Specification of multiple visual processes in metacontrast masking by means of individual differences

研究视觉刺激对感知和动作的处理的一种方法采用元对比掩蔽范式，其特征在于具有目标和与目标刺激不重叠的后续掩蔽刺激的两个刺激序列。当目标和掩蔽物之间的刺激起始时间间隔（SOA）变化时，掩蔽效应的时间过程导致掩蔽函数在某些条件下遵循U形，但在其他条件下仅随SOA增加。尽管相同的条件下，但是，我们已经发现了稳定的个人之间的差异与可见性的功能，在整个范围内的U形和增加的功能。这一发现挑战了所有假设单一机制的元对比掩蔽的帐户。个体差异反而支持元对比屏蔽的多进程帐户。因子分析的可见性功能表明，至少有三个潜变量可以区分。我们假设，这些潜在的变量指向三个过程，根据一个单独的不同的权重，个人观察员的表现作出贡献。在拟议的项目中，我们希望通过比较元对比掩蔽中的个体差异与其他功能可解释的实验条件中的个体差异来指定这些过程的功能。我们假设一个整合过程，促进感知与短SOA，运动感知过程，有助于性能与中间SOA，和分割过程，支持目标感知与长SOA。在六项研究中，我们想研究如何与刺激的轮廓，运动和深度，以及时间整合的两个刺激有助于元对比掩蔽的个体差异。本地化过程中的视觉系统，我们比较个体差异，在monoptic和dichoptic刺激条件和检查电生理反应的刺激序列中使用的元对比。这个项目可以说明个体差异如何有助于视觉处理的一般帐户。我们希望这种方法有助于指定的功能的过程，有助于在一个加权组合的视觉感知元对比掩蔽。

One approach to examine the processing of visual stimuli for perception and action employs the metacontrast masking paradigm that is characterized by at two-stimulus sequence with a target and a following masking stimulus which does not overlap with the target stimulus. When the stimulus onset asynchrony (SOA) between target and mask is varied, the time course of masking effects results in a masking function which follows a u-shape in some conditions but simply increases with SOA in other conditions. Despite identical conditions, however, we have found stable differences between individuals with visibility functions that varied in the entire range between u-shaped and increasing functions. This finding challenges all accounts of metacontrast masking that assume a single mechanism. The individual differences rather support multi-process accounts of metacontrast masking. Factor analyses of the visibility functions suggest that at least three latent variables can be distinguished. We assume that these latent variables point to three processes which contribute according to an individually different weighting to the performance of individual observers. In the proposed project we want to specify these processes in their function by comparing individual differences in metacontrast masking with individual differences in other functional interpretable experimental conditions. We assume an integration processes which facilitates perception with short SOAs, a motion perception process that contributes to performance with intermediate SOAs, and a segmentation process which supports target perception with long SOAs. In six studies we want to examine how processes related to stimulus contour, motion and depth, as well as temporal integration of two stimuli contribute to individual differences in metacontrast masking. To localize processes in the visual system we compare individual differences in monoptic and dichoptic stimulus conditions and examine electrophysiological responses to the stimulus sequence used in metacontrast. This project can exemplify how individual differences can contribute to general accounts of visual processing. We expect that this approach helps to specify the function of the processes that contribute in a weighted combination to visual perception in metacontrast masking.