Buildup and bistability in auditory streaming as an evidence accumulation process with saturation

Abstract

A repeating triplet-sequence ABA − of non-overlapping brief tones, A and B, is a valued paradigm for studying auditory stream formation and the cocktail party problem. The stimulus is "heard" either as a galloping pattern (integration) or as two interleaved streams (segregation); the initial percept is typically integration then followed by spontaneous alternations between segregation and integration, each being dominant for a few seconds. The probability of segregation grows over seconds, from near-zero to a steady value, defining the buildup function, BUF. Its stationary level increases with the difference in tone frequencies, DF, and the BUF rises faster. Percept durations have DF-dependent means and are gamma-like distributed. Behavioral and computational studies usually characterize triplet streaming either during alternations or during buildup. Here, our experimental design and modeling encompass both. We propose a pseudo-neuromechanistic model that incorporates spiking activity in primary auditory cortex, A1, as input and resolves perception along two network-layers downstream of A1. Our model is straightforward and intuitive. It describes the noisy accumulation of evidence against the current percept which generates switches when reaching a threshold. Accumulation can saturate either above or below threshold; if below, the switching dynamics resemble noise-induced transitions from an attractor state. Our model accounts quantitatively for three key features of data: the BUFs, mean durations, and normalized dominance duration distributions, at various DF values. It describes perceptual alternations without competition per se, and underscores that treating triplets in the sequence independently and averaging across trials, as implemented in earlier widely cited studies, is inadequate.

Binocular rivalry reveals an out-of-equilibrium neural dynamics suited for decision-making

“…Many aspects of this rich phenomenology are reproduced by computational models driven by some kind of ‘prediction error’ ( Mill et al, 2013 ). The dynamics of two recent auditory models ( Barniv and Nelken, 2015 ; Nguyen et al, 2020 ) are rather similar to the model presented here: while one sound pattern dominates awareness, evidence against this pattern is accumulated at a subliminal level.…”

“…Our results are consistent with a few tens of bistable variables in each pool. In the proposed mechanism, differential activity of two pools accumulates evidence against the dominant appearance until a threshold is reached and a reversal ensues (see also Barniv and Nelken, 2015 ; Nguyen et al, 2020 ). Conceivably, this discrete non-equilibrium dynamics might instantiate a variational principle of inference such as ‘maximum caliber’ ( Pressé et al, 2013 ; Dixit et al, 2018 ).…”

The Role of Temporal Coherence and Temporal Predictability in the Build-Up of Auditory Grouping

“…a frequency, level or spatial deviation in one of the objects 23,25−28 . Overall, the existing literature suggests that build-up is a high-level evidence accumulation process 21 that in uences auditory processing. It can do this by either adapting to or enhancing the important features within an object and operates on a range of grouping cues.…”

The role of temporal coherence and temporal predictability in the build-up of auditory grouping

“…a frequency, level or spatial deviation in one of the objects 21,[23][24][25][26] . Overall, the existing literature suggests that build-up is a highlevel evidence accumulation process 19 that influences subsequent perception. It can do this by either biasing perception towards, and/or enhancing perception of, the important features within an object, and operates on a range of grouping cues.…”

“…Build-up has been observed in a range of seemingly disparate auditory behaviours, such as listening to speech-in-noise 15 , speech in speech 11 , auditory stream formation 16 , the discrimination of sound textures 10 , comodulation masking release 17 , the precedence effect 12 and transitions to new spectrotemporal sound statistics 18 . Generally speaking, the longer the build-up period, the greater the behavioural benefit 10,12,[19][20][21] , although, this benefit will asymptote and can subsequently decline due to inattention 22 . The optimal build-up period can be thought of as the shortest duration of time over which performance begins to asymptote, i.e.…”