Neural dynamics of the competition between grouping organizations

Neural dynamics of the competition between grouping organizations have been studied to a limited extent. The paradigms used so far confounded grouping operations with task demands, using explicit reports of the predominantly perceived organization and biasing attention toward one grouping principle. This study explored the effect of grouping strength on ERPs elicited for conflicting grouping principles using a primed-matching paradigm, where the grouping display was irrelevant to the task. In Experiment 1, proximity was pitted against brightness similarity in a conflicting columns/rows organization. Competition level was manipulated by increasing grouping strength of one principle or the other. In Experiment 2, proximity was presented alone or in a weak/strong competition with size similarity. If conflicting organizations result in a hybrid representation, modifications would be evident for different degrees of grouping strength at early perceptual components. However, a competition-related component would appear in a later stage of processing, showing a difference between conflict and nonconflict conditions. We found no evidence for a competition specific component but did find modulations to the ERP waveforms at around 100 to 250 milliseconds from target onset. These results suggest that when grouping principles are in conflict, they produce a hybrid representation of the dominant and nondominant organizations.