psychomotor learning

Introduction

development of organized patterns of muscular activities guided by changing signals from the environment. Driving a car and eye–hand coordination tasks such as drilling a tooth, throwing a ball, typing, operating a lathe, and playing a trombone are behavioral examples. Also called sensorimotor and perceptual-motor skills, they are studied as special topics in the experimental psychology of human learning and performance. In research concerning psychomotor skills, particular attention is given to the learning of coordinated activity of the arms, hands, fingers, and feet; the role of verbal processes is not emphasized.

 

The range of skills

The term “skill” denotes a movement that is reasonably complex and the execution of which requires at least a minimal amount of practice. Thus skill excludes reflex acts. One does not become skilled at sneezing or at blinking the eyes when an object approaches. At the same time, it has become increasingly apparent to scientists investigating the performance and acquisition of motor acts that the performance of complex skills is closely linked to sensations arising from the things the performer looks at, sensations from the muscles that are involved in the movement itself, as well as stimuli received by other sensory end organs. Thus the term “sensorimotor skill,” denoting the close relationship between movement and sensation in the acquisition of complex acts, is found within the research literature with increasing frequency.

 

Simple components of bodily skills

Most of life's skills are continuous and complex and contain a multitude of integrated components; however, these complex skills may be analyzed by examination of their component parts.

The performance of a skill may be broken down into several time intervals. Initially the performer must be attentive and alert enough to be receptive to some kind of sensory information, which may in turn lead toward some kind of motor act. For this to occur the performer usually becomes aware of some kind of stimulus that is intense or distinctive enough to be perceived as different from other sensory information.

As this cue occurs the performer then must make a decision to act or not to act; and this is generally dependent upon his past experience within similar situations and with similar stimuli, as well as upon his feelings about his personal capabilities. If he decides to act, the next thing that occurs is the selection of an appropriate motor response from the entire “collection” of motor responses that he has acquired.

In the laboratory, a subject's reaction time is the time between the presentation of some kind of stimulus and the performer's initiation of response. The individual's speed of reaction in such situations is dependent upon a number of variables, including the intensity of the stimuli; for example, a person will initiate a movement more quickly to increasingly louder sounds until a limit is reached. If too loud a sound is presented it will delay the onset of the movement and result in a longer reaction time. Similarly, a longer reaction time will be recorded in such experiments if the subject is aware that he will have to initiate a complex movement or if the subject must choose from among a number of stimuli before initiating a movement (e.g.,if he must move only if one of a number of various coloured lights is turned on).

The quality of the movement then initiated is dependent upon a number of other factors, the precision of the act required, the past experience of the performer in similar skills, the speed of the movement, the force of the motor act, as well as body part or parts to be moved.

The efficient performance of many types of extremely simple motor skills may be limited by inherent response capacities built into the human nervous system. Finger tapping at more than ten times per second for example is not usually possible. A person's ability to keep a body part relatively steady may be disturbed by natural, regular, and rather predictable oscillation rates of the limbs, fingers, and of the total body (evidenced in measures of body sway).

Individuals vary greatly in their ability to exercise force with various body parts. At the same time, there are limits beyond which it is not realistic to expect humans to go when evidencing strength in various tasks.

Careful experimentation reveals that because of the complexity of the human motor system it is unlikely that an individual ever repeats an apparently similar movement in precisely the same way. Thus the acquisition of skill in a given task involves the performance of a reasonably consistent response pattern, which varies, within limits, from trial to trial.

It is a common observation that there seem to be a number of basic motor abilities that may underlie the performance of a number of life's activities. This subject was investigated rather extensively during the 1950s and 1960s. The intercorrelation of performance scores elicited from thousands of young adult subjects who participated in these investigations revealed that there are in fact a number of basic abilities that contribute to the efficient performance of both fine and gross motor skills. Although a detailed examination of these abilities is not possible here, in general it was revealed that there are five components of what might be broadly referred to as “manual dexterity,” including fine finger dexterity, arm-wrist speed and aiming ability. Similar research has explored the manner in which performance scores group themselves in skills in which larger muscles are involved. It was found, for example, that there are several kinds of strengths, including static strength (pressure measured in pounds exerted against an immovable object); this is independent of what was termed “dynamic strength” (moving the limbs with force). Muscular flexibility and balancing ability were similarly dissected into several components. Thus discussion of a single quality in human movement is inaccurate. Rather, one should refer to several specific types of ability.

Motor skills may also be classified by reference to the more general characteristics of the tasks themselves rather than by measuring and intercorrelating the scores elicited by human subjects. It is common, for example, to find the dichotomy “fine” and “gross” motor skill, in which the latter label is applied to acts in which the larger muscles are commonly involved, while the former classification denotes actions of the hands and fingers. One researcher has proposed a three-way classification system, separating human movements into “body transport movements,” in which the total body moves in space; limb movements; and manual (hand) actions. In general, however, most skills incorporate precise movements of both larger and smaller muscle groups working in harmony. The basketball player must use his larger skeletal muscles to run and jump but at the same time must employ a fine “touch,” evidencing accurate finger control, when dribbling the ball. On the other hand, when a person sits at a desk and writes, the large postural muscles that contribute to the writer's stability are invariably active.

