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Recognition memory: The relationship of accuracy and latency of response under different memory loads in retardates
JOURNAL
OF ExPERIMEST.4L
Recognition and
CHILD
Memory: Latency Memory
RICHARD
C.
URBANO,~
12, 270-277
PbTCHOLOCiY
The
Relationship
of Response Loads KEITH I;,riuersit2/
G.
(1971)
Under
of
Accuracy
Different
in Retardates1j2 SCOTT, AND of Illinois
KATHLEEN
MCCARTHY
Ten moderately retarded, well-practiced children served as Ss in a repeated measures design. The task was the recognition of pictures using a probe procedure. Accuracy decreased as a function of number of pictures (1. 5, 9. or 15) that were present and latency of response increased. Correlational analyses showed high reliabilities and high intercorrelations among the accuracy scores and among latency scores but low intercorrelations of accuracy and latency. A varimax factor rotation yielded two factors associated, respectively, with latency and accuracy.
In previous studies (Scott & Masters, 1969a,b, summarized in Scott, 1971) it was found that there was an increase in response latency and decrease in accuracy as memory load increased from one to five pictures. The two functions appeared complementary in form and could be interpreted as different dependent measures of the same psychological process. However, there are some reasons to question this interpretation. First, Ss performing with almost perfect accuracy can still show an increase in latency as the memory load increases (Sternberg, 1966). Further, it has been shown that Ss show different response latency when judgments of same and different are required on memory-probe trials (Nickerson, 1965; Scott & Masters, 196913) though no such effects were observed wit,11 accuracy. In some studies (Scott & Masters, 196913) this could be a result of a ceiling effect on accuracy but other results do not. suffer from this limitation (Scott (9: Masters, 1969d). The present study directly investigated the relationship of latency and 1 The research was supported by Grlnts HD 02898 and MH 07346 from the United States Public Health Service. A career development award, K4 HD 46,370 provided support to Keith G. Scott who should be contacted for reprints. ‘The authors acknowledge the support and assistance of Dr. Louis Belinson, Superintendent. and Mr. William Chambers, Chief Psychologist of the Lincoln State School, Lincoln, Illinois. ’ Now at the Florida State University, Tallahassee, Florida. 270
ACCURACY
AND
SPEED
OF RESPONSE
IN
MEMORY
271
response accuracy by both inferential and correlational procedures in an attempt to further define their relationship. Further, we extended the number of stimuli in our presentation sets from 5 to 15 to extend the possible range of the effects. The study also was intended to examine another related effect reported before (Scott & Masters, 1969a,b). Even after several days pretraining we observed a steady decrease in response latency over days and no parallel effect was present in the accuracy data. At least two interpretations are possible. First we have a simple practice effect and as the game is learned latency of response continues to become shorter even after accuracy of performance has asymptoted. The second interpretation relates to theory of memory storage. This interpretation would suppose that as the children are repeatedly exposed to a set of stimuli that the stimuli become progressively encoded into Long-Term Memory (LTM) and that, the LTM storage system exerts control of the short-term recognition. To examine these alternative interpretations we used highly practiced Ss drawn from a previous study but, with an entirely new set of stimulus pictures. If we have a stimulus encoding effect, the days effect, previously obtained, should persist despite the high level of practice of our Ss. METHOD
Subjects Ten Ss were drawn randomly from those who had served in a previous experiment (Scott & Masters, 196910).Their characteristics were mean Chronological Age 16.0 years, range 11.5-19.5; mean Mental Age 6.2 years, range 5.8-6.8; mean IQ 51.9, range 40-69. sti7nuzi The stimuli were 32 pictures cut from children’s Little Golden Books and pasted on black poster board 4 X 4 in. These cards were photographed with Kodak Ektachrome to produce 35-mm slides with from one to five pictures in a two matrix. When projected, they appeared full size on the rear projection screen. Checks were made to see that each picture was used as a stimulus and a test an equal number of times in the experiment. Apparatus The apparatus is described in detail elsewhere (Scott, 1970). A suite consisting of an experiment.al and a control room was used. The control room contained programming equipment (Scott, 1964, 1965), a Kodak Carousel projector to display the stimuli, and a digital printout, to automatically record accuracy, position, and latency of response.
