John Dickinson

Manual asymmetries in the reproduction of a 3-dimensional spatial location.

Two experiments examined differences in the reproduction of preselected arm positioning movements. In Experiment 1, subjects defined a position in right space with a right index finger, or a position in left space with the left index finger, and then attempted to reproduce the position with either the left or the right hand. Subjects were more accurate when vision was available and when the reproduction hand was the same as the criterion hand. Availability of vision reduced the same hand advantage. There were no accuracy differences between the left and right hands. Experiment 2 was designed to determine whether the left-left and right-right criterion and reproduction advantages evident in the no vision condition of the first experiment were accounted for by the two movements being made by the same hand or by being performed in the same space. The results demonstrated that accuracy depended primarily on whether movements were made with the same hand. No right/left hand advantage was observed. The absence of a right hand advantage in either experiment may be due to the spatial complexity of the task examined or to the relative absence of any temporal constraints.

Cognitive demands of error processing.

This study used a dual-task methodology to assess attention demands associated with error processing during an anticipation-timing task. A difference was predicted in attention demands during feedback on trials with correct responses and errors. This was addressed by requiring participants to respond to a probe reaction-time stimulus after augmented feedback presentation. 16 participants (8 men, 8 women) completed two phases, the reaction time task only and the anticipation-timing task with the probe RT task. False feedback indicating error and a financial reward manipulation were used to increase relevance of errors. Data supported the hypothesis that error processing is associated with higher cognitive demands than processing feedback denoting a correct response. Individuals responded with quicker probe reaction times during presentation of feedback on correct trials than on error trials. These results are discussed with respect to the cognitive processes which might occur during error processing and their role in motor learning.

Order effects and the weighting process in workload assessment

Operators controlling a power grid were subjects in a mental workload experiment in which they performed their normal tasks under simulated quiet and busy conditions. Workload was assessed using the NASA Task-Load Index (TLX). It was found that there were significant differences between the two conditions, but there were no order effects. The value of the weighting procedure was assessed by correlating unweighted and weighted workload ratings. Although the correlations were high, they were not perfect, indicating some value for weighting the dimensions of the TLX. Large individual differences were observed in perceived workload.

Retention of Intentional and Incidental Motor Learning.

Abstract Eighty naive subjects produced and recalled a series of four linear arm-positioning movements. Half the subjects had instructions to learn the movements and the remainder thought they were participating in a distance estimation task. The groups were subdivided and recall was tested after 0, 36, 60, and 600 seconds. Analysis of variance revealed a significant difference between modified variable error scores of incidental and intentional learners and a significant effect due to length of the retention interval. The interaction effect was also significant.

PROTOCOL ANALYSIS OF THE USE OF A CAD SYSTEM IN A HOME DESIGN TASK

The question of how humans design has been approached from a number of perspectives. Analyses have been made of the processes, strategies and problem solving techniques utilized when generating new designs [Finger 89]. One descriptive method to understanding the design process is the use of protocol analysis. This method has been successfully applied to elucidate the stages and decisions inherent in design (see, for instance, [Ullman 86, Adelson 89, Schon 88]).

Human factors design considerations for public videotex input devices

Abstract Eight experiments which formed an integral part of a comprehensive human factors investigation on the design of an input device for public videotex services are reported. Results of the first phase led to the design and construction of two simple keypad devices: a linear configuration, with function keys and numerics arranged in horizontal rows, and a square arrangement, with the function keys clustered around a touch-telephone numeric layout. Evaluation of these keypads with 130 novice users was carried out in Phase Two. While there was little difference in performance between the two pads, an interaction between user preference and duration of use was apparent. A slight preference was indicated for the linear pad on initial presentation but preference shifted towards the square arrangement as the duration of use increased. In the third, and major, phase of the research programme, the two simple keypads were compared with a small alphanumeric keypad and a full-sized keyboard. Results showed that...

The Effect of Distance and Location Cues on Linear Arm Positioning by Children

Forty-five boys in each of three age groups learned a 40 cm linear arm movement, without the aid of vision. Fifteen in each age group attempted to reproduce the movement using either distance, location, or distance plus location cues. Analysis of absolute error scores showed a significant effect of movement cue with inferiority in recall using distance cues compared with the other cue conditions. The interaction effect was also significant. The results are discussed in terms of the development of coding systems for movements in short-term memory.

One-Trial Learning: Predictions about Negative Transfer

One-trial learning, though experienced by many has received minimal attention in motor learning research. As previous study in our laboratory provided some support, the present study was designed to follow-up by examining whether there is no expected negative transfer or response competition. 24 subjects were randomly assigned to a Response-Replacement or Stimulus-Replacement group in an ABAB learning study. Prior to testing subjects learned a list of eight S-R pairs to a criterion of two consecutive error-free trials. The stimuli were eight 3-letter nonsense syllables while responses were specific hand signs taken from the Gallaudet Survival Guide to Signing. Once the list had been learned, subjects transferred to a condition in which either three responses or three stimuli were replaced. Subjects were to learn this new list to a criterion of one error-free trial. Once they learned, subjects performed three additional test trials on the new list, without intervening acquisition trials, to assess negative transfer from the old list to the new list. The response-replaced group required significantly more acquisition trials than did the stimulus-replaced group. No significant difference in errors postcriterion between the groups was found. The findings were consistent with Guthries (1952) expectations, in that once the new response had been learned, there was no retroactive interference from the initial list.

A Reliability Study of Task Walk-Through in the Computer/Communications Industry

One characteristic of the computer and communication industry is the speed with which innovation and change occur. This volatility poses special problems for the researcher involved in human factors issues in this field. A case study is reported in this paper that describes the application of cost-effective simulated trials in product design and product enhancement. A subsequent study, using more conventional research methods, is described that assessed the replicability of simulations. The results from these studies lead to the conclusion that simulated user trials are both a useful source of preliminary data to guide further evaluation and may also constitute an effective and economically viable method of providing direct input to the product development process. The procedures described offer options to human factors specialists in the computer and telecommunications industries.

Distance and location cues in retention of movements by a congenitally blind subject.

Retention of linear arm-positioning movements in a congenitally blind university student was tested with either distance or location cues and under retention conditions of rest, location, and distance interpolated tasks. Results revealed a consistent superiority for retention with location cues. The conclusion is drawn that these data would support a dual proprioceptive storage mode hypothesis.