The effect of similarity and duration on spatial interaction in peripheral vision

Abstract

Spatial interactions are extensive in the peripheral visual field, extending up to about half the retinal eccentricity of the target (Toet and Levi, Vision Res. 32, 1349-1357, 1992). In the present study it is shown that the degree and extent of peripheral spatial interaction depends in large measure on the similarity between test and flanking stimuli. The stimulus consisted of a test T surrounded by four distracting flanking Ts, each randomly oriented. The task was to determine the orientation of the test T. The test and flanking Ts differed in contrast polarity, shape, depth, color, eye of origin, or contrast. When the target and flanks differed in contrast polarity, depth, or shape, performance improved markedly for all observers. A color difference enhanced the performance of most but not all observers. Eye-of-origin had no effect, that is, spatial interaction was identical when the target and flanks were presented to the same eye, or to opposite eyes. The role of stimulus duration in spatial interaction was examined in two additional experiments. In the first, the stimulus viewing duration was increased in order to allow the observer time to serially search for the test T. In the second experiment, a postmask was presented at the location of the test T. The results of these experiments showed that the influence of similarity was independent of stimulus duration and the postmask, and suggest that serial search does not play an important role in the spatial interaction effects reported here. The extent of spatial interaction is correlated with the ability to do parallel search.

Examining Crowding Using a Real Three-Dimensional Experimental Setup

“…Thus, a comparison of similar crowded stimulus configurations between our real three-dimensional and virtual depth environments should be aspired. This could help to integrate our results to the existing research on crowding in (virtual) depth (Astle et al, 2014;Felisberti et al, 2005;Kooi et al, 1994).…”

“…Their results indicate that crowding seems to be smaller when the flankers are presented either in front of (Felisberti et al, 2005;Astle et al 2014) or behind a target (Kooi et al, 1994;Felisberti et al, 2005;Astle et al, 2014), compared to when all stimuli are presented in the same depth plane. Furthermore, similar to lateral spacing, crowding seems to decrease with increasing distance between target and flankers in depth (Astle et al, 2014).…”

“…There exist already a few studies, which deal with the influence of depth on crowding (Kooi et al, 1994;Felisberti et al, 2005;Astle et al, 2014). Their results indicate that crowding seems to be smaller when the flankers are presented either in front of (Felisberti et al, 2005;Astle et al 2014) or behind a target (Kooi et al, 1994;Felisberti et al, 2005;Astle et al, 2014), compared to when all stimuli are presented in the same depth plane.…”

“…Also, applying the finding of spacing in depth, analogously, the spacing between target and flanking stimuli could be varied in depth. One example for such a depth-spacing could be defocusing only the flankers or the target in relation to the fixation depth, as it was done in former studies using virtual depth (Astle et al, 2014;et al, 2005;Kooi et al, 1994). The focus of the current study is on developing and exploring a paradigm, in which the distance of all stimuli in relation to the fixated distance was varied analogously to eccentricity.…”

Spatial Resolution for Feature Binding Is Impaired in Peripheral and Amblyopic Vision

“…Moreover, current descriptions of crowding fail to explain various aspects of our data-for example, it is not clear that crowding would account for the set size effects we observe (in multi-segment arrays the crowding power of each segment is reduced by mutual crowding from nearby segments, so the addition of more segments causes crowding as well as disinhibition of crowding), and oblique orientation discrimination is treated like a conjunction in current descriptions of crowding (Pelli et al 2004). Finally, if anything we would expect more crowding in the stimuli we used for the discrimination tasks (where segments were all the same with respect to Ն1 dimension) than those for the conjunction task because crowding is most effective between more similar elements (Kooi et al 1994). For all these reasons, in the next section we interpret the data using our V1 model, every aspect of which is clearly specified.…”