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Studies of learning to learn: III. Conditions of improvement in successive transfer tasks
~OURNAL OF VERBAL LEARNING AND VERBAL BEHAVIOR 6,
260-267 (1966)
Studies of Learning to Learn: III. Conditions of Improvement in Successive Transfer Tasks 1 GEOFFREY KEPPEL AND LEO POSTMAN
University o/ Cali]ornia, Berkeley, Cali]ornia A previous study in this series had shown that relative to a control condition positive transfer increases and negative transfer decreases as a result of experience with the relevant paradigms. The increases in positive transfer are more pronounced than the decreases in negative transfer. The present experiment investigated the question of whether the changes in transfer reflect the acquisition of learning skills specific to each paradigm or the development of general skills which can be applied with varying degrees of success depending on the paradigm. Separate groups of Ss were given practice under different paradigms and were then tested under the same conditions of transfer. There were four training paradigms, viz., A-B, A-B'; A-B, A-C; A-B, A-Br; and A-B, C-D. The two final common testing paradigms were A-B, A-B' and A-B, A-C. All possible combinations of training and testing paradigms were used. During training improvement occurs more rapidly under conditions of positive than of negative transfer. Performance on the final common transfer task is, however, independent of the paradigm used in training. It is concluded that the learning skills acquired as a result of experience with transfer situations are general rather than paradigm-specific. A previous s t u d y in this series (Postman, 1964) showed that performance in verbal transfer tasks improves as a result of practice and that the rate of improvement is a function of experimental paradigm. F o u r different paradigms of transfer were used in that study. One of t h e s e - - A - B , A - B ' - - r e p r e s e n t e d a condition of positive transfer; two o t h e r s - A-B, A-C and A-B, A - B r - - w e r e conditions of negative transfer. An A-B, C-D control condition provided a base line for the evaluation of specific transfer effects. A separate group was assigned to each p a r a d i g m for purposes of training. All groups learned three successive sets of two paired-associate lists i This research was carried out under Contract Nonr 22(90) between the Office of Naval Research and the University of California, and was also supported in part by a grant (MH-10429) from the National Institutes of Health. Reproduction is permitted for any purpose of the United States Government. This work was performed at the Institute of Human Learning which is supported by grants from the National Science Foundation and the National Institutes of Health.
each, with the relationship between the two lists always conforming to the same p a r a digm. T h e r e was improvement in both firstlist and second-list learning for all groups. Relative to the C-D control condition, the amount of positive transfer for Condition A - B ' increased significantly as a function of practice. There was also a reliable decrease in the amount of negative transfer for Condition A-C, although the degree of change was less pronounced than for A-B'. T h e decline in negative transfer for Condition A - B r was not reliable. These changes in transfer relative to the control condition indicate that Ss acquire learning skills which increase their proficiency in conforming to the requirements of the experimental paradigms. T h e results leave open the question, however, of whether the differences in improvement as a function of the conditions of transfer reflect the differential effectiveness of learning skills specific to each p a r a d i g m or the development of general skills which could be applied with vary-
260
261
IMPROVEMENT IN TRANSFER
ing degrees of success depending on the paradigm. The interpretative problem may be illustrated with reference to the A-B' and A-Br paradigms which showed the largest and smallest changes in transfer, respectively. One interpretation would assume the acquisition of paradigm-specific skills in each case. Thus, Ss learning successive pairs of lists under the A-B' condition might develop a second-order habit of using first-list associations to mediate second-list responses (A-BB'). No equally effective mode of attack on the transfer task could be adopted as a result of experience with the A-Br paradigm. The Ss might restict themselves to first-list responses during the transfer trials and avoid all previously correct associations. These principles of performance would not, however, specify the appropriate second-list responses to a given A-term and thus facilitate performance less than the technique of mediation in A-B'. According to the alternative interpretation, experience with any transfer situation results in readily generalizable skills, such as the ability to discriminate, and to conform to, the interlist stimulus and response relations defining a given paradigm. For the reasons just mentioned, the A-B' paradigm affords a better opportunity for the application of such skills than does the A-Br paradigm. Thus, differential gains in transfer performance would not reflect variations in the skills acquired during practice but would be determined by the constraints on performance imposed by the several paradigms. To arrive at a decision between these alternative interpretations, it becomes necessary to consider the transfer of learning skills from one paradigm to another. The logic of such an analysis parallels that used in the investigation of transfer from a first to a second list. Separate groups of Ss must be given experience with different paradigms and then be tested under the same conditions of transfer. If the skills acquired during practice are
paradigm-specific, performance in the final common test situation should be higher when the conditions of transfer remain the same in training and test than when they change. No such differences in the final test situation should be found if highly generalizable skills are acquired during practice. In the present experiment different groups of Ss were given practice on the same four paradigms as were used in the previous study, viz., A-B', A-C, A-Br, and C-D. Either A-B' or A-C was used as the final common test condition. For these two paradigms a comparison could, therefore, be made between the case in which the conditions of training and testing were homogeneous and the case in which they were heterogeneous. METHOD Except for the manipulation of the relationship between training and testing paradigms, the procedure and materials were essentially the same as those in the earlier study (Postman, 1954). For convenience of further reference, the earlier experiment will be designated as LTL-2. Design. All groups learned three successive sets of two lists of paired associates each. The first two sets define the training condition, and the third set constitutes the test. For a given group, the paradigm of transfer was always the same in the first and second sets; the paradigm remained the same or changed in the third set depending on the experimental treatment. Each of the four training paradigms---A-B', A-C, A-Br, and C-D--was assigned to two independent groups. For one of these groups the test paradigm was A-B', and for the other it was A-C. With four conditions of training and two conditions of testing, the total design comprised eight independent groups. Lists. The lists consisted of eight pairs of twosyllable adjectives and were selected from those used in LTL-2. Details concerning the pool of items are given in the earlier report. Formal and meaningful similarity were minimized both within and between lists except for the use of synonymous responses in the case of the A-B' paradigm. The second lists were the same for all groups, and the paradigms of transfer were varied by the use of appropriate first lists. Within each of the eight treatment combinations the six possible orders of the three sets of lists were used equally often. Second lists were, therefore, fully counterbalanced both within and among conditions. It should be noted
262
KEPPEL
AND P O S T M A N
that the second lists and their orders were identical with those in LTL-2. Procedure: The lists were presented at a 2:2-sec rate, with a 4-sec intertrial interval. Four different random orders of presentation were used to minimize serial learning. The first list in each set was learned to a criterion of 7/8. The second list was presented for 5 trials in Sets 1 and 2, and for 10 trials in Set 3. The time interval between the first and second list in a set was 1 rain, and the interval between sets 1 min, 50 sec. The Ss were given no advance information about the number of h'sts to be presented or the relationship between the lists within each set. A series of three tests of modified free recall (MMFR), one for each set of lists, was administered immediately after the end of the third set. In accordance with the procedure devised by Barnes and Underwood (1959), S was provided with a sheet showing the stimuli used in a given pair of lists and was required to write down the responses which had been associated with each stimulus. For the A-B', A-C, and A-Br paradigms the test sheet listed 8 stimuli, with two spaces for the responses underneath each stimulus. For the C-D paradigm 16 stimuli were listed, with a single space for the response underneath each stimulus. Since the main interest was in the recall of the responses from the final common test lists, the MMFR for Set 3 was always administered first; for half the Ss the test for Set 1 was given next and finally followed by the test for Set 2, for the other half of the Ss the order of the last two tests was reversed. The Ss were allowed 3 min for the completion of each test. Subjects. With 8 treatments and 18 Ss per treatment, there were 144 Ss in the experiment. The Ss were undergraduate students who were naive to rote learning by the anticipation method. Assignment to conditions was in blocks of 8, with 1 S per experimental treatment per block. Within each condition, the 6 possible orders of the 3 sets of lists were used once each in successive subgroups of 6 blocks. The running order within blocks was determined by a table of random numbers.
