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Implicit responses in incidental learning
JOURNAL OF VERBAL LEARNING AND VERBAL BEHAVIOR 8, 1 3 6 - 1 4 2
(1969)
Implicit Responses in Incidental Learning I WILLIAM P. WALLACEAND ROBERT N. CALDERONE University of Nevada, Reno, Nevada89507
Three experiments were conducted to investigate the role of implicit associative response OAR) occurrence in incidental learning. Lists of conceptually related words were presented at a rapid rate followed by a test of free recall. Although differencesamong groups were small, recall scores and clustering scores consistently favored the intentional learners. It was suggested that the procedures which define incidental learning result in a reduction in IAR occurrence. test. The recognition test consisted of presenting each list word grouped with three words associatively related to it. During intentional learning, the list words elicit IARs (presumably the buffer associates), consequently the recognition test may have contained a source of interference due to difficulty in discriminating the words actually presented and the IARs. If IARs are infrequent in incidental learning, then the incidental learners should have experienced little of this interference on the recognition test. The occurrence of IARs is assumed to be beneficial to learning or interfere with learning only in specific situations, e.g., when the presumed IARs also occur in the list or serve to relate list members. It is suggested here that performances under intentional- and incidental-learning conditions may differ because: (a) instructed learners can more efficiently program their rehearsal than incidental learners, and (b) the occurrence of IARs is more likely when Ss are instructed to learn. Mechanic's procedure minimized rehearsal differences between groups, and his materials minimized the influence of IARs on performance. The purpose of the present experiments was to compare intentional and incidental learning when I A R occurrence was presumed to facilitate performance. A rapid presentation rate was used in an effort to neutralize the rehearsal l This study was supported in part by Grant GB8605 from the National Science Foundation and by funds advantages of groups instructed to learn. Thus, an attempt was made to minimize rehearsal from the University of Nevada Graduate School. 136
When Ss are presented with a list of verbal units and informed of an impending memory test, their performance on that test generally exceeds the performance of uninformed Ss (McLaughlin, 1965; Postman, 1964). However, in a recent series of experiments a procedure has been developed which eliminates the advantage of instructions to learn (Mechanic, 1964; Mechanic and Mechanic, 1967). In general, with the Mechanic procedure a list of nonsense syllables is presented at a rapid rate. Subjects not instructed to learn are required to pronounce each item as it appears. This procedure is assumed to minimize differences in rehearsal between intentional and incidental learners. It has been sugested that in addition to priming rehearsal, instructions to learn also prime the occurrence of implicit associative responses (IARs) (Wallace, 1968). That is, when the letters CA T are presented, instructed Ss are more likely to respond implicitly with " d o g " or some other associate of " c a t " than are uninstructed Ss. Eagle and Leiter (1964) have presented data which suggest that Ss not instructed to learn may be less susceptible to associative interference than Ss instructed to learn. They found that instructions to learn facilitated recall, but incidental learners surpassed intentional learners on a recognition
137
IARS IN INCIDENTAL LEARNING differences b e t w e e n i n t e n t i o n a l - a n d incid e n t a l - l e a r n i n g g r o u p s in s i t u a t i o n s w h e r e I A R o c c u r r e n c e was p r e s u m e d to influence performance. EXPERIMENT I M e c h a n i c a n d M e c h a n i c (1967) u s e d a 1-sec p r e s e n t a t i o n r a t e a n d f o u n d n o differences in free recall b e t w e e n a n i n c i d e n t a l - l e a r n i n g group which performed a pronouncing task a n d a n i n t e n t i o n a l - l e a r n i n g g r o u p w h i c h did n o t p e r f o r m a p r o n o u n c i n g task. T h e i r d e s i g n was r e p e a t e d in the p r e s e n t e x p e r i m e n t w i t h lists o f c o n c e p t u a l l y r e l a t e d w o r d s . S u b j e c t s i n s t r u c t e d to l e a r n w e r e e x p e c t e d to p e r f o r m b e t t e r o n a list o f h i g h c o n c e p t u a l , s i m i l a r i t y ( H S ) t h a n o n a list o f l o w c o n c e p t u a l s i m i l a r i t y (LS) d u e to the i m p l i c i t o c c u r r e n c e o f t h e c o n c e p t n a m e , o r o t h e r c a t e g o r y instances, d u r i n g l e a r n i n g . S u b j e c t s n o t i n s t r u c t e d to learn, a n d p r e s u m a b l y deficient in I A R o c c u r r e n c e , w e r e e x p e c t e d to s h o w little difference b e t w e e n l e a r n i n g a n H S list a n d a n L S list.
Method The design of this experiment involved a 2 × 2 factorial combination of instructions to learn and conceptual similarity. There were four groups of Ss: an intentional group exposed to an HS list, an intentional group exposed to an LS list, an incidental group exposed to an HS list, and an incidental group exposed to an LS list. Materials. Four of the most frequently occurring instances in each of 28 categories were selected from the Cohen, Bousfield, and Whitmarsh norms (1957). Two lists of 28 items each were constructed from this material. The words in the HS list were chosen by randomly selecting seven of the 28 categories and using all four instances in those seven categories. The words in the LS list were obtained by randomly selecting one member from each of the 28 categories. There were seven words common to both lists. In the LS list, words were randomly arranged into "categories" of four words each (for purposes of later assessing chance clustering). For example, one HS category included doctor, lawyer,professor, and dentist, whereas Germany, head, professor, and peach were included in a corresponding LS category. Each member of a given HS category was matched with a member from a corresponding LS category. Thus, any influence on recall order of item position during the study trial would affect HS and LS recall equally. In each category of the
HS and LS lists, one-half of the members were presented once and one-half were presented twice during the study trial. Procedure. The lists were presented on a Stowe memory drum at a 1-sec rate, i.e., each word appeared for 1 sec and was then replaced by the next word in the sequence. Subjects in the intentional-learning groups were told that they would be shown a list of words, and later they would be given a chance to write down as many as they could remember. Subjects in the incidental-learning groups were told they were participating in an experiment designed to investigate reaction times and changes in the pronunciation and inflection of words. They were told to pronounce each word once as soon as it appeared in the window. A microphone was located below the window of the memory drum and was connected to a tape recorder which operated within view of Ss. No reference was made to the memory test. The tape recorder was not operative during the study trial for the intentional-learning groups. After the study trial all Ss were provided with answer sheets having 28 numbered spaces. The Ss were told to write the words they had just seen in any order they wished. There was an interval of approximately 15 sec between the study trial and the recall test. A maximum of 3 min was allowed for recall. Subjects. Sixty-four undergraduate psychology students attending the summer session at Northwestern University participated in the experiment. There were 16 Ss in each condition. Subjects were assigned to conditions based on their order of appearance at the laboratory. The scheduling of times for the various conditions was determined by reference to a table of random numbers. When questioned after the experimental session, none of the 32 Ss in the incidental groups indicated that he had anticipated a memory test.
