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The facilitation of recognition by recall
JOURNAL OF VERBAL LEARNING AND VERBAL BEHAVIOR
14, 253-258 (1975)
The Facilitation of Recognition by Recall ROBERT S. LOCKHART University of Toronto
Existing evidence suggests that the free recall of an item does not facilitate its subsequent recognition. An analysis of this evidence mdmates that even if recall did facilitate the recogration of lndwidual 1terns, previously employed paradigms are such that its overall effect might not be readily apparent. Results are reported which confirm this prediction and show that the facilitating effect of free recall on recogmtlon is quite substantial. recency. Cohen's (1970) unconditionalized serial position curves do, in fact, show such positive recency. This result when taken together with the negative recency for conditionalized curves (Craik et al., 1970) suggests that final recognition is indeed facilitated by initial recall. The results reported by Rundus, Loftus, and Atkinson (1970) question the validity of this conclusion, while those of Darley and Murdock (1971) and of Hogan and Kintsch (1971) manifestly contradict it. The Darley and Murdock study found no difference in final recognition between words from lists which had been previously recalled and words from lists for which no recall had been permitted. This result is surprising, not only because of Cohen's (1970) data, but also because Darley and Murdock (1971) found that, while not aiding recognition, initial recall did facilitate final recall. If, so far as final retention is concerned, immediate recall is somewhat like an incidental learning trial, quite the opposite result might have been expected. In any case, a manipulation which facilitates recall but not recognition is of considerable theoretical interest since it is a result which poses difficulties for some current models, and offers strong support for others. Research supported by National Research Council It is important to note that in a paradigm of Canada Grant No. A0355. Requests for reprints such as that used by Darley and Murdock should be sent to Robert S. Lockhart, Department of (1971), any facilitating effect of recalling a Psychology, Umvers~tyof Toronto, Toronto, Canada, word can manifest itself only with respect to a M5S 1A1. Copyright © 1975 by Academic Press, Inc 253 All rights of reproductton m any form reserved,
The most satisfactory account of the negative recency effect in free recall (Craik, 1970) is in terms of the differences in the type of processing necessary to support long-term as opposed to short-term retention. Whereas relatively superficial processing (Craik & Lockhart, 1972) is sufficient to support the immediate recall of items from late serial positions, such items are not adequately coded for long-term retention. Negative recency has also been observed when recogration rather than recall is used as the final test of retention (Craik, Gardiner, & Watkins, t970). However, some care needs to be taken in interpreting this latter result. In this case the negative recency effect applies to the final recognition of those items initially recalled, not to the unconditionalized or absolute level. The purpose of conditionahzing in this way is, presumably, to equate items for any facilitating effects that immediate recall itself might have on an item's subsequent recognition. To the extent that such facilitation occurs, recency items would receive a disproportionate advantage since they are recalled with a high probability. If this facilitation is substantial then it is quite possible that the absolute level of final recognition would display positive
Printed m Great Britain
254
ROBERT S. LOCKHART
rather special subset of items--items that Jointly fulfill certain conditions. Obviously the tem must be recallable in immediate recall. Thus the serial position curve for immediate recall represents an upper bound on the proportion of items that can be potentially facilitated. Not only must the item be recallable, its code must be sufficiently transitory so that, were immediate recall to be prevented, the trace would deteriorate to a point where the word would not be recognized in the final retention test. Items from early and middle serial positions of a free recall list are unlikely to be of this kind, since for such words to be recallable (even in immediate recall) they must be so well coded (m long-term memory, if you will) that in all likelihood they would be subsequently recognized with or without immediate recall actually taking place. On the other hand, items from the recency portion of the serial position curve are much more likely to fulfill the required conditions. This is exactly what the negative recency effect itself suggests: Recall from late serial positions is on the basis of a code which is subject to rapid deterioration. It follows from these considerations that the overt rehearsal technique of Rundus et al. (1970) used by Darley and Murdock (1971) is less than optimal since, compared to standard free recall, it yields a rather attenuated recency effect and its slow presentation rate (5 sec) would also serve to minimize the number of items recalled on the basis of a transitory code. The preceding analysis leads to the conclusion that the facilitating effects of recall on recognition will be concentrated in the recency portion of the input serial position curve, and that the effect should be seen most clearly at fast presentation rates. The purpose of the present paper is to report results which support both of the above conclusions. METHOD
Subjects were g~ven 12 lists, each consisting of 20 common English nouns selected ran-
