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Development of intertrial organization with simultaneous presentation of stimulus items
JOURNAL OF VERBAL LEARN/NG AND VERBAL BEHAVIOR
6, 213-215 (1967)
Development of Intertrial Organization with Simultaneous Presentation of Stimulus Items1 C. R. PUFF 2 AND W . A. BOUSFIELD
University o[ Connecticut, Storrs, Connecticut 06268 A list of 10 words having zero interitem associative strength was repeatedly presented for free recall. All words were simultaneously presented in an array pattern based on two concentric circles. A significant amount of intertrial organization was obtained, and was seen to be greater than that obtained in a previous study with a serial method of presentation. These results were interpreted as evidence that the serial presentation is not a necessary condition for the development of intertrial organization, but that the method of presentation may be an important parameter of the amount of intertrial organization. T h e analysis of t h e s e q u e n t i a l o r d e r of r e c a l l of u n r e l a t e d v e r b a l i t e m s has indic a t e d t h a t Ss t e n d t o d e v e l o p a c o n s t a n t o r d e r of r e c a l l ( T u l v i n g , 1962; Bousfield, Puff, a n d C o w a n , 1964). W h i l e this p h e n o m e n o n of intertrial, or subjective, o r g a n i z a t i o n has b e e n r e l i a b l y e s t a b l i s h e d , little has b e e n r e p o r t e d a b o u t t h e g e n e r a l i t y or t h e p a r a m e t e r s of t h e t e n d e n c y . T h e p u r p o s e of t h e p r e s e n t e x p e r i m e n t w a s to exp l o r e t h e i m p o r t a n c e of t h e m e t h o d of stimulus p r e s e n t a t i o n u s e d in t h e p r e v i o u s investigations. I n t h o s e e x p e r i m e n t s , t h e w o r d s w e r e s e r i a l l y p r e s e n t e d w i t h t h e ord e r v a r y i n g f r o m trial to trial. I n o r d e r to d e t e r m i n e w h e t h e r s i m i l a r e v i d e n c e of intertrial organization could be obtained w i t h a different m e t h o d of p r e s e n t a t i o n , t h e w o r d s w e r e h e r e p r e s e n t e d in a series of a r r a y p a t t e r n s , so t h a t all w o r d s w e r e simultaneously presented and each word w a s a d j a c e n t to s e v e r a l o t h e r w o r d s at t h e t i m e of p r e s e n t a t i o n . 1 This research was supported by a grant to the second author from the Research Foundation of the University o f Connecticut. 2 Now at Franklin and Marshall College.
METHOD
Subiects. The Ss were 20 paid volunteers from undergraduate psychology courses. Stimulus Materials and Apparatus. The stimulus words were those employed in the earlier study of Bousfield, Puff, and Cowan, namely: lake, ride, tonight, enemy, subtract, turtle, big, theory, legal, and family. These words are the first 10 of 15 given in Deese's (1959) List No. 18, and were chosen from this list because of its zero interitem associative strength. A practice list of 10 male first names was arbitrarily selected. An array pattern for the simultaneous presentation of all 10 words was constructed. It was based on two concentric circles, one 4 ~ inches and one 3 inches in diameter. Five tangents to the outer circle were drawn at 72, 144, 216, 288, and 860 degrees; tangents to the inner circle were drawn at 86, 108, 180, 252, and 324 degrees. A stimulus array was then prepared by lettering each word along one of the tangent lines. The words were lettered so as to minimize the ease with which they could be read in an entirely clockwise or counter-clockwise direction, and only the stimulus words appeared in the array as it was presented to Ss. Five different experimental list arrays were prepared, with the 10 words being assigned positions according to a separate randomization in each case. Similarly, three arrays of the practice items were prepared. The arrays were projected on a screen by means of a Delineascope opaque projector. Additional ma-
213
214
PUFF AND BOUSFIELD
terials comprised mimeographed data sheets for use by Ss, and a stopwatch. Procedure. At the outset of the experimental session S was told that a group of words would be projected on the screen. The task was to learn the words and, after the completion of each presentation, to write them as rapidly as possible on the data sheet. He was further instructed that the same group of words would always appear, but that the words would be arranged differently each time. It was emphasized that the order in which the words were recalled was of no consequence and that S could write them in any order. Recall was to begin as soon as the words disappeared from the screen and to stop when E said "Stop." The stimulus array was exposed for 10 see, so that the amount of exposure time per item was similar to that affo~rded