Some humans are able to wiggle their ears, suggesting that some of the brain circuits and muscles that allow automatic ear movements towards sounds are still present.

Humans and their closest ape relatives, however, appear to have lost this ability. eLife digestĭogs, cats, monkeys and other animals perk their ears in the direction of sounds they are interested in. The existence of a pinna-orienting system in humans, one that is experimentally accessible, offers opportunities for basic as well as applied science. Upward movement (perking) differed according to the lateral focus of attention only during voluntary orienting rearward folding of the pinna’s upper-lateral edge exhibited such differences only during reflexive orienting. In both experiments, EMG recordings showed larger activity at the ear on the side of the attended stimulus, but with slightly different patterns. To test voluntary, goal-directed attention we instructed participants to listen to a short story coming from one of these speakers, while ignoring a competing story from the corresponding speaker on the opposite side. To assess reflexive, stimulus-driven attention we presented novel sounds from speakers at four different lateral locations while the participants silently read a boring text in front of them. Surface electromyograms (EMGs) were taken from muscles that either move the pinna or alter its shape. Consistent with this hypothesis, we demonstrate that the direction of auditory attention is reflected in sustained electrical activity of muscles within the vestigial auriculomotor system. Our species may nevertheless have retained a vestigial pinna-orienting system that has persisted as a 'neural fossil’ within in the brain for about 25 million years. Unlike dogs and cats, people do not point their ears as they focus attention on novel, salient, or task-relevant stimuli.

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