Memory across a short-delay: Systematic biases in memory for faces

From geometric figures to human faces, many visual stimuli vary along a continuum in featural space, anchored at one end by a highly distinctive constellation of features, at the other by a neutral set. Here we used a continuum of morphed faces to test whether errors in visual short-term memory are symmetric in feature space around the target or systematically biased toward one or the other end of the continuum. Participants were shown a face for 1 s. After a brief delay, participants were asked to choose the face they had been shown among three face options, which consisted of the target face, one face that was slightly more distinctive, and one face that was slightly more neutral. Continuums of morphed faces ranged from an average, neutral face to different distinctive celebrity faces two experiments, or from neutral facial expressions to highly emotional expressions a third experiment. Results showed that when participants made an incorrect response, they were more likely to incorrectly identify the more distinctive face than the more neutral or average face as the target face. This bias toward more extreme faces, however, was not observed for unfamiliar (non-celebrity) faces that were emotionally neutral. These findings suggest that visual memory encodes distinctive features of stimuli that lead to biases in later recognition.