Th(l S sat in full Gtle view of a onr-nay window that separated the control and espcrimcntal rooms. The stimuli were projected via a front silrcred mirror onto an 18 X 12-m. Polacoat rear-projection screen mounted on a black panel. Below the screen 7 in. apart were two 4lh X 41/-in. response levers inclined slightly to the Ss’ view. Centered between the levers was a candy receptacle to which an M & M was delivered automatically after a correct response. A photograph of the panel appears elsewhere (Scott, 1970, Fig. 5Aj. The two response levers were activated only during a test trial. For a random half of the Xs in each group, the left lever was used to indicate t,hat. the probe picture was from the set that had just been displayed and the right lever was used to indicate that the picture was not from that set. The function of the levers was reversed for the remaining Ss. Design The Miniature Experiment technique of House and Zeaman (1963’) was employed as in previous studies. A completely wit,hin S design was employed; Xumber of Stimuli (1, 3, 9, 15)) Days (l-lo), Subjects (lo), and Replications (2) within a day. The type of probe, same or different, was completely counterbalanced across all variables but could not be completely crossed with the other variables within a day. Data showing the simple effects of this variable and the absence of interact,ive effects are described elsewhere (Scott, 1971). Procedure The Ss were carefully pretrained over a period of 4 days. The general procedure described in detail elsewhere (Scott, 1971) was to show a child one or more pictures in a two-row matrix simultaneously. This was followed by the presentation of a single picture, identified by a bell ring. The child responded with a judgment, if the picture came from the matrix or did not, by pushing the appropriate lever. The daily sessions consisted of a series of such problems with acquisition of one or more pictures followed by a single picture on the test or memory-probe trial. The 22 problems on the first 2 days of pretraining contained only a single picture on the acquisition trial. The 32 pictures in the item pool, were seen as nearly an equal number of times as was possible during the 2 days. On the third and fourth days of pretraining the conditions were identical to those during the experimental days. There were t,wo pretraining orders. Eight problems, consisting of two replications of each matrix of 1, 3, 9, or 15 pictures were used for acquisit.ion. Each order contained four problems in which the probe was the same as one of the pictures from
ACCCRACY
AND
SPEED
OF
RESPOR’SE
IN
273
MEMORY
acquisition and four in which the picture was different. from any of those shown during acquisition. The sequence of number of pictures and type of probe was random within an order with the restriction that sequences of identical but alternating problem types were eliminated. The timing of a problem was as follows. Each picture was displayed for 2 set after parametric data presented elsewhere (Scott, 1971). Thus, in the acquisition of a five-item problem, the pictures all appeared together in a two-row matrix for 5 x 2 or 10 sec. The presentation of the stimuli for acquisition was followed by a retention interval of 4 set after which the bell rang for 0.1 set as the test t’rial appeared. The test-trial duration was the time S took to respond and was followed by an interproblem interval of 7 sec. There were 10 orders of the eight-problem experimental sessions. The sequence of problems within an order was random. Each S took the 10 orders daily in a different random sequence. Thus, each S had eight problems per day for 10 days for a total of 80 data points. RESULTS
Table 1 presents the mean latency of response for all responses and correct only responses. While the correct latencies are systematically shorter, both sets of data show an increase in latency of response with increasing memory load. A Number of Stimuli (4) by Days (10) by Replication (2) by Xs (10) analysis of variance of all responsesreveals a significant main effect of Number of Stimuli (F(3,27) = 7.69, p < ,001). The mean latency of response for each successive day was 75.01, 72.55, 65.69, 68.17, 61.49, 78.06, 61.22, 61.35, 63.67, and 61.44. Thus, Ss appeared to decrease their latency of response as a function of days yielding the only other significant effect (F(9,81) = 2.59, p < .05). Figure 1 shows the mean proportion correct as a function of Number of Stimuli. In a Number of Stimuli (4) by Days (10) by Replications (2) by Ss (10) analysis of variance this was the only significant effect (F(3,27) = 13.27, p < 601). The function is very similar to those obtained previously with smaller memory loads. Six of our Ss actually did better at Number of Stimuli 15 than they did at 9. We have not tested TABLE 1 MEAN LATENCIES Number
of Stimuli -.
