Abstract
Abstract: :
Purpose:To examine the spatial properties of the interference of orientation-defined texture perception by task-irrelevant colour variation. Methods:Stimuli were orientation-modulated textures comprised of 400 elongated gaussians whose orientations varied systematically across the display. The variation in orientation was either sinusoidal (narrowband) or square-wave (broadband). The variation in colour was introduced by making half the elements red and half green. The spatial frequency and amplitude of the orientation modulation was fixed while the spatial frequency of the colour variation was either homogeneous (no variation), broadband (random), or narrowband (0.5, 1, 2, 4, and 8 cycles/display). The phase of the orientation modulation and the colour modulation were both randomly selected on each trial. Observers (N=11) were required to identify the interval in which the test was orientation-modulated and the percentage of correct trials was recorded for each condition. Results:In the square-wave condition nearly all forms of irrelevant colour variation reduced performance. However, in the sinusoidal condition performance was reduced only when the colour variation was similar in spatial frequency to the test. Conclusion:The absence of interference effects in the sinusoidal condition except when test and mask were similar in spatial frequency suggests that the interference of orientation-modulation-detection by colour variation is not due to the disruption of element grouping. The results are consistent with a spatial frequency dependence in the interaction between colour variation and orientation variation.
Keywords: 597 texture • 362 color vision • 586 spatial vision