Results Correct Recall. T h e m e a n recall s c o r e s a r e p r e s e n t e d in the first t w o r o w s o f T a b l e 1. A n analysis o f v a r i a n c e o n t h e s e d a t a i n d i c a t e d that the intentional groups (INT-U--intentional learners unencumbered by the pron o u n c i n g task) r e c a l l e d m o r e w o r d s t h a n the TABLE 1 MEAN NUMBER OF CORRECT RESPONSES
Instructions
Exp. I Exp. II
Similarity
INC
INT-U
INT-O
HS LS HS LS
12.00 10.00 12.85 9.70
17.06 11.44 14.30 10.15
--13.10 11.65
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TABLE 2 incidental groups (INC), F(1, 6 0 ) = 16.54, MEAN CLUSTERING RATIOS p < .01 ; and more words were recalled in the HS conditions than in the LS conditions, Instructions F(1, 60) = 22.76,p < .01. The finding of major Similarity INC INT-U INT-O interest was the Instructions × SimilarityinterHS .384 .725 -action, F(1, 60) = 5.14, p < .05. The difference Exp. I LS .277 .182 -between recall of HS and LS lists was greater Exp. II HS .475 .599 .477 when Ss were instructed to learn than when Ss LS .214 .203 .259 were not instructed to learn. Since the differences in recall between HS and LS for in- main effect for similarity, F(1, 60)=26.16, tentional learners may be said to reflect the p < .01, and a significant interaction, F(1, 60) positive influence of IARs, it appears that = 11.76, p < .01. There was a greater amount incidental learners experienced less of this of clustering with HS lists than with LS lists, positive influence than intentional learners. and the above chance (HS minus LS) clustering There were seven items common to both for the intentional-learning group was greater HS and LS lists. Comparisons in recall of than for the incidental-learning group. The these seven items paralleled comparisons of main effect of instructions to learn was not over-all recall. It does. not appear that the significant, F(I, 60) = 3.75. similarity effects can be explained in terms of Category Recall. In the HS conditions, specific item differences between HS and LS Group INT-U was superior in recall to Group lists. INC. It was of interest to determine whether Clustering. The assumption that instructions Group INT-U recalled more categories than to learn prime IAR occurrence leads to the Group INC, or whether they recalled more prediction Of greater clustering (Ss group to- instances within each category. The mean gether words from the same category during number of categories represented in the recall recall) for the intentional HS group than for scores of Group INT-U was 6.25 and for Group the incidental HS group. Items in the LS lists INC, 5.94. The difference between these were randomly arranged into sets of four to groups was not significant, F(1, 30)--1.47. provide an empirical baseline of chance cluster- The mean number of categories recalled by ing. Clustering ratios (CRs) were determined chance (based on the performance of the LS for each S by the following formula: CR = groups) was 5.93, a value well within the range r/(n-k), where r = the number of times a word of category recall for both HS groups. was followed by another word from the same The recall-per-category score was obtained category, n - the total number of words re- by dividing the number of items recalled by the called, and k = the number of categories from number of categories represented in recall. For which at least one word was recalled. This the HS groups, Group INT-U averaged 2.73 clustering measure differs from the ratio of instances per category and Group INC averrepetition (Bousfield, Whitmarsh, and Cohen, aged 2.01. The difference between these 1958) in the denominator where n-k is used groups was significant, F(1, 3 0 ) = 19.36, instead of n-l. The rationale for this variation p < 01. The difference between the HS INC is that the first item recalled from each category group and the combined LS groups (an avercannot be counted as a repetition (r). Perfect age of 1.78 instances per category) was not clustering is indicated by a score of 1.00, and it significant, F(1, 46) = 3.01. is independent of number of items recalled. The mean CRs for each group are presented Discussion Mechanic and Mechanic (1967) used nonin the first two rows of Table 2. A 2 × 2 sense syllables and found no difference beanalysis of variance indicated a significant
IARS IN INCIDENTALLEARNING tween intentional and incidental learning groups. Highly meaningful words were used in the present experiment and superiority in recall and clustering was demonstrated forgroups instructed to learn. The results of the present study are consistent with the position that IAR occurrence is primed by instructions to learn. However, there exists the possibility that it was the pronouncing task rather than absence of instructions to learn which interfered with IAR occurrence. Experiment II included an intentional-learning group which also performed the pronouncing task.
