Setting precedent: Initial feature variability affects the subsequent precision of regularly varying sound contexts

Area of Science:

• Cognitive Neuroscience
• Auditory Perception
• Predictive Coding

Background:

• The brain simplifies sensory input through pattern recognition for event prediction.
• Sensory predictions are known to be influenced by initial experiences or first impressions.

Purpose of the Study:

• To investigate how the initial configuration of auditory stimuli affects sensory prediction and prediction error signaling.
• To explore the role of perceived environmental volatility in modulating neural responses.

Main Methods:

• Healthy adults were presented with sequences of three distinct sounds (A, B, C) with varying probabilities within blocks.
• Block types manipulated the commonality of sounds (e.g., A < B = C), and sequence order introduced initial context.
• Auditory evoked responses were measured to common and rare tones, analyzing amplitude differences based on stimulus configuration and order.

Main Results:

• Common tones elicited suppressed neural responses, indicating prediction, while rare tones triggered larger responses (prediction errors).
• Adjacent common tones were perceived as less volatile than spatially separated ones.
• Initial exposure to a more volatile auditory environment led to significantly reduced amplitude of subsequent deviance-related responses.

Conclusions:

• The brain's representation of stimulus configurations is influenced by initial contextual estimates, demonstrating a primacy bias.
• Perceived environmental variance, established early in a sequence, powerfully modulates prediction error signaling.
• This extends the concept of primacy bias to encompass the impact of initial feature variance on sensory processing.