 

Complex, integrated skills

Most of life's skills are not simple ones. They are rhythmic at times and almost always are composed of several integrated parts. Such skills are often controlled by the organization of visual information available to the performer, particularly during the early stages of learning. At the same time, the individual's ability to analyze the mechanics of a motor task, his verbal ability, and other intellectual and perceptual attributes may influence his acquisition of a skill.

Although psychomotor skills are widely distributed—e.g.,in military, athletic, musical, and industrial settings—such complex situations typically do not lend themselves to rigorous experimental research. Most scientists have found it more analytically useful to study psychomotor learning under controlled laboratory conditions. Measures of proficiency obtained in the laboratory reflect increasing accuracy and decreasing variability in a learner's performance as training progresses. If there is sufficient genetic aptitude, a person's mastery of a skill depends on his motivation to improve, on his receiving continuous information or sensory feedback about the adequacy of his performance during training, and on such factors as the rewarding effects of corrections made during successive practice periods. Skills are susceptible to inhibitory influences. The full extent of gains in proficiency often is masked by temporary losses and emerges only later, without additional practice sessions.

Psychomotor habits are mediated primarily by the sensory and motor cortex of the brain and by the neural fibres (commissures) that connect the two cerebral hemispheres. According to the majority of theoreticians, learning proceeds (habit strength develops) as a mathematical function of the amount or duration of rewarded (reinforced) practice. The effects of associative and motivational factors are believed to combine mathematically by multiplying one another, while inhibitory and oscillation (variability) factors are thought to have subtractive effects. Despite theoretical and empirical progress, much remains to be discovered about the learning and performance of psychomotor skills, especially about the interrelationships among training variables, feedback contingencies, and human-factor variables.

 

Clyde Everett NobleBryant J. Cratty

Laboratory research in psychomotor learning

Devices and tasks

Hundreds of electrical and mechanical instruments have been developed for research in psychomotor learning, but those commonly used number less than two dozen. In operating a device called a complex coordinator, the learner is instructed to make prompt, synchronized adjustments of handstick and foot-bar controls to match different combinations of stimulus lights. Another device, a discrimination reaction timer, requires that one of several toggle switches be snapped rapidly in response to designated distinctive spatial patterns of coloured signal lamps. In performing on a manual lever, a blindfolded subject must learn how far to move the handle on the basis of numerical information provided by the experimenter. With a so-called mirror tracer, a six-pointed star pattern is followed with an electrical stylus as accurately and quickly as possible, the learner being guided visually only by a mirror image. The operator of an instrument called a multidimensional pursuitmeter is required to scan four dials and to keep their indicators steady by making corrections with four controls of the type found in an airplane cockpit. On a rotary pursuitmeter the trainee's task is to hold a flexible stylus in continuous electrical contact with a small, circular metal target set into a revolving turntable.

Also employed in such research is a selective mathometer, on which the subject's problem is to discover, with cues provided by a signal lamp, which of 19 pushbuttons should be pressed in response to each of a series of distinctive images projected on a screen. While using a star discrimeter, a person receives information about his errors through earphones; his task is to learn to selectively position one lever among six radial slots in accordance with signals from differently coloured stimulus lights. A trainee on a two-hand coordinator has to manipulate two lathe crank handles synchronously to maintain contact with a target disk as it moves through an irregular course.

 

Measurements

The tasks required by the above devices produce a substantial range of psychomotor difficulty. The elements of skilled behaviour are expressed as numerical scores;e.g.,correct response and error percentages, amplitude and speed of movement, hand or foot pressures exerted, time on target, reaction time, rate of response, and indices of time-sharing activity. Most of the behaviour thus recorded lends itself readily to mathematical treatment. Laboratory devices for studying psychomotor learning characteristically exhibit high reliability (i.e.,intra-task consistency) and yield scores of useful validity (extra-task correlation) in predicting such behaviour as performance in factory work and the operation of motor vehicles and aircraft. In other words, it would appear that perceptual-motor devices reliably measure what they are designed to measure, and they also tap a significant proportion of the abilities required in real-life situations. When properly maintained and used under standardized conditions and when the resulting measurements are treated by statistical methods, the above devices are prime choices for many applied and basic research programs.

 

Phenomena of psychomotor learning

Acquisition

 

• Figure 1: Rotary pursuit acquisition curves.

 

• Figure 1: Rotary pursuit acquisition curves.

 

• Figure 1: Rotary pursuit acquisition curves.

 

• Figure 2: Selective mathometer acquisition curves.

 

• Figure 1: Rotary pursuit acquisition curves.

 

• Figure 2: Selective mathometer acquisition curves.

Speed and accuracy in the majority of psychomotor tasks studied are typically acquired very rapidly during the early stages of reinforced practice, the average rate of gain tending to drop off as the number of trials or training time increases (Figure 1). Curves based on such measures as reaction time or errors reflect the learner's improvement by a series of decreasing scores, giving an inverted picture of Figure 1. Tracking scores from the two sexes are seen in Figure 1. Other devices have yielded more complicated functions—e.g.,S-shaped curves for complex multiple-choice problems on the selective mathometer (Figure 2). Most acquisition curves obey a law of diminishing returns as high levels of skill are approached. Data such as those from tracking and multiple-choice tasks can be explained by rational mathematical equations derived from theoretical models (see formulas and captions in Figures 1 and 2). Between them, these two equations describe psychomotor acquisition curves from a wide variety of learning situations and of trainees with less than a 2 percent average error of prediction. Contrary to lay opinion, stepwise plateaus of proficiency are seldom seen, not even in learning Morse code. The “natural plateau” is a phantom.

