Measurement of forearm rotation: The technique,and its reproducibility and validity

Forearm rotation is a point of interest in the study of human movement. For the most part, earlier methods for determining this joint rotation could be applied only in restricted situations. In this paper, a new technique is described, which involves the use of a three-dimensional opto-electronic motion registration system. With only two cameras, the supination angle in almost every position can be determined. A bracelet is attached to the subject’s forearm and fixed to the radius. Wrist points are defined in relation to this bracelet (in its local coordinate system). The properties of the bracelet allow the motion-registration system to calculate its position in the global coordinate system. Given the position of the bracelet, the shoulder, and the elbow, the rotation angle can be determined. The reproducibility (error less than 2^o) of and validity of the technique are also discussed.     

Discrimination of 3-D shape and 3-D curvature from motion in active vision

We examined the ability of human observers to discriminate between different 3-D quadratic surfaces defined by motion, and with head position fed back to the stimulus to provide an up-to-date dynamical perspective view. We tested whether 3-D shape or 3-D curvature would affect discrimination performance. It appeared that discrimination of 3-D quadratic shape clearly depended on shape but not on the amount of curvature. Even when the amount of curvature was randomized, subjects’ performance was not altered. On the other hand, the discrimination of 3-D curvature clearly depended linearly on curvature with Weber fractions of 20% on the average and, to a small degree, on 3-D shape. The experiment shows that observers can easily separate 3-D shape and 3-D curvature, and that Koenderink’s shape index and curvedness provide a convenient way to specify shape. These results warn us against using just any arbitrary 3-D shape in 3-D shape perception tasks and indicate, for example, that emphasizing 3-D shape in computer displays by exaggerating curvature does not have any effect.     

Linear relations amongk sets of variables

A family of solutions for linear relations amongk sets of variables is proposed. It is shown how these solutions apply fork=2, and how they can be generalized from there tok3.The family of solutions depends on three independent choices: (i) to what extent a solution may be influenced by differences in variances of components within each set; (ii) to what extent the sets may be differentially weighted with respect to their contribution to the solution—including orthogonality constraints; (iii) whether or not individual sets of variables may be replaced by an orthogonal and unit normalized basis.Solutions are compared with respect to their optimality properties. For each solution the appropriate stationary equations are given. For one example it is shown how the determinantal equation of the stationary equations can be interpreted.     

SOCIAL VALIDATION: THE EVOLUTION OF STANDARDS OF COMPETENCY FOR TARGET BEHAVIORS

The use of social validation procedures has become widespread in recent years. Although most researchers have used social validation procedures to select target behaviors and to evaluate whether the changes produced by a treatment program should be considered socially useful, little attention has been focused upon using the social validation process to determine the optimal levels for target behaviors. This paper suggests several ways in which social validation procedures can be employed in order to select when and how much to change target behaviors.     

Cardiovascular changes during social competition in a mixed-motive game.

Male and female subjects played a mixed-motive game against a male confederate under either a 20% cooperative or an 80% cooperative strategy while cardiovascular responses were computer monitored. Females had larger heart rate responses than males during play against the competitive strategy, and the opposite was true during play against the cooperative strategy. Subjects who were more competitive during the game or who scored higher on a coronary-prone (Type A) behavior scale or who reported having an action orientation toward life stress tended to have larger heart rate responses during the game than the remaining subjects. The results draw attention to the importance of covert autonomic responses for understanding overt behavioral choices in mixed-motive games and to the potential utility of this behavioral model for studying the role of psychosocial factors in psychosomatic illnesses.     

Effects of error and errorless discrimination acquisition on reversal learning

The effectiveness of trial-and-error, graded-choice, and verbal-instruction procedures on the acquisition and maintenance of a two-choice simultaneous color discrimination in an intradimensional double-reversal learning situation was studied using 18 first-grade children. After acquiring a red-green discrimination during one 70-trial session, the discriminative roles of the stimuli were reversed for 30 trials, followed by a second reversal for 30 trials. Children in the graded-choice and verbal-instruction groups acquired and maintained the discriminations with fewer errors than children who learned by trial and error. The importance of the results in terms of two-stage discrimination learning theories is pointed out and similarities between errorless learning and overtraining are discussed.     

A multimethod analysis of selected self-esteem measures

This study investigated the convergent and discriminant validity of selected measures of global self-esteem and social self-esteem, using the multitrait-multimethod design. Orderliness was included as the third trait for appraising the discriminant validity of the self-esteem measures. Each trait was measured by three different methods: true-false self-report inventory, multipoint self-report inventory, and simple self-ratings. The Tennessee Self-Concept Scale and the Coopersmith Self-Esteem Inventory (short form) were the selected measures of global self-esteem. The revised Janis-Field Feelings of Inadequacy Scale and the Self-esteem scale of the Jackson Personality Inventory were included as measures of social self-esteem, while orderliness measures included the Order scales from the Personality Research Form and Comrey Personality Scales. Results from the multitrait-multimethod matrix and the multimethod factor analysis of data based on 93 males and 103 females provided strong evidence for the convergent and discriminant validity of the various trait measures.