Tuning to Y-like figures in the cat striate neurons

2020

Symmetry

Variants of the capital Latin letter T were prepared with the straight strokes replaced by J-, C-, or S-curves, mimicking handwritten Ts. These were used to test the hypothesis that the overestimation of the length of the T’s undivided line, relative to the length of its divided line may be understood as an adaptation to a corresponding letter schema. The illusion was greater for S-curve Ts than for C- and J-curve Ts, suggesting that approximate bilateral mirror symmetry is more important for the illusion to occur than letterness. Despite the illusion, observers were quite sensitive to the different lengths of the Ts’ curves.

Section: Discussionmentioning

confidence: 52%

The ⊥-Illusion Is Not a T-Illusion

2020

Symmetry

“…In previous publications (e.g., Landwehr, 2015, 2020), I suggested that the ⊥-illusion might be caused by a general T-schema (Chang et al, 2015; Shevelev et al, 2001) as well as by interactions between orientation-sensitive neurons (Caelli, 1977). The influence of a figural schema can be expected to diminish when the figure's elements are separated by an increasingly wide gap.…”

Section: Discussionmentioning

confidence: 99%

Interrelations between the Oppel-Kundt- and the T-illusion

2022

Perception

In order to investigate interrelations between the Oppel-Kundt- and the T-illusion, T-type figures, comprised of one dotted and one empty line (demarcated by its endpoints), separated by a gap of variable size, and rotated to oblique orientations, were judged with regard to the lengths of the two extents. The T-illusion (overestimation of the length of the undivided line) was greater for a T with a dotted undivided line and a small gap. When the divided line was dotted, the illusion vanished at a small gap and reversed at a larger one. Findings are interpreted to mirror activities of a neural T-schema as well as orientation- and density-sensitive neurons.

“…Animal or neuroscientific research may provide support for the first idea (cf. Shevelev et al, 2001), and cross-cultural studies may substantiate or falsify the second (cf. van der Kamp, Withagen, & de Wit, 2013).…”

Section: Discussionmentioning

confidence: 99%

Titchener’s ⊥ in context 1—delimited, discrete monomotif patterns, line arrangements, and branching patterns

Atten Percept Psychophys

2015

Three experiments tested the effects of the presence of nontarget ⊥s on Titchener's (1901) ⊥-illusion. Experiment 1 used patterns of four separate ⊥s, Experiment 2 used branching patterns in which four ⊥s were stuck together, and Experiment 3 used patterns of four triangles or four beehive forms for which the ⊥ could be seen as a skeleton. Three independent samples of 12 observers each had to haptically indicate the lengths of target lines and verbally judge the relative lengths of the two lines of target ⊥s. The illusion to judge or indicate the ⊥'s undivided line as longer than its divided line survived throughout except for the branching patterns: here, haptic indications did not differ between the two types of lines. Specific features of these patterns and of the ⊥ itself may be responsible for these effects.