is very little common ground in the AKELAITIS. A. J. Studies on corpus trace decay theory, or a combination callosum; study of language functions of the two best accounts for the experiments. l\loreover, using a manual (tactile and visual, lexia and graphia) response of the kind he employed unilaterally follo\ving section of corpus shown in motor STM. unnecessarily complicates the callosum. Journal of Neuropathological & Adams & Dijkstra (1966) examined interpretation and most probably Experimental Neurology, 1943, 2, the retention of a linear motor 226 response in which the basic variables neutralizes the "TTT," for it is AKELAITIS, A. J. Study of guosis, praxis, becoming apparent from a number of and language follO\ving section of corpus were length of retention interval and other studies that movements elicited callosum and anterior commissure, number of reinforcements or trials from proximal muscle system give no Journal of Neurosurgery, 1944, I, before . Absolute error was 94 found to be positively related to difference, whereas responses requiring AKELAITIS, A. J., RISTEEN, A. W., cerebral exclusively-individual finger HERREN, R. Y., & VAN WAGENEN, W. length of retention interval, and control reveal "ITT" differences. P. Studies on corpus callosum; consequently, Adams & Dijkstra contribution to study of dyspraxia and (1966) interpreted their results in The idea of trying to figure out the apraxia of corpus callosum. Archives of callosal code by using reaction time is Neurological Psychiatry (Chicago), 1942, terms of a rapidly decaying upon us. It may fade. It's not as easy 47,971 trace, which became increasingly as it sounds. Nonetheless, within the BRADSHAW, J. L., & PERRIMENT, A. D. stable with reinforcement. Stelmach Laterality effects and choice reaction year there have been a number of time in a unimanual two-finger task. (1969a), using a simple papers on the subject (Moscovitch & Perception & Psychophysics, 1970, 7, lever-positioning task, employed the Catlin, 1970; Bradshaw & Perriment, 185-188. three independent variables of 1970; Klatzkyl). These authors, using MOSCOVITCH, M., & CATLIN, J. magnitude of movement, retention Interhemispheric transmission of different responses, different stimuli, information: Measurement in normal interval, and number of prior and different almost everything else, man. Psychonomic Science, 1970, 18, positioning responses. Absolute error found differences in transmission time 211-213. was found to be positively related to POFFENBERGER, A. T. Reaction time to ranging from.l 0 to 60 msec. Finally, I retinal stimulation with special reference the number of prior positioning can only urge those interested in the to the time lost in conduction through responses and to the length of the approach to join in. nerve centers. Archives of Psychology retention interval, but the magnitude REFERENCES (New York), 1912, No. 23. of the movement was found to be AKELAITIS, A. J. Studies on corpus nonsignificant. He considered the role callosum; higher visual functions in each homonymous field following complete NOTE of proactive interference in his results 1. Klatzky, R. L. Interhemispheric section of corpus callosum. Archives of but seemed to favor the decay of the transfer of test stimulus representations in Neurological Psychiatry (Chicago), 1941, memory scanning. In preparation. memory traces as the best explanation_ 45,788 However, in a similar study, Stelmach (1969b) found that absolute errors at recall were inversely related to the similarity of prior responses and that forgetting was found to be an increasing function of the retention interval. Stelmach (1969b) noted that the results concerning the similarity of responses were in direct opposition to the findings usually observed in verbal tasks and were not consistent with the predictions from . More recently, Pepper & Herman (1970) performed a series of five The role of interference and experiments measuring the retention of the magnitude of the force of a knob which was pushed or pulled trace decay in the retention through the vertical dimension in an attempt to establish whether decay, of a sitnple psychomotor task* interference, or a combination of the two was the cause of the forgetting shown in motor STM. Pepper & STEPHEN D. SOUTHALLt and KENNETH A. BLICK Herman (1970), by application of a University of Richmond, Richmond, Va. 23173 second force response during the retention interval, showed that The purpose of the present study was to show whether interference theory interference effects, traceable to the and/or trace decay theory account for the forgetting found in motor short-term interpolated task, can be demonstrated memory. One variable was the number of prior responses (0 to 6) which the S for motor STM. The role of trace experienced on a linear slide apparatus; another variable was the length of the decay and interference theory in the retention interval (5, 40, and 75 sec). There were no significant effects due to area of motor STM is still nebulous, retention interval, number of prior responses, or the interaction between and it was the purpose of the present retention interval and prior responses. experiment to establish precisely the role of trace decay theory and/or The role that interference plays in role in motor STM has not yet been interference theory in motor STM. verbal short-term memory (STM) has confirmed, Although there have been been established for some time, but its many studies of verbal STM (Conrad & METHOD Hille, 1958; Keppel & Underwood, One hundred and five 1962; Murdock, 1961; Peterson & undergraduates from the University of Peterson, 1959), there have been Richmond participated in the *This research was supported in part by a relatively few studies on short-term Faculty Research Grant from the University experiment. Fifteen males and 20 of Richmond. retention of motor responses. It is not females served in each of the three tNow at the University of Virginia. yet clear whether interference theory, retention int.pl·v~k