RESULTS
List-1 Learning. T h e a v e r a g e n u m b e r s of trials r e q u i r e d to reach a criterion of 7 / 8 correct responses for the three first lists are p r e s e n t e d in T a b l e 1. Since these scores tended to be skewed, a l o g a r i t h m i c transform a t i o n was m a d e prior to the statistical analysis. As in L T L - 2 t h e r e is a progressive increase in speed of l e a r n i n g over t h e three sets, F ( 2 , 2 7 2 ) ~ 176.67, p < .001. N e i t h e r the differences a m o n g the p a r a d i g m s nor the i n t e r a c t i o n of sets and p a r a d i g m s was signific a n t ( F < 1). A l t h o u g h p e r f o r m a n c e on successive first lists m a y reflect differences in subject a b i l i t y or list difficulty (or b o t h ) , these comparisons i n d i c a t e a general comp a r a b i l i t y of criterion scores a m o n g the various conditions.
Changes in Trans]er: Sets 1 and 2. A summ a r y of second-list p e r f o r m a n c e can b e found in T a b l e 2 for total correct r e s p o n d i n g on T r i a l s 1-5 and in Fig. 1 for t h e n u m b e r of correct responses p e r trial. I n b o t h s u m m a r i e s the d a t a for the two test conditions h a v e b e e n combined. W i t h reference to t h e C - D p a r a digm, it a p p e a r s t h a t the usual relationships a m o n g p a r a d i g m s were found in Set 1, h e a v y n e g a t i v e t r a n s f e r for A - C a n d A - B r a n d app r o x i m a t e l y zero net transfer for A - B ' . T h e r e is a p a t t e r n of initial s u p e r i o r i t y and later i n f e r i o r i t y for A - B ' . A l t h o u g h there is a n overall increase in p e r f o r m a n c e f r o m Set 1 to Set 2, t h e relationship a m o n g p a r a d i g m s does n o t change, except for a p r o n o u n c e d increase in s u p e r i o r i t y on e a r l y trials for A-B'.
TABLE 1 ~g~EAN NUMBERS OF TRIALS TO CRITERIOlq OF 7 / 8 IN ACQTYlSITION OF FIRST Lxsws oF StTCCESSnr~ SETS
Testing paradigm (Set 3) A-B'
A-C
Training paradigm (Sets 1 and 2)
Set 1
Set 2
Set 3
Set 1
Set 2
Set 3
C-D A-C A-Br A-B"
10.44 13.61 12.61 14.33
6.11 6.28 5.67 6.17
5.50 7.11 5.00 5.67
12.17 13.89 12.00 10.00
6.89 6.72 5.83 4.17
6.00 5.50 4.61 4.17
263
IMPROVEMENT IN TRANSFER TABLE 2 MEAN NUMBERS OF CORRECT RESPONSES ON TRIALS 1-5 OF LINT-2 LEARNING FOR SETS 1 AND 2 AND THE VARIOUS TRAINING PARADIGm/IS
TABLE 3 MEAN CHANGE SCORES BETWEEN SETS 1 AND 2 ON
TRIALS 1-5 OF LIST-2 LEARNING FOR TttE C - D AND A-C PARADIGMS, S L O W AND FAST LEARNERS~ AND TWO EXPERIlVIENTS
Training paradigms C-D Set 1 Set 2
20.06 24.12
A-C
A-Br
15.56 18.72
12.17 15A7
A-B' 20.67 26.67
In order to evaluate changes in early transfer effects, Trial-1 scores were compared for Sets 1 and 2. The four paradigms showed differential improvement from Set 1 to Set 2, the interaction of Sets and Paradigm being significant, F(3,140) -- 6.86, p < .01. Orthogonal comparisons revealed a reliable difference between C-D and the experimental paradigms, F(1,140) -- 6.26, p < .02, and among the latter three conditions, F(2,140) -- 7.17, p < .01. Dunnett's test, considering C-D as a control condition, produced a significant gain only for the A-B' condition, t(140) ~5.96, p < .01. The difference among paradigms is transitory, variation in Set-2 gains over the five trials not being significant, F(3,140) -- 1.47, p > .05.