domly from a pool totalling 1790. The words were presented at one of three rates: .75, 1.5, or 5.0 sec each. A total of 120 University of Toronto undergraduates served as subjects, 40 at each presentation rate. For each of these three groups, a randomly selected half of the lists were followed by an instruction to free recall; the other half were followed by a three digit number from which subjects counted backwards by threes as rapidly as possible. The time allowed for both activities was 2 rain. To ensure adherence to the distractor task, subjects were informed that the purpose of the experiment was to study the effect of the two tasks (free recall and backward counting) on each other, and that performance on each task was equally important. Moreover, no indication was given that there would be a final recognition test. The first two lists were practice lists; one was followed by the free recall instruction, the other by a three digit number, signalhng the start of the backward counting task. In the remaining 10 lists the order of the recall and no-recall instructions was randomly determined. Subjects were run in groups of eight and heard the words through headphones in individual partitioned cubicles. To ensure an adequate sampling of materials, each group of eight subjects within a given presentation rate received a different set of 12 lists, all lists being constructed by randomly drawing words from the previously mentioned pool of 1790. However the same sets of lists were used across the three presentation rates. Following the presentation of the final list, subjects were given a 200 item, three-alternative forced-choice recognition test of the words from all 10 lists. The 400 distractors were a random selection from the same noun pool. The subjects were given a sheet containing the 200 sets of three alternatives and asked to underline the one word in each set they judged to be previously presented. They were asked to also circle the underlined word if they remembered having recalled it. As much t~me as needed was allowed for this recognition test.
FACILITATION OF RECOGNII ION BY RECALL
recency across all rates. These curves are, of course, unconditional probabilities. For lists which were immediately recalled, conditional probabilities (the probability of correct recognition given initial recall) may be plotted. These functions are shown in Figure 2 and the strong negative recency effect (at least for fast rates) is evident, replicating the results of Craik et al. (1970). It should be remembered that, as with all such conditionalized functions, the negative recency effect will be strongly influenced by item selection factors. As pointed out in the introduction, initial recall from early serial positions will usually denote an item that has been well coded, whereas this is not necessarily true of items recalled from late serial positions. A similar negative recency effect is shown in Figure 3 which g~ves the probability of correctly identifying a word as one which had been previously recalled. These hit rates may be interpreted relative to several false-alarm rates; words wrongly identified as having been recalled may be either from recalled lists, or from nonrecalled lists, or words which were entirely new (lures in the recognition test). The proportions of each of these types of items which were misidentified are respectively .08, .11, and .04. It is evident that subjects can
RESULTS
Analysm of the data to be discussed is limited to the last six input serial positions; as expected an analysis of variance applied to the data for serial positions 1-14 showed there were no differences between items from recalled and nonrecalled lists in these earlier serial positions at any of the presentation rates. Recognition levels for the late serial positions are shown in Figure I. Apart from the expected effect of rate, F(2, 105) = 31.7, two substantial effects are evident; recognition is superior for recalled lists, F(1, 105)= 44.0, and this difference increases quite sharply across the last few serial positions, the interaction between serial position and the recall condition yielding F(5, 525)=13.8. The magnitude of this interaction diminishes somewhat as rate of presentation decreases, F(10, 525) = 2.3, p < .05. This latter three-way interaction seems to be largely a consequence of the increase in the amount of negative recency in non-recalled lists as the presentation rate increases. Whereas there is a strong negative recency effect for rapidly presented nonrecalled lists, there is virtually none for lists presented at the slow, 5-sec rate. Lists which were immediately recalled show positive
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FIG. I. Probabthty of correct recognitxon for recalled and nonrecalled lists as a function of input serial position.
256
ROBERT S. LOCKHART
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FIG. 2. Probability of correct recognition for items immediately recalled.
accurately identify 1terns they have previously recalled, but that their accuracy declines at late serial position. DISCUSSION
While the results show that recalling an item facilitates the subsequent recognition of that item, it is difficult to obtain a meaningful quantification of the effect directly from the data. The reason for this d~fficulty is that the magnitude of the observed difference between recalled and non-recalled lists is a joint function of two probabilities: the probability that an item will be correctly recognized by virtue of its being recalled and the probability that an item is of the kind that would not have been recognized, had the recall not taken place.
