24.9 3.1 -4.7 0.8 -2.0
1141 1444 943 1232 1457 957 1098 905 764 1249 1140 841
-7.1 -4.7 -1.9 6.4 1.4 -1.7 -11.5 -8.2 -2.4 -3.4 -0.2 0.5
1440 1380 987 824 1151 822 1262 1227 762 1234 1277 874
-16.2 -6.5 0.1 13.1 15.6 5.3 -11.3 -12.5 -3.1 -23.4 -12.8 -3.8
1523 1409 829 850 1705 803 1360 1510 935 2028 1746 1069
T. Indow, H. Takada /Recognition
memory
221
mental design, 48 Ss were necessary. All were university students and participated in the five sessions to complete 8 combinations of n(t) and T with 8 categories. The procedures for retrieval and recognition tasks were the same as in experiment 2. The same care was taken in selecting Y or N probe words as stated in the preceeding section. The S was encouraged in the recognition task to report, after having responded to each probe word, whether the response was made with confidence or not. Results 3.1.
As there were four points (t(n), F(t)), instead of two in fig. 7, straight lines were fitted by the least square method to the respective three responses in each category. Since the results differed for each category, values of slope p and intercept LYare all given in table 4. Incorrect responses and those for which the S was “not confident” were not included in the data. Fig. 8 shows grand means over the 8 categories and straight lines fitted to these values. According to fig. 8, for all intervals T, t(n) for Y has a consistently negative slope whereast(n) for N is almost horizontal for T of 7 and 14 days and exhibits a positive slope for T of 4 hours and 28 days. However, the results in table 4 make it difficult to regard these results as general tendencies. Even after 28 days, no tendency was observed that t(n) has the same positive slope fl for both Y and N responses as is the case in ordinary recognition experiments. 3.2. Compared with Y and N responses, N’ responses were consistently faster and almost independent of n, which is common to all the results in experiments 1, 2 and in the previous study (Indow and Murase 1973). 3.3. Error response in the recognition task will be expected to have some relation with the time interval T between retrieval and recognition. As some systematic differences were observed between natural categories and artificial categories in this respect, means were taken separately for these two groups. As a function of T, the upper part of fig. 9 gives the error rates for miss (N to words in retrieved sequence) and for false recognition (Y to words not in retrieved sequence). The lower part represents, for each category group, two geometric means of ratios, RTs of error Y responses (false recognition) to RTs of correct Y responses and RTs of error N responses (miss) to RTs of correct N responses, by the same S in the same category. The results were based upon all responses without regard to S’s confidence. The miss rate was consistently about 0.1 for both types of categories, and the rate of false recognition increased as the interval T increased, more rapidly for the artificial categories. At 28 days, the rate exceeded 0.5 for the artificial categories and amounted to 0.4 for the natural categories. The ratio of RT did not so much depend upon 7’, and there was not a large difference between the two types of categories. The ratio for false recognition remained almost constant at unity. In other words, Y responses to probe words, no matter whether words were in retrieved sequences or not, were made throughout with about the same latency. The ratio for misses was far above unity suggesting that N responses were made with longer latency to probe words that had actually been in the retrieved sequence than to probe words that had not been retrieved. The S must have felt something
T. Indow, H. Takada /Recognition
222
AVERAGES 8
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Fig. 8. Mean latencies for three responses in recognition after 4 hours, retrievals of four durations with values of slope @and of intercept CL
7,14,
and 28 days after
when he eventually committed errors to miss. This phenomenon became slightly less marked as T got longer. It may also be pointed out that up to 7 days, the miss rate was smaller and the ratio of RT was larger for the natural categories than for the artificial categories but the relation was reversed for T > 14 days. 3.4. The overall mean RT of correct Y response is plotted in fig. 10 against the position k of probe words in individual retrieved sequences of t = 11 min, the
T. Indow, H. Takada /Recognition
FALSE
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224
T. Indow, H. Takada / Recognitioiz memory
longest. For k > 35, the size of some blocks of k over which t(k) was defined was made larger than the regular size of 5 since the number of responses became smaller as some Ss ceased retrieving before t = 11 min. As was the case in 1.6, and in fig. 6 of the previous article (Indow and Murase 1973), there was no marked change of RT as a function of k. The grand mean of RT was shorter for 7’ = 4 hours than for the remaining three conditions, which is also observed in fig. 8. Conclusion Again, intervening intervals between retrieval and recognition, up to 28 days, had no systematic effect in changing RT’s to be increasing functions of the number of retrieved words. It is impressive to see that /3 for Y response was consistently negative in all the time interval T. The same tendency was obtained in experiments 1 and 2 with one exception (T = 2 days). The behavior of RT for N response in this experiment was puzzling: fl5 0 for T = 7 and 14 days as is the case in experiments 1 and 2, but 0 > 0 for the smallest and the largest of 7’. It will be easy to find a statistical test by which the null hypothesis fl= 0 is rejected in these cases. The problem is not whether the result is statistically significant compared with an appropriately defined amount of random errors but whether the result is consistent and hence meaningful. Throughout the three experiments, the following conclusion will be inevitable. The relation typical in the recognition decision with lists given by the E that
where 0 is a positive constant same for Y and N responses, does not hold in the present experiments for all the range of intervening time intervals between retrieval and recognition (T = 0 to 28 days).
