Perceptual and attentional impairments of conscious access involve distinct neural mechanisms despite equal task performance.
Samuel Noorman, Timo Stein, Johannes Jacobus Fahrenfort, Simon van Gaal
Elife May 1, 2025 DOI: 10.7554/elife.97900 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Experimental EEG study Peer reviewed |
|---|---|
| Keywords | Humans Electroencephalography Photic stimulation Consciousness Perceptual masking Visual perception Female Attentional blink Young adult Conscious access EEG Decoding |
| Key findings | Late EEG processing (~200-250 ms) of complex features (collinearity, illusory triangle) was impaired by masking but spared by the attentional blink, whereas early decoding of local contrast (~80 ms) was largely unaffected by either manipulation. The authors argue this indicates distinct neural mechanisms for perceptual versus attentional impairments, with feedforward processing largely preserved under both. |
Abstract
This study investigates failures in conscious access resulting from either weak sensory input (perceptual impairments) or unattended input (attentional impairments). Participants viewed a Kanizsa stimulus with or without an illusory triangle within a rapid serial visual presentation of distractor stimuli. We designed a novel Kanizsa stimulus that contained additional ancillary features of different complexity (local contrast and collinearity) that were independently manipulated. Perceptual performance on the Kanizsa stimulus (presence vs. absence of an illusion) was equated between the perceptual (masking) and attentional (attentional blink) manipulation to circumvent common confounds related to conditional differences in task performance. We trained and tested classifiers on electroencephalogram (EEG) data to reflect the processing of specific stimulus features, with increasing levels of complexity. We show that late stages of processing (~200-250 ms), reflecting the integration of complex stimulus features (collinearity, illusory triangle), were impaired by masking but spared by the attentional blink. In contrast, decoding of local contrast (the spatial arrangement of stimulus features) was observed early in time (~80 ms) and was left largely unaffected by either manipulation. These results replicate previous work showing that feedforward processing is largely preserved under both perceptual and attentional impairments. Crucially, however, under matched levels of performance, only attentional impairments left the processing of more complex visual features relatively intact, likely related to spared lateral and local feedback processes during inattention. These findings reveal distinct neural mechanisms associated with perceptual and attentional impairments and thus contribute to a comprehensive understanding of distinct neural stages leading to conscious access.