Delicato Louise S, Derrington Andrew M
School of Biology (Psychology), Henry Wellcome Building, University of Newcastle upon Tyne, Newcastle upon Tyne, England NE2 4HH, UK.
Vision Res. 2005 Aug;45(17):2310-20. doi: 10.1016/j.visres.2005.02.020. Epub 2005 Apr 12.
If the Fourier components of a moving plaid have similar temporal frequency, spatial frequency and contrast, coherent motion is perceived according to subjective judgements. We have devised a more objective method of determining the conditions required for coherent motion. Moving plaid stimuli were created with one stationary component. Plaids with a stationary component always have a single perceived direction of motion, which is determined by the presence or absence of coherent motion. In a temporal two-interval forced-choice paradigm we used a direction discrimination task to investigate the effect of varying the temporal and spatial characteristics of the Fourier components and pattern contrast on the probability of coherent motion perception. Agreement across observers regarding the conditions required for coherent motion was excellent using this more objective method. We find that patterns do not produce coherent motion when presented at contrast threshold, irrespective of how similar the Fourier components are. We also confirm that when the temporal frequency, spatial frequency and contrast of the gratings are sufficiently similar, observers report the direction of motion indicating coherent motion.
如果移动方格的傅里叶分量具有相似的时间频率、空间频率和对比度，根据主观判断会感知到连贯运动。我们设计了一种更客观的方法来确定产生连贯运动所需的条件。通过设置一个静止分量来创建移动方格刺激。带有静止分量的方格总是具有单一的感知运动方向，这由连贯运动的存在与否决定。在一个时间双间隔强迫选择范式中，我们使用方向辨别任务来研究改变傅里叶分量的时间和空间特征以及图案对比度对连贯运动感知概率的影响。使用这种更客观的方法，观察者之间对于连贯运动所需条件的一致性非常好。我们发现，无论傅里叶分量多么相似，当图案以对比度阈值呈现时都不会产生连贯运动。我们还证实，当光栅的时间频率、空间频率和对比度足够相似时，观察者会报告表明连贯运动的运动方向。