 

Generalization and transfer

The occurrence of the phenomenon of generalization is seen in the tendency of laboratory subjects conditioned to respond to a particular stimulus (e.g.,a light) to respond as well to similar stimuli beyond the original conditions of training. As differences along a physical continuum (e.g.,brightness) between the stimuli used in training and those encountered on test trials increase, the effects of generalization decrease until there may be no transfer from one situation to another. Alternatively, the more the two situations have in common, the greater is the amount of predictable transfer. Generalization (or transfer) may be based on temporal patterns of stimuli (e.g.,rhythms), spatial cues (e.g.,triangularity), or other physical characteristics.

The measured effects of prior training on the performance of a subsequent task define the transfer of psychomotor learning. Although it may be similar, the latter task usually differs measurably from that originally practiced. A common example is the ability required of many automobile drivers to change easily from, say, a three-speed transmission with a horizontal gear lever on the steering wheel to a four-speed mechanism with a vertical floor-mounted gearshift. In laboratory tasks, the amount and direction of transfer effects are accurately predicted. In practical skills, transfer is more likely to take place between tennis and badminton, for example, than between swimming and football, and between cornet and trumpet than between piano and tuba. Similarity is not the only correlate of transfer, however, and empirical studies must take account of such factors as the amount of practice and the sequence of events in previous training.

Transfer effects may be positive, negative, or zero;i.e.,learning one task may facilitate, hinder, or have no observable influence upon performance of the next task. Flight simulators are designed to maximize the amount of positive transfer, often by ensuring high levels of behavioral similarity. Negative transfer effects (e.g.,reaching for the floor to shift gears when the lever is on the steering wheel) appear occasionally but tend to be easily overcome. Since transfer necessarily involves retention, the best schedules minimize forgetting by the inclusion of short time intervals between training and transfer.

The degree and amount of transfer are contingent upon such factors as number of common elements or principles, stimulus and response similarity, amount of predifferentiation training, the variety of learning-to-learn experiences, part–whole relationships, differences in intertask complexity, use of mnemonic aids, and the extent of proactive or retroactive interference. Transfer equations usually assume that the basic indices of performance for experimental and control groups will increase with practice, that the possible measures range from negative 100 percent through zero to positive 100 percent, and that the groups have been equated in aptitude or initial ability to learn before the experimental treatments are begun. Retroactive interference designs typically employ a sequence of original learning, interpolated learning, and relearning.

 

Retention

Learning is to acquisition as memory is to retention. Psychomotor retention scores indicate the percentage or degree of originally learned skill that is remembered or recalled as a function of elapsed time. Alterations of motor memory are reflected by changes in means, variances, and correlations between test results. In contrast to verbal behaviour, which is notoriously susceptible to forgetting through interference within a matter of seconds, mean scores for tracking and coordination skills recorded over periods ranging from two days to two years diminish scarcely at all. Yet, when intervals of three minutes to six weeks are interpolated between discrete responses on a manual lever device, performance remains stable for about two days and then becomes inconsistent; variabilities increase and correlations decrease as the subjects mis-recall more and more of their original skill. In the light of this evidence, motor memory may be viewed as a phenomenon of persistence, while forgetting is a case of inconsistence.

One hypothesis advanced to account for the greater retentivity of psychomotor behaviour, as compared to that of newly acquired verbal behaviour, is that nonverbal striped-muscle responses are more often overlearned and are less susceptible to proactive interference (i.e.,competition arising from things learned in the past). Distinctions between immediate, short-term, and long-term memory are also less prominent in studies of motor learning, possibly because of the devotion of skills specialists to efficient practice and feedback methods that ensure permanent storage of habits in the brain. This is not to say that motor skills are unforgettable; studies of short-term memory suggest that psychomotor forgetting can be swift indeed. Regardless of theoretical differences, however, psychologists generally agree that psychomotor behaviour is best remembered (and least forgotten) when overlearning is high, interference is low, reinforcing feedback is optimal, and interpolated activities are unrelated to the task being learned. Time is less important in the degradation of memory than are the events that fill the time (see also memory).

 

Reminiscence

The phenomenon of reminiscence is a gain in performance without practice. Thus, when subjects performing trial after trial without rest (massed practice) are given a short break, perhaps midway through training, scores on the very next trial will show a significant improvement when compared with those of a massed group given no break. Reminiscence effects are most prominent in tasks demanding continuous attending and responding; they are least often observed with discrete-responding apparatus. The theoretical importance of this concept derives from its role in testing a hypothesis of reactive inhibition that asserts that a decremental process cumulates in the organism as a positive function of responding to stimulation and a negative function of resting time. That the phenomenon of reminiscence also manifests bilateral transfer of skill (e.g.,from the left to the right hand) suggests that the locus of the decrement is in the central nervous system rather than in the peripheral effector organs. Indeed, merely watching another subject practicing on a rotary pursuitmeter has an inhibitory effect on a person's performance; yet the cause is neither boredom nor fatigue.

