Selective Attention Dynamically Modulates the Hierarchical Order of Perceptual and Conceptual Representations.

Mounting evidence suggests that information processing in the visual hierarchy involves a progression from low-level perceptual to high-level conceptual features during visual perception, and a reverse traversal during memory retrieval. However, the nature of this processing hierarchy and its modulation by selective attention remain unclear. By using the drift-diffusion model, we found that slower reaction times for conceptual versus perceptual tasks were primarily due to differences in decision boundaries and nondecision times, which were not compensated by faster evidence accumulation for conceptual features. Using single-trial multivariate decoding of magnetoencephalography (MEG) data, we tracked the temporal dynamics of feature representation during visual perceptual and mnemonic tasks. During perception, selective attention reversed the onset times of perceptual and conceptual features in occipital and parietal lobes, enabling earlier detection of conceptual features. Stronger theta oscillation interactions between occipital and temporal regions during task preparation correlated with earlier onset times of target features in the occipital lobe. During retrieval, selective attention led to earlier peak times for perceptual compared to conceptual features in the frontal lobe. These findings provide novel insights into the dynamic nature of hierarchical processing during perception and memory retrieval, highlighting the critical role of selective attention in modulating information accumulation speed.