Stable individual characteristics in the perception of multiple embedded patterns in multistable auditory stimuli

Tamás M Bõhm,Robert Mill,Zsuzsanna Kocsis,Orsolya Szalárdy,István Winkler,Alexandra Bendixen,Susan Denham

doi:10.3389/fnins.2014.00025

Abstract

The ability of the auditory system to parse complex scenes into component objects in order to extract information from the environment is very robust, yet the processing principles underlying this ability are still not well understood. This study was designed to investigate the proposal that the auditory system constructs multiple interpretations of the acoustic scene in parallel, based on the finding that when listening to a long repetitive sequence listeners report switching between different perceptual organizations. Using the “ABA-” auditory streaming paradigm we trained listeners until they could reliably recognize all possible embedded patterns of length four which could in principle be extracted from the sequence, and in a series of test sessions investigated their spontaneous reports of those patterns. With the training allowing them to identify and mark a wider variety of possible patterns, participants spontaneously reported many more patterns than the ones traditionally assumed (Integrated vs. Segregated). Despite receiving consistent training and despite the apparent randomness of perceptual switching, we found individual switching patterns were idiosyncratic; i.e., the perceptual switching patterns of each participant were more similar to their own switching patterns in different sessions than to those of other participants. These individual differences were found to be preserved even between test sessions held a year after the initial experiment. Our results support the idea that the auditory system attempts to extract an exhaustive set of embedded patterns which can be used to generate expectations of future events and which by competing for dominance give rise to (changing) perceptual awareness, with the characteristics of pattern discovery and perceptual competition having a strong idiosyncratic component. Perceptual multistability thus provides a means for characterizing both general mechanisms and individual differences in human perception.

Highlights

Most sound sources of interest in the world around us emit sequences of sound events, e.g., the notes in a birdsong or the words spoken in conversation
The problem of grouping, both the simultaneously present components that belong to the same sound event, and the sequential associations between events emitted by the same source, is known as auditory scene analysis (Bregman, 1990)
This demonstrates that individual participant behavior tends to be idiosyncratic; i.e., the switching behavior of an individual is more similar to their own behavior in a different test session than it is to the perceptual switching behavior of other participants (Wilcoxon rank sum test: participant 1 p = 0.0002, participants 2–6 p < 0.0001)

Summary

Introduction

Most sound sources of interest in the world around us emit sequences of sound events, e.g., the notes in a birdsong or the words spoken in conversation. The problem of grouping, both the simultaneously present components that belong to the same sound event, and the sequential associations between events emitted by the same source, is known as auditory scene analysis (Bregman, 1990). Understanding this seemingly effortless process of perceptual organization is an essential step toward explaining what determines our conscious perceptions of the world. Equal loudness curves of normal listeners (e.g., see Moore, 2003), suggest that the B tones would be perceptually louder than the A tones, and more salient In this experiment we decided to test whether switching the frequencies of the A and B tones would result in a greater tendency for listeners to report the A- than the B--pattern. Experiment 1 vs. sessions from the same participant in Experiment 2 (blue dots; median—blue diamonds, line), differences between the transition matrices of each participant and those of all other participants in Experiment 1 (red dots; median—red diamonds, line), and differences between the transition matrices of each participant from Experiment 1 and those of all other participants in Experiment 2 (magenta dots; median—magenta diamonds, line)

Objectives

Methods

Results

Discussion

Conclusion