Spatial response-code association for loudness but not brightness

TL;DR

This study found that loudness, but not brightness, is linked to spatial response codes, affecting how people judge sound intensity.

Contribution

The study provides new evidence that spatial response codes influence loudness perception but not brightness perception.

Findings

Loudness discrimination is affected by spatial response codes in terms of both response time and accuracy.

Brightness discrimination did not show significant spatial response code effects.

Cross-modal correlations between auditory and visual intensity discrimination were inconclusive.

Abstract

Cognitive associations between stimulus intensity and spatial response codes are thought to influence perceptual discrimination. We examined lateral response-set effects on auditory and visual intensity discrimination in a preregistered study with a large sample (N = 98). Participants responded to loud and bright stimuli using a button located to the left or right of the button used for soft and dim stimuli. In the auditory task, stimulus-response (SR)-mapping affected task-averaged error rates (ERs) but not task-averaged response times (RTs). However, loudness predicted response-side differences in both latency (
RTLeft−RTRight
) and accuracy (
ERLeft−ERRight
). By comparison, all tests of brightness discrimination supported the null or were inconclusive. Assessments of cross-modality correlations in SR-mapping effects were also inconclusive. These results replicate prior findings of lateral SR-mapping effects in auditory intensity discrimination and clarify inconsistencies in the visual domain. The lack of SR-mapping effects in brightness discrimination, along with inconclusive cross-modal correlations, challenges the notion of a common spatial processing mechanism for auditory and visual intensity comparison. If such a mechanism exists, its effects on visual judgments appear too subtle to be detected even in a large sample.

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