Subjects manipulated a control stick to move a cursor displayed on an oscilloscope screen through a distance A to a target of width W. Movement times were found to be a linear function of Fitts' index of difficulty, loga(2A/W). The slope of the Fitts' law relationship was considerably steeper when subjects used a velocity control system rather than a position control system. The intercept of the Fitts' law relationship was higher when a position-plussteadiness criterion was used for determining the end of a movement rather than simply a position criterion. An analysis of the trajectories of the cursor revealed the presence of a series of submovements, and their duration, accuracy, and frequency are systematically related to changes observed in the Fitts' law relationship. Conditions under which Fitts' law may not hold are discussed.Fitts' law states that the time to move a stylus from a home position to a stationary target is proportional to an index of difficulty, logs (2.4/HO (Fitts & Peterson, 1964). A is the distance from the home position to the center of the target, and W

Subjects used either a position or a velocity control system to capture stationary and moving targets. Fitts' Index of Difficulty was found to be a good predictor of capture time for the rate system. However, for the position control system, the Fitts measure failed to predict accurately the capture time for moving targets. An alternate Index of Difficulty measure is proposed which explicitly incorporates a velocity factor and which predicts the overall pattern of capture times for both systems with greater accuracy than Fitts' Index of Difficulty.

Children showing a comorbid behavior pattern of hyperactivity-impulsivity-inattention and conduct problems (HIA + CP) were contrasted to children having only an internalizing and externalizing behavior pattern (I + E) and matched controls. Children displaying the HIA + CP behavior pattern were at greater risk on a number of outcome measures in social and academic domains beginning in Grade 3 and continuing into Grade 4. The most marked differences among the three groups were found on peer measures of rejection and friendship and teacher ratings of social skills. On average, almost two-thirds of the HIA + CP group were rejected by their peers compared to one-third of the I + E group and only 12.5% controls. Over 70% of the HIA + CP group had no reciprocated friendships from Grade 3 to Grade 4 compared to less than half of the I + E group and approximately one-fourth of controls. Contrary to much theorizing in the literature, the HIA + CP and I + E groups showed average levels of academic self-concept and did not differ from controls in on measures of social self-concept and academic self-concept and general self-esteem. These findings were interpreted in light of positive illusory biases and the established link between aggressive behavior and egotism. The current article offers partial support for Lynam's (1996) notion of the "fledgling psychopath."

Childhood and adolescent depression is associated with negative outcomes in the school environment. Research demonstrates that childhood and adolescent depression often results in poor schoolwork, reduced academic achievement, impairments on cognitive tasks, and acting out behavior patterns. This longitudinal study sought to determine the extent to which affective, social, and academic variables collected in 3rd, 4th, and 5th grades could predict depressive symptoms in 6th grade (early adolescence). A primary objective was to define conceptual sets of school-based predictor variables that would reliably predict depressive symptoms in early adolescence. Results from cross-validated discriminant function analyses indicated the best group of predictors of depression in early adolescence included teacher rated academic competence, social skills, critical events, self-reported loneliness, selfimage, and self-concept. The results suggest that early school-based identifiers of depressive symptoms are found prior to early adolescence.

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