Fast saccades toward faces: face detection in just 100 ms.

Previous work has demonstrated that the human visual system can detect animals in complex natural scenes very efficiently and rapidly. In particular, using a saccadic choice task, H. Kirchner and S. J. Thorpe (2006) found that when two images are simultaneously flashed in the left and right visual fields, saccades toward the side with an animal can be initiated in as little as 120-130 ms. Here we show that saccades toward human faces are even faster, with the earliest reliable saccades occurring in just 100-110 ms, and mean reaction times of roughly 140 ms. Intriguingly, it appears that these very fast saccades are not completely under instructional control, because when faces were paired with photographs of vehicles, fast saccades were still biased toward faces even when the subject was targeting vehicles. Finally, we tested whether these very fast saccades might only occur in the simple case where the images are presented left and right of fixation by showing they also occur when the images are presented above and below fixation. Such results impose very serious constraints on the sorts of processing model that can be invoked and demonstrate that face-selective behavioral responses can be generated extremely rapidly.