 

Warm-up

Athletes and musicians often report that they get “cold” during a layoff (even for a rest period of a mere five minutes); when practice is resumed, the decrement in performance requires a warm-up before it is overcome. Similarly, on a rotary pursuitmeter, it is necessary to regain the optimal posture, grip the stylus correctly, begin the coordinated movements of eyes and hand, and recapture the proper whole-body rhythm. Warm-up produces a further gain in proficiency following the initial reminiscence effect. Mean scores continue to rise for several trials, reach a peak at the level found for distributed practice, and then fall more gradually until they merge with the curve for massed practice. When the duration of rest is extended, the amount of warm-up decrement first increases rapidly and then decreases; similar findings obtain for a succession of work and rest periods. Investigators who have tried to substitute warm-up activities other than actual pursuitmeter practice to offset or reduce the magnitude of the decrement have not been successful. At least for continuous psychomotor tasks of this sort, the need for proper, task-specific warm-up appears to be an intrinsic requirement of efficient performance. Wherever reminiscence goes, warm-up seems to follow; yet the converse does not always hold. The connection between warm-up and forgetting is uncertain.

 

Refractory period and anticipation

When required to make quick, discrete responses to two stimuli separated in time by one-half second or less, an operator's reaction time (latency) for executing the second response is typically longer than that of his first response. This difference in reaction time is called the psychological refractory period. At one time, it was thought possible that sensory feedback from the first response might stack up in the nerve centres to make the system refractory for a brief time, thereby delaying the processing of the second stimulus. Research findings that erroneous reactions could be corrected within one-tenth second would seem to negate the hypothesis. An alternative suggestion is that corrective movements are facilitated by feedback from the incorrect ones, and controlled observations appear to confirm that error-correcting responses have shorter latencies than those that are either correct or erroneous. Apparently, a false movement can be stopped on the basis of internal cues more promptly than on that of external stimuli.

Expectancy is a collateral factor with which researchers have had to reckon;i.e.,a subject may learn to accommodate himself to expect a delay between the first and second stimulus and thus be relatively unprepared should the second arrive earlier than usual. Further, people learn to be more expectant for particular kinds of stimuli than for others. When a person is uncertain about whether regularly occurring stimuli will be auditory or visual, or when their spatial direction is uncertain, performance is significantly degraded. This would suggest the possibility of divided attention; indeed, when pairs of stimuli are made perfectly predictable as to time and type, no impairment of response is observed.

If a subject can acquire suitable expectancies via training and experience, then he can improve the skill of dividing his attention and, within physiological limits, simultaneously handle an increased range of stimuli without loss of proficiency. Results from extended practice on a task requiring successive choice and dual reaction indicate that, with learning, people can reduce the psychological refractory period. The ability to develop anticipatory responses to regularly occurring stimulus cues is well established. A military gunner scanning a distant fixed target for azimuth and elevation, for example, is engaging in a preview of receptor anticipation to maximize his score. An operatic tenor who rehearses covertly the opening notes of his cadenza while the orchestra finishes the introduction is employing perceptual anticipation to optimize his rendition. Anticipatory timing is learned, and reinforcing feedback is necessary.

 

Factors affecting psychomotor skill

Amount of practice

 

• Figure 1: Rotary pursuit acquisition curves.

It has been noted above (Figure 1) that the practice of sensorimotor tasks usually produces changes in scores that reflect diminishing returns. A major influence in learning generally, repetition is the most powerful experimental variable known in psychomotor-skills research. But practice alone does not make perfect; psychological feedback is also necessary. The consensus among theoreticians is that feedback must be relevant and reinforcing to effect permanent increments of habit strength. Once developed, habit never dies; it does not even fade away.

The effects of feedback and four other important performance variables (i.e.,task complexity, work distribution, motive-incentive conditions, and environmental factors) remain to be summarized.

 

Psychological feedback

Ranking prominently among experimental variables are so-called feedback contingencies (aftereffects, knowledge of results) that may be controlled by the experimenter so as to occur concurrently with or soon after a subject's response. A learner appears to improve by knowing the discrepancy between a response he has made and the response required of him; but, in experimental practice, the investigator manipulates behaviour by transforming functions of error. Since transformations are usually numerical or spatial, sensory returns from one's action may be informative, motivating, or reinforcing. Response-produced stimulation is intrinsic to most skeletal–muscular circuits; the neural consequences of bodily movement are fed back into the central nervous system to serve the organism's regulatory and adaptive functions. When this normal feedback is interrupted or delayed, psychomotor skill is often seriously degraded. Experimentally delayed auditory feedback of a subject's oral reading produces stuttering and other speech problems; delayed visual feedback in simulated automobile steering is a greater hazard under emergency conditions than is the driver's reaction time.

Laboratory investigations have supported the following generalizations about psychomotor learning: (1) without some kind of relevant feedback, there is no acquisition of skill; (2) progressive gains in proficiency occur in the presence of relevant feedback; (3) performance is disrupted when relevant feedback is withdrawn; (4) delayed feedback in continuous (but not discrete) tasks is typically decremental; (5) augmented or supplementary feedback usually results in increments; (6) the higher the relative frequency of reinforcing feedback, the greater is the facilitation of skill; and (7) the more specific the feedback (e.g.,in designating location, direction, amount), the better is the performance.