139
F(2, 114)=2.20, and this variable did not interact with similarity, F(2, 114)=2.87. A comparison involving only conditions common to Exp. I (INT-U and INC) did not alter the outcome of this analysis. The main effect for learning conditions did reach significance when the analysis was restricted to the seven items common to both HS and LS, F(2, 114) = 3.52, p < .05. Clustering. The mean CRs are presented in the bottom two rows of Table 2. As with the recall scores, it may be noted that differences in clustering between the learning conditions were substantially reduced in Exp. II comEXPERIMENTII pared to differences in Exp. I. A 2 × 3 analysis Method of variance indicated that there was signifiExperiment II was a replication of Exp. I with the cantly greater clustering with the HS lists than addition of an intentional-learning group which also with the LS lists, F(I, 114) = 42.96, p < .01. performed the orienting task of pronouncing each The interaction between learning conditions word as it appeared (INT-O). The materials and procedures were identical with Exp. L The Ss were 120 and similarity did not approach significance, introductory psychology students attending the Uni- F(2, 114)= 1.46. Restricting the analysis to versity of Nevada. There were 20 Ss assigned randomly Groups INT-U and INC did not alter the to each of six groups. Four Ss in the incidental-learning significance of any effect. groups (two in the HS condition and two in the LS condition) were discarded and replaced by other Ss Discussion from the same population. The discarded Ss reported No firm conclusion could be reached conthat they anticipated a memory test. cerning whether the pronouncing task or Results absence of instructions to learn interfered with The results of Exp. II were similar to those IAR occurrence. In general the results of Exp. o f Exp. I in terms of the direction o f differences II are at variance with those of Exp. I in terms between intentional and incidental groups. For of significance. The direction of the differences all comparisons, higher scores were obtained between groups in the two experiments is by Ss instructed to learn. However, the magni- similar, but the magnitude of the differences is tude of the differences between groups was greatly reduced in Exp. II. The performance o f small and most often not significant. Only data G r o u p INT-O more closely approximated the on correct recall and clustering are reported. performance of Group INC, rather than G r o u p Correct Recall. The mean correct recall INT-U. Inspection of Tables 1 and 2 reveals scores for the six groups are presented in the that Group INT-U with the HS list in Exp. I bottom two rows of Table 1. It may be noted performed at a much higher level than the that differences in recall between the groups are corresponding group in Exp. II. The remaining substantially reduced in Exp. II compared to groups appear reasonably comparable bedifferences in Exp. I. A 2 x 3 analysis of tween the two experiments. Any number o f variance revealed a significant main effect for differences between Nevada and Northwestern similarity, F(1, 114) = 39.38, p < .01. Higher students may, in part, account for the disrecall scores were found for HS lists than for crepant findings. It is likely that operations LS lists. The three learning conditions (INT-U, which increase IAR occurrence will result in INT-O, and INC) did not differ reliably, higher recall and greater clustering for Group
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INT-U. If such operations do not produce a similar effect for incidental learners, then the major discrepancy between Exp. I and Exp. II may be attributed to S variables responsible for greater implicit responding by Northwestern Ss. Instructions to learn may prime I A R occurrence during learning; however, I A R occurrence during the recall trial may minimize differences between intentional and incidental learners. That is, a S in the incidental group may recall " c a t " which elicits "animal" as an I A R at the time of recall. The I A R o f " a n i m a l " may then lead to recall of other instances of that category by means of a backward association from the I A R to the category instance. It has been demonstrated that instructing Ss at the time of recall to cluster pairs of associatively related words reduces the differences in recall between intentional and incidental learners (Postman, Adams, and Bohm, 1956). It is possible that operations which reduce I A R occurrence will result in a greater difference between intentional and incidental learning. That is, the critical I A R may be less likely to occur at the time of recall, and this may be more crucial to the incidental group than it is to the intentional group. EXPERIMENT III In this experiment an effort was made to influence the level of recall and amount of clustering by manipulating variables presumed to either increase or decrease the "obviousness" of the conceptual relations linking sets of items in a free-recall list. Constrained order of presentatiol~ (all associates of one class presented first, then all associates of another class, etc.) is a variation that might be regarded as increasing the likelihood that the critical IARs will occur (compared to the random presentation used in Exp. I and Exp. II). Weingartner (1964) demonstrated that both recall and clustering were higher for a constrained presentation order than for a random presentation order. Taxonomic strength (normative frequency of occurrence of category responses)