I
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I
A-C
Slow Fast Mean
5.61 2.50 4.06
1.39 4.94 3.16
4.22 1.66 2.94
4.88 8.66 6.77
Set 2
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transfer (based on total correct responses) for A-C in Sets 1 and 2, respectively, were 6.89 and 3.05 in LTL-2 and 4.50 and 5.40 in this experiment. Although the interaction of paradigms (C-D and A-C) and experiments was not significant, F(1,104) = 3.38, p > .05, an attempt was made to localize the source of this discrepancy. One obvious point of comparison between the two experiments is the first-list performance for Set 1. Apparently as a result of sampling fluctuation, the Ss in the C-D and A-C conditions reached List-1 criterion faster in LTL-2 (9.20 trials) than in the present experiment (12.53 trials), F(1,104) = 4.99, p < .05. If this discrepancy between the two experiments is to be understood in terms of a difference in subject ability, it should be possible to produce the same difference within each experiment by separating Ss on the basis of first-list learning scores and comparing changes in transfer from Set 1 to Set 2 for these separated Ss in the two paradigms. To make this comparison, Ss in the present study were divided equally into categories of slow and fast learners based upon first-list criterion scores; ties were broken by means of a table of random numbers. A similar analysis was performed on the data of LTL-2. The results of these tabulations are presented in Table 3. For both determinations, the same relationship that was observed between the two
Comparisons with LTL-2. In general, these findings are in good agreement with LTL-2. In both experiments a significant gain for A-B' and no reliable change for A-Br, relative to C-D, were found. However, in LTL-2 there was a nonsignificant decrease between Set 1 and Set 2 in negative transfer for A-C (a trend which was significant over the three sets), while in the present study the relationship is opposite. The amounts of negative
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Present study
Subject ability
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5
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1
2
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FIG. 1. Performance on the transfer trials for each paradigm in Set 1 and Set 2.
264
KEPPEL AND POST2CLAN
experiments was found within experiments, namely, an interaction between ability level and transfer paradigm, such that there is a decrease in negative transfer for fast but not for slow Ss. This interaction was significant for the combined experiments, F(1,100) = 7.59, p < .01, but did not differ between the two experiments, F < 1. It seems reasonable to conclude, then, that the difference between the two experiments is to be attributed to the significantly superior Ss obtained in LTL-2. It may be noted that the interaction does not reflect ceiling effects for fast Ss in the C-D paradigm, since there was opportunity for considerably greater improvement than was obtained.
the two groups receiving the same p a r a d i g m for all three sets obtained the highest learning scores on the first transfer trial, this superiority was not reliable and short-lived, not being present over Trials 1-5. T h e conclusions remain unchanged when all 10 transfer trials are considered. I n short, there is no -~idence in these d a t a to indicate that e.,perience with different transfer p a r a d i g m s has a n y differential effect on the current transfer scores; i.e., the i m p o r t a n t variable is the transfer p a r a d i g m being administered, not the previous experience with other p a r a digms or the same paradigm.
Transfer in Set 3. It is in Set 3 that Ss receiving one of the four training paradigms in Sets 1 and 2 are presented with either the A-C or the A-B' testing paradigm. The mean numbers of correct responses on the 10 transfer trials are presented in Fig. 2 for the two Set-3 paradigms. A comparison of the two groups of curves indicates a large difference between the two Set-3 paradigms, but small and inconsistent differences among the Ss receiving previous experience with different training paradigms. Analyses of the number correct on Trial 1 and the total correct responses on Trials 1-5 revealed a significant superiority of the A-B' test condition, F(1,136) --46.21
p < the the and
and
15.52,
Errors in Set-3 Transfer. T h e most frequent t y p e of overt error occurring during List-2 learning was the misplaced response. While there tended to be a larger percentage of such errors for the A - B ' p a r a d i g m (13.6% vs. i 1 . 8 % ) , this difference was not significant ( F < 1). Moreover, neither the effect of training paradigms nor the interaction of training with testing paradigms was significant ( F ' s < 1). The frequencies of interlist intrusions and the number of Ss contributing them are presented in Table 4. A paired or unpaired intrusion refers to whether or not a first-list response was given to the a p p r o p r i a t e firstlist stimulus. The frequencies of interlist intrusions m a y be compared directly within each of the Set-3 paradigms, since the num-
respectively,
.01. However, for neither measure were differences within testing paradigms nor interaction of the conditions of training testing significant (all F's < 1). Although 8t
-
Test on A-B'
-
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Test on A-C
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FIG. 2. Performance on the transfer trials of Set 3 as a function of the paradigms used in training (Sets 1 and 2) and in the final common test (Set 3).
265
IMPROVEMENT IN TRANSFER TABLE 4 FREQUENCIES OF INTERLIST INTRUSIONSIlff ACQUISITIONOF SECOND LIST OF SET 3 C-D
/an
TABLE ,~ M E A N N U M B E R OF LIST-I AND LIST-2 RESPONSES RECALLED IN" M M F R FOR SET 3
A-C
A-Br
A-B'
/
]
/
n
n
n
A-B' test Paired Unpaired
15 4
7 3
13 8
7 6
29 5
12 5
28 9
13 6
A-C test Paired Unpaired
9 2
3 2
a / _____frequency; n = errors.
