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Fumie Sugimoto, Akihiro Yagi; Attentional modulation in perception of speed occurs in the first motion-processing stage. Journal of Vision 2010;10(7):99. doi: 10.1167/10.7.99.
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© ARVO (1962-2015); The Authors (2016-present)
Recently, there have been studies indicating that attention does not only improve performance, but also alters subjective perception. Turatto, Vescovi and Valsecchi (2007) found this phenomenon in perception of speed, reporting that a moving grating presented in an attended position was perceived moving faster than when presented in a less attended position. In the present study, we investigated the stages of motion information processing to find where attentional modulation occurred. Motion information processing consists of a stage where local motion is detected, and a following stage where integration is done to generate perception of coherent motion. We presented plaid patterns that have the same coherent motion but different components and measured the alteration of plaids' speed perception. If the attention affects speed perception in the local motion detection stage, the amount of change in perceived speed by attention in each plaid should be different. On the other hand, in the case that the attention affects speed perception in the integration stage, there should be no difference between the changed speeds of each plaid. We used the cueing paradigm to manipulate the participants' attention. After a cue appeared in left or right of the fixation, two plaids were presented in both peripheral positions simultaneously. The participants' task was to report the plaid that appeared to move faster. As a result, it was showed that speeds of plaids were perceived faster in cued positions. We then calculated the amount of change in perceived speed of each plaid pattern and compared them, and found that the amount of changed speed differed between each plaid. These findings indicate that the alteration in perception of speed by attention occurs in the first stage of motion processing, which perform local motion detection.
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