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.     

Social-information-processing factors in reactive and proactive aggression in children's peer groups

We examined social-information-processing mechanisms (e.g., hostile attributional biases and intention-cue detection deficits) in chronic reactive and proactive aggressive behavior in children's peer groups. In Study 1, a teacher-rating instrument was developed to assess these behaviors in elementary school children (N = 259). Reactive and proactive scales were found to be internally consistent, and factor analyses partially supported convergent and discriminant validities. In Study 2, behavioral correlates of these forms of aggression were examined through assessments by peers (N = 339). Both types of aggression related to social rejection, but only proactively aggressive boys were also viewed as leaders and as having a sense of humor. In Study 3, we hypothesized that reactive aggression (but not proactive aggression) would occur as a function of hostile attributional biases and intention-cue detection deficits. Four groups of socially rejected boys (reactive aggressive, proactive aggressive, reactive-proactive aggressive, and nonaggressive) and a group of average boys were presented with a series of hypothetical videorecorded vignettes depicting provocations by peers and were asked to interpret the intentions of the provocateur (N = 117). Only the two reactive-aggressive groups displayed biases and deficits in interpretations. In Study 4, attributional biases and deficits were found to be positively correlated with the rate of reactive aggression (but not proactive aggression) displayed in free play with peers (N = 127). These studies supported the hypothesis that attributional biases and deficits are related to reactive aggression but not to proactive aggression.