Time course of perceptual grouping

An investigation was made of the time course of perceptual grouping that is based on two qualitatively different spatial relationships: proximity and alignment. An index of grouping capacity was used to assess the processing time required before a backward pattern mask interfered with grouping. Stimuli consisted of bistable arrays of disjunct dots that were followed by a mask. Grouping cues, either proximity or alignment, were randomly assigned to either the horizontal or vertical orientation, and subjects indicated whether the dots appeared grouped as a series of horizontal or vertical lines. Spatial metrics of the cues were systematically altered until they no longer served as a cue for grouping, thereby determining the grouping threshold. The stimulus onset asynchrony (SOA) of the mask, relative to the test stimulus, ranged from 33.3 to 150 msec. The SOA at which grouping thresholds first became elevated identified the point at which the mask first interfered with the grouping process, thereby identifying the processing time required for grouping by the specified cue. The processing time for grouping by proximity and alignment differed significantly, requiring means of 87.6 and 118.8 msec, respectively, for processing to be completed. These measurements serve to identify the processing time necessary for spatially integrating stimulus elements into unified forms, thereby delineating temporal constraints at this stage of visual processing.     

Self-Esteem, Erotophobia, and Retention of Contraceptive and AIDS Information in the Classroom

It has been well documented that people with negative emotional reactions to sex (e.g., "erotophobia,""sex guilt") have less knowledge about contraception than do people with more positive reactions. Recent research has suggested that this deficit is not related to an inability to learn the information, but is due at least in part to the fact that erotophobics actively avoid contraceptive information. The current study was designed to examine the role of erotophobia and high self-esteem in resistance to learning sexual information. More specifically it compared pretest and posttest knowledge of contraception and AIDS in high self-esteem and low self-esteem, erotophobia, and erotophilic women in a university class on human reproduction. As expected, high self-esteem erotophobic subjects were less Likely than other subjects to retain contraceptive and AIDS information presented in the class. Implications of this study for contraceptive and AIDS educational strategies are discussed.     

Perceptual organization based upon spatial relationships in Alzheimer's disease

Alzheimer's disease (AD) is often accompanied by impaired object recognition, thereby reducing the ability to recognize common objects and familiar faces. Impaired recognition may stem from decreased efficacy in integrating visual information. Studies of perceptual abnormalities in AD indicate an impairment in organizing elements of the visual scene, thereby confusing components of individual forms. This type of impairment is consistent with the characteristics of neural loss, which impact cortical integration. To examine the extent to which perceptual organization is impaired in AD, psychophysical measurements were made of visual perceptual grouping based upon spatial relationships in a group of AD patients and demographically matched elderly control subjects. A comparison was also made between young and elderly control subjects to evaluate the effects of aging on these capacities. Deficits in perceptual organization were found for a subgroup of AD patients, which corresponded to impairment on facial recognition. A less profound functional decline was found for the elderly control group. The degree of impairment for AD subjects did not correlate to level of dementia, but instead appears to be idiosyncratic to individual patients. These results are consistent with impaired integrative function in AD, the degree of which reflects individual differences in the regional distribution of neuropathological changes.     

FOCUS on the Family Caregiver: A Problem‐Solving Training Intervention

Problem‐solving interventions have documented effectiveness in treating distress among a variety of clientele. The authors discuss the application of training in social problem solving with family caregivers of persons who have incurred severe physical disabilities. Specifically, the authors outline training procedures (i.e., Project FOCUS) that enable counselors to assist family caregivers in developing effective problem‐solving skills that may translate to increased wellness for each caregiver, and by extension, their care recipients.     

Caregiver Social Problem Solving Abilities and Family Member Adjustment Following Congestive Heart Failure

Family members have a considerable impact on the health and well-being of others in the family. The characteristics of family caregivers that relate to care recipients' positive and negative outcomes associated with chronic disease have received scant empirical attention. We reasoned that family caregiver social problem solving abilities would be associated with depression and life satisfaction reported by persons with congestive heart failure (CHF). Correlational analyses found that caregiver negative orientation toward solving problems was significantly predictive of higher depression and with decreased life satisfaction of persons with CHF. These findings indicate that family caregiver problem solving abilities are important factors in adjustment following CHF. Implications for clinical interventions and theoretical models of problem solving are discussed.     

Visual training improves perceptual grouping based on basic stimulus features

Training on visual tasks improves performance on basic and higher order visual capacities. Such improvement has been linked to changes in connectivity among mediating neurons. We investigated whether training effects occur for perceptual grouping. It was hypothesized that repeated engagement of integration mechanisms would enhance grouping processes. Thirty-six participants underwent 15 sessions of training on a visual discrimination task that required perceptual grouping. Participants viewed 20?×?20 arrays of dots or Gabor patches and indicated whether the array appeared grouped as vertical or horizontal lines. Across trials stimuli became progressively disorganized, contingent upon successful discrimination. Four visual dimensions were examined, in which grouping was based on similarity in luminance, color, orientation, and motion. Psychophysical thresholds of grouping were assessed before and after training. Results indicate that performance in all four dimensions improved with training. Training on a control condition, which paralleled the discrimination task but without a grouping component, produced no improvement. In addition, training on only the luminance and orientation dimensions improved performance for those conditions as well as for grouping by color, on which training had not occurred. However, improvement from partial training did not generalize to motion. Results demonstrate that a training protocol emphasizing stimulus integration enhanced perceptual grouping. Results suggest that neural mechanisms mediating grouping by common luminance and/or orientation contribute to those mediating grouping by color but do not share resources for grouping by common motion. Results are consistent with theories of perceptual learning emphasizing plasticity in early visual processing regions.     

Computer programming for generating visual stimuli

Critical to vision research is the generation of visual displays with precise control over stimulus metrics. Generating stimuli often requires adapting commercial software or developing specialized software for specific research applications. In order to facilitate this process, we give here an overview that allows nonexpert users to generate and customize stimuli for vision research. We first give a review of relevant hardware and software considerations, to allow the selection of display hardware, operating system, programming language, and graphics packages most appropriate for specific research applications. We then describe the framework of a generic computer program that can be adapted for use with a broad range of experimental applications. Stimuli are generated in the context of trial events, allowing the display of text messages, the monitoring of subject responses and reaction times, and the inclusion of contingency algorithms. This approach allows direct control and management of computer-generated visual stimuli while utilizing the full capabilities of modern hardware and software systems. The flowchart and source code for the stimulus-generating program may be downloaded from www.psychonomic.org/archive.