Differences in academic performance at school depending on handedness: matter for neuropathology?

Two studies found that left-handed children had significantly poorer academic records than did right-handed children, though the effect was small. Study 1 provided evidence that, for some academic disciplines, the important difference appeared to be between those children whose family history of handedness was concordant with their own handedness and those children whose family history of handedness was discordant with their own handedness. The inclusion of gender in asymmetry research was bolstered by Study 2. When predicting idiosyncrasies in left-handers' cognitive performance, it should be borne in mind that left-handers form a minority group as well as a neurologically distinct one.     

Development of time concepts: differentiating clock and calendar from apparent durations

To investigate the role of perception and stress on time concepts, the real-time and apparent durations of common events varying in length from 30 s to 4 years were rated by kindergarten through 12th-grade pupils, college students, professors, and stress-impaired adults (N = 1,788). The events were pleasant, neutral or unpleasant; either directly perceptible and of specific duration or perceptually vague; and happened either to oneself or to someone else. Second graders differentiated apparent from real-time durations and, therefore, already had an abstract concept of time. As predicted from differentiation theory (Gibson, E. J., 1969; Gibson, J. J., 1966, 1983), longer durations were acquired later than shorter ones; perceptually-vague durations were acquired later than clearly perceptible ones of similar length; and, as Neisser (1976) also suggested, stress did not lead to regression, nor did the personal-impersonal dimension make a difference during childhood.     

Quantitative assessment of infant reaching movements

We have identified a fundamental property of human motor behavior as a tight coupling of the curvature-speed relationship in the reaching movements of 5- to 9-month-old infants. This relationship termed a movement unit, occurs regardless of the distance of duration of the reach and in spite of the developmental change that occurs in grasping during this period. Movement unit durations are tightly clustered around 200 ms regardless of overall duration or distance or the position of the unit in the reach. The curvature-speed coupling has been identified by others in adult reaching and handwriting. Models of biological motor control must account for this invariant relationship.     

Fantasy proneness and psychopathology

Fantasy prone persons ("fantasizers") selected from "normal" populations report experiences associated with psychopathology in clinical populations (e.g., fantasies that reach hallucinatory proportions, difficulty discriminating reality from fantasy). In Study 1, we administered objective (MMPI) and projective (Rorschach) measures to high fantasy prone individuals (upper 4% of college population), medium fantasy prone individuals (middle range), and nonfantasizers (lowest 4%). Subjects who were fantasizers appeared to use fantasy for defensive or adaptive purposes compared with others and produced 8/9 modal code types on the MMPI. On the basis of the MMPI findings, a subset of fantasizers could be described as exhibiting a significant degree of psychopathology. In Study 2, a second sample of fantasy prone individuals could not be distinguished from comparison groups in contacts with professionals for help with psychological problems, use of psychotropic medication, or number of close friendships. Although fantasizers perceived themselves as less well adjusted than comparison subjects and reported greater difficulty in distinguishing fantasy from reality, most fantasizers rated their psychological functioning as adequate and above and did not differ from less fantasy prone subjects in ratings of positivity of self-concept. As demonstrated in Study 1, a subset of fantasizers did appear to be more pathological than other subjects were, with three fantasizers reporting a history of psychiatric hospitalizations. It is estimated that between 10 and 20% of fantasizers exhibit significant signs of maladjustment/psychopathology; however, as a rule, fantasy proneness does not appear to be antecedent to severe manifestations of psychopathology.     

Cognitive operations associated with individual differences in affect intensity

There are wide individual differences in the characteristic intensity of affective response to the same emotion-evoking event. The processes whereby individuals come to experience strong or mild emotional responses when exposed to the same affect-provoking stimuli are still unclear. In these studies, we propose that individual differences in affect intensity are associated with certain cognitive operations used during exposure to emotion-relevant stimuli. Specifically, cognitive operations that involve personalizing, generalizing, and selective abstraction were hypothesized to discriminate subjects high and low in affect intensity. Two studies replicated support for the hypothesis that subjects high on the affect-intensity dimension engage in more personalizing/empathic and more generalizing/elaborative cognitive operations than do subjects low on the affect-intensity dimension. The same cognitive operations discriminated groups high and low in affect intensity in response to both positive and negative emotional stimuli. Also, the cognitions that discriminated subjects high and low in affect intensity occurred only in response to affective stimuli; neutral stimuli did not evoke divergent cognitive operations for these two groups. Finally, a high degree of consistency was found in the use of emotion-relevant cognitive operations across positive and negative affective stimuli.     

Study of neuromotor reaction times under the influence of thyrotropin-releasing hormone

Neuromotor reaction times (simple, choice, and decision) were measured when Thyrotropin-releasing hormone (TRH) was administered intravenously to nine healthy men in a double-blind study. Measurements were made of simple reaction time, choice reaction time, and decision time for each subject at various intervals over a 54-hr. period. Given the observed inherent interaction of the drug with the long time used (54 hr.), most analyses were conducted across separate time epochs. Injected subjects showed inhibition in the normal improvement of simple reaction time (which occurs with practice), and they reduced the time required to make a decision. Choice reaction time, however, remained unchanged across the drug-nondrug experimental conditions.     

Vertical reversal and lateral reversal as components of inversion in recognition memory for upside-down faces

Subjects viewed upright photographs of faces, then attempted to recognize them unchanged, vertically reversed or inverted. In two of four conditions, hit scores were lower for inverted than vertically reversed faces, suggesting that lateral reversal is a meaningful component of inversion. The effect was not sufficiently strong, however, to overcome a generally high false-alarm rate for upside-down faces.     

Selected parameters of response organization in mildly mentally retarded children

The purpose of this study was to investigate the effect of response organization on reaction time (RT) and movement time (MT) of mildly mentally retarded children. Two groups of 30 subjects each were formed: a retarded group 9 yr. of age and a normal group matched for chronological age. Subjects were randomly assigned to one of three precued conditions in which they were told that the forthcoming response would be performed with the right or left hand (precue hand), be to the right or left side (precue direction), or cross or not cross the body midline (precue midline). The retarded group performed significantly more slowly than the normal group on both RT and MT. Both groups, however, were able to utilize precued hand information as opposed to other precued variables, indicating that knowing which hand to use is important when organizing responses.     

Midline and off-midline tongue and right- and left-hand vibrotactile thresholds of stutterers and normal-speaking individuals

Vibrotactile thresholds for 7 male stutterers and 7 normal-speaking men (age range for both groups = 19 to 32 yr.) were obtained from the right, midline, and left sides of the lingual dorsum, and the thenar eminences of both hands. The stutterers showed slightly higher (less sensitive) mean thresholds than the normal speakers for all three lingual test sites. This was not the case for the thresholds obtained from both hands. The preliminary data suggest that oral peripheral sensory integrity might be somewhat different for stutterers than for normal-speaking individuals.