Conference on Cognitive Computational Neuroscience

Relating behavioural and brain data is essential for understanding how the brain identifies and distinguishes individual objects. Prior work has shown that human brain activity associated with perceived similarity is well explained by explicit behavioural similarity judgements. However the nature of such judgements cannot fully explain representational geometries observed in the visual cortex. Here, we use a combination of behavioural tasks in an attempt to identify behaviourally-relevant brain representations across the visual ventral stream. We derived behavioural representations from three tasks: an explicit multi-arrangements task, a high-level semantic labelling task, and an implicit same-different task. We investigate the spatiotemporal neural profiles of these behavioural representations by comparing behavioural representations with fMRI and EEG recordings using representational similarity analysis (RSA). All three task representations correlated highly with neural activity in anterior regions of the ventral stream at time points associated with late stage visual processing. Additionally, the same-different task exhibited high correlations propagating throughout the ventral stream in more posterior regions, as well as at earlier time points. These results highlight the importance of using implicit similarity judgements to complement the neural information explained by higher-level, conscious similarity judgements.