by the 1-see rate of presentation in the earlier study. A period of 30 see, from the time S began writing, was allowed for completing the recall. One trial with each of the three practice arrays was administered first. Approximately 2 rain after the practice trials, S was given the experimental arrays. After the first errorless recall, S was told that he had correctly recalled all the words. It was also indicated that the experiment would continue while S was to try to write the words more rapidly. Thereafter, if S required fewer than 30 see for recall, E stopped the clock when the tenth word was written. The recall time was shown to S after each additional trial and S was regularly urged to go faster. The five arrays were repeatedly presented in the order one through five, and trials were continued to the criterion of five consecutive errorless recalls. RESULTS The recall protocols for each S were scored in s u c c e s s i v e p a i r s to obtain two measures: the n u m b e r of words recalled and the amount of observed inteltrial repetition ( O - I T R ) . A u n i t of O - I T R was scored each time a pair of words recalled consecutively on trial t was again recalled consecutively on trial t-}- 1. Subsequently, the amount of expected intertrial repetition ( E - t T R ) was also determined for all successive pairs of recalls. T h e E - I T R for any pair of recalls, as calculated b y the formula used b.y Bousfleld, Puff, and Cowan, was a function of the n u m b e r of
words recalled on each of the two trials and the total n u m b e r of words presented in the stimulus list. Because of the wide individual differences in the n u m b e r of trials to criterion, each S's series of values for each of the measures (words recalled, O-ITR, and E - I T R ) was converted to deciles b y the Vincent method. Then for each S, the E - I T R for each decile was subtracted from the O - I T R for the corresponding decries. Group means for all measures were found b y averaging over Ss within decries, and are shown in Table 1. Inspection of the m e a n words recalled TABLE 1 GROUP MEANS OF BASIC MEASURES FOR SUCCESSIVE DECILES OF RECALL
Deciles
Mean words recalled
Mean O-ITR
1 2
5.07 7.73
.78
.34
.44
1.91
.59
1.82
3 4 5 6 7 8 9 10
8.85 8.38 9.05 8.96 8.50 9.78 9.45 10.00
2.58 1.72 3.18 3.~8 2.92 4.48 4.37 5.79
.73 .68 .76 .75 .74 .87 .85 .90
1.85 1.04 2.42 ~.53 $.18 8.61 8.5~ 4.89
Mean E-ITR
Mean O-E difference
indicates that the learning shows the typical negatively accelerated form, with most of the words being mastered during the first several d e c r i e s - t h e remainder of the trials being required to master only a few items and presumably to overcome the tendency for response oscillation occurring from trial to trial. Inspection of t h e m e a n differences b e t w e e n O - I T R and E-ITR, on the other hand, shows t h a t relatively substantial increases in intertrial organization continue throughout the learning. The deviation of the observed sequential ordering from the expected amount was evaluated at three stages of the learn-
215
METHOD AND INTERTBIAL ORGANIZATION
ing. Specifically, three decile blocks were formed by combining the initial three deciles, the middle four deciles, and the final three deciles. The difference between the O-ITR and E-ITR measures for each of these blocks was tested with the following results: for the first decile block, t(19) z 5.60, p < .001; for the second decile block, t(19) ----5.48, p < .001; and for the final decile block, t ( 1 9 ) ~ 1 0 . 0 5 , p < .001. Page's (1964) L-test was applied to the differences between O-ITR and E-ITI~ across deciles for all Ss. The result, L(10, 20) --6791, p < .001, indicated that the magnitude of the difference between O-ITR and E-ITR increased monotonically over deciles. Discussion The significant deviations of O-ITR from E-ITR during ea.ch of the three successive decile blocks show that a significant amount of intertrial organization was obtained with the array presentation. Furthermore, the deviation of O-ITR from E-ITR increased monotonically over deeiles. In these respects, the data provided by the array presentation are identical in form to those obtained with the serial presentation employed by Bousfield, Puff, and Cowan. The serial method of presentation is then not a necessary condition for the development of significant intertrial organization. However, a closer comparison of the present results with those of Bousfield, Puff, and Cowan suggests that the method of stimulus presentation may be an important parameter of the amount of intertrial organization. An analysis of the deviations of O-ITR from E-ITR for corresponding deciles with the two methods shows that the array presentation resulted in appreciably more (an average of three times as much) intertrial organization per decile.
