Orienting to threat: faster localization of fearful facial expressions and body postures revealed by saccadic eye movements

Abstract

Most studies investigating speeded orientation towards threat have used manual responses. By measuring orienting behaviour using eye movements a more direct and ecologically valid measure of attention can be made. Here, we used a forced-choice saccadic and manual localization task to investigate the speed of discrimination for fearful and neutral body and face images. Fearful/neutral body or face pairs were bilaterally presented for either 20 or 500 ms. Results showed faster saccadic orienting to fearful body and face emotions compared with neutral only at the shortest presentation time (20 ms). For manual responses, faster discrimination of fearful bodies and faces was observed only at the longest duration (500 ms). More errors were made when localizing neutral targets, suggesting that fearful bodies and faces may have captured attention automatically. Results were not attributable to low-level image properties as no threat bias, in terms of reaction time or accuracy, was observed for inverted presentation. Taken together, the results suggest faster localization of threat conveyed both by the face and the body within the oculomotor system. In addition, enhanced detection of fearful body postures suggests that we can readily recognize threat-related information conveyed by body postures in the absence of any face cues.

Figure 1

Schematic representation of presentation sequence. After a 1000 ms fixation episode, a time gap (blank screen) for 200 ms preceded the simultaneous presentation of two stimuli (one fearful and one neutral) in the left and right visual fields for 20 or 500 ms. This was followed by the appearance of two fixation points for 1000 ms.

Figure 2

Mean accuracy levels (percentage of correct responses) in the saccadic ((a) 20 ms and (b) 500 ms) and manual ((c) 20 ms and (d) 500 ms) modes (grey bars, fear target; white bars, neutral target). Error bars represent standard errors of the mean (s.e.m.).

Figure 3

Mean saccadic ((a) 20 ms and (b) 500 ms) and manual ((c) 20 ms and (d) 500 ms) reaction times (grey bars, fear target; white bars, neutral target). Error bars represent s.e.m.