Discussion It became clear from the pattern of t(n), RT as a function of the length of list, that the recognition decision in the present three experiments is different from the recognition decision in the previous study (Indow and Murase 1973). There are several similarities and differences between the two experimental paradigms. Features common to both cases are as follows: (a) Positive set in the sense of Sternberg (1969, 1975) consisted of meaningful words belonging to a category, natural or artificial. (b) The size of set was larger than in most recognition experiments. (c) What was dealt with was episodic memory (Tulving 1972) because judgment was made on whether a probe word happened to be there or not. (d) The recognition task was made by a fixed-set
T. Indow, H. Takada /Recognition
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225
procedure (Sternberg 1969, 1975) and several probe words were presented in succession to a fixed positive set. (e) Presentation probabilities of the three kinds of probe word (for Y, N, and N’ responses) were appropriately controlled. On the other hand, differences between the two are as follows: (f) In the previous case, a positive set was given by the experimenter and the subject memorized it to one perfect recitation. The recognition task was given immediately after memorization. (g) In the present case, a positive set was always generated by the subject as a retrieving process and the recognition task was given either immediately after the retrieval (experiment 1) or after an interval T of 4 hours to 28 days (experiments 2 and 3). In the previous study, if words are stored as a list in memory and scanned at the moment when a probe word is given, it would be in STM and the results are in accordance with what is expected from serial and exhaustive scanning. In the present experiments, if retrieved words are kept in memory as a list, it would be in STM when T = 0,but it cannot be in STM when T > 0.It may be in a part of LTM, the temporal storage which is different from that part of LTM where respective words are permanently kept as semantic memory. The latter was called as “archival memory” (Nickerson 1977) or “lexical memory” (Atkinson and Juola 1974). Atkinson and Juola named the temporal storage as “E/K store”. No matter where the memory of self-generated list is and no matter when the recognition task is given, the results of the present experiments made the hypothesis untenable that the recognition under discussion is based on serial and exhaustive scanning through the list in memory. Then, on what basis is the recognition made in the present case? When a probe word is given, the subject understands the word and, in addition, makes the recognition decision. Hence, the memory of that word in the permanent store of LTM must be reached anyway, and each word must have a list or network of attributes corresponding to its meaning. As assumed by Anderson and Bower in ordinary recognition (1972), suppose that once a word is retrieved, a tag indicating that fact is added to the list of attributes. Then, the recognition decision can be made according to whether or not the tag exists in the list of attributes and the scanning through the list of words in STM or E/K store is not necessary, even if the words are stored there as a list. The same mechanism may underlie the monitoring system of discriminating “new” words from “old” ones in retrieval from long-term memory
226
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(semantic) which was referred to in the beginning of the article. The situation may not be very different also in the previous case (Indow and Murase 1973). In this case, when a list of words is presented by the experimenter, the subject understands each word and memorizes the list. Suppose a tag indicating that the word is in the list (episodic) is created in the list of attributes, then the recognition can be made, not by scanning the list in STM, but by means of the tag, provided it is clear enough. When a list is self-generated through retrieval, the tag on each retrieved word is strong enough to make it almost unnecessary to scan the list in memory even if the list is in memory. Besides, the tag is persistent as mentioned in 3.3. For example, the miss rate did not increase over 28 days, and RT was longer for miss responses than for correct N responses, suggesting that the tag existed even when it was missed. When a list presented by the experimenter is memorized, the tag seems to be not so powerful and more fragile. In order to make the recognition decision with the list, whenever the tag is not clear enough, the subject has to rely upon the list in memory. The finding that /3, slope of t(n), was much smaller in the previous experiment (Indow and Murase 1973) than in the Sternberg’s case may be understood if scanning through STM occurred with a probability p and recognition through the tag in the list of attributes in LTM occurred in the rest of cases. The same idea was proposed by Atkinson and Juola (1974). The values of p in our case were about 8 msec and if0 for the scanning through STM is about 40 msec (Sternberg 1975: fig. 9), then p = 0.2 [21.It is of interest to reconsider from this point of view the forgetting or retention curve; a traditional study on human memory (Sternberg 1975). If lists of meaningful words are used rather than nonsense syllables and retention is tested by recognition, as in a study by Strong (1913), again what is dealt with is episodic memory and it is questionable whether forgetting is due to decay of the internal representation of the list in a part of LTM, “E/K store”, or due to fading of the tag in the list of attributes of each word in “archival memory” or “lexical memory”. In the discussion above, it was assumed that, whenever a word is [2] Of recognition decision, Y or N, in the present experiment, a possibility of accounting for p < 0 will be to assume that the S occasionally scan the complementary set in semantic memory; the set of words in a given category which have not yet been retrieved. According to whether the word is found therein or not, the response should be N or Y. The size of the set linearly decreases as the retrieval proceeds. The complementary set may exist for natural categories, but it is hard to imagine how it is formed for artificial categories.
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given, its list of attributes in LTM, its semantic memory, is directly accessed. To assume the direct access is analogous to assume “action at a distance” in physics. Both are processes mysterious to human mind. As effort of physicists has been devoted to convert it to “action in direct contact or through medium”, someday our effort must be focused upon how to understand the apparent direct access, how to reduce it to a result of scanning or resonnance, etc. There is another problem which has been left untouched; how the assumed tag in a list of attributes is detected. It may be by scanning through the list or by direct access. If the former is the case and the scanning is serial and exhaustive, then the detection time has to increase lineraly with the length of attribute list, ie., complexity of the word. In the aforementioned discussion, both processes were assumed to be completed instantaneously; the direct access and the detection of the tag. There will be no doubt that each process is extremely fast even if it takes time.
References Anderson, J.R. and G.H. Bower, 1972. Recognition and retrieval Review 79, 79-132. Atkinson, R.C. and J.F. Juola, 1974. ‘Search and decision processes In: D.H. Krantz, R.D. Lute, R.C. Atkinson and P. Suppes (eds.), ments in mathematical psychology I. San Francisco: W.H. Freeman. Boustield, W.A. and H.W. Sedgewick, 1944. An analysis of sequences
processes.
Psychological
in recognition Contemporary pp. 243-293. of restricted
memory’. developassociative
responses. Journal of General Psychology 30,149-165. Burrows, D. and R. Okada, 1975. Memory retrieval from long and short lists. Science 188, 1031-1033. Indow, T., 1980. ‘Some characteristics of word sequence retrieved from a given category’. In: R.S. Nickerson (ed.), Attention and performance VIII. Hillsdale, NJ: Lawrence Erlbaum Associates Inc. pp. 621-636. Indow, T. and A. Murase, 1973. Experiments on memory and visual scannings. Japanese Psychological Research 15, 136-146. Indow, T. and K. Togano, 1970. On retrieving sequence from long-term memory. Psychological Review 77,317-331. Juola, J.F., G.A. Taylor and M.E. Young, 1974. Stimulus encoding and decision processes in recognition memory. Journal of Experimental Psychology 102, 1108-1115. Nickerson, R.D., 1977. ‘Some comments on human archival memory as a large data base’. In: Proceedings, very large data bases, Third International Conference on Very Large Data Bases. Tokyo, Japan. pp. 159-168. Sternberg, S., 1966. High-speed scanning in human memory. Science 153,652-654. Sternberg, S., 1969. Memory scanning: mental processes revealed by reaction-time experiments. American Scientist 57,421-457. Stemberg, S., 1975. Memory scannings: new findings and current controversies. Quarterly Jour-
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nal of Experimental Psychology 27, l-32. Strong, E.K., Jr., 1913. The effect of time-interval upon recognition memory. Psychological Review 20,339-372. (eds.), Tulving, E., 1972. ‘Episodic and semantic memory’. In: E. Tulving and W. Donaldson Organization of memory. New York: Academic Press. pp. 381-403.