Experiments with a manual lever device, for example, suggest that when feedback is introduced and withdrawn at four stages of practice, the effect on error scores is profound. Knowledge of results given early and late has effects similar enough to reject any hypothesis that learning arises merely from repetition. These experiments indicate that practice makes perfect only if reinforced; the result of unreinforced practice is extinction of the correct response and a proliferation of errors. Studies employing a complex mirror-tracking apparatus have clarified the role of reinforcing feedback. Targeting performance was facilitated by presenting distinctive supplementary visual feedback cues previously associated with aversive (electrical shock) and nonaversive consequences. Moreover, the amount of facilitation grew curvilinearly with the number of cue conditioning trials. Work on human incentive learning thus demonstrates that the rate of gain in psychomotor proficiency can be regulated by stimuli that have been accompanied by positive or negative aftereffects. Persistence of the acquired reinforcing effects, considered with their cumulative quantitative properties, enhances the attractiveness of theoretical interpretations that emphasize continuity and reinforcement as contrasted with theories based on discontinuity and contiguity alone. Clark Hull's system (1943) is the classic model.

 

Task complexity

The complexity of discrete psychomotor tasks may be specified either as the number of response sequences a subject can make or as some measure of a subject's uncertainty about choices among stimuli. Still other factors that have been investigated as instances of complexity include variations in the number of possible responses at each choice point, different lengths of series, and regular versus unpredictable stimulus sequences.

 

 

• Figure 2: Selective mathometer acquisition curves.

Experimental procedures involving an increase of complexity produce more errors, require more trials to reach proficiency, and result in longer latencies per trial. Difficulty in psychomotor learning, therefore, generally increases with the complexity of the task to be mastered. An example of this phenomenon appears in Figure 2. Subjects exhibit continually altered probabilities of response during training sessions, and an average person with enough practice on a discrete sensorimotor task can learn to perceive, select, and react as fast to ten stimuli as he can to two. Apparently, it is not the number of choices among stimuli as much as it is the number of choices among responses that slows up a subject's processing activities and complicates his decision problems. Indeed, by limiting response alternatives (e.g.,circumscribing the physical range of a trainee's movements or providing supplementary auditory and visual indicators of error), a training device can facilitate the acquisition or transfer of skill.

 

Work distribution

Hazardous though generalizations about work and rest in psychomotor learning may be, a few guiding principles are notable: (1) massed practice is usually superior to distributed practice for simple discrete-trial tasks; (2) distributed practice is usually superior for complex continuous-action tasks; (3) short practice sessions are generally superior to long practice sessions; (4) long rest periods are generally superior to short rest periods, although forgetting must be counteracted; (5) for continuous-tracking tasks practiced under constant work sessions and variable rest periods, the final proficiency level grows curvilinearly as the intertrial interval is lengthened; (6) gains in proficiency under distributed practice, or with interpolated rest periods during massed practice, are usually in terms of performance rather than of learning; (7) losses in proficiency under massed practice, or with increased work load, usually pertain to inhibitory rather than motivational decrements; (8) under certain conditions (e.g.,“cramming” for examinations) it may be most efficient to mass practice as long as adequate rest can be obtained before criterion performance is demanded; (9) reminiscence increments and warm-up decrements are intimately related to schedules of work and rest; (10) decrement is not the same as fatigue.

Quite apart from the practical question of the optimal management of training programs (e.g.,in coaching oarsmen in racing shells), the aversive inhibitory consequences of sustained action that are recognized as subjective fatigue and behavioral decrement are clearly adaptive. By a reflex negative-feedback mechanism, inhibitory impulses may prevent an organism from working itself to exhaustion. With few exceptions, the presumption in favour of spaced practice can safely be taken out of the psychomotor-skills laboratory and applied in the gymnasium, lake, and playing field. Research on the skills involved in, for example, archery, badminton, basketball, golf, javelin throwing, juggling, marksmanship, rowing, and tennis supports the notion of distributing training by means of short workouts and frequent breaks.

 

Motive-incentive conditions

Motivational processes are states of the organism that serve to activate reaction tendencies. Such states are classified as primary (innate) or secondary (acquired, learned) motivation. Though common physiological needs (e.g.,for food, water, avoidance of pain) may evoke psychological drives (e.g.,hunger, thirst, pain), the concepts of need and drive are not perfectly correlated. Some needs (e.g.,oxygen demand) seem to have no specific behavioral drive, and for some drives, clear-cut biological needs remain to be identified (e.g.,curiosity). Despite this apparent discrepancy, there is a theoretical consensus that psychological drive arouses the body to action, energizes its latent responses, and supports its behaviour over time. Most theorists believe that motivation (drive) and learning (habit) interact (in a multiplicative—drive times habit equals action—manner) in generating response. In other words, to produce action both are theoretically indispensable, but neither is sufficient alone. A person is not likely to perform a skill if he does not want to and cannot do so if he does not know what to do. The multiplicative theory implies that the same level of psychomotor proficiency may arise from quite different combinations of learning and motivation. Moreover, the organism's temporary drive state seems clearly to affect the adequacy of reinforcing feedback (e.g.,offers of monetary reward do little to arouse one who is already trying his level best). While these theoretical interpretations often apply well to laboratory animals, their application to human acquisition of skill is complicated because incentive learning in man can become very abstract.

