Contributions of clinical neuropsychology to the study of schizophrenia

Clinical neuropsychological findings are examined with respect to competing hypotheses about localized neuropathology in schizophrenia. Two general models of structural and functional impairment are described. The first addresses deficits in cortical/subcortical processes concerned with arousal, attention, and higher cortical functions. The second addresses impairments in the balance of lateralized functions consistent with left hemisphere overactivation. Empirical data provide support for both models, and suggest that the explanatory power of these models may vary when they are applied to different subtypes of schizophrenia.     

TEACHING ELEMENTARY STUDENTS WITH DEVELOPMENTAL DISABILITIES TO RECRUIT TEACHER ATTENTION IN A GENERAL EDUCATION CLASSROOM: EFFECTS ON TEACHER PRAISE AND ACADEMIC PRODUCTIVITY

Four fourth graders with developmental disabilities were trained to recruit teacher attention while they worked on spelling assignments in a general education classroom. The students were taught to show their work to the teacher two to three times per session and to make statements such as, “How am I doing?” or “Look, I'm all finished!” Training was conducted in the special education classroom and consisted of modeling, role playing, error correction, and praise. A multiple baseline across students design showed that recruitment training increased (a) the frequency of students' recruiting, (b) the frequency of teacher praise received by the students, (c) the percentage of worksheet items completed, and (d) the accuracy with which the students completed the spelling assignments.     

Self-control in rhesus macaques (Macaca mulatta): controlling for differential stimulus exposure

Previous research on self-control using macaques (Macaca fascicularis) showed these animals have a strong bias for a delayed, larger reinforcer (Self-control) over an immediate, smaller reinforcer (Impulsive). Typical studies of self-control have used a discrete trials methodology with a secondary discriminative stimulus during the delay periods. This results in a greater exposure to the stimulus representing the self-controlled option and may account for some of the early exclusive preference for self-control observed. The present experiment examined self-control bias in three rhesus macaques (Macaca mulatta) while controlling for differential durations of stimulus exposure. Subjects were presented stimuli via a computer monitor and made choices by touching the stimulus at which point both stimuli were removed for the delay periods. All three subjects displayed a nearly exclusive bias for the delayed, larger reinforcer self-control). These results are consistent with previous studies, despite the variations in methodology and species.     

Differences between African American and European American first-year college students in the relationship between self-efficacy, outcome expectations, and academic achievement

First-year African American and European American college students were surveyed to examine ethnic differences in how their social cognitive beliefs (self-efficacy and outcome expectations) influenced their academic achievement. It was hypothesized that outcome expectations may better explain academic achievement for African Americans due to the fact that they may perceive that external factors such as discrimination may influence their academic outcomes. Because European Americans are less likely to anticipate discrimination, they are more likely to believe that their outcomes would be the result of their own behavior. Higher levels of self-efficacy were related to better academic achievement for both ethnic groups. However, African Americans with negative outcome expectations (e.g. my education will not lead to a well paying job) had better achievement than those with more positive outcome expectations. This pattern was not found for European Americans. Potential explanations for the relationship between outcome expectations and academic achievement for African Americans such as racial socialization for preparation for bias are discussed and implications for interventions are addressed.     

The visual discrimination of bending

The sensitivity of observers to nonrigid bending was evaluated in two experiments. In both experiments, observers were required to discriminate on any given trial which of two bending rods was more elastic. In experiment 1, both rods bent within the same oriented plane, and bent either in a frontoparallel plane or bent in depth. In experiment 2, the two rods within any given trial bent in different, randomly chosen orientations in depth. The results of both experiments revealed that human observers are sensitive to, and can reliably detect, relatively small differences in bending (the average Weber fraction across experiments 1 and 2 was 9.0%). The performance of the human observers was compared to that of models that based their elasticity judgments upon either static projected curvature or mean and maximal projected speed. Despite the fact that all of the observers reported compelling 3-D perceptions of bending in depth, their judgments were both qualitatively and quantitatively consistent with the performance of the models. This similarity suggests that relatively straightforward information about the elasticity of simple bending objects is available in projected retinal images.     

Computer-controlled displays of bending motions

This paper describes a physical model and the mathematical equations specifying the dynamics of a bending line. A computer program is also described that will control real-time displays of a line of points in three-dimensional space and collect psychophysical data from human observers discriminating between different bending motions.     

Effects of stimulus-response correspondence and verbal expectancy on choice reaction time.

The effects of S-R correspondence, verbal prediction, and stimulus discriminability were examined in a discrete, two-choice reaction-time task. Correctness of prediction and S-R correspondence were significant main effects. In addition, responses were significantly faster for correct predictions on noncorresponding trials than for incorrect predictions on corresponding trials. This latter finding indicates that an expectancy mechanism can partially offset the negative effect of spatial S-R noncorrespondence on absolute magnitude of choice reaction time.