SoylentNews

taylorvich [soylentnews.org] writes:

https://medicalxpress.com/news/2025-03-perceptions-songbird-parallels-human-speech.html [medicalxpress.com]

Expectations can influence perception in seemingly contradictory ways, either by directing attention to expected stimuli and enhancing perceptual acuity or by stabilizing perception and diminishing acuity within expected stimulus categories. The neural mechanisms supporting these dual roles of expectation are not well understood. Here, we trained European starlings to classify ambiguous song syllables in both expected and unexpected acoustic contexts. We show that birds employ probabilistic, Bayesian integration to classify syllables, leveraging their expectations to stabilize their perceptual behavior. However, auditory sensory neural populations do not reflect this integration. Instead, expectation enhances the acuity of auditory sensory neurons in high-probability regions of the stimulus space. This modulation diverges from patterns typically observed in motor areas, where Bayesian integration of sensory inputs and expectations predominates. Our results suggest that peripheral sensory systems use expectation to improve sensory representations and maintain high-fidelity representations of the world, allowing downstream circuits to flexibly integrate this information with expectations to drive behavior.

Past neuroscience and psychology studies have shown that people's expectations of the world can influence their perceptions, either by directing their attention to expected stimuli or by reducing their sensitivity (i.e., perceptual acuity) to variations within the categories of stimuli we expect to be exposed to.

While the effects of expectations on perceptions are now well-documented, their neural underpinnings remain poorly understood.

Researchers at University of California San Diego (UC San Diego) carried out a study involving songbirds aimed at better understanding how expectation-fueled biases in perception shape brain activity and behavior.

Their findings, published in Nature Neuroscience, suggest that the perceptions of songbirds, like those of humans, are influenced by expectations, with peripheral sensory systems utilizing expectations to enhance sensory perception and retain high-fidelity representations of the world.

"This work was inspired by an observation about human speech, namely that listeners are able to comprehend speech even though there is a great degree of variability in the sound entering their ears," Tim Sainburg, first author of the paper, told Medical Xpress.

"Not only are we tasked with understanding speech in noisy environments, but we also have to deal with variability in the actual speech signal."

Human speakers are known to have different voices, while also pronouncing many words differently. Past studies suggest that the human brain possesses robust underlying mechanisms designed to address these differences, by grouping speech sounds into stable perceptual categories, a process referred to as "categorical perception."

"One of these mechanisms is that we use context to cue and bias our perception," said Sainburg. "The goal of our study was to understand how that bias works in behavior and in the brain."

Timothy Q. Gentner's lab at UC San Diego, which Sainburg is a part of, often examines the vocal behavior and perceptions of songbirds. This is because songbirds are known to share many similarities with humans in terms of their vocal behavior, thus studying them can help to better understand human speech and speech-related perceptions.

"Behaviorally, we were interested in how expectation biases perception in songbirds," explained Sainburg.

Original Submission