The effects of flankers on contrast detection and discrimination in binocular, monocular, and dichoptic presentations

Abstract

We investigated how two co-aligned adjacent stimuli (flankers) influence threshold versus pedestal contrast (TvC) functions in binocular, monocular, and dichoptic presentations. Targets were presented to the two eyes or to only one eye. Pedestals and flankers were presented to the same eye to which the target was presented (binocular or monocular presentations) or to the other eye (dichoptic presentation). In the binocular presentation of targets and pedestals, the binocular flankers lowered thresholds at low pedestal contrasts. The monocular flankers had a similar effect to the binocular flanker, although the threshold reduction was smaller. In the dichoptic presentation of a target and a pedestal, flankers lowered thresholds when flankers were presented to the eye where targets were presented. In contrast, dichoptic flankers elevated thresholds at intermediate pedestal contrasts when a pedestal was also dichoptically presented. We fitted binocular contrast gain control models to the data. It follows from the fitting results that flankers modulate outputs from spatial filters in the monocular processing stage of contrast gain control.

On the functions, mechanisms, and malfunctions of intracortical contextual modulation

“…Much has now been learned about facilitation by flankers, including evidence that it involves amplifying modulation (Chen and Tyler, 2008;Huang, Hess and Dakin, 2006;Maehara, Huang and Hess, 2010), can be cancelled by non-collinear flanks (Solomon and Morgan, 2000); depends upon input from other parts of the adjacent surround (Mareschal and Clifford, 2013), and is itself modulated by attention (Ramalingam et al, 2013). Psychophysical studies show that detection is improved when the flankers precede the target, or are presented simultaneously with it, but not when the target precedes the flankers (Polat and Sagi, 2006).…”

The two-stage process in visual working memory consolidation

“…The two-stage process hypothesis could be explained by the frameworks of both discrete resource theory 11 , 21 – 24 and continuous resource theory 25 – 28 , which are two broad theories proposed for the nature of VWM. In the framework of the discrete resource theory, the recent slots + averaging model suggests that VWM has a limited number of available discrete resources, like “slot” 11 .…”