This statement may be formalized in terms of a simple finite state model which also serves to provide some insight into the magnitude of the facilitation. The model is purely descriptive in the sense that it is concerned merely to quantify certain aspects of the data, not with underlying mechanisms. Items from a list may be classified into one of four states representing whether or not the item is recallable in immediate recall (R or P,) together with whether or not it is recognizable m final recognition (G or G). Thus an item in state R G is one which would be recalled in immediate recall (if such were permitted) but would not be recognized in final recognition. It is only items of this type that can potentially be facilitated by the act of initial recall, and the parameter of current interest ~s the prob
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FIG. 3. Probabihty of correctly identifying an item as having been recalled in immediate recall test.
FACILITATION OF RECOGNITION BY RECALL
ability that an item in state R G makes a transition into state R G as a consequence of immediate recall being allowed to occur. Denote this probabihty by a and let r be the probability that, in the absence of an immediate recall test, an item is in state RG. Then for a k-alternative forced choice recognition test, the probability of a correct recognition is simply 1/k for R G items in nonrecalled lists, and a + (1 - a)/k for R G items in recalled lists. Thus the increment in recognition probability as a consequence of immediate recall taking place is given by
:ra 0 For items to be recalled but not subsequently recognized, they must jointly fulfill three conditions: They must be in state R(3, they must remain in that state, despite immediate recall, and finally, they must not be guessed. Thus the expected proportion, p, of items recalled but not subsequently recognized is r(1 - a)(1 - l/k). From this we can obtain an expression for r, and substituting it in the above equation for D, we get
D=p That is, the effect on final recognition of initially recalling an item is dlrectly proportional to the probability that an item will be recalled but not recognized. If this probability is near zero then D will be near zero, even if a is substantially greater than zero. This situation exists in both Hogan and Kintsch (1971) and in Darley and Murdock (1971). Since D a n d p are observed, they may be used to obtain estimates of a. While both of these observed probabilities vary with serial position and the rate of presentation, a will be taken to be independent of such factors, although it is almost certainly the case that, in general, the facilitating effects of recall vary with serial position (Bartlett & Tulving, 1974). However,
257
the present experimental paradigm permits only a single estimate of a since D is nonzero only for the last few serial positions. Moreover, such an estimate can be considered a lower bound, in that recall from earlier serial positions should yield larger values of a. It should be kept in mind that a is a transition parameter which may take on a high value for items in early serial positions, even although such items manifest no facilitation from initial recall. This is so because such facilitation is a function not only of a but also of p and the latter is typically near zero for these early items. The single least-squares estimate of a for the data shown in Figure 1 is .43, a value which represents a substantial degree of facilitation. If applied to the initial presentation of an item, this transition probability would yield a performance level of .57 in a three-alternative forced-choice recognition test, a value which is approximately equal to final recognition of nonterminal items from lists presented at a 1.5-sec rate. There is little variability in the value of a if it is estimated separately for each presentation rate; the respective values for the fast, medium, and slow rates are .44, .43 and .39. Values of a may be calculated for each serial position point in Figure 1, but the results are less stable, especially as D becomes small, and no meaningful trend is evident. It is important to note that the issue is not one of failing to replicate previous results. In fact, the data in Figure 1 for the 5 second rate are in close agreement with those reported by Darley and Murdock (1971). The point to be stressed is that the effects of recall on subsequent recognition frequently will be concealed because recallable items will usually be recognized even without the aid of the recall test. Although the present experiment was not directly concerned with negative recency effects, it does serve to clarify one point. Since the initial recall of terminal items influences their delayed recogmtion, previous attempts to examine negative recency in a delayed recognition test (Crmk et aI., 1970; Cohen,
258
ROBERT S. LOCKHART
