Skill, strength, handedness, and fatigue

Thirty male subjects, 20 of whom were self-classified left-handers and 10 right-handers, were tested on a grip-strength task and a handwriting task with each hand, both under normal conditions and in a situation of induced experimental fatigue. On the basis of questionnaire scores, the left-handers were sub-divided into two groups comprising the 10 most left-handed and the 10 least left-handed subjects. The test of grip strength showed a small but significant deterioration in performance of both hands from fatigue. With the handwriting task, a similar significantly adverse effect of fatigue was recorded for all groups as well as a large significant difference in performance between the preferred and nonpreferred hands under normal conditions, which decreased under fatigue. An explanation of these differential effects is discussed in terms of the greater efficiency of the preferred hand in the highly developed skill of handwriting.     

Qualitative dynamics of disordered human locomotion: a preliminary investigation

A qualitative approach to the evaluation of disordered locomotion is introduced within the framework of dynamical systems theory. Exemplar phase plane and angle-angle plots of knee and ankle movements were constructed from limb trajectories of neurologically impaired individuals and qualitatively compared with similar plots, reflecting normal locomotion. In phase plane trajectories of normal locomotion, characteristics of spring-like dynamics dominated the loading and unloading phases whereas those of ballistic pendular dynamics were seen during swing. The overall squareness of the normal phase plane trajectories suggested precisely timed and narrowly focused controls. in contrast, phase plane records from hemiparetic subjects had markedly reduced segmental velocities, pronounced velocity reversals in both stance and swing, and a loss of overall squareness. Knee-ankle plots of normal locomotion revealed important features of intersegmental coordination such as coupled out-of-phase coordination in loading and unloading, a decoupled phase offset in early swing, and a kind of active partitioning in late swing in which one segment moved while the other remained constant. These intersegmental relations were absent or distorted in the hemiparetic angle-angle plots. It is suggested that this qualitative approach, together with electromyography and force dynamics, may allow the characterization of the movement disorders associated with given neuropathologies.     

The role of propulsive muscles of the shoulder during quadrupedalism in vervet monkeys (Cercopithecus aethiops): implications for neural control of locomotion in primates

In comparative anatomical studies of the shoulder, the humeral retractors are often grouped together as propulsive muscles, which are important in the propulsive stroke of the forelimb during quadrupedal locomotion. Electromyographic (EMG) analyses of these muscles in opossums, cats, and dogs in general have confirmed such conclusions. An EMG study of chimpanzee shoulder muscles during knuckle-walking found, however, that the humeral retractors are either inactive or perform a function unrelated to propulsion (Larson & Stern, 1987). This contrast in muscle recruitment patterns between chimpanzees and more "typical" mammalian quadrupeds was attributed to the derived morphology of the chimpanzee shoulder. The present study examines the activity patterns of the humeral retractors in the vervet monkey, a primate more closely resembling nonprimate mammals in its shoulder morphology. The results of this EMG analysis show that despite the significant differences in anatomy between chimpanzees and vervets, the two species display very similar muscle recruitment patterns during quadrupedalism, and there is evidence for this same pattern in other species of primates. These differences in muscle activity patterns between primates and nonprimate mammals may be related to changes in the neurological control of locomotion in primates due to the evolutionary development of manipulative abilities in the primate forelimb.     

Autobiographical memory in a case of multiple personality disorder

Previous research on multiple personality disorder (MPD) has been concerned with between-personalities amnesia, and little attention has been paid to within-personality memory function. This study examined the autobiographical memory of a multiple personality patient, I.C., with cueing procedures that have proven useful in previous studies of normal and abnormal memory. Results indicated that I.C. was able to retrieve autobiographical episodes from the recent past, although her performance differed in several respects from that of matched controls. The study also revealed a striking deficit in I.C.'s autobiographical memory for childhood: She was unable to recall a single episode from prior to the age of 10 in response to various retrieval cues, whereas control subjects had no difficulty recalling numerous childhood episodes. This phenomenon of extended childhood amnesia has not been reported previously in studies of MPD.     

Painting Group Portraits: Studying Life Outcomes for Aggressive and Withdrawn Children

Aggression and social withdrawal have long been of interest to personality psychologists. The present article presents a longitudinal study of the development of children selected from a community sample who were high on aggression and withdrawal. The selection of outcome variables is discussed, and outcomes during adolescence are described. For both males and females, high aggressiveness was predictive of low intelligence, poor school achievement, and psychiatric problems. For females, high aggressiveness was also predictive of general health problems. High social withdrawal was predictive of poor school achievement. Females who were high on withdrawal also had an elevated rate of abortions. Individuals who were high on both aggression and withdrawal had relatively poor social competence, had general problems with behavior, had low intelligence, and were performing poorly in school.     

Occupational Representativeness and Prestige Rating: Some Observations

The authors examine occupational representativeness for its effect on prestige ratings. Compositions of occupational listings do not affect ratings. Career counseling implications are noted.     

Developmental levels of processing in metaphor interpretation

We outline a theory of metaphor interpretation. The theory posits varying levels of semantic processing and formalizes them in terms of kinds of semantic-mapping operators that transform properties of the metaphoric vehicle (i.e., predicate) into properties of the metaphoric topic (i.e., subject). We used cognitive-developmental theory to estimate the mental-processing complexity of the various mapping operators, and thereby to predict the timing of their emergence in childhood, and to construct a measure of the metaphoric-processing levels. Metaphor interpretations collected from children (aged 6-12 years) and adults were coded and scored according to the processing levels. In two separate developmental studies, processing score increased with age in a predictable way. Growth in a mental-attentional resource accounted for much of the developmental variance in metaphor interpretation. Possible moderating effects of knowledge and context are discussed.     

Is dependence on phonological information in children's reading a product of instructional approach?

Eight-year-old British children were found to be less accurate at rejecting pseudohomophones than ordinary nonwords in a lexical decision task, but 8-year-old New Zealand children did not show this effect. A subsequent homophone decision task showed that this difference was not due to the New Zealand children being unable to distinguish pseudohomophones from other nonwords. The New Zealand children, however, were less accurate than the British children in pronouncing the pseudohomophones they had identified. It was argued that the British children tended to sound out the items before making a choice in the lexical decision task, which gave salience to phonological rather than visual information, resulting in increased errors to the pseudohomophones. It was concluded that where the British children showed this dependency on use of phonological information it was a product of the teaching approach they had experienced.     

Cheating following success and failure in heavy and moderate social drinkers

Two groups of American undergraduates (moderate and heavy social drinkers) completed a matrix task and received either positive or negative feedback on their performance. Following this they were given a maze task, which was designed so that cheating could be detected. Heavy drinkers cheated more than moderate drinkers under success conditions (positive feedback). Heavy drinkers who received positive feedback also cheated more than heavy drinkers who received negative feedback. The results are interpreted in terms of self-handicapping theory.