Emotional effects on time-to-contact judgments: arousal, threat, and fear of spiders modulate the effect of pictorial content.

Recently, responses to looming visual stimuli have been shown to depend on the emotional content of the stimulus. A threatening stimulus is judged to arrive sooner compared to a neutral stimulus, possibly buying the organism time to prepare defensive actions. Here, we explored the underlying mechanism. We found that time-to-contact judgments of threatening pictures did not differ from those of highly arousing pleasant pictures (Experiment 1), suggesting that arousal, not fear, modulates the perception of looming. Specific fear modulated the effects of arousal (Experiment 2): Spider-fearful participants' judgments showed a threat advantage effect, while non-fearful participants' judgments were less affected by emotional content. In Experiment 3, arrival times were less overestimated when pictures induced arousal. However, this effect interacted with the valence of the stimulus: For unpleasant stimuli, arousal induced shorter time-to-contact judgments, whereas for pleasant stimuli, an inverted U-shaped relation was found. We propose a general content effect to explain the overestimation with neutral pictures: Pictorial content may draw visual attention to inner contours instead of to the outer edges of the picture. This could delay time-to-contact judgments according to the known size-arrival effect. Our results add to the growing literature examining affective influences on visual perception.