Perceptual dimensional constraints in response selection processes.

Most processing stages theorists assume that response selection processes are largely autonomous from earlier perceptual analysis of information. We report findings that challenge this assumption and suggest that a much more complex interaction exists between perception and action. Specifically our study demonstrates that the initial analysis of visual objects into features from different dimensions strongly constrains postperceptual processes of response selection. When a target that is associated with a response on the basis of one dimension is presented simultaneously with flankers that are associated with a response on the basis of another dimension, the response to the target is not affected by the identity of the flankers. These findings hold under a variety of conditions and appear to be specific to perceptual dimensions. When both target and flankers are associated with a response on the basis of the same dimension, the response to the target is affected by the identity of the flankers even when the target and flankers are perceptually dissimilar or belong to different semantic categories (digits and letters). We propose a model of response selection that can account for these findings. The model assumes that initial response selection processes for simple features are performed within dimensional modules and suggests a specific mediating role for spatial attention. We argue that this model is compatible with several other lines of research.