Jack A. Adams

Historical Review and Appraisal of Research on the Learning, Retention, and Transfer of Human Motor Skills

This review of human motor skills is historical and critical, and starts about 100 years ago. Three historical periods are identified. The main topics are knowledge of results, distribution of practice, transfer of training, retention, and individual differences in motor learning. Basic research is emphasized, but applied research is included also. The article concludes with projections for the future that are based on past research and the present research climate. Why review nearly a century of research on motor skills? A good experiment can result from bouncing off the last one or a small subset of experiments in the literature, so why bother with the panorama? Any good scientific question always seems to have a long story. Perceptive investigators see the key variables and issues of a scientific topic early, and the generations that follow persist in efforts to understand those variables and issues. The first answer to my question, then, is that a sense of history helps an investigator lock onto important themes. Experiments enriched by history could contribute to the science rather than only brightening an inconsequential corner. Second, a sense of history tends to shunt an investigator away from the fads and fashions of his or her field. Fads and fashions are those inconsequential corners that are temporarily magnified out of proportion and that draw the energy of investigators who either have not seen the worth of persisting themes or who allow themselves to be turned from them. Third, the canons of scholarship are based on history because they require that (a) the origins of ideas be known so that ones own ideas are in perspective and, (b) earlier experiments be known so that the knowledge increment in ones own empirical findings is clear. My aim is to organize variables and issues for learning, retention, and transfer that have regularly attracted investigators of human motor skills, and to discuss the experiments that have been done to understand them. The last historical review of human motor skills was by Irion (1966). My review differs from Irions in that I cover more material, have a different perspective, and update developments in the field. This article begins with a definition of the domain, and then divides the historical coverage into three historical periods: the Early Period, 1880-1940; the Middle Period, 19401970; and the Present Period, 1970 to the present. The periods are delineated by surges in research activity, although I cannot always be strict about the dividing line. The surge associated

Monitoring of Complex Visual Displays— II. Effects of Visual Load and Response Complexity on Human Vigilance1

A vigilance experiment was performed on the characteristics of visual monitoring behavior in complex tasks like those found in modern semi-automatic systems. The activationist hypothesis, which contends that human alertness is a function of stimulation level, served as framework for the experiment. Under investigation were sources of environmental and response-produced stimulation that might he related to hitman alertness. A. simulated semi-automatic air defense surveillance task was used. Environmental stimulation was manipulated by requiring six or thirty-six visual stimulus sources to be monitored for a 3-hr observation period. Response-produced stimulation was a function of response complexity. No vigilance decrement was found for per cent of signals correctly detected. Response latency declined significantly, but slightly, for groups that had simple response conditions but not for groups with complex response requirements. Results were discussed in terms of issues in operationally defining sources of stimulation for the activationist hypothesis, and the cautions that must be observed in generalising from the simple tasks of most vigilance experiments to the complex tasks of semi-automatic systems.

Issues in Human Reliability

The correct premise of the topic of human reliability is that system personnel fail in their responding just as equipment does, and so they must be considered along with the equipment in the specification of system reliability. The goal of human reliability efforts as they are presently pursued is to find measures of the reliability of human performance that are expressed in the same terms as measures of equipment reliability and can be combined with them to produce system reliability. The thesis of this paper is that conceptualizing human reliability in these terms raises methodological problems that are likely to prevent this goal from being achieved. What is lacking are: a definition of human failure, units of human behavior whose reliability can be determined, a way to synthesize the reliability of larger behavioral sequences from the units if we could specify them, and a way to integrate human reliability, if it could be determined, with equipment reliability. Monte Carlo modeling is seen as a promising approach to the topic.

Proprioception Variables as Determiners of Anticipatory Timing Behavior

Anticipatory timing, where the human operator initiates an accurate response before the actual occurrence of the environmental event, is one of the most striking and least studied aspects of skilled motor performance. An experiment was performed on temporal and control system variables that could influence the timing of responses in a tracking task. Verification was sought for a proprioceptive trace hypothesis that holds the time-varying proprioceptive after-effects of movements to be the internal trace that persists in time and cues the occurrence of a future response. Ninety-six subjects participated. A 2×2×2 randomized factorial design used two values each of movement amplitude, spring loading, and signal duration as a means of manipulating proprioceptive stimuli and their time trace. Results supported the hypothesis. Signal duration and spring loading of the control induced significant effects for the number of beneficial anticipations, but movement amplitude had no significant effect. It was concluded that proprioception has a role in response timing, in addition to its traditional one of informative feedback.

