<p>The effects of priming with an image of an animal versus an image of an object on basic and superordinate categorization parameters were studied in 19 young healthy subjects. In both basic and superordinate categorization, priming with an animal image, which is evolutionarily more significant, elicited an increase in the amplitude of the early N50 negativity wave to the salient stimulus in the temporal leads, indicating an increased level of attention. The effect of the animal primer on behavioral responses and the later components of the potential depended on the level of categorization. Basic categorization produced an increase in motor reaction time, while superordinate categorization increased task accuracy. In basic categorization, priming with an animal image resulted in increases in the amplitudes of the occipitotemporal P130 and frontal N130 components, which were accompanied by a decrease in central late positivity (LP). The increases in the amplitudes of these components may indicate difficulty in separating relevant and irrelevant visual information due to a shift of attention to the primer, while the decrease in LP indicates difficulty in matching the stimulus with the category description stored in memory. During superordinate categorization, use of animal images as primer led to greater amplitudes of the frontal P50 component, the occipital P130, and central LP. Changes in P50 and P130 may reflect implicit categorization of animal images based on low-frequency descriptions with a subsequent decrease in interference between the primer and the stimulus; the increase in LP indicates easier matching of the stimulus with the category description and an increase in endogenous attention during priming using animal images.</p>