response Correct All responses
only
59.36 59.84
62.89 67.50
68.46 68.89
70.01 71.22
274
URBAA-0,
1
SCOTT,
AND
MCCARTHY
3
9
NUMBER
OF
15
STIMULI
FIG. 1. The mean proportion of correct responses Each plot is the mean of 200 binary observations.
as a function
of the memory
load.
this inversion which does not appear in other similar, and subsequent, studies (Scott, 1971). To examine the relationship between accuracy and latency of response we first concerned ourselves with the reliability of our measures. Table 2 gives t’he Spearman-Brown split-half reliabilities. With the exception of Accuracy at Matrix Size 15 these are quite high for so few measures. The intercorrelations of the accuracy and latency measures are given in Table 3. It is immediately apparent that generally sizeable correlations exist among the latency and among the accuracy measures.However, the cross correlations between latency and accuracy are not large. TABLE SPEARMAN-BROWN
Number
SPLIT-HALF
2 RELIABILITIES
of stimuli
Correlation”
Latency 1 3 9
.95 .69 .96 .94
15 Accuracy 1 3 9 15
a The
correlations
are based
.75 .Hl
.80 .45 on 20 measures
per subject
split
into
two
replications.
ACCURACY
AiSD
SPEED
OF RESPONSE
TABLE INTEKCORRELSTION~
IN
3
OF LATENCY
AND
ACCURACY
SCORES
Accuracies
Latency Matrix
Lat,ency
Accuracies
275
MEMORY
-
size
1
3
9
15
1
3
9
1 3 9 15 1 3 9 15
1.00 .82 .91 .92 .oo --.21 .03 .35
1.00 .96 .84 -.09 --.09 .lO .23
1.00 .89 -.07 -.06 .08 .39
1.00 .21 -.03 .18 .19
1.00 .73 .79 .17
1.00 .72 .47
1.00 .31
15
1.00
Next t,he data were factored. The characteristic rook of the first two principal axis factors are 3.81 and 2.54, respectively, and account for 85% of the common variance. The loadings of the latency and accuracy measures on the Varimax rotation of these two factors are presented in Table 4. The first factor is closely associated with the latency measures and the second with the accuracy measures. DISCUSSION
The data clearly show that, despite the complementary appearance of the group functions that S’s latency and accuracy scores are not highly correlat,ed and might provide different theoretical inferences about the underlying processes. The general accuracy and latency functions are similar to others obtained in a series of experiments (Scott & Masters, 1969a,b,c,d). One interpretation is that the memory search proposed by Sternberg (1966) is well indexed by latency but also high memory loads errors become more frequent. These accuracy scores may as readily be TABLE \T.\KIMAX
Number Latency
of stimuli 1 3 9 15 1 3 9 15
4
ROTATED-FACTOR
Factor .96 .94 .99 .93 --.03 - .12 .07 .34
LOADINGS
I
Factor --.03 - .Ol .02 .13 .88 .91 83 .48
II
tluc to ;i f;iilure to store a:: :L failure to retrica\.ct and a given sul)jcct m:l> or map not ~110~ both latency and accuracy efYcctx. Ai result might )-w that in yome casts correlations of latency and accuracy may bc obtainctl though not, reflecting the same processes. The use of larger numbc~ of stimuli produced a much higher level of performance than had been expected. With 15 items close to chance performance was expected but as can be F:cen in Fig. 1 was not obtained. The Xs were carefully questioned about what they were remembering but could not supply coherent answers. It may be worth noting that task performance seems to rely on visual imagery (Paivio, 1969), when tried by adult 8s. With 15 pict’ures, drawn from a repeatedly used pool of 32, any attempt to rehearse results in enormous interference and confusion in the short period available. Most adults would make very few errors on the task provided they are not distracted. We find