Physiological explanations of human behaviour that depend on the concept of primary motives (derived from research with rats and dogs) run into difficulties in view of the fact that primary motivation and reward do not appear to be critical in most studies of human skill acquisition. Thus, instead of giving food pellets (as to a rat), an experimenter delivers praise to a human subject; rather than receiving feedback by electric shock, the human can be guided by a needle moving on a dial or a buzzer signalling an error. At any rate, despite efforts to distinguish such motivational factors as general drives from selective incentives, attempts to demonstrate significant motivational effects in human psychomotor learning have met with only modest success. Among exceptions to the above are a few studies with standard apparatus (e.g.,the complex coordinator) and with special devices that have indicated that such incentives as money, verbal threats, electric shock, exhortations, and social competition may be relevant. Significant effects frequently fail to appear in experiments, and findings are often contradictory, so it has been suggested that the intrinsic challenge of the gadgetry, coupled with the subjects' already high pre-experimental motivation, leaves human volunteers unaffected by such weak laboratory manipulations of motive-incentive conditions as the foregoing (see also emotion and motivation).

 

Environmental factors

Many practical skills must be executed outside the laboratory under unfavourable conditions of temperature, humidity, illumination, and motion. It is generally found that, below the limiting levels of extreme stress, such conditions affect psychomotor performance to a greater extent than they affect psychomotor learning. Representative findings have included the following: (1) isolation and sensory deprivation cause dramatic reductions in vigilance and monitoring skills within an hour; (2) environmental temperatures above or below 70° ± 5° F tend to lower scores on tracking apparatus but do not impair learning; (3) lack of oxygen slows reaction time, especially when the atmosphere corresponds to altitudes of 20,000 feet or higher; (4) accelerations of the body in a centrifuge or rotating platform disrupt postural coordination and produce systematic shifts in the perception of the vertical; (5) although such people as acrobats, dancers, pilots, and skaters can adapt well to high accelerations, even they lose equilibrium if deprived of the customary visual frame of reference; (6) rather mild centrifugal effects of slow, constant rotation may induce acute motion sickness and associated degradation of psychomotor proficiency in normal persons; (7) while some controlled work–rest schedules of crews during confinement in a small cabin upset daily sleep rhythms and lead to decrements in watchkeeping, memory, and procedural skills, a schedule of four-hours-on versus four-hours-off duty can be maintained for several months without significant impairment; and (8) faulty identifications of visual displays on an eye–hand matching task have been produced in volunteer subjects exposed to controlled infectious diseases (e.g.,respiratory tularemia, phlebotomus fever, viral encephalitis).

Other environmental stress variables found to exert negative influences are vibration, low illumination, high atmospheric pressure, noise, glare, toxic gases, ionization, and subgravity. Certain drugs have positive effects on psychomotor performance (e.g.,amphetamines, magnesium pemoline, methyl caffeine, pipradrol); some have deleterious effects (e.g.,alcohol, barbiturates, diphenhydramine hydrochloride, lysergic acid, meprobamate, phenothiazines, scopolamine, tetrahydrocannabinol, tripelennamine); and others are either neutral or have inconsistent effects (e.g.,caffeine, nicotine).

 

Individual and group differences

Statistical indices of psychomotor ability (e.g.,means, variances, correlations) not only differ among individuals but may also serve to distinguish from each other groups of persons classified by such traits as age, sex, race, personality, and intelligence. Comparative psychological studies of monozygotic (identical, one-egg) and dizygotic (fraternal, two-egg) twins have indicated that high coefficients of heritability—measured as a ratio of genotypic to phenotypic variance—exist for perceptual, spatial, and motor abilities.

 

Age

The most pervasive differences in human performance on psychomotor apparatus are associated with chronological age, and scores obtained from nearly all the devices mentioned above are sensitive to age differences. Researchers generally report a rapid increase in psychomotor proficiency from about the age of five years to the end of the second decade, followed by a few years of relative stability and then by a slow, almost linear decrease as the ninth decade is approached. For simple hand or foot reactions, complex discrimination-reaction time, and coordinated automobile steering, the peak of skill is attained between ages 15 and 20 on the average, and then performance declines—at age 70 it is about the level of age 10. This is a two-stage process: first, a developmental phase (e.g.,through maturation), followed by the more gradual deterioration of aging. Common athletic skills (e.g.,balancing, catching, gripping, jumping, reaching, running, and throwing) also improve through childhood, and it is well known that most athletes reach their prime before the end of the third decade. Olympic events requiring great muscular strength or stamina (e.g.,swimming) are dominated by athletes in their teens and 20s, whereas practitioners of more refined technical skills (e.g.,gymnastics) tend to be older. Self-paced, leisurely sports (e.g.,golf) are favoured over opponent-paced, combative activities (e.g.,tennis) as the aging process continues. Hereditary potentialities require several years to become established. It is probable that the genetic factors that underlie growth rates, and the age sequence in which different kinds of behaviour first appear, affect learning as well as performance.

 

Sex

 

• Figure 1: Rotary pursuit acquisition curves.

