Slips of the ear: When knowledge deceives perception

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Credit: Blank et al., JNeurosci (2018)

Misperception of speech results from a weak representation of the difference between what we expect to hear and what is actually said, according to a human neuroimaging study published in JNeurosci. The research provides new evidence for how the brain creates perceptual illusions when speech is degraded at cocktail parties, in song lyrics or for older listeners.

The ability to draw on past experience is important to keep up with a conversation, especially in noisy environments where speech sounds are hard to hear. However, these prior expectations can sometimes mislead listeners; convincing them that they heard something that a speaker did not actually say.

To investigate the neural underpinnings of speech misperception, Helen Blank, Matt Davis, and colleagues presented participants with pairs of written and degraded spoken words that were either identical, clearly different or similar-sounding. Reading and hearing similar sounding words (like kick followed by pick), led to frequent misperception.

Using functional magnetic resonance imaging the researchers found that misperception was associated with reduced activity in the left superior temporal sulcus, a brain region critical for processing speech sounds. Furthermore, when perception of speech was more successful, this brain region represented the difference between prior expectations and heard speech (like the initial k/p in kick-pick).

These results provide new evidence that speech perception involves comparing what we hear with what we expect. This mechanism — predictive coding — has implications for treating age-related hearing loss or understanding auditory hallucinations in disorders such as schizophrenia.

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Article: Neural Prediction Errors Distinguish Perception and Misperception of Speech
DOI: https://doi.org/10.1523/JNEUROSCI.3258-17.2018
Corresponding author: Helen Blank (University Medical Center Hamburg-Eppendorf, Germany)

Media contacts: Matt Davis (MRC Cognition and Brain Sciences Unit, University of Cambridge, UK), [email protected] and Vicky Collins, [email protected]

About JNeurosci

JNeurosci, the Society for Neuroscience's first journal, was launched in 1981 as a means to communicate the findings of the highest quality neuroscience research to the growing field. Today, the journal remains committed to publishing cutting-edge neuroscience that will have an immediate and lasting scientific impact, while responding to authors' changing publishing needs, representing breadth of the field and diversity in authorship.

About The Society for Neuroscience

The Society for Neuroscience is the world's largest organization of scientists and physicians devoted to understanding the brain and nervous system. The nonprofit organization, founded in 1969, now has nearly 37,000 members in more than 90 countries and over 130 chapters worldwide.

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       <h4>Related Journal Article</h4>http://dx.doi.org/10.1523/JNEUROSCI.3258-17.2018 
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