While the expectation of a more rapid development of intertrial organization with the array presentation does not appear to follow from any specific theory, several general kinds of speculation might be found to be relevant. Presumably, having all of the words simultaneously available for study should afford the maximal opportunity for discovering the intrinsic relations among them, or some other effective strategy for organizing them into higherorder sequential units, and for repeatedly rehearsing them only in accordance with the chosen strategy. Furthermore, Bousfield, Puff, and Cowan proposed that the serial method of presentation has some initial interfering or negative effects on the development of intertrial organization. More specifically, they proposed that the serial presentation of multiple randomizations produces different imposed serial effects on each trial, which until they become equalized in strength, contribute to varying orders of recall, The present study, of course, provides n o internal evidence concerning either of these, so their eventual usefulness remains to be determined, as does the reliability of the difference between the array and serial methods of presentation. REF~q]ENCES
BOUSFIELD, W. A., PUFF, C. R., AND COWAN,
T. M. The development of constancies in sequential organization during repeated free recall. J. verb. Learn. verb. Behav., 1964,
3, 489--495. DEESE, J. Influence of inter-item associative strength upon immediate free recall. Psychol. Rep., 1959, 5, 305-312. PACE, E. B. Ordered hypotheses for multiple treatments: A significancetest for linear ranks. I. Amer. statist. Ass., 1963, 58, 216-230. TVLVING,E. Subjective organization in free recall of "unrelated" words. Psychol. Rev., 1962, 69, 344-354. (Received June 14, 1965)
6, 213-215 (1967)
Development of Intertrial Organization with Simultaneous Presentation of Stimulus Items1 C. R. PUFF 2 AND W . A. BOUSFIELD
University o[ Connecticut, Storrs, Connecticut 06268 A list of 10 words having zero interitem associative strength was repeatedly presented for free recall. All words were simultaneously presented in an array pattern based on two concentric circles. A significant amount of intertrial organization was obtained, and was seen to be greater than that obtained in a previous study with a serial method of presentation. These results were interpreted as evidence that the serial presentation is not a necessary condition for the development of intertrial organization, but that the method of presentation may be an important parameter of the amount of intertrial organization. T h e analysis of t h e s e q u e n t i a l o r d e r of r e c a l l of u n r e l a t e d v e r b a l i t e m s has indic a t e d t h a t Ss t e n d t o d e v e l o p a c o n s t a n t o r d e r of r e c a l l ( T u l v i n g , 1962; Bousfield, Puff, a n d C o w a n , 1964). W h i l e this p h e n o m e n o n of intertrial, or subjective, o r g a n i z a t i o n has b e e n r e l i a b l y e s t a b l i s h e d , little has b e e n r e p o r t e d a b o u t t h e g e n e r a l i t y or t h e p a r a m e t e r s of t h e t e n d e n c y . T h e p u r p o s e of t h e p r e s e n t e x p e r i m e n t w a s to exp l o r e t h e i m p o r t a n c e of t h e m e t h o d of stimulus p r e s e n t a t i o n u s e d in t h e p r e v i o u s investigations. I n t h o s e e x p e r i m e n t s , t h e w o r d s w e r e s e r i a l l y p r e s e n t e d w i t h t h e ord e r v a r y i n g f r o m trial to trial. I n o r d e r to d e t e r m i n e w h e t h e r s i m i l a r e v i d e n c e of intertrial organization could be obtained w i t h a different m e t h o d of p r e s e n t a t i o n , t h e w o r d s w e r e h e r e p r e s e n t e d in a series of a r r a y p a t t e r n s , so t h a t all w o r d s w e r e simultaneously presented and each word w a s a d j a c e n t to s e v e r a l o t h e r w o r d s at t h e t i m e of p r e s e n t a t i o n . 1 This research was supported by a grant to the second author from the Research Foundation of the University o f Connecticut. 2 Now at Franklin and Marshall College.