4 1
4 1
4 11
4 6
1 5
C-D
1 4
number of Ss contributing
ber of opportunities to make errors 'was roughly the same. As is usually the case, relatively few interlist intrusions were given in the A-C paradigm; the only difference of note is the large number of unpaired errors for the A-Br training condition. In comparison, relatively high frequencies of intrusions were found with the A-B' paradigm, a difference which is underestimated by the use of uncorrected error frequencies. While the training conditions do not appear to produce differential numbers of unpaired errors, the A-B' and A-Br training conditions result in approximately twice as many paired intrusions as do the C-D and A-C training paradigms. The high frequency of interlist intrusions during the acquisition of the test list in the A-B' paradigm is coupled with pronounced negative acceleration of the learning curve. This pattern, which was also observed in L T L - 2 , suggests that mediational chaining not only produces facilitation early in transfer but a/so becomes a source of interference in the later stages of acquisition. As the mediator (B) and mediated response (B') approach each other in strength, differentiation between the two members of the chain becomes increasingly difficult. The resulting competition of responses is reflected both in the slope of the acquisition curve and in the high rate and persistence of overt interlist intrusions. MMFR T e s t . At the completion of Set 3,
A-C
A-Br
A-B'
7.22 7.83
7.22 7.6i
4.67 7.11
5.89 7.72
A-B' test List 1 List 2
7.17 7.78
List 1 List 2
5.28 7.39
7.06 7.56 A-C test 4.78 7.50
Ss were given a series of M M F R tests. As noted in LTL-2, certain qualifications must be made concerning comparisons of successive sets. In view of the interpretative problem involved in comparisons between sets, and the fact that similar findings for Sets 1 and 2 were found in the two experiments, the results of the M M F R test will be given for Set 3 only. Table 5 shows the mean numbers of responses recalled and correctly paired from both lists of Set 3 as a function of testing and training paradigms. First-list recall is high and essentially identical for the various training paradigms under the A-B" test paradigm. On the other hand, as would be expected, first-list recall is considerably lower under the A-C test paradigm. Moreover, there appear to be differences among the four training paradigms, the two positive or zero transfer conditions (A-B' and C-D) scoring higher than the two negative transfer conditions (A-C and A-Br). While this difference is significant, F(1,68) = 4.52, p ~ .05, the overall difference among training paradigms is unreliable, F(3,68) -- 1.93, p ~ .05. Recall of second-list responses is uniformly high. DISCUSSION
The changes in transfer between Sets 1 and 2 duplicated the essential findings of LTL-2. The question that is now raised by these data and which formed the basis of the present experiment is whether the changes in transfer reflect the acquisition of skills which are specific to the training paradigm or the development of general skills which are differentially effective when applied to a specific
266
KEPPEL
AND
training paradigm. For example, the impressive increase in positive transfer for A-B' might indicate that Ss develop facility with the use of A-B-B' mediational chains, and that this development only occurs with the A-B' paradigm. On the other hand, there was some evidence offered in LTL-2 which was consistent with the hypothesis that mediational chains may be developed in both the A-C and A-Br paradigms. The design employed in the present study, in which Ss received training with various transfer paradigms but were tested with either the A-B' or A-C paradigms, allowed for differential predictions by the two hypotheses: (a) if specific skills are involved, homogeneous transfer conditions should be superior to the heterogeneous conditions, and (b) if general skills are involved, training paradigms should not influence transfer on the common testing paradigms. The results of this study unequivocally show that transfer to an A-B' or A-C paradigm is primarily determined by the current testing paradigm and is relatively unaffected by training with the same or different paradigms. There was a tendency, however, for the M M F R test to show a difference in List-1 recall as a function of training paradigm. Although the overall difference among conditions was not significant, there was a greater decrement in List-1 recall, under the A-C testing paradigm, for the two negative transfer conditions (A-C and A-Br) relative to the zero and positive transfer conditions (C-D and A-B'). Since it has been shown that unlearning of first-list associations can occur in both the A-C and A-Br paradigms (McGovern, 1964), it is possible that Ss learned to unlearn interfering associations and that these specific skills were applied to the final A-C situation. On the other hand, this difference in first-list recall may indicate differences in interlist discriminability. Specifically, the two transfer lists of Sets 1 and 2 were learned to a higher degree for C-D and A-B' than for either A-C or A-Br. Thus, it is possible that
POSTMAN
this strength differential allowed a more effective rejection of prior-list responses for C-D and A-B'. In order to test this hypothesis, a tabulation was made of all inter-set intrusions occurring during the recall of Set 3. The frequencies of such intrusions were 3, 11, 7 ,and 8 for the A-B', C-D, A-C, and A-Br training paradigms, respectively. These differences do not support the hypothesis that the higher List-1 recall was the result of greater prior-list discriminability. The basic conclusions which are suggested by the data of the present experiment and those of LTL-2 can best be listed as a series of points. (a) Improvement in first-list learning over the three sets is considerable and is not a function of second-list relationships. Thus, any specific skills which may be acquired in specific transfer paradigms do not appear to be differentially effective in influencing the learning speed of the three unrelated first lists. (b) As S's experience with a particular paradigm is increased, there are changes in the amount of transfer, the A-B' paradigm becoming more positive, the A-C paradigm becoming less negative, at least for fast Ss. (c) At least with the A-B' and A-C paradigms, prior experience with the same and with other transfer paradigms has equivalent effects on performance. These results indicate that Ss acquire general learning skills under all conditions of transfer, but that these skills are employed with differential success under various paradigms. The results are also consistent with the assumption that the skills developed in training are paradigm-specific but can be generalized at once to new paradigms. The consequences of these two formulations are identical, and the present data do not permit a distinction between them. (d) Changes in transfer depend upon the ability level of the Ss: A slow S tends to show increases in negative transfer with practice, i.e., performance increases more on C-D than on A-C, while a fast S shows decreases in negative transfer, i.e., performance on A-C increases more than on C-D. Similar findings
267
IMPROVEMENT IN TRANSFER
have been reported by Duncan (1960) for a lever-moving task which corresponds to an A-B, C-B paradigm (different stimuli, same responses). Specifically, Duncan found that slow Ss showed impressively greater improvement over successive sets of unrelated lists than did fast Ss. Although the transfer paradigm employed by Duncan was not C-D, the similarity of findings may indicate that under conditions of low interlist interference (C-D and C-B), Ss of different learning abilities are differentially influenced by the acquisition of a series of relatively unrelated tasks. If it is assumed that the functioI1 depicting the relationship between learning speed on successive unrelated lists is negatively accelerated, it is conceivable that fast learners will benefit less on successive lists than slow learners, the former being at a higher point on the practice curve than the latter at the outset. This speculation is supported by the smaller gain in C-D performance between
Sets 1 and 2 in LTL-2 (2.94 responses) than in the present study (4.06 responses). On the other hand, the fast learner may also learn how to combat interlist interference more quickly than does the slow learner. In either case, it is clear that differences in the amounts of transfer are significantly influenced by differences in the initial ability level of the Ss receiving successive sets of transfer tasks. ~xEFERENCES
BARNES,J. M., and UNDERWOOD,B. J. 'Fate' of firstlist associations in transfer theory. Y. exp. Psychol., 1959, 58, 97-105. DUNCAN, C. P. Description of learning to learn in human subjects. Amer..I. Psychol., 1960, 73, 108-114. McGowRN, J. B. Extinction of associations in four transfer paradigms. Psychol. Monogr., 1964, 78, No. 16 (Whole No. 593). POS~a.AN, L. Studies of learning to learn: II. Changes in transfer as a function of practice. J. verb. Learn. verb. Behav., 1964, 3, 437-447. (Received November 20, 1964)
260-267 (1966)
Studies of Learning to Learn: III. Conditions of Improvement in Successive Transfer Tasks 1 GEOFFREY KEPPEL AND LEO POSTMAN