was high in both Exp. I and Exp. II, and lowering this might result in a reduction in the occurrence of the critical IARs. Bousfield et aL (1958) demonstrated that both recall and clustering were higher for category responses of high taxonomic strength compared to lowstrength responses. In the present experiment, intentional and incidental learning of an HS list was compared. The HS list was presented in either a random (R) or constrained (C) order, and the taxonomic strength of category members was either high (H) or low (L). Method The experiment involved a factorial combination of three variables." Learning conditions (INT-U, INT-O, and INC), presentation order, and taxonomic strength. Four comparisons are provided between the learning conditions, i.e., comparisons between intentional and incidental learning with a high-random (HR) list, a high-constrained (HC) list, a low-random (LR) list and a low-constrained (LC) list. The procedure was identical to that used in Exp. II. Materials. The HS list of Exp. I and Exp. II was presented to six groups. The remaining six groups were presented with a list constructed from low-frequency category responses to the seven HS categories. These low-frequency responses were selected from the Cohen et al. norms (1957). For example, the low-frequency responses selected from the category of professions were: writer, coach, baker, and farmer. There were 28 words in each list and all words occurred a single time during the study trial. The order of the words was random with two restrictions: In the random order, items from a common category did not appear in adjacent positions, and in the constrained order, all items from a common category appeared before any item from a new category was presented. The arrangement of categories and items within categories was random. Subjects. The Ss were 192 introductory psychology students attending the University of Nevada. Sixteen Ss were assigned randomly to each of the 12 groups. One S in the LR INC group reported anticipating the memory test and was replaced. Results Correct Recall. The present experiment was conceived as four separate experiments involving INT-U, INT-O, and I N C comparisons. It was of interest to determine if intentional and incidental learning differences were present
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for any of the lists. An analysis of variance with simple effects for the three learning conditions (Winer, 1962) was applied to all major response scores. The mean total correct responses are presented in Table 3. It may be seen from Table 3 that, with the exception of the LR condition, the groups are ordered consistently with highest recall for INT-U followed by INT-O. Group INC had the lowest recall for each list. Differences among INT-U, INT-O, and INC were significant only when taxonomic strength was low and words were presented in a constrained order, F(2, 180) = 3.79, p < .05. Recall for Group INT-O (LC list) was about equidistant between Group INT-U and Group INC. Constrained presentation order resulted in higher recall than random order, F(1, 180) = 98.28, p < .01, and there was higher recall for words of high taxonomic strength compared to words of low taxonomic strength, F(1,180) = 32.60, p < .01. These latter findings are in agreement with the results of Weingartner (1964) and Bousfield et al. (1958). No other effects were significant. TABLE 3 MEAN NUMBEROF CORRECT RESPONSESIN EXP. III Instructions Lists
INC
INT-U
INT-O
HR HC LRLC
12.94 15.38 9.50 10.62
15.06 17.81 9.75
13.88 17,00 10,50
13.56
12.19
Clustering. The mean CRs are presented in Table 4. With the exception of one reversal between Group INT-O and Group INC in the HR conditions, INT-U showed the greatest amount of clustering, with INT-O second and INC third. The analysis of variance with simple effects indicated that differences in clustering between INT-U, INT-O, and I N C were significant only for the LC list, F(2, 180) = 3.43,p < .05. There was only a slight difference in amount of clustering between Group INT-O and Group INT-U, with both superior to Group INC. As with correct recall, both
taxonomic strength and presentation order produced significant main effects, F(1, 180) = 17.67,p < .01 and F(1,180) = 179.49,p < .01, respectively. TABLE 4 MEAN CLUSTERINGRATIOS IN EXP. III Instructions Lists
INC
INT-U
INT-O
HR HC LR LC
.497 .848 .260 .683
.594 .917 .385 ,865
.431 .861 .294 .855
Category Recall. The mean number of categories represented in recall ranged from 4.94 to 6.25. Analysis of the simple effects did not reveal any significant differences between learning conditions. There were significantly more categories represented in recall when category instances were high in taxonomic strength than when they were low, F(1,180) -15.40, p < . 0 1 , and more categories were represented in recall when presentation order was random than when it was constrained, F(1,180) = 11.79,p < .01. The words-per-category measure did not indicate any differences between INT-U, INT-O, and INC. More words were recalled per category with lists of high taxonomic strength, F(1, 180) = 62.39, p < .01 and when presentation order was constrained, F(1, 180) = 92.92, p < .01. Discussion The presentation order and taxonomic strength variables did not appear to differentially affect intentional and incidental learning. All groups showed higher levels of recall and clustering when the presentation order was constrained as compared to random, and all groups showed higher levels of recall and clustering when taxonomic strength was high as compared to low. The largest separation between groups appeared with the combination of constrained order and low taxonomic strength.
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WALLACEAND CALDERONE
This experiment was consistent with the previous experiments in showing that Ss instructed to learn were superior in recall and clustering to Ss not instructed to learn. The difference as a function of instructions to learn was more p r o n o u n c e d f o r high-similarity material than for low-similarity material, although this was not always supported statistically. Both recall and clustering differences a m o n g groups appeared with category instances of low as well as high taxonomic strength, and when presentation order was constrained as well as random. However, these differences were significant only for the c o m b i n a t i o n o f H R (in Exp. I but not in Exp. II or Exp. III) and L C (Exp. III). In all cases, performing the p r o n o u n c i n g task had a depressing effect on recall and cl,ustering~for intentional learners, but in absolute ~alues their performance still exceeded the performance o f incidental learners. These results are consistent with the interpretation that I A R s do not occur as readily under conditions o f incidental learning as they do under conditions o f intentional learning. REFERENCES BOUSFIELD, W. A., COHEN,B. H., AND WHITMARSH,G.
A. Associative clustering in the recall of words of different taxonomic frequencies of occurrence. PsychoL Rep., 1958, 4, 39--44.
