The time course of visuo-semantic representations in the human brain is captured by combining vision and language models

Abstract: The human visual system provides us with a rich and meaningful percept of the world, transforming retinal signals into visuo-semantic representations. For a model of these representations, here we leveraged a combination of two currently dominating approaches: vision deep neural networks (DNNs) and LLMs. Using large-scale human electroencephalography (EEG) data recorded during object image viewing, we built encoding models to predict EEG responses using representations from a vision DNN, an LLM, and their fusion. We show that the fusion encoding model outperforms encoding models based on either the vision DNN or the LLM alone, as well as previous modelling approaches, in predicting neural responses to visual stimulation. The vision DNN and the LLM complemented each other in explaining stimulus-related signal in the EEG responses. The vision DNN uniquely captured earlier and broadband EEG signals, whereas the LLM uniquely captured later and low frequency signals, as well as detailed visuo-semantic stimulus information. Together, this provides a more accurate model of the time course of visuo-semantic processing in the human brain.