Visual tilt effects

An experimenter would sit behind the disk to set the stimuli and to record the subject's adjusted position of the line.

According to Durant's paper in 2006,[8] in the direct form of tilt effects, the largest illusion occurs when the test stimulus and the context surround are presented simultaneously; the spatial gap, the relative contrast and depth cues result in a reduced TI.

Experiments also show that both TI and TAE occur for contextual and test stimuli that differ in color and luminance.

A hypothesis proposed by Blakemore et al. (1971)[19] suggested that TAE and TI were both caused by lateral inhibition between cortical orientation detectors.

Based on this theory, those cortical neurons tuned to orientations between the test and contextual stimuli would normally be excited by either stimulus alone.

[26][27] Furthermore, mechanistic models of orientation tuning are used to assess the neural basis of experimental findings on tilt effects.

[28] Changes on tuning curves would shift population response resulting in tilt biases.

Schwartz et al. (2009)[29] proposed that natural scene statistics could also effect changes on orientation tuning curves with the presence of context.

The coordination between the surround and the center across segmentation boundaries is greatly reduced,[30] and our visual system takes advantage of this natural statistics feature: increased evidence for segmentation information leads the visual system to decouple the coordination between the center and surround.

[31][32] In their model, a segmentation probability between the test center and context is introduced to control the amount of contextual modulation.

Schwartz et al. (2007)[28] reviewed the psychophysical and electrophysiological parallels between the TI and TAE, which are probably revealing functional commonality between spatial and temporal context.