METHOD
Subiects. The Ss were 20 paid volunteers from undergraduate psychology courses. Stimulus Materials and Apparatus. The stimulus words were those employed in the earlier study of Bousfield, Puff, and Cowan, namely: lake, ride, tonight, enemy, subtract, turtle, big, theory, legal, and family. These words are the first 10 of 15 given in Deese's (1959) List No. 18, and were chosen from this list because of its zero interitem associative strength. A practice list of 10 male first names was arbitrarily selected. An array pattern for the simultaneous presentation of all 10 words was constructed. It was based on two concentric circles, one 4 ~ inches and one 3 inches in diameter. Five tangents to the outer circle were drawn at 72, 144, 216, 288, and 860 degrees; tangents to the inner circle were drawn at 86, 108, 180, 252, and 324 degrees. A stimulus array was then prepared by lettering each word along one of the tangent lines. The words were lettered so as to minimize the ease with which they could be read in an entirely clockwise or counter-clockwise direction, and only the stimulus words appeared in the array as it was presented to Ss. Five different experimental list arrays were prepared, with the 10 words being assigned positions according to a separate randomization in each case. Similarly, three arrays of the practice items were prepared. The arrays were projected on a screen by means of a Delineascope opaque projector. Additional ma-
213
214
PUFF AND BOUSFIELD
terials comprised mimeographed data sheets for use by Ss, and a stopwatch. Procedure. At the outset of the experimental session S was told that a group of words would be projected on the screen. The task was to learn the words and, after the completion of each presentation, to write them as rapidly as possible on the data sheet. He was further instructed that the same group of words would always appear, but that the words would be arranged differently each time. It was emphasized that the order in which the words were recalled was of no consequence and that S could write them in any order. Recall was to begin as soon as the words disappeared from the screen and to stop when E said "Stop." The stimulus array was exposed for 10 see, so that the amount of exposure time per item was similar to that affo~rded by the 1-see rate of presentation in the earlier study. A period of 30 see, from the time S began writing, was allowed for completing the recall. One trial with each of the three practice arrays was administered first. Approximately 2 rain after the practice trials, S was given the experimental arrays. After the first errorless recall, S was told that he had correctly recalled all the words. It was also indicated that the experiment would continue while S was to try to write the words more rapidly. Thereafter, if S required fewer than 30 see for recall, E stopped the clock when the tenth word was written. The recall time was shown to S after each additional trial and S was regularly urged to go faster. The five arrays were repeatedly presented in the order one through five, and trials were continued to the criterion of five consecutive errorless recalls. RESULTS The recall protocols for each S were scored in s u c c e s s i v e p a i r s to obtain two measures: the n u m b e r of words recalled and the amount of observed inteltrial repetition ( O - I T R ) . A u n i t of O - I T R was scored each time a pair of words recalled consecutively on trial t was again recalled consecutively on trial t-}- 1. Subsequently, the amount of expected intertrial repetition ( E - t T R ) was also determined for all successive pairs of recalls. T h e E - I T R for any pair of recalls, as calculated b y the formula used b.y Bousfleld, Puff, and Cowan, was a function of the n u m b e r of
words recalled on each of the two trials and the total n u m b e r of words presented in the stimulus list. Because of the wide individual differences in the n u m b e r of trials to criterion, each S's series of values for each of the measures (words recalled, O-ITR, and E - I T R ) was converted to deciles b y the Vincent method. Then for each S, the E - I T R for each decile was subtracted from the O - I T R for the corresponding decries. Group means for all measures were found b y averaging over Ss within decries, and are shown in Table 1. Inspection of the m e a n words recalled TABLE 1 GROUP MEANS OF BASIC MEASURES FOR SUCCESSIVE DECILES OF RECALL
Deciles
