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Serial position effects in immediate serial recall
yOURNAL OF VERBAL LEARNING AND VERBAL BEHAVIOR ~, 284-287 (1963)
Serial Position Effects in Immediate Serial Recall 1 JOI-IN C. J A H N K E
Miami University, Oxford, Ohio
Increasing the length of list to be learned typically produces the following changes in the bowed serial position curve of serial anticipation learning: (a) bowing of the serial position curve becomes more pronounced; and (b) performance on middle and final items of the series becomes relatively poorer than performance on the initial items (Robinson and Brown, 1926). Thus far, study of the influence of length of list on serial position effects has been based upon anticipation learning and repeated measurements on the same S. The purpose of the present experiment is to determine the effect of length of list on serial position effects in immediate memory. In the present experiment a list is presented only once to S, who then must attempt recall of the items in correct serial order. METHOD
Subjects. The Ss were 101 women students enrolled in classes in introductory psychology at Miami University. The data from 3 additional Ss were discarded because of procedural error. None of the Ss h a d previously served in a n y experimental s t u d y of immediate memory. Materials and Procedure. T h e procedure involved the immediate recall of a list of either 5, 6, 7, 8, or 9 English consonants. A particular S was tested on 1 This study was facilitated by support from the Faculty Research Committee, Miami University, and from Contract AF 33(657)-10456 with the Aerospace Medical Laboratories, Engineering Psychology Branch, Wright-Patterson Air Force Base, Ohio. The writer is indebted to C. P. D u n c a n and R. A. Hoppe, who critically read drafts of this report, a n d to Miss Leslie Gillette, who collected the data.
only one length of list. T h e Ss were tested individually and were told that a list of letters would be read to them. The letters were read without inflection or emphasis at a 1/sec. rate by a w o m a n E. The Ss were told to listen carefully and were told the n u m b e r of letters in the list b u t were not told w h a t the letters would be, or how m a n y trials they would receive. The Ss were instructed to memorize the letters in the order they were given a n d to write the letters in that order in the appropriate spaces on an answer sheet. The answer sheets were the same for all Ss a n d were prepared in the form of a 9 X 9 grid. The Ss were instructed to indicate with a dash ( - - ) in the appropriate space of the grid a n y letter which could not be recalled. The time allowed for recall was 5 sec. plus the n u m b e r of seconds required to read the list; thus, for example, an S receiving an arrangement of 7 consonants was allowed 12 sec. for recall. This procedure was found to provide sufficient time for recall. The stimulus materials were the nine consonants occurring most frequently in printed English text (Underwood and Schuh, 1960, p. 69). No letter was repeated in any list of a given length. Of necessity, different letters were used in the series of different lengths. Since it has been shown (Korn and Lindley, 1963) that the frequency of occurrence of consonants influences their immediate retention, an a t t e m p t was made to hold the m e a n frequencies of occurrence of the consonants constant across the lists of different lengths. The consonants in each list and the m e a n frequencies of occurrence of the letters in the different lists were as follows: CLDTS, 3582.40; C S H D T L , 3584.67; C R T H L N M , 3574.43; C S D R L T M N , 3587.50; a n d C T R D L S M H N , 3588.44. Each of the preceding arrangements of consonants was one of those actually used in the study. The preceding mean frequencies are the means of the absolute frequencies of the letters according to the U count (Underwood and Schulz, 1960, p. 69). For the 6- and 8-consonant lists, arrangements of the consonants were determined by a balanced 284
285
SERIAL POSITION IN RECALL
I00 , go .A <
~ so t- 7o oI.d n.-
60
~
50
0u z
W U
4O
W Z
3O
w i I
i 2
i 3
I 4
I .5
I
6
I 7
I 8
I g
SERIAL POSITION
