Figure 1.

Schematic illustration of study and test phases. Study phase: images of animals and tools were presented in their complete form (a lion as an example). Test phase: in the identification task (i.e., priming task), subjects were asked to name each picture, presented in an ascending sequence of nine levels of filtering (see text for details); in the recognition task, old and new images were displayed asking subjects whether they had been presented in the study phase or not.