Metacognitive awareness in the sound-induced flash illusion

Abstract

Hundreds (if not thousands) of multisensory studies provide evidence that the human brain can integrate temporally and spatially discrepant stimuli from distinct modalities into a singular event. This process of multisensory integration is usually portrayed in the scientific literature as contributing to our integrated, coherent perceptual reality. However, missing from this account is an answer to a simple question: how do confidence judgements compare between multisensory information that is integrated across multiple sources, and multisensory information that comes from a single, congruent source in the environment? In this paper, we use the sound-induced flash illusion to investigate if confidence judgements are similar across multisensory conditions when the numbers of auditory and visual events are the same, and the numbers of auditory and visual events are different. Results showed that congruent audiovisual stimuli produced higher confidence than incongruent audiovisual stimuli, even when the perceptual report was matched across the two conditions. Integrating these behavioural findings with recent neuroimaging and theoretical work, we discuss the role that prefrontal cortex may play in metacognition, multisensory causal inference and sensory source monitoring in general. This article is part of the theme issue 'Decision and control processes in multisensory perception'.

Keywords: metacognition; multisensory integration; sound-induced flash illusion.

Figure 1.

Average behavioural reports across subjects and individual averages in the beep–flash illusion conditions. All error bars represent standard error of the mean. (a) The average number of flashes reported across subjects in each condition. (b) The average confidence in the type 1 judgement about the number of flashes. (c) Average confidence for judgements with the same type 1 Report. The pair of bars in the left part of this panel reflect trials where subjects report perceiving one flash in these two conditions, and the pair in the right of this panel reflect trials where subjects report perceiving two flashes.