FIG. 1. Serial position curves for the first trial for each length of series. latin-square design, and Ss serving in these conditions were given only a single trial (one attempt to recall a single arrangement of consonants). For the 5-, 7-, and 9-consonant lists, arrangements of the consonants were determined by a latin-square design in which a particular consonant did not precede or follow any other consonant systematically. The number of Ss assigned to the five experimental conditions was established so that the latin squares for each length of list would be replicated a whole number of times. Except for this restriction, the Ss were assigned to the five experimental conditions at random. The number of Ss in the five conditions, in order of increasing length of list, were 20, 18, 21, 24, and 18. RESULTS M e a n correct recall on the first trial m a y be seen in Fig. 1 as a function of length of list. Only letters reported in their correct serial position were included in this analysis. I t m a y be seen in Fig. 1 that retention becomes poorer as the number of items in the list increases. T h e proportions of total letters recalled correctly on Trial 1 were 1.000, .963, .830, .620, and .568 for the five conditions, given in order of increasing length of list. Some indication of bowing m a y be seen to exist in Fig. 1 for all curves except that for
the 5-consonant lists, for which recall was perfect. I n general, the serial position curves show retention to be highest for the initial item in a list, poorest for items just p a s t the middle of a list, and intermediate for the final item of a list. Figure 1 shows that recall for the first item of a list, regardless of the length of list, was almost perfect. Recall of items at the middle of the list is negatively related to length of list, as would be recall of the final item i f the result for the 8-consonant lists were excluded. Figure 1 shows the bowing of the serial position curves becomes more pronounced the greater the number of letters to be recalled, with perhaps the exception of the curve for the 8-consonant condition. Inspection of the raw d a t a for Ss serving in this condition, however, suggests that their performance on letters late in the list, as shown in Fig. 1, is underestimated. Even though these Ss were told beforehand that they would hear a list of 8 letters, 10 of these 24 Ss p u t a letter or a dash in each of the nine spaces on their answer sheets. (This a p p a r e n t confusion appeared only among Ss in the 8-consonant condition.) When, for these 10 Ss only, two
286
JAHNKE
or more items in correct sequence but displaced not more than one place from correct serial position were scored as correct, improvement was found in performance at serial positions 6, 7, and 8. When these data were used to re-plot the curve for the 8-consonant condition, definite bowing appeared in the serial position curve. Contrary to results shown in Fig. 1, there was now a monotonic inverse relationship between recall of the final item of the list and length of list. Mean recall on the first trial was also determined with the use of a second response measure: a letter recalled was scored as correct if it was from the series presented, even if it was not recalled in its given serial position. Such scoring greatly, reduced the number of errors and largely eliminated the bowing of the" serial position curves for the shorter series and its regularity for the longer. However, the general features of the bowed serial position curves shown in Fig. 1 were maintained in the curves for the 8- and 9consonant conditions. Counts were made of the number and kinds of errors occurring on the first trial for the lists of different lengths. Except for those occurring in the 8-consonant condition, all errors could be classified into one of four categories: (a) omissions; (b) intrusions; (c) repetitions of letters within a list; and (d) misplacements of letters within a list. None or very few errors of any type were made on the first trial by Ss serving in the 5- and 6-consonant conditions. Misplacements and omissions were by far the more frequently occurring in the remaining conditions, with misplacements more frequent than omissions for the the 8- and 9-consonant conditions. DISCUSSION
The salient findings of the present study were as follows. (1) Bowed serial position curves were found for the immediate serial recall of all but the very shortest list of items.
