Identity processing in multiple-face tracking.

Research has shown that observers in a multiple-object tracking task are poor at recognizing the identity of successfully tracked objects (Z. W. Pylyshyn, 2004). Employing the same paradigm, we examined identity processing and its relationship with tracking performance for human faces. Experiment 1 showed that although identity recognition was poorer after the target faces were learned in a dynamic display, identification performance was still much higher than the chance level. The experiment also found that on average about two face identities can be correctly traced to their locations. Experiment 2 showed that tracking performance decreased significantly for unique upright faces relative to the unique inverted or identical upright faces, suggesting that upright faces activate some level of mandatory identity processing that interferes and competes with visual tracking for attentional resources. Experiment 3 found that only target faces receive identity processing in the tracking task. Experiment 4 showed that switching face identities during tracking impaired tracking performance. This may indicate that identity encoding is to some extent obligatory during multiple-face tracking. Furthermore, Experiment 5 suggested that attentional resources can be consciously allocated either to maximize identity encoding or tracking, resulting in a tradeoff between the two. The results reveal a bias for face identity processing, which may differ significantly from multiple-object tracking.