Eric Knudsen - Sound Map Vision Guides Development

Sound Map Vision Guides Development

Knudsen's work has shown that vision is the dominant sense in changing the auditory sound map. Binocular displacing prisms were used to shift owls’ visual world, which resulted in a corresponding shift in the sound map. The disparity between the owls’ visual and auditory experience was reconciled by reinterpretation of auditory cues to match visual experience, even though the visual information was incorrect and the auditory was not. Even when other sensory information indicates to the owl that its visual input is misleading, this input exerts an apparently innate dominance over the other senses. In owls raised with displacing prisms, this persistent reliance on inaccurate information is particularly apparent: “Even though interaction with the environment from the beginning of life has proven to owls that their visual perception of stimulus source location is inaccurate, they nevertheless use vision to calibrate sound localization, which in this case leads to a gross error in sound localization”. This dominance does have limitations, however; in 1985, Eric Knudsen and Phyllis Knudsen conducted a study which showed that vision can alter the magnitude but not the sign of an auditory error.

While monaural occlusion and visual displacement both alter the associations between sensory cues and corresponding spatial locations, there are significant differences in the mechanisms at work: “The task under is to use visionto assign abnormal combinations of cue values to appropriate locations in space. In contrast, prisms cause a relatively coherent displacement of visual space while leaving auditory cues essentially unchanged. The task under these conditions is to assign normal ranges and combinations of cue values to abnormal locations in space”.