COMPARING REACTION TIMES AND ACCURACY RATES IN A SAME / DIFFERENT TASK WITH FACIAL EXPRESSIONS
AbstractThe relationship was examined between two performance measures of a same / different task:different reaction times (RTs) and percentage of different judgements. A set of facialexpressions (FEs) of emotion (N=15) included seven emotion prototypes and eightintermediate morphs. The FEs were presented pairwise for 500 ms, 100 times each pair. Thepercentage of different judgements behaved as an index of perceptual dissimilarity. Contraryto expectation, the relationship between the two measures was non-monotonic: As a FE pairbecame more similar, different RTs increased but only to a maximum at an intermediate levelof similarity where different and same responses were equally likely. Below that level, foreven more similar FE pairs, different RTs became progressively shorter. We explain thephenomenon by a dual-process model: incompletely developed FE percept implies a decisionbased predominantly on global (shared) features and, thus, feeds in a fast same-processfollowed by premature responses.