some decrease in latency as a function of days t.hough the data do appear rather noisy. The effect of days would suggest further investigation perhaps starting out the testing with less familiar materials than pictures and also using separate sets of pictures for pretraining and the experimental sessions. Also an attempt is needed to separate the effects of decision time from the time it takes to make a response (Bogartz & Witte, 1966). For the present our data are most compatible with the interpretation that the latency days effect we have previously obtained is a slow asymptoting practice effect probably of a motor kind. If the retarded Xs of 6 years mental age can store 15 items with a moderate degree of accuracy, the limit of normal adult ability and t.he relat’ed developmental and ability trends are of considerable interest. Miller’s (1956) limit of seven, plus or minus two seems not to apply to recognition data of this sort. While the arcrage functions reported might be accounted for by a sampling model, WC did have an individual S with 100% accuracy with 15 pict’ures. In fact 8 of 10 Ss were at better than 75% accuracy. REFEREXCES R. S., & WITTE. K. L. On the locus of the stimulus familiarization effect in young children. Ja~rnnl of Experimental Child Psychology, 1966. 4, 317-331. Houss, B. J., & ZEAIMAN, D. Miniature experiments in the discrimination learning of retardates. In L. P. Lipsitt and C. C. Spiker (Eds.), Advances ,in chilrl delrelopment and behazrior. Vol. 1. New York: Academic Press. 1963. MILLER. G. A. The magical number sewn, plus or minus two: some limits on om capacity for processing information. Psychological Review, 1956, 63, 81-97. NIC.KERSON, R. S. Response times for “same’‘-“different” judgments. Percrplucrl Motor Skills, 1965, 20, 15-18. P.4rvro. A. Mental imagery in associative learning and memory. Psychologicrrl RelGrw, 1969. 76. 41-263. BOGARTZ.
ACCURACY
AKD
SPEED
OF RESPOIL’SE
IN
MEMORY
277
K, G. A device for the punching of timed tape for programmers. Joz~rnnl of Experimental Analysis of Behrwior, 1965, 8, 105106. SCOTT, K. G. A programmer for discrimination learning studies. Journal of Experimental Child Psychology, 1964, 7, 66. SCOTT, K. G. A multiple-choice audio-visual discrimination apparatus with quick interchange display and response panels. Jox~al of Experimental Child Psychology, 1970, 9, 43-50. SCOTT. K. G.. & MASTERS, L. Recognition Memory: Retardates recognition of pictures presented successively or simultaneously. K. Scott (Ed.), Progress Report No. 1, Grant USPH HD 02898, University of Illinois, 1969a. SCOTT, K. G., & MASTERS, L. Recognition memory: Simultaneous and successive presentation modes as between and within factors in the retarded. K. Scott (Ed.), Progress Report No. 1, Grant USPH HD 02898. University of Illinois. 1969h. SCOTT, K. G., & MASTERS, L. Recognition memory: The interaction of load and recall interval in retardates memory. K. Scott (Ed.), Progress Report No. 1, Grant USPH HD 02898, University of Illinois, 1969c. SCOTT, K. G., & MASTERS, L. Recognition memory: Proactive inhibition in retardates recall at different memory loads. K. Scott (Ed.). Progress Report No. 1, Grant USPH HD 02898, University of Illinois, 1969d. &SCOTT, K. G. Recognition memory: A research strategy and a summary of initial findings. In N. R. Ellis (Ed.). International reoiew of research in mental retnrdation. Vol. 5. New York: Academic Press, 1971, pp. 83-111. STERNBERG, S. High speed scanning in human memory. Science, 1966, 153, (3736), 652654. SCOTT,
OF ExPERIMEST.4L
Recognition and
CHILD
Memory: Latency Memory
RICHARD
C.