COHEN,B. H., BOUSFIELD,W. A., ANDWHITMARSH,G. A. Cultural norms for verbal items in 43 categories. Technical Report No. 22, 1957, University of Connecticut, Contract Nonr 631 (00), Office of Naval Research. EAGLE, M., AND LEITER,E. Recall and recognition in intentional and incidental learning. J. exp. PsychoL, 1964, 66, 58-63. McLAUGHLIN, B. "Intentional" and "incidental" learning in human subjects: The role of instructions to learn and motivation. Psychol. Bull., 1965, 63, 359-376. MECHANIC, A. The responses involved in the rote learning of verbal materials. J. verb. Learn. verb. Behav., 1964, 3, 30-36. MECHANIC,A., AND MECHANIC,J. D. Response activities and the mechanism of selectivity in incidental learning. J. verb. Learn. verb. Behav., 1967, 6, 389-397. POSTMAN, L. Short-term memory and incidental learning. In A. W. Melton (Ed.), Categories of human learning. New York: Academic Press, 1964~ POSTMAN,L., ADAMS,P. A., ANDBOHM,A~ W. Studies in incidental learning: V. Recall for~order and associative clustering. J. exp. Psychol., 1956, 51, 334-342. WALLACE, W. P. Incidental learning: The influence of associative similarity and formal similarity in producing false recognition. J. verb. Learn. verb. Behav., 1968, 7,-50-54. WEINGARTNER, H. The free recall of sets of associatively related words. J. verb. Learn. verb. Behav., 1964, 3, 6-10. WINER, B. J. Statistical principles in experimental design. New York: McGraw-Hill, 1962. (Received June 12, 1968)
(1969)
Implicit Responses in Incidental Learning I WILLIAM P. WALLACEAND ROBERT N. CALDERONE University of Nevada, Reno, Nevada89507
Three experiments were conducted to investigate the role of implicit associative response OAR) occurrence in incidental learning. Lists of conceptually related words were presented at a rapid rate followed by a test of free recall. Although differencesamong groups were small, recall scores and clustering scores consistently favored the intentional learners. It was suggested that the procedures which define incidental learning result in a reduction in IAR occurrence. test. The recognition test consisted of presenting each list word grouped with three words associatively related to it. During intentional learning, the list words elicit IARs (presumably the buffer associates), consequently the recognition test may have contained a source of interference due to difficulty in discriminating the words actually presented and the IARs. If IARs are infrequent in incidental learning, then the incidental learners should have experienced little of this interference on the recognition test. The occurrence of IARs is assumed to be beneficial to learning or interfere with learning only in specific situations, e.g., when the presumed IARs also occur in the list or serve to relate list members. It is suggested here that performances under intentional- and incidental-learning conditions may differ because: (a) instructed learners can more efficiently program their rehearsal than incidental learners, and (b) the occurrence of IARs is more likely when Ss are instructed to learn. Mechanic's procedure minimized rehearsal differences between groups, and his materials minimized the influence of IARs on performance. The purpose of the present experiments was to compare intentional and incidental learning when I A R occurrence was presumed to facilitate performance. A rapid presentation rate was used in an effort to neutralize the rehearsal l This study was supported in part by Grant GB8605 from the National Science Foundation and by funds advantages of groups instructed to learn. Thus, an attempt was made to minimize rehearsal from the University of Nevada Graduate School. 136
When Ss are presented with a list of verbal units and informed of an impending memory test, their performance on that test generally exceeds the performance of uninformed Ss (McLaughlin, 1965; Postman, 1964). However, in a recent series of experiments a procedure has been developed which eliminates the advantage of instructions to learn (Mechanic, 1964; Mechanic and Mechanic, 1967). In general, with the Mechanic procedure a list of nonsense syllables is presented at a rapid rate. Subjects not instructed to learn are required to pronounce each item as it appears. This procedure is assumed to minimize differences in rehearsal between intentional and incidental learners. It has been sugested that in addition to priming rehearsal, instructions to learn also prime the occurrence of implicit associative responses (IARs) (Wallace, 1968). That is, when the letters CA T are presented, instructed Ss are more likely to respond implicitly with " d o g " or some other associate of " c a t " than are uninstructed Ss. Eagle and Leiter (1964) have presented data which suggest that Ss not instructed to learn may be less susceptible to associative interference than Ss instructed to learn. They found that instructions to learn facilitated recall, but incidental learners surpassed intentional learners on a recognition
137
IARS IN INCIDENTAL LEARNING differences b e t w e e n i n t e n t i o n a l - a n d incid e n t a l - l e a r n i n g g r o u p s in s i t u a t i o n s w h e r e I A R o c c u r r e n c e was p r e s u m e d to influence performance. EXPERIMENT I M e c h a n i c a n d M e c h a n i c (1967) u s e d a 1-sec p r e s e n t a t i o n r a t e a n d f o u n d n o differences in free recall b e t w e e n a n i n c i d e n t a l - l e a r n i n g group which performed a pronouncing task a n d a n i n t e n t i o n a l - l e a r n i n g g r o u p w h i c h did n o t p e r f o r m a p r o n o u n c i n g task. T h e i r d e s i g n was r e p e a t e d in the p r e s e n t e x p e r i m e n t w i t h lists o f c o n c e p t u a l l y r e l a t e d w o r d s . S u b j e c t s i n s t r u c t e d to l e a r n w e r e e x p e c t e d to p e r f o r m b e t t e r o n a list o f h i g h c o n c e p t u a l , s i m i l a r i t y ( H S ) t h a n o n a list o f l o w c o n c e p t u a l s i m i l a r i t y (LS) d u e to the i m p l i c i t o c c u r r e n c e o f t h e c o n c e p t n a m e , o r o t h e r c a t e g o r y instances, d u r i n g l e a r n i n g . S u b j e c t s n o t i n s t r u c t e d to learn, a n d p r e s u m a b l y deficient in I A R o c c u r r e n c e , w e r e e x p e c t e d to s h o w little difference b e t w e e n l e a r n i n g a n H S list a n d a n L S list.
Method The design of this experiment involved a 2 × 2 factorial combination of instructions to learn and conceptual similarity. There were four groups of Ss: an intentional group exposed to an HS list, an intentional group exposed to an LS list, an incidental group exposed to an HS list, and an incidental group exposed to an LS list. Materials. Four of the most frequently occurring instances in each of 28 categories were selected from the Cohen, Bousfield, and Whitmarsh norms (1957). Two lists of 28 items each were constructed from this material. The words in the HS list were chosen by randomly selecting seven of the 28 categories and using all four instances in those seven categories. The words in the LS list were obtained by randomly selecting one member from each of the 28 categories. There were seven words common to both lists. In the LS list, words were randomly arranged into "categories" of four words each (for purposes of later assessing chance clustering). For example, one HS category included doctor, lawyer,professor, and dentist, whereas Germany, head, professor, and peach were included in a corresponding LS category. Each member of a given HS category was matched with a member from a corresponding LS category. Thus, any influence on recall order of item position during the study trial would affect HS and LS recall equally. In each category of the
HS and LS lists, one-half of the members were presented once and one-half were presented twice during the study trial. Procedure. The lists were presented on a Stowe memory drum at a 1-sec rate, i.e., each word appeared for 1 sec and was then replaced by the next word in the sequence. Subjects in the intentional-learning groups were told that they would be shown a list of words, and later they would be given a chance to write down as many as they could remember. Subjects in the incidental-learning groups were told they were participating in an experiment designed to investigate reaction times and changes in the pronunciation and inflection of words. They were told to pronounce each word once as soon as it appeared in the window. A microphone was located below the window of the memory drum and was connected to a tape recorder which operated within view of Ss. No reference was made to the memory test. The tape recorder was not operative during the study trial for the intentional-learning groups. After the study trial all Ss were provided with answer sheets having 28 numbered spaces. The Ss were told to write the words they had just seen in any order they wished. There was an interval of approximately 15 sec between the study trial and the recall test. A maximum of 3 min was allowed for recall. Subjects. Sixty-four undergraduate psychology students attending the summer session at Northwestern University participated in the experiment. There were 16 Ss in each condition. Subjects were assigned to conditions based on their order of appearance at the laboratory. The scheduling of times for the various conditions was determined by reference to a table of random numbers. When questioned after the experimental session, none of the 32 Ss in the incidental groups indicated that he had anticipated a memory test.