University o/ Cali]ornia, Berkeley, Cali]ornia A previous study in this series had shown that relative to a control condition positive transfer increases and negative transfer decreases as a result of experience with the relevant paradigms. The increases in positive transfer are more pronounced than the decreases in negative transfer. The present experiment investigated the question of whether the changes in transfer reflect the acquisition of learning skills specific to each paradigm or the development of general skills which can be applied with varying degrees of success depending on the paradigm. Separate groups of Ss were given practice under different paradigms and were then tested under the same conditions of transfer. There were four training paradigms, viz., A-B, A-B'; A-B, A-C; A-B, A-Br; and A-B, C-D. The two final common testing paradigms were A-B, A-B' and A-B, A-C. All possible combinations of training and testing paradigms were used. During training improvement occurs more rapidly under conditions of positive than of negative transfer. Performance on the final common transfer task is, however, independent of the paradigm used in training. It is concluded that the learning skills acquired as a result of experience with transfer situations are general rather than paradigm-specific. A previous s t u d y in this series (Postman, 1964) showed that performance in verbal transfer tasks improves as a result of practice and that the rate of improvement is a function of experimental paradigm. F o u r different paradigms of transfer were used in that study. One of t h e s e - - A - B , A - B ' - - r e p r e s e n t e d a condition of positive transfer; two o t h e r s - A-B, A-C and A-B, A - B r - - w e r e conditions of negative transfer. An A-B, C-D control condition provided a base line for the evaluation of specific transfer effects. A separate group was assigned to each p a r a d i g m for purposes of training. All groups learned three successive sets of two paired-associate lists i This research was carried out under Contract Nonr 22(90) between the Office of Naval Research and the University of California, and was also supported in part by a grant (MH-10429) from the National Institutes of Health. Reproduction is permitted for any purpose of the United States Government. This work was performed at the Institute of Human Learning which is supported by grants from the National Science Foundation and the National Institutes of Health.
each, with the relationship between the two lists always conforming to the same p a r a digm. T h e r e was improvement in both firstlist and second-list learning for all groups. Relative to the C-D control condition, the amount of positive transfer for Condition A - B ' increased significantly as a function of practice. There was also a reliable decrease in the amount of negative transfer for Condition A-C, although the degree of change was less pronounced than for A-B'. T h e decline in negative transfer for Condition A - B r was not reliable. These changes in transfer relative to the control condition indicate that Ss acquire learning skills which increase their proficiency in conforming to the requirements of the experimental paradigms. T h e results leave open the question, however, of whether the differences in improvement as a function of the conditions of transfer reflect the differential effectiveness of learning skills specific to each p a r a d i g m or the development of general skills which could be applied with vary-
260
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IMPROVEMENT IN TRANSFER
ing degrees of success depending on the paradigm. The interpretative problem may be illustrated with reference to the A-B' and A-Br paradigms which showed the largest and smallest changes in transfer, respectively. One interpretation would assume the acquisition of paradigm-specific skills in each case. Thus, Ss learning successive pairs of lists under the A-B' condition might develop a second-order habit of using first-list associations to mediate second-list responses (A-BB'). No equally effective mode of attack on the transfer task could be adopted as a result of experience with the A-Br paradigm. The Ss might restict themselves to first-list responses during the transfer trials and avoid all previously correct associations. These principles of performance would not, however, specify the appropriate second-list responses to a given A-term and thus facilitate performance less than the technique of mediation in A-B'. According to the alternative interpretation, experience with any transfer situation results in readily generalizable skills, such as the ability to discriminate, and to conform to, the interlist stimulus and response relations defining a given paradigm. For the reasons just mentioned, the A-B' paradigm affords a better opportunity for the application of such skills than does the A-Br paradigm. Thus, differential gains in transfer performance would not reflect variations in the skills acquired during practice but would be determined by the constraints on performance imposed by the several paradigms. To arrive at a decision between these alternative interpretations, it becomes necessary to consider the transfer of learning skills from one paradigm to another. The logic of such an analysis parallels that used in the investigation of transfer from a first to a second list. Separate groups of Ss must be given experience with different paradigms and then be tested under the same conditions of transfer. If the skills acquired during practice are
paradigm-specific, performance in the final common test situation should be higher when the conditions of transfer remain the same in training and test than when they change. No such differences in the final test situation should be found if highly generalizable skills are acquired during practice. In the present experiment different groups of Ss were given practice on the same four paradigms as were used in the previous study, viz., A-B', A-C, A-Br, and C-D. Either A-B' or A-C was used as the final common test condition. For these two paradigms a comparison could, therefore, be made between the case in which the conditions of training and testing were homogeneous and the case in which they were heterogeneous. METHOD Except for the manipulation of the relationship between training and testing paradigms, the procedure and materials were essentially the same as those in the earlier study (Postman, 1954). For convenience of further reference, the earlier experiment will be designated as LTL-2. Design. All groups learned three successive sets of two lists of paired associates each. The first two sets define the training condition, and the third set constitutes the test. For a given group, the paradigm of transfer was always the same in the first and second sets; the paradigm remained the same or changed in the third set depending on the experimental treatment. Each of the four training paradigms---A-B', A-C, A-Br, and C-D--was assigned to two independent groups. For one of these groups the test paradigm was A-B', and for the other it was A-C. With four conditions of training and two conditions of testing, the total design comprised eight independent groups. Lists. The lists consisted of eight pairs of twosyllable adjectives and were selected from those used in LTL-2. Details concerning the pool of items are given in the earlier report. Formal and meaningful similarity were minimized both within and between lists except for the use of synonymous responses in the case of the A-B' paradigm. The second lists were the same for all groups, and the paradigms of transfer were varied by the use of appropriate first lists. Within each of the eight treatment combinations the six possible orders of the three sets of lists were used equally often. Second lists were, therefore, fully counterbalanced both within and among conditions. It should be noted
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AND P O S T M A N
that the second lists and their orders were identical with those in LTL-2. Procedure: The lists were presented at a 2:2-sec rate, with a 4-sec intertrial interval. Four different random orders of presentation were used to minimize serial learning. The first list in each set was learned to a criterion of 7/8. The second list was presented for 5 trials in Sets 1 and 2, and for 10 trials in Set 3. The time interval between the first and second list in a set was 1 rain, and the interval between sets 1 min, 50 sec. The Ss were given no advance information about the number of h'sts to be presented or the relationship between the lists within each set. A series of three tests of modified free recall (MMFR), one for each set of lists, was administered immediately after the end of the third set. In accordance with the procedure devised by Barnes and Underwood (1959), S was provided with a sheet showing the stimuli used in a given pair of lists and was required to write down the responses which had been associated with each stimulus. For the A-B', A-C, and A-Br paradigms the test sheet listed 8 stimuli, with two spaces for the responses underneath each stimulus. For the C-D paradigm 16 stimuli were listed, with a single space for the response underneath each stimulus. Since the main interest was in the recall of the responses from the final common test lists, the MMFR for Set 3 was always administered first; for half the Ss the test for Set 1 was given next and finally followed by the test for Set 2, for the other half of the Ss the order of the last two tests was reversed. The Ss were allowed 3 min for the completion of each test. Subjects. With 8 treatments and 18 Ss per treatment, there were 144 Ss in the experiment. The Ss were undergraduate students who were naive to rote learning by the anticipation method. Assignment to conditions was in blocks of 8, with 1 S per experimental treatment per block. Within each condition, the 6 possible orders of the 3 sets of lists were used once each in successive subgroups of 6 blocks. The running order within blocks was determined by a table of random numbers.
