The tilt after-effect: changes with stimulus size and eccentricity

Dynamics of contrast adaptation in central and peripheral vision

“…The average maximum aftereffects also did not differ significantly, t (8) = 1.46, p > 0.18. Larger TAEs in the periphery have been reported in previous studies (Harris & Calvert, 1985; Muir & Over, 1970; Over et al, 1972). In our study the adapting contrast was 90% in center and 30% in periphery, and this may be one reason for the similar aftereffects we observed.…”

“…Similarly, many visual aftereffects increase in magnitude with eccentricity. These include tilt aftereffects (Harris & Calvert, 1985; Muir & Over, 1970), motion aftereffects (Castet, Keeble, & Verstraten, 2002; Wright, 1986), shape aftereffects (Gheorghiu, Kingdom, Bell, & Gurnsey, 2011; Suzuki & Cavanagh, 1998), and face aftereffects (Tangen, Murphy, & Thompson, 2011; Webster, Kaping, Mizokami, & Duhamel, 2004). Although the scaling of cortical magnification might explain the larger tilt aftereffect found in the periphery (Harris & Calvert, 1985), it cannot account for the eccentricity-dependent increase in the shape aftereffect, and Gheorghiu et al (2011) suggested that the differences might instead reflect greater adaptation gain (i.e., larger post-adaptation sensitivity suppression) or an eccentricity-dependent decrease in the stimulus-selectivity of the adapted mechanisms.…”

Outline- and solid-angle orientation illusions have different determinants

“…The experiments suggest this conclusion because: (1) solid-angle illusions do not occur at all unless the test edge is straight, but this is not true of outline illusions (Experiments 1 and 2); (2) when test edges are vertical or horizontal, outline effects are reduced, presumably due to neural anisotropies, but solid-angle effects are eradicated completely (Experiments I, 3, and 4); and (3) manipulations that decrease acuity for parallelism, such as increasing the separation of the matched edges or decreasing their length, have the effect of increasing solid-angle illusions but either decrease or have no effect on outline effects (Experiments 5 and 6). These conclusions are not inconsistent with the hypothesis that orientation, position, and collinearity are neurally coded in parallel (Harris & Calvert, 1985;Wenderoth et al, 1986b). Indeed, consistent with this hypothesis are the reduction in outline effects when edges are straight (Experiment 2) and the observation that a parallel chevron match to a solid Bourdon figure simultaneously appears parallel at all points yet appears insufficiently bent.…”

“…On the basis of other evidence from studies of the tilt illusion and aftereffect (Wenderoth & Johnson, 1984;Harris & Calvert, 1985), Wenderoth, O'Connor, and Johnson (1986c) interpreted their data as consistent with This research was supported by the Australian Research Grants Scheme, Grant A28515620 I, to the first author. This grant alsoprovided for the second author's research assistance.…”

The basis of the Bourdon illusion

“…In fact, I have argued consistently that perceptual processes can only possibly reflect neural interactions directly ,and that attempts to distinguish between neurally based effects and "higher order" or "hypothesis testing" processes are meaningless and obscurantist, and reflect current ignorance of mechanisms rather than their nonexistence (Wenderoth & Johnstone, 1987;Wenderoth & Latimer, 1978). It can be noted in addition that the idea of separate neural channels coding orientation, position, and collinearity was adapted from the same model put forward to explain tilt aftereffect data in an entirely different context (Harris & Calvert, 1985).…”