Results Correct Recall. T h e m e a n recall s c o r e s a r e p r e s e n t e d in the first t w o r o w s o f T a b l e 1. A n analysis o f v a r i a n c e o n t h e s e d a t a i n d i c a t e d that the intentional groups (INT-U--intentional learners unencumbered by the pron o u n c i n g task) r e c a l l e d m o r e w o r d s t h a n the TABLE 1 MEAN NUMBER OF CORRECT RESPONSES
Instructions
Exp. I Exp. II
Similarity
INC
INT-U
INT-O
HS LS HS LS
12.00 10.00 12.85 9.70
17.06 11.44 14.30 10.15
--13.10 11.65
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TABLE 2 incidental groups (INC), F(1, 6 0 ) = 16.54, MEAN CLUSTERING RATIOS p < .01 ; and more words were recalled in the HS conditions than in the LS conditions, Instructions F(1, 60) = 22.76,p < .01. The finding of major Similarity INC INT-U INT-O interest was the Instructions × SimilarityinterHS .384 .725 -action, F(1, 60) = 5.14, p < .05. The difference Exp. I LS .277 .182 -between recall of HS and LS lists was greater Exp. II HS .475 .599 .477 when Ss were instructed to learn than when Ss LS .214 .203 .259 were not instructed to learn. Since the differences in recall between HS and LS for in- main effect for similarity, F(1, 60)=26.16, tentional learners may be said to reflect the p < .01, and a significant interaction, F(1, 60) positive influence of IARs, it appears that = 11.76, p < .01. There was a greater amount incidental learners experienced less of this of clustering with HS lists than with LS lists, positive influence than intentional learners. and the above chance (HS minus LS) clustering There were seven items common to both for the intentional-learning group was greater HS and LS lists. Comparisons in recall of than for the incidental-learning group. The these seven items paralleled comparisons of main effect of instructions to learn was not over-all recall. It does. not appear that the significant, F(I, 60) = 3.75. similarity effects can be explained in terms of Category Recall. In the HS conditions, specific item differences between HS and LS Group INT-U was superior in recall to Group lists. INC. It was of interest to determine whether Clustering. The assumption that instructions Group INT-U recalled more categories than to learn prime IAR occurrence leads to the Group INC, or whether they recalled more prediction Of greater clustering (Ss group to- instances within each category. The mean gether words from the same category during number of categories represented in the recall recall) for the intentional HS group than for scores of Group INT-U was 6.25 and for Group the incidental HS group. Items in the LS lists INC, 5.94. The difference between these were randomly arranged into sets of four to groups was not significant, F(1, 30)--1.47. provide an empirical baseline of chance cluster- The mean number of categories recalled by ing. Clustering ratios (CRs) were determined chance (based on the performance of the LS for each S by the following formula: CR = groups) was 5.93, a value well within the range r/(n-k), where r = the number of times a word of category recall for both HS groups. was followed by another word from the same The recall-per-category score was obtained category, n - the total number of words re- by dividing the number of items recalled by the called, and k = the number of categories from number of categories represented in recall. For which at least one word was recalled. This the HS groups, Group INT-U averaged 2.73 clustering measure differs from the ratio of instances per category and Group INC averrepetition (Bousfield, Whitmarsh, and Cohen, aged 2.01. The difference between these 1958) in the denominator where n-k is used groups was significant, F(1, 3 0 ) = 19.36, instead of n-l. The rationale for this variation p < 01. The difference between the HS INC is that the first item recalled from each category group and the combined LS groups (an avercannot be counted as a repetition (r). Perfect age of 1.78 instances per category) was not clustering is indicated by a score of 1.00, and it significant, F(1, 46) = 3.01. is independent of number of items recalled. The mean CRs for each group are presented Discussion Mechanic and Mechanic (1967) used nonin the first two rows of Table 2. A 2 × 2 sense syllables and found no difference beanalysis of variance indicated a significant
IARS IN INCIDENTALLEARNING tween intentional and incidental learning groups. Highly meaningful words were used in the present experiment and superiority in recall and clustering was demonstrated forgroups instructed to learn. The results of the present study are consistent with the position that IAR occurrence is primed by instructions to learn. However, there exists the possibility that it was the pronouncing task rather than absence of instructions to learn which interfered with IAR occurrence. Experiment II included an intentional-learning group which also performed the pronouncing task.
