Faces are more attractive than motion: evidence from two simultaneous oddball paradigms.

OBJECTIVE

The P300 event-related potential reflects high-level cognitive processing; it is also sensitive to attentional modulation, impeding its use in malingering detection. Can this be overcome by particularly salient stimuli, e.g., motion or faces?

METHODS

In 11 subjects, we ran two concurrent, uncorrelated oddball sequences ("main sequence" and "distractor sequence"). We modulated the subjects' attention via three types of tasks: (1) count main oddballs, (2) passive viewing, and (3) count distractor oddballs. For the main sequence, the frequent stimulus was homogeneously gray, and oddballs were (a) stationary gratings, (b) moving gratings, or (c) faces. For the distractor sequence, the frequent stimulus was a black fixation target, with a white fixation target as oddball.

RESULTS

P300 amplitudes were larger for faces than for stationary and moving gratings. Median P300 amplitudes were largest when attending; the P300 was substantially reduced in the "passive" condition (down to 30% for gratings and down to 80% for faces) and somewhat more for the "distraction" condition (down to 40% for gratings and down to 55% for faces). With distraction, significant P300s occurred in 9 of 11 subjects for faces, only in 5 or 4 with stationary or moving gratings, respectively.

CONCLUSIONS

Face-evoked P300s were more resistant to distraction than those to stationary or moving gratings. This provides support for the socio-cognitive role of faces being associated with privileged processing mechanisms. Attentional modulation of P300 depends on stimulus category. Face stimuli may help to objectively access higher level processing while minimizing willful influences.