Researchers Note Tradeoffs In Auditory Perception

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Main Category: Ear, Nose and Throat
Also Included In: Biology / Biochemistry
Article Date: 19 May 2008 - 17:00 PDT

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New research published in the open-access journal PLoS Biology finds error in an often-made assumption in the field of sensory neuroscience. Merav Ahissar (Hebrew University, Jerusalem, Israel) and colleagues were studying a key issue regarding the determination of the greatest amount of task-relevant information that is encoded in our brain. The researchers showed that contrary to common belief, all of the information is in fact not available for making perceptual decisions.

Perception is the process of becoming aware and understanding sensory information (what we see, hear, taste, etc.) While studying hearing, Ahissar and colleagues demonstrated that when speech is covered up by noise, the perception processes of discriminating and understanding the speech only draw information that is represented at higher cortical areas rather than from the entire brain. This means that if a listener is determining whether a speaker said "day" or "night," for example, the listener is likely to be able to tell the difference. If, however, a listener must choose between words like "day" and "bay," a finer discrimination skill is required. Only under certain conditions can the information pertaining to the fine spectral and temporal details be used for successful discrimination. One condition, often used in psychoacoustic experiments, is systematic repetition of the word. A second condition is when a listener decides to focus solely on word identification, removing the need for comprehension. The authors note that these conditions are "non-ecological" and not feasible in most situations.

The researchers write, "Taken together, the auditory system seems to favor ecologically more likely conditions and yet retains flexibility for the less likely ones. Discriminations that are prevalent in natural situations are fast and still use all low-level information, whereas discriminations that are less likely to occur are either fast or use all low-level information. The results presented here, however, show that the auditory system cannot achieve both."

"Similar defaults and tradeoffs characterize the relations between processing hierarchies and perception at the various sensory modalities," they conclude.

Low-level information and high-level perception: The case of speech in noise
Nahum M, Nelken I, Ahissar M
PLoS Biology (2008). 6(5):e126.
doi:10.1371/journal.pbio.0060126
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About PLoS Biology

PLoS Biology is an open-access, peer-reviewed general biology journal published by the Public Library of Science (PLoS), a nonprofit organization of scientists and physicians committed to making the world's scientific and medical literature a public resource. New articles are published online weekly; issues are published monthly. For more information, visit http://www.plosbiology.org

About the Public Library of Science

The Public Library of Science (PLoS) is a non-profit organization of scientists and physicians committed to making the world's scientific and medical literature a freely available public resource. For more information, visit http://www.plos.org

Written by: Peter M Crosta
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