Abstract
Background: It is known that: (a) Emotion modulates attentional processing of visual stimuli. For instance, emotional stimuli diminish the attentional blink -the deficit in the processing of the second of 2 temporally proximal non-emotional stimuli (Anderson & Phelps, 2001). (b) Transient (exogenous) covert attention enhances contrast sensitivity and spatial resolution at an attended location, rendering a more discriminable stimulus (Carrasco et al., 2000, 2002). To assess whether emotion interacts with attention in early vision, we investigated whether an emotional cue (fearful face) would enhance contrast sensitivity more than a non-emotional cue (neutral face). Methods: Observers performed a 2AFC contrast threshold orientation discrimination task. Using a peripheral cueing paradigm (e.g., Carrasco et al. 2000, 2002), in each trial observers were briefly presented (75 ms) with either a single peripheral cue adjacent to the target location (eliciting transient covert attention), or an uninformative distributed cue (baseline condition), in which all 4 possible target locations were cued. The cues were Ekman faces of either neutral or fear expression. Following an ISI of 40 ms, observers were presented (40 ms) with 4 iso-eccentric gratings. The target, tilted 4 to the left or right, appeared among vertical distracters. Results & Conclusion: (a) A neutral peripheral cue enhanced contrast sensitivity as compared to a neutral distributed cue; (b) a distributed emotional cue (fearful face) increased contrast sensitivity as compared to a distributed neutral cue; (c) an emotional peripheral cue (fearful face) increased contrast sensitivity beyond the effect of a peripheral neutral cue (neutral face). This is the first behavioral evidence indicating that an emotional cue increases contrast sensitivity, a process that can be carried out in V1. More importantly, we show that emotion interacts with attention at a remarkably early stage of visual processing.
NSF #: BCS-9910734/HCP