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“School of Cognitive Sciences”

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Paper   IPM / Cognitive Sciences / 7457
School of Cognitive Sciences
  Title:   Attentional Modulation of Adaptation to Illusory Lines
1 . L. Montaser kouhsari
2 . R. Rajimehr
  Status:   Published
  Journal: Journal of Vision
  No.:  4
  Year:  2004
  Pages:   434-444
  Supported by:  IPM
Selective visual attention modulates neuronal activation in various cortical areas. This type of neuronal modulation could happen even in the early stages of visual processing where specific attributes of visual stimuli are processed. It has been shown that different forms of visual aftereffects such as tilt aftereffect, motion aftereffect and figural aftereffect are modulated by attention. In this study we investigated the effect of visual attention on adaptation to illusory lines. In the first experiment orientation selective adaptation to a peripheral illusory line was measured in three conditions: 1) poor attention condition in which subjects performed a dual task (even-odd judgment) at the fixation point during the adaptation period, 2) partial attention condition in which subjects only observed successively presented digits at the fixation point and did not perform the task during the adaptation period and 3) full attention condition in which no visual stimuli were presented at the fixation point. Results showed that the magnitude of adaptation systematically decreased as the attentional load at the fixation point increased. In the second experiment two transparent illusory contours were presented during the adaptation period and tilt aftereffects to attended and non-attended illusory lines were compared. The magnitude of tilt aftereffect to the attended illusory line was significantly greater than that to the non-attended illusory line even when non-attended illusory contour was more visually salient. Since visual areas V2 and V1 seem to be the first stage in the processing of illusory contours, we could conclude that visual attention has modulatory effects on the activation of neurons in these areas.

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