1970; Engle, 1974) have confounded input effects with those of initial recall. Conditionalizing on initial recall serves only to complicate matters since at introduces item selection factors. A clear picture is provided by the final recognition of items f r o m lists not immediately recalled; negative recency exists in delayed recognition and its magnitude increases with the rate of initial presentation. It is interesting to note that this same trend exists for the accuracy of identifying a word as having been recalled. The data in Figure 3 have n o t been condationalized on correct recognition (this can be done by dividing the values in Figure 3 by the corresponding values m Figure 2) but even after conditionalizing, negative recency is still present. Thus even for items correctly recognized, the fact o f recall is better remembered for items from nonterminal serial positions. This result is exactly what would be expected if the processing involved in free recalling an item is qualitatively different (deeper) for nonterminal serial positaons. REFERENCES BARTLETT,J. C., ~%TuLVING,E. Effects of temporal and semantic encoding in immediate recall upon sub-
sequent retrieval. Journal of Verbal Learning and Verbal Behavior, 1974, 13, 297-309. COHEN, R. L. Recency effects in long-term recall and recognmon. Journal of Verbal Learning and Verbal Behavtor, 1970, 9, 672-678. CRAIK,F. I. M. The fate of primary memory atems in free recall. Journal of Verbal Learnmg and Verbal Behavwr, 1970, 9, 143-148. CRAIK,F. I. M, GARDINER,J. M , & WATKINS,M. J. Further evidence for a negative recency effect m free recall. Journal of Verbal Learning and Verbal Behavior, 1970, 9, 554-560. CRAIK,F. I. M., & LOCKHART,R. S. Levels of processing: A framework for memory research. Journal of Verbal Learmng and Verbal Behavwr, 1972, 11, 671-684. DARLEY,C. F , & MURDOCK,B. B., JR. Effects of prior free recall testing on final recall and recognmon. Journal of Experimental Psychology, 1971, 91, 66-73. ENGLE,R. W. Negative recency in delayed recognition. Journal of Verbal Learning and Verbal Bebavtor, 1974, 13, 209-216. HOOAN,R. M., & KTNTSCH,W. Differential effects of study and test trials on long-term recognition and recall. Journal of Verbal Learning and Verbal Behavtor, 1971, 10, 562-567. RUNDUS, D., LOFTUS,G. R., & ATKINSON,R. C. Immediate free recall and three week delayed recogration. Journal of Verbal Learnmg and Verbal Behavtor, 1970, 9, 684-688. (Received June 24, 1974)
14, 253-258 (1975)
The Facilitation of Recognition by Recall ROBERT S. LOCKHART University of Toronto
Existing evidence suggests that the free recall of an item does not facilitate its subsequent recognition. An analysis of this evidence mdmates that even if recall did facilitate the recogration of lndwidual 1terns, previously employed paradigms are such that its overall effect might not be readily apparent. Results are reported which confirm this prediction and show that the facilitating effect of free recall on recogmtlon is quite substantial. recency. Cohen's (1970) unconditionalized serial position curves do, in fact, show such positive recency. This result when taken together with the negative recency for conditionalized curves (Craik et al., 1970) suggests that final recognition is indeed facilitated by initial recall. The results reported by Rundus, Loftus, and Atkinson (1970) question the validity of this conclusion, while those of Darley and Murdock (1971) and of Hogan and Kintsch (1971) manifestly contradict it. The Darley and Murdock study found no difference in final recognition between words from lists which had been previously recalled and words from lists for which no recall had been permitted. This result is surprising, not only because of Cohen's (1970) data, but also because Darley and Murdock (1971) found that, while not aiding recognition, initial recall did facilitate final recall. If, so far as final retention is concerned, immediate recall is somewhat like an incidental learning trial, quite the opposite result might have been expected. In any case, a manipulation which facilitates recall but not recognition is of considerable theoretical interest since it is a result which poses difficulties for some current models, and offers strong support for others. Research supported by National Research Council It is important to note that in a paradigm of Canada Grant No. A0355. Requests for reprints such as that used by Darley and Murdock should be sent to Robert S. Lockhart, Department of (1971), any facilitating effect of recalling a Psychology, Umvers~tyof Toronto, Toronto, Canada, word can manifest itself only with respect to a M5S 1A1. Copyright © 1975 by Academic Press, Inc 253 All rights of reproductton m any form reserved,
