“School of Cognitive Sciences”
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| Paper IPM / Cognitive Sciences / 8977 |
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First-order motion consists of moving luminance-defined attributes. Secondorder
motion, on the other hand, consists of moving patterns whose motion
attributes are not luminance-defined. The detection of first and second-order
motion is thought to be mediated by different mechanisms. Here, we compare
the ability of Parkinson disease patients (PDPs) to detect first-order/secondorder
motion with normal subjects. Subjects had to discriminate the drift
direction of first-order motion (luminance-modulated noise) and a novel
second-order motion pattern (named as noised base motion) over a range of
stimulus speeds and strength. The results show that although acuity of firstorder
motion detection in PDPs is almost the same as in normal subjects, but
this is not the case for second-order motion detection. Regarding the lack of
some certain neurotransmitters in PDPs, our results unveil some of the
underlying mechanisms of the motion detection hierarchy. As some
researchers have proposed, the tracking function of attention constitutes the
high-level motion system. We propose that the deficit in PDPs motion
detection system may indicate attentional deficit, which we chose to call
`attentional rigidity'.
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