URBANO,~
12, 270-277
PbTCHOLOCiY
The
Relationship
of Response Loads KEITH I;,riuersit2/
G.
(1971)
Under
of
Accuracy
Different
in Retardates1j2 SCOTT, AND of Illinois
KATHLEEN
MCCARTHY
Ten moderately retarded, well-practiced children served as Ss in a repeated measures design. The task was the recognition of pictures using a probe procedure. Accuracy decreased as a function of number of pictures (1. 5, 9. or 15) that were present and latency of response increased. Correlational analyses showed high reliabilities and high intercorrelations among the accuracy scores and among latency scores but low intercorrelations of accuracy and latency. A varimax factor rotation yielded two factors associated, respectively, with latency and accuracy.
In previous studies (Scott & Masters, 1969a,b, summarized in Scott, 1971) it was found that there was an increase in response latency and decrease in accuracy as memory load increased from one to five pictures. The two functions appeared complementary in form and could be interpreted as different dependent measures of the same psychological process. However, there are some reasons to question this interpretation. First, Ss performing with almost perfect accuracy can still show an increase in latency as the memory load increases (Sternberg, 1966). Further, it has been shown that Ss show different response latency when judgments of same and different are required on memory-probe trials (Nickerson, 1965; Scott & Masters, 196913) though no such effects were observed wit,11 accuracy. In some studies (Scott & Masters, 196913) this could be a result of a ceiling effect on accuracy but other results do not. suffer from this limitation (Scott (9: Masters, 1969d). The present study directly investigated the relationship of latency and 1 The research was supported by Grlnts HD 02898 and MH 07346 from the United States Public Health Service. A career development award, K4 HD 46,370 provided support to Keith G. Scott who should be contacted for reprints. ‘The authors acknowledge the support and assistance of Dr. Louis Belinson, Superintendent. and Mr. William Chambers, Chief Psychologist of the Lincoln State School, Lincoln, Illinois. ’ Now at the Florida State University, Tallahassee, Florida. 270
ACCURACY
AND
SPEED
OF RESPONSE
IN
MEMORY
271
response accuracy by both inferential and correlational procedures in an attempt to further define their relationship. Further, we extended the number of stimuli in our presentation sets from 5 to 15 to extend the possible range of the effects. The study also was intended to examine another related effect reported before (Scott & Masters, 1969a,b). Even after several days pretraining we observed a steady decrease in response latency over days and no parallel effect was present in the accuracy data. At least two interpretations are possible. First we have a simple practice effect and as the game is learned latency of response continues to become shorter even after accuracy of performance has asymptoted. The second interpretation relates to theory of memory storage. This interpretation would suppose that as the children are repeatedly exposed to a set of stimuli that the stimuli become progressively encoded into Long-Term Memory (LTM) and that, the LTM storage system exerts control of the short-term recognition. To examine these alternative interpretations we used highly practiced Ss drawn from a previous study but, with an entirely new set of stimulus pictures. If we have a stimulus encoding effect, the days effect, previously obtained, should persist despite the high level of practice of our Ss. METHOD
Subjects Ten Ss were drawn randomly from those who had served in a previous experiment (Scott & Masters, 196910).Their characteristics were mean Chronological Age 16.0 years, range 11.5-19.5; mean Mental Age 6.2 years, range 5.8-6.8; mean IQ 51.9, range 40-69. sti7nuzi The stimuli were 32 pictures cut from children’s Little Golden Books and pasted on black poster board 4 X 4 in. These cards were photographed with Kodak Ektachrome to produce 35-mm slides with from one to five pictures in a two matrix. When projected, they appeared full size on the rear projection screen. Checks were made to see that each picture was used as a stimulus and a test an equal number of times in the experiment. Apparatus The apparatus is described in detail elsewhere (Scott, 1970). A suite consisting of an experiment.al and a control room was used. The control room contained programming equipment (Scott, 1964, 1965), a Kodak Carousel projector to display the stimuli, and a digital printout, to automatically record accuracy, position, and latency of response.
