A new "tilt" illusion reveals the relation between border ownership and border binding

Abstract

The "association field" models of contour detection predict specific spatial conditions for linking or grouping neighboring elements into smooth contours. We previously suggested that the "association field" model may account for perceptual binding of near-collinear luminance edges of same contrast polarity and their consequent unification into a unique contrast border with illusory tilt. This approach is now developed into a new version of the tilt illusion, the seesaw illusion, in which the contrast border is perceived as inverting concave-convex illusory curvature when background luminance is inverted, indicating that contrast polarity must be incorporated into the notion of "association field" to account for the seesaw illusion. We found that although tile-edge segmentation into alternating black-white segments produces conflicting local tilts, the illusion remains, up to 16 arcmin edge distance. This occurs at extreme background luminance for long segments (where only congruent edge segments of higher contrast bind, the others being perceptually assimilated into the background surface) and, when segments are too short for their orientation to be detected, at all background luminance values except that equidistant from black and white stripes. Our findings provide further confirmation that these are striking border ownership phenomena, demonstrating that figure/ground organization precedes perceptual binding of edges through association fields.

Effects of Temporal Features and Order on the Apparent duration of a Visual Stimulus

“…No significant difference emerged from the comparison between the Static and Mixed conditions (paired t -tests, all p  > 0.1, Not Significant). Confirming previous reports (Brown, 1995; Kanai et al, 2006; Kaneko and Murakami, 2009), the Static standard looked shorter-lived than the Drifting comparison for all standard durations (all p  < 0.001) apart from 2400 ms ( p  = 0.102, Not Significant). One might argue that the duration estimates for the Mixed stimulus (which contains static and drifting intervals in equal proportions) could result from a linear combination of the estimates of its static and drifting components.…”

“…– a static stimulus appeared shorter in duration than a drifting stimulus, confirming previous observations (Brown, 1995; Kanai et al, 2006; Kaneko and Murakami, 2009). …”

“…One might argue that our stimuli (drifting gratings) do not change in spatial location and therefore they might not be readily segmented into subunits. However, the findings that a similar increase in perceived duration to that observed for translating stimuli also occurs for flickering stimuli (Goldstone and Lhamon, 1974; Lhamon and Goldstone, 1974; Kanai et al, 2006) and for drifting Gabors (Kaneko and Murakami, 2009), which do not contain changes in spatial location, argue against this view. Kaneko and Murakami (2009) proposed a slightly different account for the speed-induced time expansion.…”

“…However, the findings that a similar increase in perceived duration to that observed for translating stimuli also occurs for flickering stimuli (Goldstone and Lhamon, 1974; Lhamon and Goldstone, 1974; Kanai et al, 2006) and for drifting Gabors (Kaneko and Murakami, 2009), which do not contain changes in spatial location, argue against this view. Kaneko and Murakami (2009) proposed a slightly different account for the speed-induced time expansion. According to their view, the rate at which our internal clock (Creelman, 1962; Treisman, 1963; Treisman et al, 1990) produces ticks is increased with stimulus speed in order to increase the temporal resolution of the system.…”

“…Kanai et al (2006), using a variety of visual stimuli including squares, random dot patterns, expanding gratings, and flickering Gaussian blobs, reported that apparent duration increased with stimulus temporal frequency, rather than speed, but only up to 4–8 Hz. Kaneko and Murakami (2009), using drifting Gabors, observed that perceived duration is positively related to speed, rather than temporal frequency, and the effect does not seem to saturate at high speed levels.…”