Threatening pictures induce shortened time-to-contact estimates.

The ability to estimate the time remaining until collision occurs with an approaching object (time-to-collision, TTC) is crucial for any mobile animal. In the present study, we report three experiments examining whether higher level cognitive factors, represented by affective value of approaching objects, could affect judgments of TTC. A theory of TTC estimates based purely on the optical variable tau does not predict an influence of the affective value of an approaching object. In Experiments 1 and 2, we compared TTC estimates of threatening and neutral pictures that approached our participants on a screen and disappeared from view before a collision would have occurred. Images were taken from the International Affective Picture System. Threatening pictures-in particular, the picture of a frontal attack-were judged to collide earlier than neutral pictures. In Experiment 3, the approaching stimuli were faces with different emotional expressions. TTC tended to be underestimated for angry faces. We discuss these results, considering the roles of affective and cognitive mechanisms modulating TTC estimation and general time perception.