The neural dynamics underlying prioritisation of task-relevant information

TL;DR

This study investigates how the human brain prioritizes relevant visual information in complex, overlapping stimuli using EEG and decoding techniques, revealing early neural responses are rich in information and modulated by attention based on perceptual features.

Contribution

It demonstrates that early neural responses contain detailed information about multiple stimuli and that attention enhances this information depending on stimulus size and perceptual features.

Findings

Neural responses encode information about both attended and unattended stimuli.

Attention increases stimulus decodability in neural responses.

Smaller stimuli show earlier attentional modulation effects.

Abstract

The human brain prioritises relevant sensory information to perform different tasks. Enhancement of task-relevant information requires flexible allocation of attentional resources, but it is still a mystery how this is operationalised in the brain. We investigated how attentional mechanisms operate in situations where multiple stimuli are presented in the same location and at the same time. In two experiments, participants performed a challenging two-back task on different types of visual stimuli that were presented simultaneously and superimposed over each other. Using electroencephalography and multivariate decoding, we analysed the effect of attention on the neural responses to each individual stimulus. Whole brain neural responses contained considerable information about both the attended and unattended stimuli, even though they were presented simultaneously and represented in overlapping receptive fields. As expected, attention increased the decodability of stimulus-related information contained in the neural responses, but this effect was evident earlier for stimuli that were presented at smaller sizes. Our results show that early neural responses to stimuli in fast-changing displays contain remarkable information about the sensory environment but are also modulated by attention in a manner dependent on perceptual characteristics of the relevant stimuli. Stimuli, code, and data for this study can be found at https://osf.io/7zhwp/.