Several of these lists were short enough to be within the memory span of the college student, a finding which may be taken as evidence for a continuity between sub-span and supra-span memory (cf. Melton, 1963). (2) Bowing was found to become more pronounced as the length of list increased. This result is consistent with those of studies of serial anticipation learning (Robinson and Brown, 1926) and of immediate memory using the method of free recall (Bousfield, Whitmarsh, and Esterson, 1958; Deese and Kaufman, 1957; Murdock, 1962) and may be interpreted as reflecting increasing interference associated with increasing numbers of items. The differential effect of such interference must be borne in mind, however. It will be recalled that retention of items at the beginning of the lists was independent of list-length and that this was not so for other items in the lists. (3) For the conditions of this study, the shape of the bowed serial position curve was that typical of serial anticipation learning. Bearing this point in mind, it should also be noted that the immediate serial recall of a list of items is much like a single, unpaced anticipation trial in rote serial learning and that all learning depends upon the retention of the effects of practice from one trial to another (e.g., Hull, 1940; Peterson and Peterson, 1959; Underwood, 1949). Such considerations afford a basis for suggesting that the serial effects of rote serial learning reflect, at least in part, the transfer of serial effects of immediate memory from trial to trial. This suggestion receives some support from another correspondence between serial phenomena of rote serial learning and immediate memory: when presentation of a list of items is serial, but recall is unrestricted as to order, the bowed serial position curve is a mirror image of that obtained when recall is also serial (Deese, 1957; Deese and Kaufman, 1957; Murdock, 1962; Raffel, 1936). (A possible resolution of the
SERIAL POSITION IN RECALL a p p a r e n t l y contradictory result of Bousfield, Whitmarsh, and Esterson (1958) has been offered b y M u r d o c k (1962).) T h e results of the present s t u d y shed no light on the cause of serial effects in immediate memory. I t m a y be suggested, however, that s t u d y of the variables of which the effects are a function m a y prove helpful in understanding both m e m o r y and learning.
SUMMARY
This study examined
the effects of serial
position and length of series on immediate serial recall. Arrangements of either 5, 6, 7, 8, or 9 English consonants were presented according to latin-square designs to groups, respectively, of 20, 18, 21, 24, and 18 women college students. Bowed serial position curves of recall typical of serial anticipation learning were obtained on the first trial for each of the series of different lengths, except for the 5-consonant series, for which recall was perfect. Recall was poorer and bowing of the serial position curve Was greater as the length of series increased. Attention was directed to the similarity between the serial effects of immediate memory and rote serial learning. REFERENCES
BOUSFIELD, W. A., WHIT1M[ARSI-I,G. A., AND ESTERSON,
J. Serial position effects and the "Marbe Effect"
287
in the free recall of meaningful words. J. gen. Psychol., 1958, 59, 255-262. DEESE, J. Serial organization in the recall of disconnected items. Psychol. Rep., 1957, 3, 577-582. DEESE, J., AND KAUFMAN, R. A. Serial effects in recall of unorganized and sequentially organized verbal material. J. exp. Psychol., 1957, 54, 180-187. HULL, C. L., HOVLAND, C. I., ROSS, R. T., HALL, M., PERXlNS, D. T., AND FITCIL F. B. Mathematico-deductive theory of rote learning: A study in scientific methodology. New Haven,
Connecticut: Yale Univer. Press, 1940. KORN, J. H., AND LINDLEY, R. H. Immediate memory for consonants as a function of frequency of occurrence and frequency of appearance. J. exp. Psychol., 1963, in press. MELTON, A. W. Implications of short-term memory for a general theory of memory. J. verb. Learning verb. Behav., 1963, 2, 1-21. MURDOCK, B. B., JR. The serial position effect of free recall. J. exp. Psychol., 1962, 64, 482-488. PETERSON, L. R., AND PETERSON, M. J. Short-term retention of individual verbal items. J. exp. Psychol., 1959, 58, 193-198. RAFFEL, G. Two determinants of the effect of primacy. Amer. J. Psychol., 1936, 48, 654-657. ROBINSON, E. S., AND BROWN, M. A. Effect of serial position upon memorization. Amer. Y. Psychol., 1926, 37, 538-552. UNDERWOOD, B. J. Experimental psychology. New York: Appleton-Century-Crofts, 1949. UNDERWOOD, B. J., AND SCHULZ, R. W. Meaningfulness and verbal learning. Philadelphia: Lippincott, 1960. (Received January 22, 1963)
