| Title | Researchers Find a Neural 'Auto-Correct' Feature We Use to Process Ambiguous Sounds | |
| Date | Saturday August 25 2018, @09:09AM | |
| Author | chromas | |
| Topic | ||
| from the Worms,-Roxanne!-Worms! dept. | ||
Submitted via IRC for SoyCow4408
Our brains have an "auto-correct" feature that we deploy when re-interpreting ambiguous sounds, a team of scientists has discovered. Its findings, which appear in the Journal of Neuroscience, point to new ways we use information and context to aid in speech comprehension.
"What a person thinks they hear does not always match the actual signals that reach the ear," explains Laura Gwilliams, a doctoral candidate in NYU's Department of Psychology, a researcher at the Neuroscience of Language Lab at NYU Abu Dhabi, and the paper's lead author. "This is because, our results suggest, the brain re-evaluates the interpretation of a speech sound at the moment that each subsequent speech sound is heard in order to update interpretations as necessary.
It's well known that the perception of a speech sound is determined by its surrounding context -- in the form of words, sentences, and other speech sounds. In many instances, this contextual information is heard later than the initial sensory input.
This plays out in every-day life -- when we talk, the actual speech we produce is often ambiguous. For example, when a friend says she has a "dent" in her car, you may hear "tent." Although this kind of ambiguity happens regularly, we, as listeners, are hardly aware of it.
"This is because the brain automatically resolves the ambiguity for us -- it picks an interpretation and that's what we perceive to hear," explains Gwilliams. "The way the brain does this is by using the surrounding context to narrow down the possibilities of what the speaker may mean."
In the Journal of Neuroscience study, the researchers sought to understand how the brain uses this subsequent information to modify our perception of what we initially heard.
To do this, they conducted a series of experiments in which the subjects listened to isolated syllables and similarly sounding words (e.g., barricade, parakeet). In order to gauge the subjects' brain activity, the scientists deployed magnetoencephalography (MEG), a technique that maps neural movement by recording magnetic fields generated by the electrical currents produced by our brain.
Their results yielded three primary findings:
- The brain's primary auditory cortex is sensitive to how ambiguous a speech sound is at just 50 milliseconds after the sound's onset.
- The brain "re-plays" previous speech sounds while interpreting subsequent ones, suggesting re-evaluation as the rest of the word unfolds
- The brain makes commitments to its "best guess" of how to interpret the signal after about half a second.
Source: https://www.sciencedaily.com/releases/2018/08/180822082637.htm
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