Although the assessment of sexual differences in perceptual and reactive abilities is complicated by a number of factors (e.g.,age, race, and personality), girls and women tend to be more proficient than boys and men in such psychomotor skills as finger dexterity and inverted-alphabet printing. On the other hand, males generally do better than females at pursuit tracking, repetitive tapping, maze learning, and reaction-time tasks. On rotary pursuit-meter tests, women are not only less accurate but more variable than men of the same age and race (Figure 1). Although males appear to be superior to females in aptitude and capacity, these advantages disappear when subgroups are carefully matched for initial ability. In contrast, speed scores on discrimination-reaction tests reveal clearly diverging trends for college men and women trained intensively for several days (960 trials). This seems to be a genuine sex difference rather than an element of measurement or selection. Though both groups were equated for intelligence and had similar error scores, females began to suffer cumulative impairment on the fourth day of practice, whereas males kept improving. Sizable average differences in reaction latency as well as in movement time are characteristic of the sexes on other tasks.

Whereas girls tend to attain their maximum proficiency in speeded tasks earlier in life than boys do, males continue to gain over a longer period and maintain their superiority over females for about half a century of the lifespan. After puberty, boys excel at most athletic skills demanding stamina and strength (e.g.,jumping, running, throwing). Thus, female Olympic swimming and track-and-field records are inferior to those of males and are achieved by girls who are noticeably younger than male champions in the same events. Sex has also been implicated in experiments employing complex coordinators, mirror tracers, and selective mathometers, with boys and men typically surpassing girls and women. Not all psychomotor differences associated with sex are intrinsically biological; unequal opportunities, distinctive social learning, role playing, and other culturally conditioned influences undoubtedly modulate the learning and execution of skills by males and females.

 

Race

All mankind is of one species. Zoologically, human races are all mutually interfertile subspecies—i.e.,breeding populations that differ in the relative frequencies of one or more genes. Although the variety of possible traits is practically limitless, random mating is not the case. Because of historical inbreeding tendencies, it is statistically improbable that any two human races have the same means and variances for all psychological traits. Not surprisingly, therefore, significant differences in psychomotor behaviour are found among ethnic groups throughout the world.

In one classic set of data (1904) on form-board skill (fitting nine geometric forms into correct holes), the average time in seconds for completing the task varied for different races—e.g.,seven African Pygmies (82.20), 12 Philippine Negritos (63.30), 55 American Indians and Eskimos (34.24), and 74 U.S. whites (27.80). Average error scores fell in the same order and, consistent with a genetic hypothesis, hybrid groups were appropriately ranked in between. These small samples were, however, not necessarily representative;i.e.,no effort was made to equate for differences in cultural values and psychomotor experiences found in different societies. Furthermore, since these were average differences, no conclusions about individual persons were warranted. It is interesting that the rankings were found to change for other psychomotor tasks;e.g.,on a test of tapping and aiming skill, Eskimos surpassed all others, followed by Filipinos, who were in turn trailed by Caucasians. A more recent study (1967) discovered that a sample of Mongoloid Chamorro people from Saipan and another of Indians from the U.S. exceeded white norms on a test of maze-tracing ability. In both studies, people of mixed races tended to make intermediate scores, a fact consistent with contemporary research in behavioral genetics and physical anthropology.

No particular race is found to be uniformly superior in all psychomotor aptitudes and capacities, but environmental causes seem to be inadequate to explain differences in rate of acquisition and final level of performance on standard apparatus. For some tasks (e.g.,on the rotary pursuitmeter) psychologists report that the degree of initial hereditary determination seems to reach 90 percent, thus leaving little room for sociological variables to operate. Teams conducting research with infant tests have noted that Congoid babies in both Africa and the United States are more precocious in sensorimotor maturation than are Caucasoid babies in Africa, the United States, or Europe, and that this precocity lasts about three years, after which whites outperform the blacks. By adolescence, Negro subjects score significantly less well than whites on complex coordinator, rotary pursuitmeter, discrimination reaction, selective mathometer, and two-hand coordinator tasks. On the other hand, Chinese- and Japanese-American infants lag behind Caucasians in motor development but perform better than both whites and blacks on certain eye–hand coordination and dexterity tasks at later ages.

Many research workers believe that social, economic, educational, and attitudinal variables that might unequally influence minority groups are of little consequence in the psychomotor field. They point out, for instance, that Chinese, Jewish, Negro, and Puerto Rican children, when tested by members of their own cultures, show distinctive patterns of basic perceptual and motor abilities, and their particular skill profiles are unaffected by differences in socio-economic level. Malnutrition (e.g.,protein deficiency) is not believed to be a plausible explanation unless there has been severe deprivation during the perinatal period. According to much of the literature, blacks generally do better than whites on chemical taste tests, rhythmic discrimination, visual acuity, colour perception, and resistance to special optical illusions; Mongoloids show better taste sensitivity and less colour blindness than Caucasoids; and on certain physical-fitness tests male Afro-American athletes are not only superior to their white countrymen but their relative proficiency is inversely correlated with the degree of Caucasoid admixture.

