A negative compatibility effect in priming of emotional faces

The negative compatibility effect (NCE) is the surprising result that low-visibility prime arrows facilitate responses to opposite-direction target arrows. Here we compare the priming obtained with simple arrows to the priming of emotions when categorizing human faces, which represents a more naturalistic set of stimuli and for which there are no preexisting response biases. When inverted faces with neutral expressions were presented alongside emotional prime and target faces, only strong positive priming occurred. However, when the neutral faces were made to resemble the target faces in geometry (upright orientation), time (flashing briefly), and space (appearing in the same location), positive priming gradually weakened and became negative priming. Implications for theories of the NCE are discussed.