Th(l S sat in full Gtle view of a onr-nay window that separated the control and espcrimcntal rooms. The stimuli were projected via a front silrcred mirror onto an 18 X 12-m. Polacoat rear-projection screen mounted on a black panel. Below the screen 7 in. apart were two 4lh X 41/-in. response levers inclined slightly to the Ss’ view. Centered between the levers was a candy receptacle to which an M & M was delivered automatically after a correct response. A photograph of the panel appears elsewhere (Scott, 1970, Fig. 5Aj. The two response levers were activated only during a test trial. For a random half of the Xs in each group, the left lever was used to indicate t,hat. the probe picture was from the set that had just been displayed and the right lever was used to indicate that the picture was not from that set. The function of the levers was reversed for the remaining Ss. Design The Miniature Experiment technique of House and Zeaman (1963’) was employed as in previous studies. A completely wit,hin S design was employed; Xumber of Stimuli (1, 3, 9, 15)) Days (l-lo), Subjects (lo), and Replications (2) within a day. The type of probe, same or different, was completely counterbalanced across all variables but could not be completely crossed with the other variables within a day. Data showing the simple effects of this variable and the absence of interact,ive effects are described elsewhere (Scott, 1971). Procedure The Ss were carefully pretrained over a period of 4 days. The general procedure described in detail elsewhere (Scott, 1971) was to show a child one or more pictures in a two-row matrix simultaneously. This was followed by the presentation of a single picture, identified by a bell ring. The child responded with a judgment, if the picture came from the matrix or did not, by pushing the appropriate lever. The daily sessions consisted of a series of such problems with acquisition of one or more pictures followed by a single picture on the test or memory-probe trial. The 22 problems on the first 2 days of pretraining contained only a single picture on the acquisition trial. The 32 pictures in the item pool, were seen as nearly an equal number of times as was possible during the 2 days. On the third and fourth days of pretraining the conditions were identical to those during the experimental days. There were t,wo pretraining orders. Eight problems, consisting of two replications of each matrix of 1, 3, 9, or 15 pictures were used for acquisit.ion. Each order contained four problems in which the probe was the same as one of the pictures from
ACCCRACY
AND
SPEED
OF
RESPOR’SE
IN
273
MEMORY
acquisition and four in which the picture was different. from any of those shown during acquisition. The sequence of number of pictures and type of probe was random within an order with the restriction that sequences of identical but alternating problem types were eliminated. The timing of a problem was as follows. Each picture was displayed for 2 set after parametric data presented elsewhere (Scott, 1971). Thus, in the acquisition of a five-item problem, the pictures all appeared together in a two-row matrix for 5 x 2 or 10 sec. The presentation of the stimuli for acquisition was followed by a retention interval of 4 set after which the bell rang for 0.1 set as the test t’rial appeared. The test-trial duration was the time S took to respond and was followed by an interproblem interval of 7 sec. There were 10 orders of the eight-problem experimental sessions. The sequence of problems within an order was random. Each S took the 10 orders daily in a different random sequence. Thus, each S had eight problems per day for 10 days for a total of 80 data points. RESULTS
Table 1 presents the mean latency of response for all responses and correct only responses. While the correct latencies are systematically shorter, both sets of data show an increase in latency of response with increasing memory load. A Number of Stimuli (4) by Days (10) by Replication (2) by Xs (10) analysis of variance of all responsesreveals a significant main effect of Number of Stimuli (F(3,27) = 7.69, p < ,001). The mean latency of response for each successive day was 75.01, 72.55, 65.69, 68.17, 61.49, 78.06, 61.22, 61.35, 63.67, and 61.44. Thus, Ss appeared to decrease their latency of response as a function of days yielding the only other significant effect (F(9,81) = 2.59, p < .05). Figure 1 shows the mean proportion correct as a function of Number of Stimuli. In a Number of Stimuli (4) by Days (10) by Replications (2) by Ss (10) analysis of variance this was the only significant effect (F(3,27) = 13.27, p < 601). The function is very similar to those obtained previously with smaller memory loads. Six of our Ss actually did better at Number of Stimuli 15 than they did at 9. We have not tested TABLE 1 MEAN LATENCIES Number
of Stimuli -.