Serial Position Effects in Immediate Serial Recall 1 JOI-IN C. J A H N K E
Miami University, Oxford, Ohio
Increasing the length of list to be learned typically produces the following changes in the bowed serial position curve of serial anticipation learning: (a) bowing of the serial position curve becomes more pronounced; and (b) performance on middle and final items of the series becomes relatively poorer than performance on the initial items (Robinson and Brown, 1926). Thus far, study of the influence of length of list on serial position effects has been based upon anticipation learning and repeated measurements on the same S. The purpose of the present experiment is to determine the effect of length of list on serial position effects in immediate memory. In the present experiment a list is presented only once to S, who then must attempt recall of the items in correct serial order. METHOD
Subjects. The Ss were 101 women students enrolled in classes in introductory psychology at Miami University. The data from 3 additional Ss were discarded because of procedural error. None of the Ss h a d previously served in a n y experimental s t u d y of immediate memory. Materials and Procedure. T h e procedure involved the immediate recall of a list of either 5, 6, 7, 8, or 9 English consonants. A particular S was tested on 1 This study was facilitated by support from the Faculty Research Committee, Miami University, and from Contract AF 33(657)-10456 with the Aerospace Medical Laboratories, Engineering Psychology Branch, Wright-Patterson Air Force Base, Ohio. The writer is indebted to C. P. D u n c a n and R. A. Hoppe, who critically read drafts of this report, a n d to Miss Leslie Gillette, who collected the data.
only one length of list. T h e Ss were tested individually and were told that a list of letters would be read to them. The letters were read without inflection or emphasis at a 1/sec. rate by a w o m a n E. The Ss were told to listen carefully and were told the n u m b e r of letters in the list b u t were not told w h a t the letters would be, or how m a n y trials they would receive. The Ss were instructed to memorize the letters in the order they were given a n d to write the letters in that order in the appropriate spaces on an answer sheet. The answer sheets were the same for all Ss a n d were prepared in the form of a 9 X 9 grid. The Ss were instructed to indicate with a dash ( - - ) in the appropriate space of the grid a n y letter which could not be recalled. The time allowed for recall was 5 sec. plus the n u m b e r of seconds required to read the list; thus, for example, an S receiving an arrangement of 7 consonants was allowed 12 sec. for recall. This procedure was found to provide sufficient time for recall. The stimulus materials were the nine consonants occurring most frequently in printed English text (Underwood and Schuh, 1960, p. 69). No letter was repeated in any list of a given length. Of necessity, different letters were used in the series of different lengths. Since it has been shown (Korn and Lindley, 1963) that the frequency of occurrence of consonants influences their immediate retention, an a t t e m p t was made to hold the m e a n frequencies of occurrence of the consonants constant across the lists of different lengths. The consonants in each list and the m e a n frequencies of occurrence of the letters in the different lists were as follows: CLDTS, 3582.40; C S H D T L , 3584.67; C R T H L N M , 3574.43; C S D R L T M N , 3587.50; a n d C T R D L S M H N , 3588.44. Each of the preceding arrangements of consonants was one of those actually used in the study. The preceding mean frequencies are the means of the absolute frequencies of the letters according to the U count (Underwood and Schulz, 1960, p. 69). For the 6- and 8-consonant lists, arrangements of the consonants were determined by a balanced 284
285
SERIAL POSITION IN RECALL
I00 , go .A <
~ so t- 7o oI.d n.-
60
~
50
0u z
W U
4O
W Z
3O
w i I
i 2
i 3
I 4
I .5
I
6
I 7
I 8
I g
SERIAL POSITION