139
F(2, 114)=2.20, and this variable did not interact with similarity, F(2, 114)=2.87. A comparison involving only conditions common to Exp. I (INT-U and INC) did not alter the outcome of this analysis. The main effect for learning conditions did reach significance when the analysis was restricted to the seven items common to both HS and LS, F(2, 114) = 3.52, p < .05. Clustering. The mean CRs are presented in the bottom two rows of Table 2. As with the recall scores, it may be noted that differences in clustering between the learning conditions were substantially reduced in Exp. II comEXPERIMENTII pared to differences in Exp. I. A 2 × 3 analysis Method of variance indicated that there was signifiExperiment II was a replication of Exp. I with the cantly greater clustering with the HS lists than addition of an intentional-learning group which also with the LS lists, F(I, 114) = 42.96, p < .01. performed the orienting task of pronouncing each The interaction between learning conditions word as it appeared (INT-O). The materials and procedures were identical with Exp. L The Ss were 120 and similarity did not approach significance, introductory psychology students attending the Uni- F(2, 114)= 1.46. Restricting the analysis to versity of Nevada. There were 20 Ss assigned randomly Groups INT-U and INC did not alter the to each of six groups. Four Ss in the incidental-learning significance of any effect. groups (two in the HS condition and two in the LS condition) were discarded and replaced by other Ss Discussion from the same population. The discarded Ss reported No firm conclusion could be reached conthat they anticipated a memory test. cerning whether the pronouncing task or Results absence of instructions to learn interfered with The results of Exp. II were similar to those IAR occurrence. In general the results of Exp. o f Exp. I in terms of the direction o f differences II are at variance with those of Exp. I in terms between intentional and incidental groups. For of significance. The direction of the differences all comparisons, higher scores were obtained between groups in the two experiments is by Ss instructed to learn. However, the magni- similar, but the magnitude of the differences is tude of the differences between groups was greatly reduced in Exp. II. The performance o f small and most often not significant. Only data G r o u p INT-O more closely approximated the on correct recall and clustering are reported. performance of Group INC, rather than G r o u p Correct Recall. The mean correct recall INT-U. Inspection of Tables 1 and 2 reveals scores for the six groups are presented in the that Group INT-U with the HS list in Exp. I bottom two rows of Table 1. It may be noted performed at a much higher level than the that differences in recall between the groups are corresponding group in Exp. II. The remaining substantially reduced in Exp. II compared to groups appear reasonably comparable bedifferences in Exp. I. A 2 x 3 analysis of tween the two experiments. Any number o f variance revealed a significant main effect for differences between Nevada and Northwestern similarity, F(1, 114) = 39.38, p < .01. Higher students may, in part, account for the disrecall scores were found for HS lists than for crepant findings. It is likely that operations LS lists. The three learning conditions (INT-U, which increase IAR occurrence will result in INT-O, and INC) did not differ reliably, higher recall and greater clustering for Group
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INT-U. If such operations do not produce a similar effect for incidental learners, then the major discrepancy between Exp. I and Exp. II may be attributed to S variables responsible for greater implicit responding by Northwestern Ss. Instructions to learn may prime I A R occurrence during learning; however, I A R occurrence during the recall trial may minimize differences between intentional and incidental learners. That is, a S in the incidental group may recall " c a t " which elicits "animal" as an I A R at the time of recall. The I A R o f " a n i m a l " may then lead to recall of other instances of that category by means of a backward association from the I A R to the category instance. It has been demonstrated that instructing Ss at the time of recall to cluster pairs of associatively related words reduces the differences in recall between intentional and incidental learners (Postman, Adams, and Bohm, 1956). It is possible that operations which reduce I A R occurrence will result in a greater difference between intentional and incidental learning. That is, the critical I A R may be less likely to occur at the time of recall, and this may be more crucial to the incidental group than it is to the intentional group. EXPERIMENT III In this experiment an effort was made to influence the level of recall and amount of clustering by manipulating variables presumed to either increase or decrease the "obviousness" of the conceptual relations linking sets of items in a free-recall list. Constrained order of presentatiol~ (all associates of one class presented first, then all associates of another class, etc.) is a variation that might be regarded as increasing the likelihood that the critical IARs will occur (compared to the random presentation used in Exp. I and Exp. II). Weingartner (1964) demonstrated that both recall and clustering were higher for a constrained presentation order than for a random presentation order. Taxonomic strength (normative frequency of occurrence of category responses)
was high in both Exp. I and Exp. II, and lowering this might result in a reduction in the occurrence of the critical IARs. Bousfield et aL (1958) demonstrated that both recall and clustering were higher for category responses of high taxonomic strength compared to lowstrength responses. In the present experiment, intentional and incidental learning of an HS list was compared. The HS list was presented in either a random (R) or constrained (C) order, and the taxonomic strength of category members was either high (H) or low (L). Method The experiment involved a factorial combination of three variables." Learning conditions (INT-U, INT-O, and INC), presentation order, and taxonomic strength. Four comparisons are provided between the learning conditions, i.e., comparisons between intentional and incidental learning with a high-random (HR) list, a high-constrained (HC) list, a low-random (LR) list and a low-constrained (LC) list. The procedure was identical to that used in Exp. II. Materials. The HS list of Exp. I and Exp. II was presented to six groups. The remaining six groups were presented with a list constructed from low-frequency category responses to the seven HS categories. These low-frequency responses were selected from the Cohen et al. norms (1957). For example, the low-frequency responses selected from the category of professions were: writer, coach, baker, and farmer. There were 28 words in each list and all words occurred a single time during the study trial. The order of the words was random with two restrictions: In the random order, items from a common category did not appear in adjacent positions, and in the constrained order, all items from a common category appeared before any item from a new category was presented. The arrangement of categories and items within categories was random. Subjects. The Ss were 192 introductory psychology students attending the University of Nevada. Sixteen Ss were assigned randomly to each of the 12 groups. One S in the LR INC group reported anticipating the memory test and was replaced. Results Correct Recall. The present experiment was conceived as four separate experiments involving INT-U, INT-O, and I N C comparisons. It was of interest to determine if intentional and incidental learning differences were present