RESULTS
List-1 Learning. T h e a v e r a g e n u m b e r s of trials r e q u i r e d to reach a criterion of 7 / 8 correct responses for the three first lists are p r e s e n t e d in T a b l e 1. Since these scores tended to be skewed, a l o g a r i t h m i c transform a t i o n was m a d e prior to the statistical analysis. As in L T L - 2 t h e r e is a progressive increase in speed of l e a r n i n g over t h e three sets, F ( 2 , 2 7 2 ) ~ 176.67, p < .001. N e i t h e r the differences a m o n g the p a r a d i g m s nor the i n t e r a c t i o n of sets and p a r a d i g m s was signific a n t ( F < 1). A l t h o u g h p e r f o r m a n c e on successive first lists m a y reflect differences in subject a b i l i t y or list difficulty (or b o t h ) , these comparisons i n d i c a t e a general comp a r a b i l i t y of criterion scores a m o n g the various conditions.
Changes in Trans]er: Sets 1 and 2. A summ a r y of second-list p e r f o r m a n c e can b e found in T a b l e 2 for total correct r e s p o n d i n g on T r i a l s 1-5 and in Fig. 1 for t h e n u m b e r of correct responses p e r trial. I n b o t h s u m m a r i e s the d a t a for the two test conditions h a v e b e e n combined. W i t h reference to t h e C - D p a r a digm, it a p p e a r s t h a t the usual relationships a m o n g p a r a d i g m s were found in Set 1, h e a v y n e g a t i v e t r a n s f e r for A - C a n d A - B r a n d app r o x i m a t e l y zero net transfer for A - B ' . T h e r e is a p a t t e r n of initial s u p e r i o r i t y and later i n f e r i o r i t y for A - B ' . A l t h o u g h there is a n overall increase in p e r f o r m a n c e f r o m Set 1 to Set 2, t h e relationship a m o n g p a r a d i g m s does n o t change, except for a p r o n o u n c e d increase in s u p e r i o r i t y on e a r l y trials for A-B'.
TABLE 1 ~g~EAN NUMBERS OF TRIALS TO CRITERIOlq OF 7 / 8 IN ACQTYlSITION OF FIRST Lxsws oF StTCCESSnr~ SETS
Testing paradigm (Set 3) A-B'
A-C
Training paradigm (Sets 1 and 2)
Set 1
Set 2
Set 3
Set 1
Set 2
Set 3
C-D A-C A-Br A-B"
10.44 13.61 12.61 14.33
6.11 6.28 5.67 6.17
5.50 7.11 5.00 5.67
12.17 13.89 12.00 10.00
6.89 6.72 5.83 4.17
6.00 5.50 4.61 4.17
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IMPROVEMENT IN TRANSFER TABLE 2 MEAN NUMBERS OF CORRECT RESPONSES ON TRIALS 1-5 OF LINT-2 LEARNING FOR SETS 1 AND 2 AND THE VARIOUS TRAINING PARADIGm/IS
TABLE 3 MEAN CHANGE SCORES BETWEEN SETS 1 AND 2 ON
TRIALS 1-5 OF LIST-2 LEARNING FOR TttE C - D AND A-C PARADIGMS, S L O W AND FAST LEARNERS~ AND TWO EXPERIlVIENTS
Training paradigms C-D Set 1 Set 2
20.06 24.12
A-C
A-Br
15.56 18.72
12.17 15A7
A-B' 20.67 26.67
In order to evaluate changes in early transfer effects, Trial-1 scores were compared for Sets 1 and 2. The four paradigms showed differential improvement from Set 1 to Set 2, the interaction of Sets and Paradigm being significant, F(3,140) -- 6.86, p < .01. Orthogonal comparisons revealed a reliable difference between C-D and the experimental paradigms, F(1,140) -- 6.26, p < .02, and among the latter three conditions, F(2,140) -- 7.17, p < .01. Dunnett's test, considering C-D as a control condition, produced a significant gain only for the A-B' condition, t(140) ~5.96, p < .01. The difference among paradigms is transitory, variation in Set-2 gains over the five trials not being significant, F(3,140) -- 1.47, p > .05.
