Processing of positional information in the human visual system

Immediately preceding stimuli increase the detection of a less detectable but not a more detectable stimulus

“…Moreover, the same asymmetry may occur for physical stimuli when memory is not involved, because of the same survival advantage, which is a prediction that should be easy to test. Furthermore, a line assimilates in spatial location to a more detectable line but not to an equally detectable line (Rentschler, Hilz, & Grimm, 1975), hinting that assimilation may tend to be similarly asymmetric in general.…”

The influence of contrast and spatial factors in the perceived shape of boundaries

“…One possible explanation follows from previous psychophysical research documenting the misperception of distances separating segments or edges (Badcock & Westheimer, 1985a, 1985bGreene & Brown, 1995;Rentschler, Hilz, & Grimm, 1975). Both attraction and repulsion effects have been described-that is, a test line appeared that was located, with respect to the flank line, at a distance shorter than the true value and farther away, respectively.…”

“…For high-contrast flanks with a separation of 3.69 arcmin, negative polarity of flanking boundary shows stronger and wider attraction effects than positive polarity, a result consistent with that observed in our experiments with edges of the same contrast polarity. Other research revealed interaction ranges beyond this limit (Hotopf & Brown, 1988;Rentschler et al, 1975;Rivest & Cavanagh, 1996; see also Polat & Sagi, 1994, in research on contrast sensitivity), but the hypothesis that locates the stronger interaction phenomena within this short-range limit appears to be sufficiently well founded.…”

“…In Experiment 3, we set in opposition two alternative explanations of these effects. The first follows from the well-known finding of a shift of perceived position (attraction and repulsion) between closely presented target contours (Badcock & Westheimer, 1985b;Hotopf & Brown, 1988;Rentschler et al, 1975), which predicts local interactions, either end to end or point to point, where they laterally overlap. The second explanation also assumes a spatial interaction between two noncollinear contours but, differently from the attraction/repulsion hypothesis, predicts that the interaction regards the edges, or part of them, and produces an inward tilt (so that the edges with the same contrast polarity perceptually align) or an outward tilt (so that edges of opposite contrast polarity are perceived to be more misaligned).…”

A special class of nonlinear interactions in the visual system of the fly

“…The foreground--background discrimination by the fly and our interpretation of it may also be relevant to some psychophysical [21][22][23][24] and electrophysiological data [25][26][27][28][29][30].…”