Robert B. Wilberg

The generation of movement patterns during the acquisition of a pursuit tracking task

Abstract In these two experiments the organization and generation of a movement sequence was investigated. The subjects learned a pursuit tracking task in which the stimulus was a periodic complex sine wave. An input blanking paradigm was used to enable a quantitative assessment of the waveform being generated by the subjects. The learned response that was produced by subjects from memeory during input blanking appeared to have been organized in terms of the component frequencies of that response. The amplitude and phase relationship of the lower harmonics of the stimulus were of major concern to the subjects early in learning, while the higher harmonics remained relatively unimportant. After an extended number of learning trials the subjects generated a response that was a closer approximation of the stimulus especially with respect to the higher harmonics of the composite waveform. A discussion of how these findings relate to a process oriented description of response organization is undertaken.

IMMEDIATE REPRODUCTION OF TEMPORAL INFORMATION UNDER FOUR COGNITIVE STRATEGIES

The main purpose was to determine the retention characteristics of temporal information when subjects experienced time under a retention interval of immediate reproduction and various cognitive strategies for time estimation. Four levels of cognitive strategy were used, viz., conscious, mental counting, counting aloud without auditory cues, and counting aloud with auditory cues. The latter three cognitive strategies were experimenter-defined, time-aiding techniques. Subjects were instructed to refrain from employing time-aiding techniques under a conscious cognitive strategy for time estimation. Visual durations of 1, 2, and 4 sec. were estimated by 12 subjects under the method of reproduction. Two measures of performance were computed, viz., variable and constant errors. The general conclusions were: (a) the effectiveness of mental counting, counting aloud without auditory cues, and counting aloud with auditory cues as cognitive strategies over conscious cognitive strategy in terms of variability depends on the duration used, and (b) in terms of accuracy and variability an increase in the number of cues under time-aiding techniques does not necessarily produce better performance.

Long-Term Memory for a Single Movement

Equivocable experimental results obtained over several decades of motor learning and memory research, have served more to cloud the theoretical picture than to enhance our understanding of movement memory. The reasons for this slate are practical as well as theoretical in nature. In the presence of so many disparate interpretations arising from the data, perhaps the simplist approach would be to virtually disregard the structuralist viewpoint and develop a set of experiments to provide a more functionalislic data-base. Two experiments involving movement length and temporal duration were completed. Comparisons are made to other non-verbal experiments involving the memory for single items. Persistance of the memory may be related to its associated episodic content.

Information load and response consistency in sequential short-term motor memory.

The short-term retention of movement sequences of varying information loads was investigated to determine whether the recall accuracy was based upon central movement sources (motor plans) or upon peripheral sources (afferent input). A 2-dimensional joystick apparatus was used and the experimental variables were: information load (2, 4, and 8 movements), input control (S-controlled and E-controlled), and recall consistency (first and second recall). Measures of absolute, constant, and variable error were analyzed in a treatment by Ss design, using university Ss (N = 12). Information load was inversely related to recall accuracy. S-controlled input was more accurate than E-controlled input at the highest load, and response consistency was high for all conditions. These results were discussed in the context of the utilization of motor plans rather than peripheral traces in this type of task.

SHORT-TERM RETENTION OF TEMPORAL VISUAL INFORMATION

The main purpose was to determine the short-term retention characteristics of temporal information when subjects experienced time under a conscious cognitive strategy for time estimation, i.e., subjects were instructed to refrain from employing time-aiding techniques. Visual durations of 1 and 4 sec. were estimated by 12 subjects under the method of reproduction. Six levels of retention interval were used, viz., immediate reproduction, self-paced reproduction, i.e., the subjects were allowed to recall whenever they wished, 15 and 30 sec. of rest, and 15 and 30 sec. of interpolated activity, i.e., counting backwards by threes. The variable error was used to evaluate effects of forgetting. When subjects held a duration of 4 sec. in memory for a period of 15 or 30 sec. of rest, they became more variable than when they recalled the item immediately, at their own pace or when the duration to be remembered was only 1 sec. long. When an interpolated task was required during the retention interval, its variability was similar to the results obtained under an unfulfilled retention interval for both durations. The presence of an interaction between duration and retention interval under the variable error was explained in terms of memory.

Response Accuracy Based upon Recall from Visual and Kinesthetic Short-Term Memory.

Abstract Visual and kinesthetic short-term memories were subjected to: (a) immediate recall, (b) delayed (10 sec.) recall, and (c) delayed recall with interpolated task. On the basis of recent investigations, the exact nature of kinesthetic and visual input in short-term memory (STM) was unclear. Since the kinesthetic input was the least investigated and seemed to be the cause of the uncertainty, one kinesthetic factor (three levels), pressure (torque measured in pound-inches) was used as the second factor in a two-factor experiment. The results on the first factor, STM, coincided with those of previous investigators. The result of the second factor, pressure, was that kinesthetic input of that nature was not usable information in a replacement task.

CONSISTENT REPRODUCTION OF MOVEMENT SEQUENCES DURING ACQUISITION OF A PURSUIT TRACKING TASK

A pursuit tracking task is used as a vehicle to investigate the manner in which response consistency is affected by practice. Detailed examination of movement patterns shows that subjects can reproduce the mid-phase of a movement relatively consistently while the accelerative and decelerative phases of the movement remain highly variable. The findings are discussed with reference to Sparrows 1983 concept of efficiency in conjunction with Norman and Shallices 1980 model of automated action.

SHORT-TERM RETENTION OF TEMPORAL INFORMATION UNDER A MENTAL COUNTING COGNITIVE STRATEGY

The main purpose was to determine the short-term retention characteristics of temporal information when subjects experienced time under a time-aiding technique for time estimation, i.e., subjects were instructed to use a mental-counting cognitive strategy. Visual durations of 1 and 4 sec. were estimated by 12 subjects under the method of reproduction. Six levels of retention interval were used, viz., immediate reproduction, self-paced reproduction, 15 sec. of rest, 30 sec. of rest, 15 and 30 sec. of interpolated activity, i.e., counting backwards by threes. The variable error was used to evaluate effects of forgetting. When subjects hold durations of 1 and 4 sec. in memory for a period of 15 or 30 sec. with or without interpolated activity, they become more variable than if they recall the item immediately or at their own pace. The constant error was used as an index of bias. Subjects overestimated the 1 sec. and underestimated the 4 sec. durations. The results were compared with a prior study done under a conscious cognitive strategy for time estimation, i.e., subjects were instructed to refrain from employing time-aiding techniques.

Memory for Movement: Discussion of Adams and Saltzman and Kelso

Four issues arising from the papers of Adams, and Saltzman and Kelso are examined. These are: the rise of knowledge about motor memory, the relationship of motor memory to memory for movement, the relationship between motor and verbal memory, and the problem of interpreting motor memory by means of regress.

Context effects in movement recognition

Abstract An experiment was performed in which ten subjects made comparative judgements of two objectively equally long movement lengths. Additional movements, known as anchor movements, occured before, between, or after the comparison pair in order to decide whether such anchor movements would operate proactively (i.e., producing an effect on the reception of the subsequent stimulus) or retroactively (i.e., affecting the memory trace of the preceding stimulus). The results are interpreted to mean anchor movements act retroactively.