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Paper IPM / Cognitive / 7498

School of Cognitive Sciences

Title:

Attention dependent illusory line-tilt aftereffect

Author(s):

1 .	L. Montaser kouhsari
2 .	R. Rajimehr

Status:

In Proceedings

Proceeding:

Journal of Vision

Year:

2003

Supported by:

IPM

Abstract:

Selective visual attention modulates neuronal activation in different cortical areas. This type of neuronal modulation could be happened even in the early stages of visual processing where specific attributes of visual stimuli are processed. It has been psychophysically showed that visual aftereffects such as figural aftereffect (Shulman, 1992), motion aftereffect (Rees, Frith

Lavie, 1997) and tilt aftereffect (TAE) (Spivey, 2000) are modulated by attention. In this study we investigated the effect of visual attention on the tilt aftereffect of illusory lines. The stimuli contained a tilted illusory line (15 degree clockwise or counterclockwise from vertical or horizontal) induced by two colorful line gratings abutting each other with a phase shift. In the adaptation phase two transparent stimuli were presented for 30 sec and subjects were asked to selectively attend to one of the tilted illusory lines. The attended illusory line was announced to subjects before each trial by the color of its line gratings. Following adaptation, TAE was measured by presenting a vertical or horizontal illusory line in the same location. The TAE for the attended illusory line was significantly greater than non-attended illusory line (P < 0.05). The results showed that the illusory line-TAE depends on the presence of attention. Since visual area V2 seems to be the first stage in the processing of illusory lines, we could conclude that selective attention modulates the activation of V2 neurons

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