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for any of the lists. An analysis of variance with simple effects for the three learning conditions (Winer, 1962) was applied to all major response scores. The mean total correct responses are presented in Table 3. It may be seen from Table 3 that, with the exception of the LR condition, the groups are ordered consistently with highest recall for INT-U followed by INT-O. Group INC had the lowest recall for each list. Differences among INT-U, INT-O, and INC were significant only when taxonomic strength was low and words were presented in a constrained order, F(2, 180) = 3.79, p < .05. Recall for Group INT-O (LC list) was about equidistant between Group INT-U and Group INC. Constrained presentation order resulted in higher recall than random order, F(1, 180) = 98.28, p < .01, and there was higher recall for words of high taxonomic strength compared to words of low taxonomic strength, F(1,180) = 32.60, p < .01. These latter findings are in agreement with the results of Weingartner (1964) and Bousfield et al. (1958). No other effects were significant. TABLE 3 MEAN NUMBEROF CORRECT RESPONSESIN EXP. III Instructions Lists
INC
INT-U
INT-O
HR HC LRLC
12.94 15.38 9.50 10.62
15.06 17.81 9.75
13.88 17,00 10,50
13.56
12.19
Clustering. The mean CRs are presented in Table 4. With the exception of one reversal between Group INT-O and Group INC in the HR conditions, INT-U showed the greatest amount of clustering, with INT-O second and INC third. The analysis of variance with simple effects indicated that differences in clustering between INT-U, INT-O, and I N C were significant only for the LC list, F(2, 180) = 3.43,p < .05. There was only a slight difference in amount of clustering between Group INT-O and Group INT-U, with both superior to Group INC. As with correct recall, both
taxonomic strength and presentation order produced significant main effects, F(1, 180) = 17.67,p < .01 and F(1,180) = 179.49,p < .01, respectively. TABLE 4 MEAN CLUSTERINGRATIOS IN EXP. III Instructions Lists
INC
INT-U
INT-O
HR HC LR LC
.497 .848 .260 .683
.594 .917 .385 ,865
.431 .861 .294 .855
Category Recall. The mean number of categories represented in recall ranged from 4.94 to 6.25. Analysis of the simple effects did not reveal any significant differences between learning conditions. There were significantly more categories represented in recall when category instances were high in taxonomic strength than when they were low, F(1,180) -15.40, p < . 0 1 , and more categories were represented in recall when presentation order was random than when it was constrained, F(1,180) = 11.79,p < .01. The words-per-category measure did not indicate any differences between INT-U, INT-O, and INC. More words were recalled per category with lists of high taxonomic strength, F(1, 180) = 62.39, p < .01 and when presentation order was constrained, F(1, 180) = 92.92, p < .01. Discussion The presentation order and taxonomic strength variables did not appear to differentially affect intentional and incidental learning. All groups showed higher levels of recall and clustering when the presentation order was constrained as compared to random, and all groups showed higher levels of recall and clustering when taxonomic strength was high as compared to low. The largest separation between groups appeared with the combination of constrained order and low taxonomic strength.
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This experiment was consistent with the previous experiments in showing that Ss instructed to learn were superior in recall and clustering to Ss not instructed to learn. The difference as a function of instructions to learn was more p r o n o u n c e d f o r high-similarity material than for low-similarity material, although this was not always supported statistically. Both recall and clustering differences a m o n g groups appeared with category instances of low as well as high taxonomic strength, and when presentation order was constrained as well as random. However, these differences were significant only for the c o m b i n a t i o n o f H R (in Exp. I but not in Exp. II or Exp. III) and L C (Exp. III). In all cases, performing the p r o n o u n c i n g task had a depressing effect on recall and cl,ustering~for intentional learners, but in absolute ~alues their performance still exceeded the performance o f incidental learners. These results are consistent with the interpretation that I A R s do not occur as readily under conditions o f incidental learning as they do under conditions o f intentional learning. REFERENCES BOUSFIELD, W. A., COHEN,B. H., AND WHITMARSH,G.
A. Associative clustering in the recall of words of different taxonomic frequencies of occurrence. PsychoL Rep., 1958, 4, 39--44.
COHEN,B. H., BOUSFIELD,W. A., ANDWHITMARSH,G. A. Cultural norms for verbal items in 43 categories. Technical Report No. 22, 1957, University of Connecticut, Contract Nonr 631 (00), Office of Naval Research. EAGLE, M., AND LEITER,E. Recall and recognition in intentional and incidental learning. J. exp. PsychoL, 1964, 66, 58-63. McLAUGHLIN, B. "Intentional" and "incidental" learning in human subjects: The role of instructions to learn and motivation. Psychol. Bull., 1965, 63, 359-376. MECHANIC, A. The responses involved in the rote learning of verbal materials. J. verb. Learn. verb. Behav., 1964, 3, 30-36. MECHANIC,A., AND MECHANIC,J. D. Response activities and the mechanism of selectivity in incidental learning. J. verb. Learn. verb. Behav., 1967, 6, 389-397. POSTMAN, L. Short-term memory and incidental learning. In A. W. Melton (Ed.), Categories of human learning. New York: Academic Press, 1964~ POSTMAN,L., ADAMS,P. A., ANDBOHM,A~ W. Studies in incidental learning: V. Recall for~order and associative clustering. J. exp. Psychol., 1956, 51, 334-342. WALLACE, W. P. Incidental learning: The influence of associative similarity and formal similarity in producing false recognition. J. verb. Learn. verb. Behav., 1968, 7,-50-54. WEINGARTNER, H. The free recall of sets of associatively related words. J. verb. Learn. verb. Behav., 1964, 3, 6-10. WINER, B. J. Statistical principles in experimental design. New York: McGraw-Hill, 1962. (Received June 12, 1968)