Abstract
Most contextual modulations, such as center-surround and crowding exhibit a suppressive effect. In contrast, collinear configuration is a unique case of contextual modulation in which the effect can be either facilitative or suppressive, depending on the context. Physiological and psychophysical studies revealed several spatial and temporal rules that determine the modulation effect: 1) spatial configuration: collinear configuration can be either facilitative or suppressive, whereas non-collinear configurations may be suppressive; 2) separation between the elements: suppression for close separation that coincides with the size of the receptive field and facilitation outside the receptive field; 3) activity dependent: facilitation for low contrast (near the threshold) and suppression for high contrast; 4) temporal properties: suppression is fast and transient, whereas facilitation is delayed and sustained; 5) attention may enhance the facilitation; 6) slow modulation: perceptual learning can increase the facilitatory effect over a time scale of several days; 7) fovea and periphery: similar rules can be applied when spatial scaling to the size of receptive field is done. It is believed that the role of collinear facilitation is to enhance contour integration and object segmentation, whereas center-surround is important for pop-out. Our recent studies suggest that these rules can serve as a unified model for spatial and temporal masking as well as for crowding.
Meeting abstract presented at VSS 2013