BASIC AND SUPERORDINATE IMAGE CATEGORIZATION. INFLUENCE OF THE CONGRUENCE DEGREE AND TEMPORAL PARAMETERS OF PREVIOUS STIMULUS PRESENTATION

Abstract

The influence of temporal characteristics of mask presentation on performance in basic and superordinate image categorization tasks was investigated in young healthy subjects using a forward masking model. The masks could be congruent, noncongruent, or semantically neutral to the stimulus images. In the first series of experiments, the influence of stimulus onset asynchrony (SOA, the time interval between the onset of the mask and the onset of the stimulus) was studied. SOA varied from 100 to 350 ms in steps of 50 ms, whereas mask duration remained unchanged and equaled 100 ms. In the second series, the influence of mask duration was investigated. It varied from 100 to 250 ms in steps of 50 ms, while SOA remained constant at 250 ms. It was found that superordinate categorization was performed faster. This could be due to the fact that superordinate categorization involves a low-frequency information of stimulus description that is rapidly transmitted through the magnocellular visual pathway. The basic categorization was more sensitive to the temporal properties of the mask and its category. Changes in SOA had a stronger effect than those in mask duration. Assuming that SOA changes affect the early perceptual phase of stimulus processing, the sensitivity of this phase to irrelevant information seems to be reflected in the stronger influence of SOA changes on basic categorization compared to superordinate categorization.