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5.61 2.50 4.06
1.39 4.94 3.16
4.22 1.66 2.94
4.88 8.66 6.77
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transfer (based on total correct responses) for A-C in Sets 1 and 2, respectively, were 6.89 and 3.05 in LTL-2 and 4.50 and 5.40 in this experiment. Although the interaction of paradigms (C-D and A-C) and experiments was not significant, F(1,104) = 3.38, p > .05, an attempt was made to localize the source of this discrepancy. One obvious point of comparison between the two experiments is the first-list performance for Set 1. Apparently as a result of sampling fluctuation, the Ss in the C-D and A-C conditions reached List-1 criterion faster in LTL-2 (9.20 trials) than in the present experiment (12.53 trials), F(1,104) = 4.99, p < .05. If this discrepancy between the two experiments is to be understood in terms of a difference in subject ability, it should be possible to produce the same difference within each experiment by separating Ss on the basis of first-list learning scores and comparing changes in transfer from Set 1 to Set 2 for these separated Ss in the two paradigms. To make this comparison, Ss in the present study were divided equally into categories of slow and fast learners based upon first-list criterion scores; ties were broken by means of a table of random numbers. A similar analysis was performed on the data of LTL-2. The results of these tabulations are presented in Table 3. For both determinations, the same relationship that was observed between the two
Comparisons with LTL-2. In general, these findings are in good agreement with LTL-2. In both experiments a significant gain for A-B' and no reliable change for A-Br, relative to C-D, were found. However, in LTL-2 there was a nonsignificant decrease between Set 1 and Set 2 in negative transfer for A-C (a trend which was significant over the three sets), while in the present study the relationship is opposite. The amounts of negative
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FIG. 1. Performance on the transfer trials for each paradigm in Set 1 and Set 2.
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KEPPEL AND POST2CLAN
experiments was found within experiments, namely, an interaction between ability level and transfer paradigm, such that there is a decrease in negative transfer for fast but not for slow Ss. This interaction was significant for the combined experiments, F(1,100) = 7.59, p < .01, but did not differ between the two experiments, F < 1. It seems reasonable to conclude, then, that the difference between the two experiments is to be attributed to the significantly superior Ss obtained in LTL-2. It may be noted that the interaction does not reflect ceiling effects for fast Ss in the C-D paradigm, since there was opportunity for considerably greater improvement than was obtained.
the two groups receiving the same p a r a d i g m for all three sets obtained the highest learning scores on the first transfer trial, this superiority was not reliable and short-lived, not being present over Trials 1-5. T h e conclusions remain unchanged when all 10 transfer trials are considered. I n short, there is no -~idence in these d a t a to indicate that e.,perience with different transfer p a r a d i g m s has a n y differential effect on the current transfer scores; i.e., the i m p o r t a n t variable is the transfer p a r a d i g m being administered, not the previous experience with other p a r a digms or the same paradigm.
Transfer in Set 3. It is in Set 3 that Ss receiving one of the four training paradigms in Sets 1 and 2 are presented with either the A-C or the A-B' testing paradigm. The mean numbers of correct responses on the 10 transfer trials are presented in Fig. 2 for the two Set-3 paradigms. A comparison of the two groups of curves indicates a large difference between the two Set-3 paradigms, but small and inconsistent differences among the Ss receiving previous experience with different training paradigms. Analyses of the number correct on Trial 1 and the total correct responses on Trials 1-5 revealed a significant superiority of the A-B' test condition, F(1,136) --46.21
p < the the and
and
15.52,
Errors in Set-3 Transfer. T h e most frequent t y p e of overt error occurring during List-2 learning was the misplaced response. While there tended to be a larger percentage of such errors for the A - B ' p a r a d i g m (13.6% vs. i 1 . 8 % ) , this difference was not significant ( F < 1). Moreover, neither the effect of training paradigms nor the interaction of training with testing paradigms was significant ( F ' s < 1). The frequencies of interlist intrusions and the number of Ss contributing them are presented in Table 4. A paired or unpaired intrusion refers to whether or not a first-list response was given to the a p p r o p r i a t e firstlist stimulus. The frequencies of interlist intrusions m a y be compared directly within each of the Set-3 paradigms, since the num-
respectively,
.01. However, for neither measure were differences within testing paradigms nor interaction of the conditions of training testing significant (all F's < 1). Although 8t
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FIG. 2. Performance on the transfer trials of Set 3 as a function of the paradigms used in training (Sets 1 and 2) and in the final common test (Set 3).
265
IMPROVEMENT IN TRANSFER TABLE 4 FREQUENCIES OF INTERLIST INTRUSIONSIlff ACQUISITIONOF SECOND LIST OF SET 3 C-D
/an
TABLE ,~ M E A N N U M B E R OF LIST-I AND LIST-2 RESPONSES RECALLED IN" M M F R FOR SET 3
A-C
A-Br
A-B'
/
]
/
n
n
n
A-B' test Paired Unpaired
15 4
7 3
13 8
7 6
29 5
12 5
28 9
13 6
A-C test Paired Unpaired
9 2
3 2
a / _____frequency; n = errors.
