Invisible expressions evoke core impressions.

Participants viewed "hybrid" faces that showed a facial expression (anger, fear, happiness, or sadness) only in the lowest spatial frequency (1-6 cycles/image), which was blended with the same face's neutral expression in the rest of the bandwidth (7-128 cycles/image). Participants rated the portrayed persons (compared to neutral images) as "friendly" when the lowest spatial frequencies showed a positive expression and "unfriendly" when the lowest spatial frequencies showed negative expressions. In contrast, the same hybrid images were explicitly judged as neutral and their "hidden" emotional expressions could not be explicitly recognized, as also confirmed by d' sensitivity measures. Finally, one patient (SS) who had the left anterior temporal lobe surgically resected (including the amygdala), failed to show the above described unconscious effects on friendliness judgments when viewing "afraid" and "sad" hybrid faces. We conclude that the lowest spatial frequencies of facial expressions can evoke "core" emotions without knowledge or awareness of a specific emotion but these core emotions can convey a clear "impression" of a person's character. Copyright 2010 APA