The most satisfactory account of the negative recency effect in free recall (Craik, 1970) is in terms of the differences in the type of processing necessary to support long-term as opposed to short-term retention. Whereas relatively superficial processing (Craik & Lockhart, 1972) is sufficient to support the immediate recall of items from late serial positions, such items are not adequately coded for long-term retention. Negative recency has also been observed when recogration rather than recall is used as the final test of retention (Craik, Gardiner, & Watkins, t970). However, some care needs to be taken in interpreting this latter result. In this case the negative recency effect applies to the final recognition of those items initially recalled, not to the unconditionalized or absolute level. The purpose of conditionahzing in this way is, presumably, to equate items for any facilitating effects that immediate recall itself might have on an item's subsequent recognition. To the extent that such facilitation occurs, recency items would receive a disproportionate advantage since they are recalled with a high probability. If this facilitation is substantial then it is quite possible that the absolute level of final recognition would display positive
Printed m Great Britain
254
ROBERT S. LOCKHART
rather special subset of items--items that Jointly fulfill certain conditions. Obviously the tem must be recallable in immediate recall. Thus the serial position curve for immediate recall represents an upper bound on the proportion of items that can be potentially facilitated. Not only must the item be recallable, its code must be sufficiently transitory so that, were immediate recall to be prevented, the trace would deteriorate to a point where the word would not be recognized in the final retention test. Items from early and middle serial positions of a free recall list are unlikely to be of this kind, since for such words to be recallable (even in immediate recall) they must be so well coded (m long-term memory, if you will) that in all likelihood they would be subsequently recognized with or without immediate recall actually taking place. On the other hand, items from the recency portion of the serial position curve are much more likely to fulfill the required conditions. This is exactly what the negative recency effect itself suggests: Recall from late serial positions is on the basis of a code which is subject to rapid deterioration. It follows from these considerations that the overt rehearsal technique of Rundus et al. (1970) used by Darley and Murdock (1971) is less than optimal since, compared to standard free recall, it yields a rather attenuated recency effect and its slow presentation rate (5 sec) would also serve to minimize the number of items recalled on the basis of a transitory code. The preceding analysis leads to the conclusion that the facilitating effects of recall on recognition will be concentrated in the recency portion of the input serial position curve, and that the effect should be seen most clearly at fast presentation rates. The purpose of the present paper is to report results which support both of the above conclusions. METHOD
Subjects were g~ven 12 lists, each consisting of 20 common English nouns selected ran-
domly from a pool totalling 1790. The words were presented at one of three rates: .75, 1.5, or 5.0 sec each. A total of 120 University of Toronto undergraduates served as subjects, 40 at each presentation rate. For each of these three groups, a randomly selected half of the lists were followed by an instruction to free recall; the other half were followed by a three digit number from which subjects counted backwards by threes as rapidly as possible. The time allowed for both activities was 2 rain. To ensure adherence to the distractor task, subjects were informed that the purpose of the experiment was to study the effect of the two tasks (free recall and backward counting) on each other, and that performance on each task was equally important. Moreover, no indication was given that there would be a final recognition test. The first two lists were practice lists; one was followed by the free recall instruction, the other by a three digit number, signalhng the start of the backward counting task. In the remaining 10 lists the order of the recall and no-recall instructions was randomly determined. Subjects were run in groups of eight and heard the words through headphones in individual partitioned cubicles. To ensure an adequate sampling of materials, each group of eight subjects within a given presentation rate received a different set of 12 lists, all lists being constructed by randomly drawing words from the previously mentioned pool of 1790. However the same sets of lists were used across the three presentation rates. Following the presentation of the final list, subjects were given a 200 item, three-alternative forced-choice recognition test of the words from all 10 lists. The 400 distractors were a random selection from the same noun pool. The subjects were given a sheet containing the 200 sets of three alternatives and asked to underline the one word in each set they judged to be previously presented. They were asked to also circle the underlined word if they remembered having recalled it. As much t~me as needed was allowed for this recognition test.