response Correct All responses
only
59.36 59.84
62.89 67.50
68.46 68.89
70.01 71.22
274
URBAA-0,
1
SCOTT,
AND
MCCARTHY
3
9
NUMBER
OF
15
STIMULI
FIG. 1. The mean proportion of correct responses Each plot is the mean of 200 binary observations.
as a function
of the memory
load.
this inversion which does not appear in other similar, and subsequent, studies (Scott, 1971). To examine the relationship between accuracy and latency of response we first concerned ourselves with the reliability of our measures. Table 2 gives t’he Spearman-Brown split-half reliabilities. With the exception of Accuracy at Matrix Size 15 these are quite high for so few measures. The intercorrelations of the accuracy and latency measures are given in Table 3. It is immediately apparent that generally sizeable correlations exist among the latency and among the accuracy measures.However, the cross correlations between latency and accuracy are not large. TABLE SPEARMAN-BROWN
Number
SPLIT-HALF
2 RELIABILITIES
of stimuli
Correlation”
Latency 1 3 9
.95 .69 .96 .94
15 Accuracy 1 3 9 15
a The
correlations
are based
.75 .Hl
.80 .45 on 20 measures
per subject
split
into
two
replications.
ACCURACY
AiSD
SPEED
OF RESPONSE
TABLE INTEKCORRELSTION~
IN
3
OF LATENCY
AND
ACCURACY
SCORES
Accuracies
Latency Matrix
Lat,ency
Accuracies
275
MEMORY
-
size
1
3
9
15
1
3
9
1 3 9 15 1 3 9 15
1.00 .82 .91 .92 .oo --.21 .03 .35
1.00 .96 .84 -.09 --.09 .lO .23
1.00 .89 -.07 -.06 .08 .39
1.00 .21 -.03 .18 .19
1.00 .73 .79 .17
1.00 .72 .47
1.00 .31
15
1.00
Next t,he data were factored. The characteristic rook of the first two principal axis factors are 3.81 and 2.54, respectively, and account for 85% of the common variance. The loadings of the latency and accuracy measures on the Varimax rotation of these two factors are presented in Table 4. The first factor is closely associated with the latency measures and the second with the accuracy measures. DISCUSSION
The data clearly show that, despite the complementary appearance of the group functions that S’s latency and accuracy scores are not highly correlat,ed and might provide different theoretical inferences about the underlying processes. The general accuracy and latency functions are similar to others obtained in a series of experiments (Scott & Masters, 1969a,b,c,d). One interpretation is that the memory search proposed by Sternberg (1966) is well indexed by latency but also high memory loads errors become more frequent. These accuracy scores may as readily be TABLE \T.\KIMAX
Number Latency
of stimuli 1 3 9 15 1 3 9 15
4
ROTATED-FACTOR
Factor .96 .94 .99 .93 --.03 - .12 .07 .34
LOADINGS
I
Factor --.03 - .Ol .02 .13 .88 .91 83 .48
II
tluc to ;i f;iilure to store a:: :L failure to retrica\.ct and a given sul)jcct m:l> or map not ~110~ both latency and accuracy efYcctx. Ai result might )-w that in yome casts correlations of latency and accuracy may bc obtainctl though not, reflecting the same processes. The use of larger numbc~ of stimuli produced a much higher level of performance than had been expected. With 15 items close to chance performance was expected but as can be F:cen in Fig. 1 was not obtained. The Xs were carefully questioned about what they were remembering but could not supply coherent answers. It may be worth noting that task performance seems to rely on visual imagery (Paivio, 1969), when tried by adult 8s. With 15 pict’ures, drawn from a repeatedly used pool of 32, any attempt to rehearse results in enormous interference and confusion in the short period available. Most adults would make very few errors on the task provided