Comparing the Influences of Masking, Crowding, Response Conflict, and Cortical Scaling on Simple Shape Identification with Foveal Targets

Two experiments were conducted to compare the effects of masking and crowding on simple shape perception. The target stimuli were presented in foveal vision, where masking effects are generally investigated and where crowding effects are typically small compared to peripheral vision. The second experiment investigated the potential involvement of the dorsal visual pathway by testing if a peripheral crowding stimulus could interfere with the perception of a target shape, if it were scaled to account for low visual acuity? The results of both experiments indicated strong congruency effects, especially for pattern and metacontrast masking (which, in some respects, is similar to crowding). Congruency effects were generally weak for distractors presented further from the target. In Experiment 2, cortically scaled distractors only showed a potential influence in the forward masking condition. Perhaps this is an indication of a priming effect from the distant crowding stimuli. Further research might reveal the extent to which crowding displays can test physiologically motivated hypotheses.