FACILITATION OF RECOGNII ION BY RECALL
recency across all rates. These curves are, of course, unconditional probabilities. For lists which were immediately recalled, conditional probabilities (the probability of correct recognition given initial recall) may be plotted. These functions are shown in Figure 2 and the strong negative recency effect (at least for fast rates) is evident, replicating the results of Craik et al. (1970). It should be remembered that, as with all such conditionalized functions, the negative recency effect will be strongly influenced by item selection factors. As pointed out in the introduction, initial recall from early serial positions will usually denote an item that has been well coded, whereas this is not necessarily true of items recalled from late serial positions. A similar negative recency effect is shown in Figure 3 which g~ves the probability of correctly identifying a word as one which had been previously recalled. These hit rates may be interpreted relative to several false-alarm rates; words wrongly identified as having been recalled may be either from recalled lists, or from nonrecalled lists, or words which were entirely new (lures in the recognition test). The proportions of each of these types of items which were misidentified are respectively .08, .11, and .04. It is evident that subjects can
RESULTS
Analysm of the data to be discussed is limited to the last six input serial positions; as expected an analysis of variance applied to the data for serial positions 1-14 showed there were no differences between items from recalled and nonrecalled lists in these earlier serial positions at any of the presentation rates. Recognition levels for the late serial positions are shown in Figure I. Apart from the expected effect of rate, F(2, 105) = 31.7, two substantial effects are evident; recognition is superior for recalled lists, F(1, 105)= 44.0, and this difference increases quite sharply across the last few serial positions, the interaction between serial position and the recall condition yielding F(5, 525)=13.8. The magnitude of this interaction diminishes somewhat as rate of presentation decreases, F(10, 525) = 2.3, p < .05. This latter three-way interaction seems to be largely a consequence of the increase in the amount of negative recency in non-recalled lists as the presentation rate increases. Whereas there is a strong negative recency effect for rapidly presented nonrecalled lists, there is virtually none for lists presented at the slow, 5-sec rate. Lists which were immediately recalled show positive
z _o }z
.8
255
I oNON RECALLED LISTS / • o RECALLED L STS _ ]
.7
o
/
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6
rr
rr .5 O (.~
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i
]
15 16 17 SERIAL
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I
18 19
2i0
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I I I I 210 16 17 18 19
POSITION
FIG. I. Probabthty of correct recognitxon for recalled and nonrecalled lists as a function of input serial position.
256
ROBERT S. LOCKHART
4, •
bJ 0
..,t~
. . . ' ~ . " ° - - ~ . _ . ~_----"~ -o.
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SERIAL POSITION
FIG. 2. Probability of correct recognition for items immediately recalled.
accurately identify 1terns they have previously recalled, but that their accuracy declines at late serial position. DISCUSSION
While the results show that recalling an item facilitates the subsequent recognition of that item, it is difficult to obtain a meaningful quantification of the effect directly from the data. The reason for this d~fficulty is that the magnitude of the observed difference between recalled and non-recalled lists is a joint function of two probabilities: the probability that an item will be correctly recognized by virtue of its being recalled and the probability that an item is of the kind that would not have been recognized, had the recall not taken place.
This statement may be formalized in terms of a simple finite state model which also serves to provide some insight into the magnitude of the facilitation. The model is purely descriptive in the sense that it is concerned merely to quantify certain aspects of the data, not with underlying mechanisms. Items from a list may be classified into one of four states representing whether or not the item is recallable in immediate recall (R or P,) together with whether or not it is recognizable m final recognition (G or G). Thus an item in state R G is one which would be recalled in immediate recall (if such were permitted) but would not be recognized in final recognition. It is only items of this type that can potentially be facilitated by the act of initial recall, and the parameter of current interest ~s the prob
8
7
6
o u_
"
"o,
5
_
4
I • '~ ' J
w0~01
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5
SERIAL
POSITION
FIG. 3. Probabihty of correctly identifying an item as having been recalled in immediate recall test.
