Ears Wide Shut: A Complete Failure to Recognize Relevant Acoustic Stimuli.

The filtering out of apparently extraneous and redundant stimuli is critical for the effective processing of novel and relevant sensory information. But brain mechanisms that evolved to perform this function are necessarily less than perfect, in some cases failing to filter out irrelevant stimuli and in others filtering out important information. We report here on a stimulus from everyday life-the sound made by an arriving elevator, which contains information indicating the car's direction of movement-that not one of over 1,100 study participants was aware of, despite encountering this information repeatedly throughout their lives. Evidence of implicit knowledge of this information was also absent, suggesting that this valuable information is filtered out at an early stage of sensory processing.