The tilt illusion: Repulsion and attraction effects in the oblique meridian

A shape-contrast effect for briefly presented stimuli.

“…In another direction of research, shape-contrast effects can be used to infer the tuning properties (width and symmetry of tuning; the tuning curves shown in Figure 27 are for a qualitative illustration only) of the "shape-tuned units" just as classic aftereffects have been used to infer the tuning characteristics of the retinotopic neural channels tuned to low-level image features (edge orientation, spatial frequency, and position; e.g., Blakemore & Campbell, 1969;Blakemore et al, 1970;Mitchell & Muir, 1976;O'Tool & Wenderoth, 1977;see Braddick et al, 1978, for a review). In a recent study, for example, Suzuki and Rivest (1998) used ellipses of a variety of aspect ratios as the priming and the test stimuli to determine the tuning properties of the aspect-ratio (line-on-circle) effect.…”

The effects of exposure duration and surrounding frames on direct and indirect tilt aftereffects and illusions

“…Subsequent research has not only confirmed the occurrence of both direct and indirect TAEs (e.g., Mitchell & Muir, 1976;Morant & Harris, 1965;Muir & Over, 1970), but also shown that both of these effects occur when the inducing and test stimuli are presented simultaneously, in the paradigm termed the tilt illusion, or TI (e.g., O'Toole & Wenderoth, 1977;Over, Broerse, & Crassini, 1972;Wenderoth & Johnstone, 1988a). Partly for this reason, but for others too, many authors have suggested common mechanisms for the T AE and the TI (e.g., Magnussen & Kurtenbach, 1980;Wenderoth & Johnstone, 1987).…”

“…Inhibition and satiation are repulsion mechanisms and seem unable to account easily for remote attraction effects. Although O'Toole and Wenderoth (1977) suggested a model in which disinhibition could explain indirecteffects, this has not been tested directly. Wenderoth, O'Connor, and Johnson (1986) measured TIs using linelength variations, which, according to neurophysiological evidence, should have maximized the opportunity for indirect effects to occur, if their mechanism was disinhibition.…”

“…The single line or grating will be perceived in its correct orientation because this is signaled by the most active cells, which are those tuned to the stimulus's orientation. If, however, two lines or gratings are simultaneously present-say, one vertical and one tilted 10 0 -15 0 -the inhibitory flank set up by each stimulus will subtract from the excitatory peak of the other, causing the net pair of excitatory peaks to shift apart (or toward each other, if the angular separation is smaller;, see O'Toole & Wenderoth, 1977). Since the perceived orientations depend on the most active neurons, the stimuli will repel each other perceptually, accounting for repulsion, or direct, TIs.…”

Orthogonal Expansion: A Neglected Factor in Tilt Illusions

“…4a have been studied. Prominent in this framework is the attempt to make a link between illusions and aftereffects (see, e.g., O'Toole & Wenderoth, 1977;Morikawa, 1987). Thus, there have been a large number of studies in which a background of inducing lines is presented first, then after a short lag, the target line is presented alone.…”