Emotional content influences eye-movements under natural but not under instructed conditions.

In everyday life, people can freely decide if and where they would like to move their attention and gaze, often influenced by physical and emotional salience of stimuli. However, many laboratory paradigms explicitly instruct participants when and how to move their eyes, leading to unnatural instructed eye-movements. The current preregistered study compared eye-movements to peripherally appearing faces with happy, angry and neutral expressions under natural and instructed conditions. Participants reliably moved their eyes towards peripheral faces, even when they were not instructed to do so; however, eye-movements were significantly slower under natural than under instructed conditions. Competing central stimuli decelerated eye-movements independently of instructions. Unexpectedly, the emotional salience only affected eye-movements under natural conditions, with faster saccades towards emotional than towards neutral faces. No effects of emotional expression occurred when participants were instructed to move their eyes. The study shows that natural eye-movements significantly differ from instructed eye-movements and emotion-driven attention effects are reduced when participants are artificially instructed to move their eyes, suggesting that research should investigate eye-movements under natural conditions.