From encoding to recognition: Exploring the shared neural signatures of visual memory

This study investigated the shared neural dynamics underlying encoding and recognition processes across diverse visual object stimulus types in short term experimental familiarization, using EEG-based representational similarity analysis and multivariate cross-classification. Building upon previous research, we extended our exploration to the encoding phase. We show early visual stimulus category effects around 150 ms post-stimulus onset and old/new effects around 400 to 600 ms. Notably, a divergence in neural responses for encoding, old, and new stimuli emerged around 300 ms, with items encountered during the study phase showing the highest differentiation from old items during the test phase. Cross-category classification demonstrated discernible memory-related effects as early as 150 ms. Anterior regions of interest, particularly in the right hemisphere, did not exhibit differentiation between experimental phases or between study and new items, hinting at similar processing for items first encountered, irrespective of experiment phase. While short-term experimental familiarity did not consistently adhere to the old >new pattern observed in long-term personal familiarity, statistically significant effects are observed specifically for experimentally familiarized faces, suggesting a potential unique phenomenon specific to facial stimuli. Further investigation is warranted to elucidate underlying mechanisms and determine the extent of face-specific effects. Lastly, our findings underscore the utility of multivariate cross-classification and cross-dataset classification as promising tools for probing abstraction and shared neural signatures of cognitive processing.