Mean words recalled
Mean O-ITR
1 2
5.07 7.73
.78
.34
.44
1.91
.59
1.82
3 4 5 6 7 8 9 10
8.85 8.38 9.05 8.96 8.50 9.78 9.45 10.00
2.58 1.72 3.18 3.~8 2.92 4.48 4.37 5.79
.73 .68 .76 .75 .74 .87 .85 .90
1.85 1.04 2.42 ~.53 $.18 8.61 8.5~ 4.89
Mean E-ITR
Mean O-E difference
indicates that the learning shows the typical negatively accelerated form, with most of the words being mastered during the first several d e c r i e s - t h e remainder of the trials being required to master only a few items and presumably to overcome the tendency for response oscillation occurring from trial to trial. Inspection of t h e m e a n differences b e t w e e n O - I T R and E-ITR, on the other hand, shows t h a t relatively substantial increases in intertrial organization continue throughout the learning. The deviation of the observed sequential ordering from the expected amount was evaluated at three stages of the learn-
215
METHOD AND INTERTBIAL ORGANIZATION
ing. Specifically, three decile blocks were formed by combining the initial three deciles, the middle four deciles, and the final three deciles. The difference between the O-ITR and E-ITR measures for each of these blocks was tested with the following results: for the first decile block, t(19) z 5.60, p < .001; for the second decile block, t(19) ----5.48, p < .001; and for the final decile block, t ( 1 9 ) ~ 1 0 . 0 5 , p < .001. Page's (1964) L-test was applied to the differences between O-ITR and E-ITI~ across deciles for all Ss. The result, L(10, 20) --6791, p < .001, indicated that the magnitude of the difference between O-ITR and E-ITR increased monotonically over deciles. Discussion The significant deviations of O-ITR from E-ITR during ea.ch of the three successive decile blocks show that a significant amount of intertrial organization was obtained with the array presentation. Furthermore, the deviation of O-ITR from E-ITR increased monotonically over deeiles. In these respects, the data provided by the array presentation are identical in form to those obtained with the serial presentation employed by Bousfield, Puff, and Cowan. The serial method of presentation is then not a necessary condition for the development of significant intertrial organization. However, a closer comparison of the present results with those of Bousfield, Puff, and Cowan suggests that the method of stimulus presentation may be an important parameter of the amount of intertrial organization. An analysis of the deviations of O-ITR from E-ITR for corresponding deciles with the two methods shows that the array presentation resulted in appreciably more (an average of three times as much) intertrial organization per decile.
While the expectation of a more rapid development of intertrial organization with the array presentation does not appear to follow from any specific theory, several general kinds of speculation might be found to be relevant. Presumably, having all of the words simultaneously available for study should afford the maximal opportunity for discovering the intrinsic relations among them, or some other effective strategy for organizing them into higherorder sequential units, and for repeatedly rehearsing them only in accordance with the chosen strategy. Furthermore, Bousfield, Puff, and Cowan proposed that the serial method of presentation has some initial interfering or negative effects on the development of intertrial organization. More specifically, they proposed that the serial presentation of multiple randomizations produces different imposed serial effects on each trial, which until they become equalized in strength, contribute to varying orders of recall, The present study, of course, provides n o internal evidence concerning either of these, so their eventual usefulness remains to be determined, as does the reliability of the difference between the array and serial methods of presentation. REF~q]ENCES
BOUSFIELD, W. A., PUFF, C. R., AND COWAN,
T. M. The development of constancies in sequential organization during repeated free recall. J. verb. Learn. verb. Behav., 1964,
3, 489--495. DEESE, J. Influence of inter-item associative strength upon immediate free recall. Psychol. Rep., 1959, 5, 305-312. PACE, E. B. Ordered hypotheses for multiple treatments: A significancetest for linear ranks. I. Amer. statist. Ass., 1963, 58, 216-230. TVLVING,E. Subjective organization in free recall of "unrelated" words. Psychol. Rev., 1962, 69, 344-354. (Received June 14, 1965)