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|Title:||Sensitivity to spatial and temporal modulations of first-order and second-order motion.|
|Authors:||Hutchinson, C. V.|
|Citation:||Vision Research, 2006, 46 (3), pp.324-335|
|Abstract:||This study characterises the spatiotemporal “window of visibility” for first-order motion (luminance-modulated noise) and three varieties of second-order motion (contrast-modulated, polarity-modulated and spatial length-modulated noise). Direction-identification thresholds (minimum modulation depth producing 79.4% correct) were measured for each motion pattern (acuity permitting) over a five octave range of spatial and temporal frequencies (0.5–16 c/deg and 0.5–16 Hz respectively). Thresholds were converted into modulation sensitivity (1/threshold). For first-order motion patterns, sensitivity functions were generally bandpass. However, for second-order motion patterns, functions were predominantly lowpass in nature. In particular, the functions corresponding to contrast-modulated and polarity-modulated noise were virtually identical in terms of shape and sensitivity. However, sensitivity to modulations of spatial length was extremely poor and more lowpass, suggesting that additional strategies, perhaps a feature-based system, may be required for encoding motion of images of this type.|
|Appears in Collections:||Published Articles, School of Psychology|
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