Psychon. Sci., 1971, Vol. 22 (4) 223 The apparatus was a block of wood, Table 1 One reason why till' resulb in the 5 cm high, 7 cm wide, and 68 cm long, Mean Absolute Error (in Millimeters) for present study were nonsignificant with a 2-cm-wide groove cut down the the Seven Prior Response Conditions at could have been the manner in which length of the board in the center of the Three Retention Intervals the prior responses were administered. the 7-cm side. A slide which measured Retention Intervals Stelmach (1969a) administered either 2.5 cm long and slightly less than 2 cm Number two or four prior positioning responses wide fit snugly in the groove and had a of Prior 5 40 75 Group immediately before the target position knob on the top which enabled the Ss Responses Sec Sec Sec Means response. He then had the S recall the to move the slide in the groove. 0 23 28 28 26.3 responses in reverse order of Another slide, used as a stop by the E, 1 23 22 25 23.3 presentation, but, unknown to the S, was put in the groove during the 2 30 32 23 28.3 he only recorded the target position practice trials and removed during the 3 25 25 25 25.0 response. The difference between recall trials. 4 24 23 28 25.0 Stelmach's study and the present one All Ss came into the experimental 5 23 24 24 23.7 is that his prior positioning responses room and were seated across the table 6 22 23 28 24.3 Group were not recalled until after the target from the They were told that they 24.3 25.3 25.8 E. Means position response, while in the present were to remember and duplicate as study each response was recalled well as possible a series of movements before another was administered. This along a straight line which they were could be the reason that interference to make on the slide apparatus in front intertrial interval of 20 sec. During the was not shown in the present study. of them. They were told that on the intertrial interval the E recorded the After a response was administered and instruction, "Move," they were to length of the S's response. After E recalled, it could be dismissed by the S move the slide from right to left by recorded the response to the nearest and he could concentrate on the next, means of the knob until they hit a millimeter, he moved the slide back to whereas in Stelmach's study the Shad stop. After 3 sec the instruction, the starting position and told the S to to retain either three or five responses "Return," was given, and they put his hand on the slide and prepare at one time; this, therefore, produced returned' the slide to the starting for another trial. the interference that evidenced itself position. It was at this point that the RESULTS AND DISCUSSION in Stelmach's study. Presumably, a retention interval of 5, 40, or 75 sec Recall scores for each S were combination of Stelmach's method of began. During this interval S was not calculated as the absolute error in producing interference and the present to move his hand from the knob but millimeters from perfect target experimental design would provide a could rest his arm on the desk. On the reproduction. The mean absolute error more definitive answer concerning the instruction, "Estimate," he was to for each of the seven prior response role of interference and trace decay in attempt to duplicate his response in conditions at the three retention motor STM. According to Stelmach one continuous movement. intervals is shown in Table 1. Each cell (1969b), "When there is more data After the previous instructions had mean is based on 35 Ss, and visual available on the short-term retention been read to the S and any questions inspection of the cell means reveals no of motor responses, it will be better answered, the S was blindfolded. He apparent trends. According to the known whether motor behavior grasped the knob on top of the slide, group means, absolute error does not follows the same empirical laws that and on the instruction, "Move," he appear to increase as the number of govern verbal responses [po 43]." moved the slide until he hit a stop. prior responses increases, nor does The S's hand remained in this position absolute error show any appreciable for 3 sec. On the instruction, change over the three retention REFERENCES "Return," he returned the slide to the intervals. ADAMS, J. A .• & DIJKSTRA. S. Short-term starting position which was at the end A two-factor analysis of variance memory for motor responses. Journal of of the groove at the S's right. A with repeated measures was performed Experimental Psychology. 1966. 71. 314-318. permanent stop was located there, to on the data, using the .05 level of CONRAD. R.. & HILLE. B. A. Decay stop the slide when the S had moved it significance, and all comparisons theory of immediate memory and paced back to the starting position. produced F < 1. Neither retention recall. Canadian Journal of Psychology. 1958.12.1-6. There were seven different lengths interval nor number of prior responses KEPPEL. G.. & UNDERWOOD. B. J. of movements which the Ss made. The was significant. The interaction of Proactive inhibition in short-term lengths were 10, 14, 18, 22, 26, 30, retention interval and number of retention of single items. Journal of and 34 cm. The lengths were presented previous responses was also Verbal & Verbal Behavior. 1962.1.153-161. in seven different randomized nonsignificant. MURDOCK. B. B.. JR. The retention of sequences, with each length appearing A number of experiments in motor individual items. Journal of Experimental in each ordinal position once, in order STM have found that retention of a Psychology. 1961. 62.618-625. PEPPER, R. L .• & HERMAN. L. M. Decay to prevent any sequential effect from simple motor response is a decreasing and interference effects in the short-term smaller to larger lengths, or vice versa. function of the length of the retention retention of a discrete motor act. Journal In addition, the seven randomized interval (Adams & Dijkstra, 1966; of Experimental Psychology Monograph, 1970,83. No.2. Part 2. 1-18. sequences occurred equally often Stelmach, 1969a, b; 1970). In PETERSON. L. R .• & PETERSON. M. J. under each time interval and five Ss addition, the effect of interference in Short-term retention of individual verbal serving in each sequence. motor STM has been demonstrated in items. Journal of Experimental After the S moved back to the some studies (Stelmach, 1969a; Pepper Psychology. 1959.58.193-198. STELMACH. G. E. Prior positioning starting position, the E started timing & Herman, 1970), while other studies responses as a factor in short-term the retention interval of 5, 40, or report no effect due to interference retention of a simple motor task. Journal 75 sec. At the end of the retention (Stelmach, 1969b, 1970). Since the of Experimental Psychology, 1969a. 81. results of both retention interval and 523-526. period, the E gave the instruction, STELMACH. G. E. Short-term motor "Estimate," at which time the S number of prior responses in the retention as a function of attempted to duplicate his response. present study were nonsignificant, no response-similarity. Journal of Motor After the S had made the continuous conclusions can be drawn concerning Behavior. 1969b. 1. 37-44. STELMACH. G. E. Kinesthetic recall and movement, he removed his hand from the roles of proactive interference or information reduction activity. Journal of the slide, and the E started timing the decay of memory trace. Motor Behavior, 1970. 2. 183-194.

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