Genetic behavioral differences among human populations—just as those of morphology—appear to be the rule rather than the exception. Tarahumara Indians far surpass other races in endurance at long-distance running contests; Andeans and Tibetans are superbly adapted to working at high altitudes; Eskimos excel on psychomotor tasks performed under low-temperature stress. It is plausible that the inherited factors underlying behavioral aptitudes and capacities have evolved from different selective pressures in different ecological niches. As is true for age and sex, however, hereditary and environmental variables are complexly intertwined in racial studies. Nevertheless, genetic determinants seem to be far more powerful in the etiology of original psychomotor aptitudes. It does not follow that learnability is weak. Quantitative experiments demonstrate that heritabilities can be systematically altered by controlled practice; this is a theoretical discovery of broad implications for practical training programs. At the same time, it would appear that the hereditary control of several psychomotor abilities tends to be less pronounced at the end of training than at the beginning.

 

Other factors

A number of other personal characteristics have been found to be of significance in psychomotor behaviour. For instance: (1) speed scores in reaction-time tasks are positively correlated with body temperature in adults, one of the many indices of variation within the individual; (2) psychotics show longer reaction times and poorer tracking scores than do people of normal personality; (3) right-handed operators are favoured on the rotary pursuitmeter, while left-handed persons tend to do better on the complex coordinator; (4) left-handed people are more variable in finger-dexterity and paper-cutting skills and also are more prone to show signs of ambidexterity; (5) intelligence quotients (IQ) are weakly related to physical strength or endurance yet are strongly associated with performance in such psychomotor activities as running the 35-yard dash, balancing on one foot, discrimination reaction, rotary pursuit, and selective mathometry—these correlations are especially high when based on groups that comprise a full range of IQs (from retardates to college students); (6) typically one's body build (somatotype) is associated with his athletic skills—the best fencers, oarsmen, and basketball players, for example, tend to be tall and lean (ectomorphic); top swimmers, divers, and pole-vaulters are likely to be broad-shouldered and slim-hipped (mesomorphic); champion wrestlers, shot putters, and weight lifters are apt to be thick-trunked and short-limbed (endomorphic). While these genetically determined somatotypes do not guarantee athletic prowess, they definitely do favour success in certain sports rather than others. Similar considerations apply to vocal and instrumental musical aptitudes wherein unique combinations of such anatomical structures as lips, teeth, larynx, tongue, eyes, ears, hands, and arms can facilitate the attainment of virtuoso skill.

In short, psychomotor abilities and learning underlie some of the most fundamental human activities, contributing to the full spectrum of work, play, creativity, love, and the very survival of individual and species.

 

Clyde Everett Noble

Additional Reading

A.L. Irion, “A Brief History of Research on the Acquisition of Skill,” inEdward A. Bilodeau(ed.),Acquisition of Skill(1966), contains an excellent historical survey.Robert S. WoodworthandHarold Schlosberg,Woodworth & Schlosberg's Experimental Psychology, 3rd ed. byJ.W. Klinget al.,2 vol. (1972), is one of the best standard reference works.Clyde E. Noble, “S-O-R and the Psychology of Human Learning,”Psychological Reports, 18:923–943 (1966), offers a brief introduction to human learning.Arthur Weever Melton(ed.),Apparatus Tests(1947), is a classic volume on psychomotor devices used in aviation psychology. Reviews of the psychomotor field can be found in two articles inAnnual Review of Psychology:E.A. BilodeauandI. McD. Bilodeau, “Motor-Skills Learning,” 12:243–280 (1961); andClyde E. Noble, “The Learning of Psychomotor Skills,” 19:203–250 (1968); and inJ.A. Adams, “Historical Review and Appraisal of Research on the Learning, Retention, and Transfer of Human Motor Skills,”Psychological Bulletin, 101(1):41–47 (January 1987).Clark L. Hull,Principles of Behavior(1943, reissued 1966); andKenneth W. Spence,Behavior Theory and Conditioning(1956, reprinted 1978), are two of the most influential books on general behaviour theory from the reinforcement viewpoint.Clyde E. Noble, “A Theory of Psychomotor Skill: Derivation and Data,”Psychonomic Science, 21:344 (1970), makes a specific application to psychomotor learning.Richard A. Schmidt,Motor Control and Learning: A Behavioral Emphasis, 2nd ed. (1988), discusses motor learning from a behavioral and physiological perspective. Two volumes presenting detailed information-processing analyses of skill arePaul M. FittsandMichael I. Posner,Human Performance(1967, reprinted 1979); andA.T. Welford,Fundamentals of Skill(1968).K.M. Newell, “Motor Skill Acquisition,”Annual Review of Psychology, 42:213–237 (1991), presents a more recent discussion of information processing in the acquisition of motor skills.E.A. Bilodeau(ed.),Principles of Skill Acquisition(1969), provides an eclectic, simplified treatment of current topics by several authors.Robert N. Singer,Motor Learning and Human Performance, 3rd ed. (1980), is oriented mainly toward athletic proficiency and physical education. Articles of specialized interest, as indicated by their titles, areJ.A. Adams, “Response Feedback and Learning,”Psychological Bulletin, 70:486–504 (1968);Clyde E. Noble, “Acquisition of Pursuit Tracking Skill Under Extended Training As a Joint Function of Sex and Initial Ability,”Journal of Experimental Psychology, 86:360–373 (December 1970); andR.B. Payne, “Functional Properties of Supplementary Feedback Stimuli,”Journal of Motor Behavior, 2:37–43 (1970).

Clyde Everett Noble

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