Cortical Dynamics of Boundary Segmentation and Reset: Persistence, Afterimages, and Residual Traces

Using a neural network model of boundary segmentation and reset, Francis, Grossberg, and Mingolla (1994) linked the percept of persistence to the duration of a boundary segmentation after stimulus offset. In particular, the model simulated the decrease of persistence duration with an increase in stimulus duration and luminance. Thc present article reveals further evidence for the neural mechanisms used by the theory. Simulations show that the model reset signals generate orientational afterimages, such as the MacKay effect, when the reset signals can be grouped by a subsequent boundary segmentation that generates illusory contours through them. Simulations also show that the same mechanisms explain properties of residual traces, which increase in duration with stimulus duration and luminance. The model hereby discloses previously unsuspected mechanistic links between data about persistence and afterimages, and helps to clarify the sometimes controversial issues surrounding distinctions between persistence, residual traces, and afterimages.Air Force Office of Scientific Research (F49620-92-J-0499); Office of Naval Research (N00014-91-J-4100, N00014-92-J-4015

Combining simultaneous with temporal masking

Simultaneous and temporal masking are two frequently used techniques in psychology and vision science. Although there are many studies and theories related to each masking technique, there are no systematic investigations of their mutual relationship, even though both techniques are often applied together. Here, the authors show that temporal masking can both undo and enhance the deteriorating effects of simultaneous masking depending on the stimulus onset asynchrony between the simultaneous and temporal masks. For the task and stimuli used in this study, temporal masking was largely unaffected by the properties of the simultaneous mask. In contrast, simultaneous masking seems to depend strongly on spatial grouping and was strongly affected by the properties of the temporal mask. These findings help to identify the nature of both temporal and simultaneous masking and promote understanding of the role of spatial and temporal grouping in visual perception

A neural circuit for visual information spreading

I describe a neural circuit made of integrate-and-fire neurons that instantiates a mechanism for the spreading of visual information. The circuit is simple and operates at a reasonable time scale with reasonable parameter values. Slight alterations to the anatomy allow the circuit to spread information across surfaces (constrained by the surface boundaries) as for brightness and color effects or across a group/object (as for some attention effects)

Understanding Perceived Overqualification: Expanding the Criterion Space, Establishing Drivers, and Developing a Model

As applicants with more qualifications enter the workforce and managers reject individuals with more skills than a job requires, overqualification grows in importance to organizations. Perceived overqualification, or an individual’s self-perception as overqualified, is an under-researched topic, however. This dissertation outlines a theoretical model for understanding both how perceived overqualification develops and how it impacts outcomes. Results show that generalized self-efficacy and objective overqualification predict perceived overqualification. Furthermore, perceived overqualification affects state positive affect, job satisfaction, absenteeism, and self-esteem through justice perceptions. Implications for future research and practice are also detailed