Knowledge of Collision Modulates Defensive Multisensory Responses to Looming Insects in Arachnophobes

We investigated the role of contextual knowledge in defensive responses to visual stimuli (spiders and butterflies) looming toward the hand. Human participants responded to tactile stimuli delivered to the same hand at 6 possible locations during an insect's approach. Tactile reaction times were faster when looming stimuli were closer to the hand, especially for spiders, and faster when insects loomed on a collision path than on a near-miss path. This latter finding suggests that human reactions to looming stimuli are not merely automatic reflexes but that contextual knowledge about the trajectory of looming objects is included in predicting their impact. Public Significance StatementWe present evidence for the idea that the defensive system that protects us from harmful collisions with looming agents or objects uses knowledge about the trajectories of objects to modulate its response.