MONITORING OF COMPLEX VISUAL DISPLAYS. IV. TRAINING FOR VIGILANCE.

An experiment was performed to test the hypothesis that knowledge of results (KR) in a vigilance task can be used as a training technique that will transfer positively to subsequent non-KR sessions where feedback is absent. Three groups, fifteen subjects each, participated in a visual monitoring task for four sessions of three hours each. One group received KR about response proficiency after each response in the first two sessions and a second group received only a neutral remark each time from the experimenter. The final two sessions were standard vigilance tasks without feedback. A third control group had the standard task throughout. The KR group had reliably superior performance on all sessions although within-session vigilance decrement was uninfluenced. The neutral stimulation group did not differ from the control condition. It is suggested that KR administered in a training situation can produce improved vigilance during actual system use where KR is absent.

Retroactive inhibition and natural language mediation

Natural language mediators (NLMs) or idiosyncratic associations, were studied for their effect on A-B recall in an A-B, A-C paradigm. A list of eight paired adjectives was used, and NLMs were obtained by questionnaire after original learning, interpolated learning, and recall. The level of NLM usage was high, being 66% in original learning and 70% in interpolated learning. No loss of NLMs was found from original learning to recall. Recall was positively related to the presence of NLMs in learning A-B, but independent of whether A-C items were mediated or rote. The results were discussed in terms of NLMs being either a correlate of the associative process or a direct determinant of it, but no basis was found for a choice between these alternative interpretations. In both cases it was considered likely that items with NLMs in original learning had reduced retroactive inhibition because NLMs were an index of greater associative strength. Another possibility was that an NLM decreased retroactive inhibition by decreasing the similarity of pairs.

On the Evaluation of Training Devices

The theme of the paper is ways of evaluating flight simulators for aircrew training. The transfer of training experiment and the rating method are the two present-day ways of evaluating the worth of a simulator. The transfer experiment requires the trainee to practice in the simulator and then be tested in the parent aircraft to demonstrate the training value of the simulator. The rating method requires the pilot to be experienced in the parent aircraft and to rate the simulator for similarity to the aircraft. If similarity is high, the training value is assumed to be high. Arguments are presented that both of these methods are flawed. It is contended that a simulator, or any other system, need not necessarily be tested if it is based on reliable scientific laws and the success of other systems, based on the same laws, has been high. Good laws produce accurate prediction, and when outcome can be predicted it is redundant to conduct a system evaluation. With uncertainty about laws, the requirement for system testing increases. The psychological principles underlying simulators are reviewed.

Monitoring of complex visual displays: iii. effects of repeated sessions on human vigilance

A vigilance experiment was performed using a visual monitoring task with multiple stimulus sources. Under investigation were effects of repeated sessions on monitoring behavior. Nine 3-hour sessions were given on consecutive days. Following a longer 7-day interval, a 10th session was given. The main findings were a significant decrement in detection latency within each session, but no statistically reliable evidence for a between-sessions effect. Evidence was presented to suggest that the spatial configuration of stimulus sources was a factor for vigilance decrement because efficiency of the observing response decreased as a function of observation time.

The Forgetting of Instrument Flying Skills

A laboratory study of forgetting was conducted, using an aircraft simulator as the research device. Two groups of subjects were used, with one group receiving twice the amount of original training as the other. The retention interval was four months for both groups. The principal result was that discrete procedural response sequences had statistically and practically significant loss over the retention interval, but proficiency in controlling flight parameters (tracking) and statistically significant losses in only some instances and never in operationally significant amounts.

Do Cognitive Factors in Motor Performance Become Nonfunctional with Practice

Cognitive factors in motor behavior were defined as verbal and imagery mediators for a discrete, sequential motor task. The question was asked whether these mediators become nonfunctional with extended practice. Non-motor interference training was given in inappropriate verbal and imagery mediation. If cognitive factors in the motor task involve verbal an/or imagery dimensions, and they dominate early in learning, then the non motor interference training should produce relatively large negative transfer effects in the motor performance early in learning and little or no such effects late in learning. The results did not conform to expectation; small negative transfer effects were found both early and late in learning. The discussion considered several possible reason for the outcome: the motor task was dominated by visual and proprioception factors rather than cognitive ones, the method of delivering knowledge of results may have minimized cognitive factors, or the hypothesis is wrong.