FIG. 1. Serial position curves for the first trial for each length of series. latin-square design, and Ss serving in these conditions were given only a single trial (one attempt to recall a single arrangement of consonants). For the 5-, 7-, and 9-consonant lists, arrangements of the consonants were determined by a latin-square design in which a particular consonant did not precede or follow any other consonant systematically. The number of Ss assigned to the five experimental conditions was established so that the latin squares for each length of list would be replicated a whole number of times. Except for this restriction, the Ss were assigned to the five experimental conditions at random. The number of Ss in the five conditions, in order of increasing length of list, were 20, 18, 21, 24, and 18. RESULTS M e a n correct recall on the first trial m a y be seen in Fig. 1 as a function of length of list. Only letters reported in their correct serial position were included in this analysis. I t m a y be seen in Fig. 1 that retention becomes poorer as the number of items in the list increases. T h e proportions of total letters recalled correctly on Trial 1 were 1.000, .963, .830, .620, and .568 for the five conditions, given in order of increasing length of list. Some indication of bowing m a y be seen to exist in Fig. 1 for all curves except that for
the 5-consonant lists, for which recall was perfect. I n general, the serial position curves show retention to be highest for the initial item in a list, poorest for items just p a s t the middle of a list, and intermediate for the final item of a list. Figure 1 shows that recall for the first item of a list, regardless of the length of list, was almost perfect. Recall of items at the middle of the list is negatively related to length of list, as would be recall of the final item i f the result for the 8-consonant lists were excluded. Figure 1 shows the bowing of the serial position curves becomes more pronounced the greater the number of letters to be recalled, with perhaps the exception of the curve for the 8-consonant condition. Inspection of the raw d a t a for Ss serving in this condition, however, suggests that their performance on letters late in the list, as shown in Fig. 1, is underestimated. Even though these Ss were told beforehand that they would hear a list of 8 letters, 10 of these 24 Ss p u t a letter or a dash in each of the nine spaces on their answer sheets. (This a p p a r e n t confusion appeared only among Ss in the 8-consonant condition.) When, for these 10 Ss only, two
286
JAHNKE
or more items in correct sequence but displaced not more than one place from correct serial position were scored as correct, improvement was found in performance at serial positions 6, 7, and 8. When these data were used to re-plot the curve for the 8-consonant condition, definite bowing appeared in the serial position curve. Contrary to results shown in Fig. 1, there was now a monotonic inverse relationship between recall of the final item of the list and length of list. Mean recall on the first trial was also determined with the use of a second response measure: a letter recalled was scored as correct if it was from the series presented, even if it was not recalled in its given serial position. Such scoring greatly, reduced the number of errors and largely eliminated the bowing of the" serial position curves for the shorter series and its regularity for the longer. However, the general features of the bowed serial position curves shown in Fig. 1 were maintained in the curves for the 8- and 9consonant conditions. Counts were made of the number and kinds of errors occurring on the first trial for the lists of different lengths. Except for those occurring in the 8-consonant condition, all errors could be classified into one of four categories: (a) omissions; (b) intrusions; (c) repetitions of letters within a list; and (d) misplacements of letters within a list. None or very few errors of any type were made on the first trial by Ss serving in the 5- and 6-consonant conditions. Misplacements and omissions were by far the more frequently occurring in the remaining conditions, with misplacements more frequent than omissions for the the 8- and 9-consonant conditions. DISCUSSION
The salient findings of the present study were as follows. (1) Bowed serial position curves were found for the immediate serial recall of all but the very shortest list of items.
