The Role of Emotional Content in the Control of Eye Movements
The anti-saccade paradigm has been a favourite among researchers of attention and the control of eye movements. Most pro/anti-saccade studies have utilized meaningless stimuli, though stimulus meaning is known to have an impact on looking behaviour in free viewing conditions. Here, we explore the role of content in the control of pro/antisaccades by contrasting two alternative views on the impact of emotional stimuli. One view supports an "informativeness" hypothesis, where visual processing is directed towards threatening stimuli, suggesting that RT should be particularly large for negative, high arousal pictures in an antisaccade task. An alternative view emphasizes approach and withdrawal behaviours. Here negative images are thought to encourage avoidance behaviours, causing faster RTs for antisaccades; whereas positive pictures encourage approach behaviours, causing faster RTs for prosaccades. Participants performed an antisaccade task in which they were presented with an image to the left or right visual field and instructed to look at or away from the image. The experimental design included five groups of images, with a factorial combination of valence (positive or negative) and arousal (high or low), and a neutral condition. In Experiments one and two the instruction was given 200 ms before the picture was presented and did not produce any effects of emotional content. Thus, if participants are given advanced notice of the upcoming saccade, the initiation of that saccade is not influenced by the emotional content of the target image. In experiments three and four, the cue was presented 200 ms after the onset of the target image. This change of SOA provided an effect of emotional content was observed in experiments three and four which was illustrated by slowed RTs for both pro- and anti-saccades. However erotic images appeared to slow down latencies across both saccades which were accompanied by high error rates.