Neural Prediction Errors Distinguish Perception and Misperception of Speech.

Area of Science:

• Neuroscience
• Cognitive Science
• Psychology

Background:

• Prior expectations enhance perception of degraded or ambiguous sensory signals.
• Misperception of speech, or
• slips of the ear
• can occur when expectations lead to incorrect auditory processing.

Purpose of the Study:

• To investigate two mechanisms by which prior expectations can lead to misperception of degraded speech.
• To compare neural responses associated with accepting prior expectations versus correctly rejecting them when auditory input deviates.

Main Methods:

• Used crossmodal predictions from written words to prime degraded speech perception.
• Employed functional magnetic resonance imaging (fMRI) and multivariate representational similarity analysis.
• Combined behavioral data with neural activity from male and female listeners.

Main Results:

• Veridical perception of degraded speech is associated with neural representations of prediction error in the left superior temporal sulcus.
• The strength of neural prediction error representations, rather than confirmation of expected input, differentiates correct perception from misperception.
• Findings suggest insufficient representation of deviations between expectations and sensory signals underlies misperception.

Conclusions:

• Prior expectations can lead to illusory perception when sensory input mismatches expectations.
• Neural mechanisms distinguishing correct perception from misperception involve the processing of prediction errors.
• This research reframes understanding of illusory perception, emphasizing the role of representing deviations.