Several of these lists were short enough to be within the memory span of the college student, a finding which may be taken as evidence for a continuity between sub-span and supra-span memory (cf. Melton, 1963). (2) Bowing was found to become more pronounced as the length of list increased. This result is consistent with those of studies of serial anticipation learning (Robinson and Brown, 1926) and of immediate memory using the method of free recall (Bousfield, Whitmarsh, and Esterson, 1958; Deese and Kaufman, 1957; Murdock, 1962) and may be interpreted as reflecting increasing interference associated with increasing numbers of items. The differential effect of such interference must be borne in mind, however. It will be recalled that retention of items at the beginning of the lists was independent of list-length and that this was not so for other items in the lists. (3) For the conditions of this study, the shape of the bowed serial position curve was that typical of serial anticipation learning. Bearing this point in mind, it should also be noted that the immediate serial recall of a list of items is much like a single, unpaced anticipation trial in rote serial learning and that all learning depends upon the retention of the effects of practice from one trial to another (e.g., Hull, 1940; Peterson and Peterson, 1959; Underwood, 1949). Such considerations afford a basis for suggesting that the serial effects of rote serial learning reflect, at least in part, the transfer of serial effects of immediate memory from trial to trial. This suggestion receives some support from another correspondence between serial phenomena of rote serial learning and immediate memory: when presentation of a list of items is serial, but recall is unrestricted as to order, the bowed serial position curve is a mirror image of that obtained when recall is also serial (Deese, 1957; Deese and Kaufman, 1957; Murdock, 1962; Raffel, 1936). (A possible resolution of the
SERIAL POSITION IN RECALL a p p a r e n t l y contradictory result of Bousfield, Whitmarsh, and Esterson (1958) has been offered b y M u r d o c k (1962).) T h e results of the present s t u d y shed no light on the cause of serial effects in immediate memory. I t m a y be suggested, however, that s t u d y of the variables of which the effects are a function m a y prove helpful in understanding both m e m o r y and learning.
SUMMARY
This study examined
the effects of serial
position and length of series on immediate serial recall. Arrangements of either 5, 6, 7, 8, or 9 English consonants were presented according to latin-square designs to groups, respectively, of 20, 18, 21, 24, and 18 women college students. Bowed serial position curves of recall typical of serial anticipation learning were obtained on the first trial for each of the series of different lengths, except for the 5-consonant series, for which recall was perfect. Recall was poorer and bowing of the serial position curve Was greater as the length of series increased. Attention was directed to the similarity between the serial effects of immediate memory and rote serial learning. REFERENCES
BOUSFIELD, W. A., WHIT1M[ARSI-I,G. A., AND ESTERSON,
J. Serial position effects and the "Marbe Effect"
287
in the free recall of meaningful words. J. gen. Psychol., 1958, 59, 255-262. DEESE, J. Serial organization in the recall of disconnected items. Psychol. Rep., 1957, 3, 577-582. DEESE, J., AND KAUFMAN, R. A. Serial effects in recall of unorganized and sequentially organized verbal material. J. exp. Psychol., 1957, 54, 180-187. HULL, C. L., HOVLAND, C. I., ROSS, R. T., HALL, M., PERXlNS, D. T., AND FITCIL F. B. Mathematico-deductive theory of rote learning: A study in scientific methodology. New Haven,
Connecticut: Yale Univer. Press, 1940. KORN, J. H., AND LINDLEY, R. H. Immediate memory for consonants as a function of frequency of occurrence and frequency of appearance. J. exp. Psychol., 1963, in press. MELTON, A. W. Implications of short-term memory for a general theory of memory. J. verb. Learning verb. Behav., 1963, 2, 1-21. MURDOCK, B. B., JR. The serial position effect of free recall. J. exp. Psychol., 1962, 64, 482-488. PETERSON, L. R., AND PETERSON, M. J. Short-term retention of individual verbal items. J. exp. Psychol., 1959, 58, 193-198. RAFFEL, G. Two determinants of the effect of primacy. Amer. J. Psychol., 1936, 48, 654-657. ROBINSON, E. S., AND BROWN, M. A. Effect of serial position upon memorization. Amer. Y. Psychol., 1926, 37, 538-552. UNDERWOOD, B. J. Experimental psychology. New York: Appleton-Century-Crofts, 1949. UNDERWOOD, B. J., AND SCHULZ, R. W. Meaningfulness and verbal learning. Philadelphia: Lippincott, 1960. (Received January 22, 1963)