The effect of perceived surface orientation on perceived surface albedo in binocularly viewed scenes

We examined how observers discount perceived surface orientation in estimating perceived albedo (lightness). Observers viewed complex rendered scenes binocularly. The orientation of a test patch was defined by depth cues of binocular disparity and linear perspective. On each trial, observers first estimated the orientation of the test patch in the scene by means of a gradient probe and then matched its perceived albedo to a reference scale. We found that observers' perception of orientation was nearly veridical and that they substantially discounted perceived orientation in estimating perceived albedo.

The development of a Q-sort behavioral rating procedure for pediatric HIV patients

Developed a Q-sort procedure to assess social, emotional, and motivational behavior associated with central nervous system disease among 180 HIV-infected pediatric patients. These ratings were factor analyzed and scales were derived based on the factor structure. Younger (M age = 1.03 years) patients with HIV-associated encephalopathy were rated as more apathetic and nonsocial in their behavior than nonencephalopathic younger patients. Older (M age = 7.8 years) encephalopathic patients had significantly higher scores on scales measuring depression, autism, and irritability compared to nonencephalopathic patients from this age group. A subgroup (26 patients) showed a significant decrease in these elevated scores after a 6-month course of AZT.

Psychiatric chronicity and diagnosis

The relationship between psychiatric chronicity and schizophrenia in the postacute phase was examined by comparing posthospitalized chronic schizophrenics and chronic nonschizophrenics on symptoms, social functioning, and recidivism. No differences were found between the groups on any of these variables, indicating a general similarity of clinical picture for chronic schizophrenics and chronic nonschizophrenics in the postacute phase. These results were contrasted with two other comparisons made irrespective of diagnosis: (1) Patients with better social functioning were compared to patients performing less well socially; (2) patients living with others were compared with patients living in isolated settings. In both these comparisons, significant differences in the clinical picture were found between the two groups. Thus, living situation and degree of social functioning both appear to have more relevance for the postacute phase than does diagnosis. These results were related to the genetic and outcome literature on chronic psychiatric disorder to advance the view that the diagnosis of chronicity is more crucial for the understanding of severe emotional disorders than the traditional symptom-based DSM-III classification system.

Amitriptyline and scopolamine in an animal model of depression

Adult male Sprague-Dawley rats were subjected to acute (95 dB white noise) or chronic stress, or their combination. In comparison with unstressed controls, stressed rats were more active upon several measures of open field activity. A history of chronic stress eliminated the acute stress induced activation. Concurrent treatment of chronically stressed rats with amitriptyline or scopolamine, or with a combination of both drugs resulted in selective behavioral improvement (i.e., in motor activity, latency, defecation) for amitriptyline and combined treatment rats, with significant restoration of the normal behavioral response. Scopolamine however was only marginally effective. A higher dose of scopolamine proved effective, but only with a marked disruption of baseline activity. Examination of plasma corticosterone titers indicated that chronic stress induced an elevation of basal levels and that this was reversed by amitriptyline, scopolamine, and combined drug treatment. Thus while behavioral depression and elevated corticosteroids may covary they are not identically mediated.