4 1
4 1
4 11
4 6
1 5
C-D
1 4
number of Ss contributing
ber of opportunities to make errors 'was roughly the same. As is usually the case, relatively few interlist intrusions were given in the A-C paradigm; the only difference of note is the large number of unpaired errors for the A-Br training condition. In comparison, relatively high frequencies of intrusions were found with the A-B' paradigm, a difference which is underestimated by the use of uncorrected error frequencies. While the training conditions do not appear to produce differential numbers of unpaired errors, the A-B' and A-Br training conditions result in approximately twice as many paired intrusions as do the C-D and A-C training paradigms. The high frequency of interlist intrusions during the acquisition of the test list in the A-B' paradigm is coupled with pronounced negative acceleration of the learning curve. This pattern, which was also observed in L T L - 2 , suggests that mediational chaining not only produces facilitation early in transfer but a/so becomes a source of interference in the later stages of acquisition. As the mediator (B) and mediated response (B') approach each other in strength, differentiation between the two members of the chain becomes increasingly difficult. The resulting competition of responses is reflected both in the slope of the acquisition curve and in the high rate and persistence of overt interlist intrusions. MMFR T e s t . At the completion of Set 3,
A-C
A-Br
A-B'
7.22 7.83
7.22 7.6i
4.67 7.11
5.89 7.72
A-B' test List 1 List 2
7.17 7.78
List 1 List 2
5.28 7.39
7.06 7.56 A-C test 4.78 7.50
Ss were given a series of M M F R tests. As noted in LTL-2, certain qualifications must be made concerning comparisons of successive sets. In view of the interpretative problem involved in comparisons between sets, and the fact that similar findings for Sets 1 and 2 were found in the two experiments, the results of the M M F R test will be given for Set 3 only. Table 5 shows the mean numbers of responses recalled and correctly paired from both lists of Set 3 as a function of testing and training paradigms. First-list recall is high and essentially identical for the various training paradigms under the A-B" test paradigm. On the other hand, as would be expected, first-list recall is considerably lower under the A-C test paradigm. Moreover, there appear to be differences among the four training paradigms, the two positive or zero transfer conditions (A-B' and C-D) scoring higher than the two negative transfer conditions (A-C and A-Br). While this difference is significant, F(1,68) = 4.52, p ~ .05, the overall difference among training paradigms is unreliable, F(3,68) -- 1.93, p ~ .05. Recall of second-list responses is uniformly high. DISCUSSION
The changes in transfer between Sets 1 and 2 duplicated the essential findings of LTL-2. The question that is now raised by these data and which formed the basis of the present experiment is whether the changes in transfer reflect the acquisition of skills which are specific to the training paradigm or the development of general skills which are differentially effective when applied to a specific
266
KEPPEL
AND
training paradigm. For example, the impressive increase in positive transfer for A-B' might indicate that Ss develop facility with the use of A-B-B' mediational chains, and that this development only occurs with the A-B' paradigm. On the other hand, there was some evidence offered in LTL-2 which was consistent with the hypothesis that mediational chains may be developed in both the A-C and A-Br paradigms. The design employed in the present study, in which Ss received training with various transfer paradigms but were tested with either the A-B' or A-C paradigms, allowed for differential predictions by the two hypotheses: (a) if specific skills are involved, homogeneous transfer conditions should be superior to the heterogeneous conditions, and (b) if general skills are involved, training paradigms should not influence transfer on the common testing paradigms. The results of this study unequivocally show that transfer to an A-B' or A-C paradigm is primarily determined by the current testing paradigm and is relatively unaffected by training with the same or different paradigms. There was a tendency, however, for the M M F R test to show a difference in List-1 recall as a function of training paradigm. Although the overall difference among conditions was not significant, there was a greater decrement in List-1 recall, under the A-C testing paradigm, for the two negative transfer conditions (A-C and A-Br) relative to the zero and positive transfer conditions (C-D and A-B'). Since it has been shown that unlearning of first-list associations can occur in both the A-C and A-Br paradigms (McGovern, 1964), it is possible that Ss learned to unlearn interfering associations and that these specific skills were applied to the final A-C situation. On the other hand, this difference in first-list recall may indicate differences in interlist discriminability. Specifically, the two transfer lists of Sets 1 and 2 were learned to a higher degree for C-D and A-B' than for either A-C or A-Br. Thus, it is possible that
POSTMAN
this strength differential allowed a more effective rejection of prior-list responses for C-D and A-B'. In order to test this hypothesis, a tabulation was made of all inter-set intrusions occurring during the recall of Set 3. The frequencies of such intrusions were 3, 11, 7 ,and 8 for the A-B', C-D, A-C, and A-Br training paradigms, respectively. These differences do not support the hypothesis that the higher List-1 recall was the result of greater prior-list discriminability. The basic conclusions which are suggested by the data of the present experiment and those of LTL-2 can best be listed as a series of points. (a) Improvement in first-list learning over the three sets is considerable and is not a function of second-list relationships. Thus, any specific skills which may be acquired in specific transfer paradigms do not appear to be differentially effective in influencing the learning speed of the three unrelated first lists. (b) As S's experience with a particular paradigm is increased, there are changes in the amount of transfer, the A-B' paradigm becoming more positive, the A-C paradigm becoming less negative, at least for fast Ss. (c) At least with the A-B' and A-C paradigms, prior experience with the same and with other transfer paradigms has equivalent effects on performance. These results indicate that Ss acquire general learning skills under all conditions of transfer, but that these skills are employed with differential success under various paradigms. The results are also consistent with the assumption that the skills developed in training are paradigm-specific but can be generalized at once to new paradigms. The consequences of these two formulations are identical, and the present data do not permit a distinction between them. (d) Changes in transfer depend upon the ability level of the Ss: A slow S tends to show increases in negative transfer with practice, i.e., performance increases more on C-D than on A-C, while a fast S shows decreases in negative transfer, i.e., performance on A-C increases more than on C-D. Similar findings
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IMPROVEMENT IN TRANSFER
have been reported by Duncan (1960) for a lever-moving task which corresponds to an A-B, C-B paradigm (different stimuli, same responses). Specifically, Duncan found that slow Ss showed impressively greater improvement over successive sets of unrelated lists than did fast Ss. Although the transfer paradigm employed by Duncan was not C-D, the similarity of findings may indicate that under conditions of low interlist interference (C-D and C-B), Ss of different learning abilities are differentially influenced by the acquisition of a series of relatively unrelated tasks. If it is assumed that the functioI1 depicting the relationship between learning speed on successive unrelated lists is negatively accelerated, it is conceivable that fast learners will benefit less on successive lists than slow learners, the former being at a higher point on the practice curve than the latter at the outset. This speculation is supported by the smaller gain in C-D performance between
Sets 1 and 2 in LTL-2 (2.94 responses) than in the present study (4.06 responses). On the other hand, the fast learner may also learn how to combat interlist interference more quickly than does the slow learner. In either case, it is clear that differences in the amounts of transfer are significantly influenced by differences in the initial ability level of the Ss receiving successive sets of transfer tasks. ~xEFERENCES
BARNES,J. M., and UNDERWOOD,B. J. 'Fate' of firstlist associations in transfer theory. Y. exp. Psychol., 1959, 58, 97-105. DUNCAN, C. P. Description of learning to learn in human subjects. Amer..I. Psychol., 1960, 73, 108-114. McGowRN, J. B. Extinction of associations in four transfer paradigms. Psychol. Monogr., 1964, 78, No. 16 (Whole No. 593). POS~a.AN, L. Studies of learning to learn: II. Changes in transfer as a function of practice. J. verb. Learn. verb. Behav., 1964, 3, 437-447. (Received November 20, 1964)