The tau effect put to the test of time

Benoît Schwaller (1)

1 LGeco - Laboratoire de Génie de la Conception

When equally spaced points on the skin of a blindfolded human individual are stimulated in rapid succession, stimuli separated by a shorter temporal interval are perceived as closer together in space than stimuli separated by a longer temporal interval. This perceptual illusion is known as the tactile variant of the tau effect. Here, a specific case of extinction of this phenomenon is discussed in the light of current theory. Psychophysical data of two blindfolded observers, tested under conditions of successive tactile stimulations of two points on the skin of the lower arm, with constant spacing and separated by two randomly varying temporal intervals, show that the tau effect occurs in the first trial blocks, and then vanishes over time. The data are discussed in the light of long-range interactions between somatosensory cortical neurons which, over a certain period of time, achieve a stable and reliable representation of tactile space independent of temporal variations. A neural state observer model for neural integration with temporal bias reduction is exploited to account for the individual data, and discussed in the light of previous explanations. The conclusions call for research into the conditions under which perceptual illusion may vanish, based on the hypothesis that such extinction studies could generate an even deeper insight into adaptive brain mechanisms than previously considered.

Mots clés: time; space; mental representations; tactile sensations

Domaines: Sciences cognitives

Benoît Schwaller. The tau effect put to the test of time. [Research Report] Université de Strasbourg, CNRS. 2014. ⟨hal-01059985⟩