they are not distracted. We find some decrease in latency as a function of days t.hough the data do appear rather noisy. The effect of days would suggest further investigation perhaps starting out the testing with less familiar materials than pictures and also using separate sets of pictures for pretraining and the experimental sessions. Also an attempt is needed to separate the effects of decision time from the time it takes to make a response (Bogartz & Witte, 1966). For the present our data are most compatible with the interpretation that the latency days effect we have previously obtained is a slow asymptoting practice effect probably of a motor kind. If the retarded Xs of 6 years mental age can store 15 items with a moderate degree of accuracy, the limit of normal adult ability and t.he relat’ed developmental and ability trends are of considerable interest. Miller’s (1956) limit of seven, plus or minus two seems not to apply to recognition data of this sort. While the arcrage functions reported might be accounted for by a sampling model, WC did have an individual S with 100% accuracy with 15 pict’ures. In fact 8 of 10 Ss were at better than 75% accuracy. REFEREXCES R. S., & WITTE. K. L. On the locus of the stimulus familiarization effect in young children. Ja~rnnl of Experimental Child Psychology, 1966. 4, 317-331. Houss, B. J., & ZEAIMAN, D. Miniature experiments in the discrimination learning of retardates. In L. P. Lipsitt and C. C. Spiker (Eds.), Advances ,in chilrl delrelopment and behazrior. Vol. 1. New York: Academic Press. 1963. MILLER. G. A. The magical number sewn, plus or minus two: some limits on om capacity for processing information. Psychological Review, 1956, 63, 81-97. NIC.KERSON, R. S. Response times for “same’‘-“different” judgments. Percrplucrl Motor Skills, 1965, 20, 15-18. P.4rvro. A. Mental imagery in associative learning and memory. Psychologicrrl RelGrw, 1969. 76. 41-263. BOGARTZ.
ACCURACY
AKD
SPEED
OF RESPOIL’SE
IN
MEMORY
277
K, G. A device for the punching of timed tape for programmers. Joz~rnnl of Experimental Analysis of Behrwior, 1965, 8, 105106. SCOTT, K. G. A programmer for discrimination learning studies. Journal of Experimental Child Psychology, 1964, 7, 66. SCOTT, K. G. A multiple-choice audio-visual discrimination apparatus with quick interchange display and response panels. Jox~al of Experimental Child Psychology, 1970, 9, 43-50. SCOTT. K. G.. & MASTERS, L. Recognition Memory: Retardates recognition of pictures presented successively or simultaneously. K. Scott (Ed.), Progress Report No. 1, Grant USPH HD 02898, University of Illinois, 1969a. SCOTT, K. G., & MASTERS, L. Recognition memory: Simultaneous and successive presentation modes as between and within factors in the retarded. K. Scott (Ed.), Progress Report No. 1, Grant USPH HD 02898. University of Illinois. 1969h. SCOTT, K. G., & MASTERS, L. Recognition memory: The interaction of load and recall interval in retardates memory. K. Scott (Ed.), Progress Report No. 1, Grant USPH HD 02898, University of Illinois, 1969c. SCOTT, K. G., & MASTERS, L. Recognition memory: Proactive inhibition in retardates recall at different memory loads. K. Scott (Ed.). Progress Report No. 1, Grant USPH HD 02898, University of Illinois, 1969d. &SCOTT, K. G. Recognition memory: A research strategy and a summary of initial findings. In N. R. Ellis (Ed.). International reoiew of research in mental retnrdation. Vol. 5. New York: Academic Press, 1971, pp. 83-111. STERNBERG, S. High speed scanning in human memory. Science, 1966, 153, (3736), 652654. SCOTT,