FACILITATION OF RECOGNITION BY RECALL
ability that an item in state R G makes a transition into state R G as a consequence of immediate recall being allowed to occur. Denote this probabihty by a and let r be the probability that, in the absence of an immediate recall test, an item is in state RG. Then for a k-alternative forced choice recognition test, the probability of a correct recognition is simply 1/k for R G items in nonrecalled lists, and a + (1 - a)/k for R G items in recalled lists. Thus the increment in recognition probability as a consequence of immediate recall taking place is given by
:ra 0 For items to be recalled but not subsequently recognized, they must jointly fulfill three conditions: They must be in state R(3, they must remain in that state, despite immediate recall, and finally, they must not be guessed. Thus the expected proportion, p, of items recalled but not subsequently recognized is r(1 - a)(1 - l/k). From this we can obtain an expression for r, and substituting it in the above equation for D, we get
D=p That is, the effect on final recognition of initially recalling an item is dlrectly proportional to the probability that an item will be recalled but not recognized. If this probability is near zero then D will be near zero, even if a is substantially greater than zero. This situation exists in both Hogan and Kintsch (1971) and in Darley and Murdock (1971). Since D a n d p are observed, they may be used to obtain estimates of a. While both of these observed probabilities vary with serial position and the rate of presentation, a will be taken to be independent of such factors, although it is almost certainly the case that, in general, the facilitating effects of recall vary with serial position (Bartlett & Tulving, 1974). However,
257
the present experimental paradigm permits only a single estimate of a since D is nonzero only for the last few serial positions. Moreover, such an estimate can be considered a lower bound, in that recall from earlier serial positions should yield larger values of a. It should be kept in mind that a is a transition parameter which may take on a high value for items in early serial positions, even although such items manifest no facilitation from initial recall. This is so because such facilitation is a function not only of a but also of p and the latter is typically near zero for these early items. The single least-squares estimate of a for the data shown in Figure 1 is .43, a value which represents a substantial degree of facilitation. If applied to the initial presentation of an item, this transition probability would yield a performance level of .57 in a three-alternative forced-choice recognition test, a value which is approximately equal to final recognition of nonterminal items from lists presented at a 1.5-sec rate. There is little variability in the value of a if it is estimated separately for each presentation rate; the respective values for the fast, medium, and slow rates are .44, .43 and .39. Values of a may be calculated for each serial position point in Figure 1, but the results are less stable, especially as D becomes small, and no meaningful trend is evident. It is important to note that the issue is not one of failing to replicate previous results. In fact, the data in Figure 1 for the 5 second rate are in close agreement with those reported by Darley and Murdock (1971). The point to be stressed is that the effects of recall on subsequent recognition frequently will be concealed because recallable items will usually be recognized even without the aid of the recall test. Although the present experiment was not directly concerned with negative recency effects, it does serve to clarify one point. Since the initial recall of terminal items influences their delayed recogmtion, previous attempts to examine negative recency in a delayed recognition test (Crmk et aI., 1970; Cohen,
258
ROBERT S. LOCKHART
1970; Engle, 1974) have confounded input effects with those of initial recall. Conditionalizing on initial recall serves only to complicate matters since at introduces item selection factors. A clear picture is provided by the final recognition of items f r o m lists not immediately recalled; negative recency exists in delayed recognition and its magnitude increases with the rate of initial presentation. It is interesting to note that this same trend exists for the accuracy of identifying a word as having been recalled. The data in Figure 3 have n o t been condationalized on correct recognition (this can be done by dividing the values in Figure 3 by the corresponding values m Figure 2) but even after conditionalizing, negative recency is still present. Thus even for items correctly recognized, the fact o f recall is better remembered for items from nonterminal serial positions. This result is exactly what would be expected if the processing involved in free recalling an item is qualitatively different (deeper) for nonterminal serial positaons. REFERENCES BARTLETT,J. C., ~%TuLVING,E. Effects of temporal and semantic encoding in immediate recall upon sub-
sequent retrieval. Journal of Verbal Learning and Verbal Behavior, 1974, 13, 297-309. COHEN, R. L. Recency effects in long-term recall and recognmon. Journal of Verbal Learning and Verbal Behavtor, 1970, 9, 672-678. CRAIK,F. I. M. The fate of primary memory atems in free recall. Journal of Verbal Learnmg and Verbal Behavwr, 1970, 9, 143-148. CRAIK,F. I. M, GARDINER,J. M , & WATKINS,M. J. Further evidence for a negative recency effect m free recall. Journal of Verbal Learning and Verbal Behavior, 1970, 9, 554-560. CRAIK,F. I. M., & LOCKHART,R. S. Levels of processing: A framework for memory research. Journal of Verbal Learmng and Verbal Behavwr, 1972, 11, 671-684. DARLEY,C. F , & MURDOCK,B. B., JR. Effects of prior free recall testing on final recall and recognmon. Journal of Experimental Psychology, 1971, 91, 66-73. ENGLE,R. W. Negative recency in delayed recognition. Journal of Verbal Learning and Verbal Bebavtor, 1974, 13, 209-216. HOOAN,R. M., & KTNTSCH,W. Differential effects of study and test trials on long-term recognition and recall. Journal of Verbal Learning and Verbal Behavtor, 1971, 10, 562-567. RUNDUS, D., LOFTUS,G. R., & ATKINSON,R. C. Immediate free recall and three week delayed recogration. Journal of Verbal Learnmg and Verbal Behavtor, 1970, 9, 684-688. (Received June 24, 1974)