Disambiguation of two-tone images aligns object representations in the EEG

Abstract

Electrophysiological responses to visual objects carry information about stimulus identity and semantic category, but it remains difficult to know whether such information represents conceptual knowledge or merely regularities in physical image features. Here, we presented two-tone images before and after disambiguation via corresponding photographs to seventeen healthy participants while recording EEG to dissociate the learned image concept from its physical properties. After disambiguation, EEG responses to learned two-tone images became more similar to the responses of their photo counterparts. This effect emerged approximately 100 ms after stimulus onset and peaked at 350 ms. However, we found no evidence for a generalization of the response pattern to the stimulus semantic category. Furthermore, alignment to the photo counterparts was only detectable after explicit visual disambiguation rather than spontaneous recognition. Together, these findings indicate that EEG can capture specific learned conceptual modulations of responses to visually degraded stimuli, while also showing that low-level visual properties dominate the representational structure.