A severe capacity limit in the consolidation of orientation information into visual short-term memory

Previous research has suggested that two color patches can be consolidated into visual short-term memory (VSTM) via an unlimited parallel process. Here we examined whether the same unlimited-capacity parallel process occurs for two oriented grating patches. Participants viewed two gratings that were presented briefly and masked. In blocks of trials, the gratings were presented either simultaneously or sequentially. In Experiments 1 and 2, the presentation of the stimuli was followed by a location cue that indicated the grating on which to base one’s response. In Experiment 1, participants responded whether the target grating was oriented clockwise or counterclockwise with respect to vertical. In Experiment 2, participants indicated whether the target grating was oriented along one of the cardinal directions (vertical or horizontal) or was obliquely oriented. Finally, in Experiment 3, the location cue was replaced with a third grating that appeared at fixation, and participants indicated whether either of the two test gratings matched this probe. Despite the fact that these responses required fairly coarse coding of the orientation information, across all methods of responding we found superior performance for sequential over simultaneous presentations. These findings suggest that the consolidation of oriented gratings into VSTM is severely limited in capacity and differs from the consolidation of color information.     

Perfect visual short-term memory for periodic patterns

Abstract

The short-term memory for spatial frequency information was assessed by measuring the spatial frequency discrimination thresholds for briefly flashed luminance gratings as a function of the time interval between the test and reference gratings, using a computer-controlled two-interval forced-choice procedure. Discrimination thresholds were stable for interstimulus intervals in the range 1–30 sec under all conditions tested. At low contrasts, short exposure times and low spatial frequencies discrimination thresholds increased, but no interactions between stimulus parameters affecting thresholds and interstimulus interval were observed. It is concluded that factors limiting spatial discrimination are associated with the sensory coding stage. Spatial discrimination and visual memory may be based on a common representation, which is perfectly retained in short-term memory. Visual half-field tests revealed no hemispheric differences in the processing and retention of spatial frequency information.     

Environmental enrichment results in cortical and subcortical changes in levels of synaptophysin and PSD-95 proteins

Experience-dependent plasticity is thought to involve selective change in pre-existing brain circuits, involving synaptic plasticity. One model for looking at experience-dependent plasticity is environmental enrichment (EE), where animals are exposed to a complex novel environment. Previous studies using electron microscopy showed that EE resulted in synaptic plasticity in the visual cortex and hippocampus. However, the areas in the brain that have been examined following EE have been limited. The present study quantified potential synaptic plasticity throughout the brains of C57BL/6 mice using an enzyme-linked immunosorbent assay (ELISA) for two synaptic proteins, synaptophysin and PSD-95. EE resulted in increased synaptophysin and PSD-95 levels through major brain regions, including anterior and posterior areas of the forebrain, hippocampus, thalamus, and hypothalamus. However, no changes in synaptophysin were detected in the cerebellum. These results demonstrate that EE results in an increase in levels of both pre- and post-synaptic proteins in multiple regions of the brain, and it is possible that such changes represent the underlying synaptic plasticity occurring in EE.     

Reinvigorating the Study of Careers

Before discussing how to innovate the study of career development using insights from life-span psychology and life course sociology, researchers might benefit from reconsidering whether they are studying careers or studying vocational behavior. While the word “career” seems ubiquitous in vocational psychology research, there are important differences between the study of vocational behavior, occupational roles, and career development. In this article, I urge researchers to (a) reconsider the meaning of career and research on career development, (b) adopt prospective, longitudinal research designs, and (c) concentrate first on processes of development and then on the content of careers. Considering these suggestions may ready vocational psychology for true innovations such as studying human development through work and relationships.     

Self-Presentation Concerns and Health Behaviors Among Cosmetic Surgery Patients

The present investigation examined the relationship between self-presentational motives and physical activity in a population of cosmetic surgery participants. Participants were 50 female and 5 male cosmetic surgery patients (CSPs; M age = 38.5 years) who completed a battery of self-report measures following either vein or acne treatment. Analyses revealed significant group differences on self-presentational concern and public self-consciousness between: (a) those who elected the treatment for appearance motives and those who elected treatment for health-based motives, and (b) the more frequent (3 or more times per week) and less frequent (2 or less times per week) exercisers. Greater self-presentational concerns and greater public self-consciousness were associated with having appearance-related motives for treatment and with being a less frequent exerciser.     

The Role of Prototypical Situations in the Perceptions of Prejudice of African Americans1

Inman and Baron (1996) found that African Americans and Whites possess prototypes for racist behavior that involve Whites oppressing African Americans. However, prototypical content may be more detailed and specific for African Americans because of differing cultural experiences. In the present experiment, undergraduates read stories about interpersonal encounters representing prototypical and nonprototypical situations. Actor race ambiguity was manipulated by the presence or absence of photographs. As expected, Whites tended to make equal ratings of prejudiced behavior for prototypical and nonprototypical situations. However, African Americans perceived more prejudice in prototypical vignettes than in nonprototypical vignettes. They also perceived stronger prejudicial displays and more dispositional motivation for targets in prototypical vignettes. The results suggest that African Americans have heightened sensitivity to prejudice in specific situations, a factor that may contribute to racial confrontations and misunderstandings.