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In the horizontal-vertical illusion (HVI), the length of the vertical line is overestimated, whereas in the bisection illusion (BI), the horizontal bisecting line is expected to be overestimated. Here, only half of our 22 observers showed the expected BI, whereas the other half underestimated the bisecting line. Observers also differed in their judgments of(More)
We studied the time course of apparent rotation and directional reversal in Leviant's Enigma figure. On average, periods of clockwise rotation lasted 5.0 s as opposed to 4.4 for counter-clockwise rotation, resulting in an average reversal frequency of 6.4 within 30 s. At the beginning of a trial, clockwise rotation was perceived almost twice as often as(More)
The idea of a largely segregated processing of color and form was initially supported by observations that geometric-optical illusions vanish under isoluminance. However, this finding is inconsistent with some psychophysical studies and also with physiological evidence showing that color and luminance are processed together by largely overlapping sets of(More)
We investigated the figural dynamics of filling-in processes in figures with more than one possible figure-ground organisation. Using a central disk and two concentric rings as well as similar stimuli consisting of three nested squares or parallel stripes, we tested for filling-in with different equiluminant colour combinations. We observed four modes of(More)
We introduce a new virtual environment (VE) called SQUARELAND, consisting of a 10×10 block maze, which allows for all kinds of investigations in human wayfinding. It enables researchers to quickly implement experiments on indoor-and outdoor wayfinding, including variations of route length, route complexity, availability of landmarks, etc. The basic setup(More)
Looking at the world with one eye, we do not notice a scotoma in the receptor-free area of the visual field where the optic nerve leaves the eye. Rather we perceive the brightness, color, and texture of the adjacent area as if they were actually there. The mechanisms underlying this kind of perceptual filling-in remain controversial. To better understand(More)
Spatial cognition research has recently made much progress in understanding the cognitive representations and processes underlying human wayfinding. Many theoretical assumptions about the concept of landmark salience have been established. In this context it is important to define perceptual (or visual) and structural landmark salience. Structural salience(More)