Animal image priming effects in basic–level and superordinate-level categorization

The effect of priming with an animal image versus an object image on basic-level and superordinate-level categorization parameters was investigated in 19 healthy young subjects. For both basic- and superordinate-level categorization, priming with an animal image, as more evolutionarily significant, causes an increase in the amplitude of early N50 negativity to the salient stimulus in temporal areas, indicating an increase in attention. The effect of the animal prime on behavioral responses and on later potential components depends on the categorization level. In basic-level categorization there is an increase in motor reaction time, and in superordinate-level categorization there is an increase in accuracy. During basic-level categorization with animal primes, an increase in the amplitudes of the occipitotemporal P130 and frontal N130 components is accompanied by a decrease in central late positivity (LP). The increased P130 and N130 amplitudes may indicate an increased difficulty in separating significant and insignificant visual information due to a shift of attention to the prime. The decrease in LP amplitude is probably related to difficulties in processing the stimulus at the stage of comparing it with the category description stored in memory. During superordinate-level categorization, the animal prime, compared to the object prime, induces increases in the amplitude of the frontal P50, occipital P130, and central LP components. Presumably, the increase in P50 reflects the implicit categorization of the prime by its low-frequency description, which reduces prime-stimulus interference at later stages of processing. The increase in LP amplitude reflects the facilitated stage of matching the stimulus to the categorization description, as well as an increase in endogenous attention during processing of the animal prime.