On the role of selective attention in visual perception

Luck, Steven J.; Ford, Michelle A. · 1998 · OpenAlex-citations

DOI: 10.1073/pnas.95.3.825

archive: archived pipeline: cataloged verified

Get this paper ↗ (DOI — opens at the source; we link to it, we don't host it)

Summary

This paper addresses the "locus-of-selection" problem in cognitive psychology: determining whether selective attention operates during perceptual processing (early selection) or after stimulus identification is complete (late selection). The authors argue that behavioral measures are insufficient for distinguishing these stages because they reflect the combined output of multiple cognitive systems. Instead, they propose that selective attention serves a specific computational role in visual perception: resolving ambiguities in neural coding that arise when multiple objects are processed simultaneously. This "ambiguity resolution theory" suggests that attention is necessary to bind distinct features (e.g., color and orientation) into a coherent object representation, a process known as solving the "binding problem." To test this hypothesis, Luck and Ford utilized event-related potentials (ERPs), specifically the N2pc component, which serves as an electrophysiological marker of perceptual-level attentional allocation. They conducted two experiments comparing feature detection tasks (identifying a unique color among distractors) with conjunction discrimination tasks (identifying a specific color-orientation combination). Crucially, they introduced a demanding central task (discriminating a noisy letter at fixation) to consume attentional resources, thereby discouraging subjects from voluntarily allocating attention to the visual search array unless it was strictly necessary for performance. This design allowed the researchers to isolate whether perceptual attention was required for accurate identification or merely for working memory storage. The results demonstrated a clear dissociation between the two task types. In the feature detection experiment, subjects performed accurately even when the central task eliminated the N2pc component, indicating that perceptual-level attention was not required to identify simple features. In contrast, during the conjunction discrimination experiment, the N2pc component persisted despite the attentional load of the central task, albeit with a delayed onset. This indicated that subjects were forced to allocate spatial attention to bind the color and orientation features of the target. The authors contrast these findings with previous psychophysical studies that suggested attention is required for all identification, arguing that those studies likely measured postperceptual mechanisms related to working memory rather than perceptual processing. The significance of these findings lies in providing empirical support for the ambiguity resolution theory of attention. The study concludes that selective attention is not a unitary process but involves distinct mechanisms at different stages. Specifically, perceptual-level attention is computationally necessary primarily when the visual system must resolve ambiguous neural representations by binding multiple features into a single object. This clarifies the role of attention in visual perception, distinguishing it from postperceptual attentional mechanisms that govern the transfer of information to working memory and awareness.

Provenance

The full processing record for this entry. Every stage of this paper's journey through the pipeline is logged — what ran, with which tool and model, how many attempts it took, and when it last completed.

Summary generated by qwen3.6-27b-prismaquant on 2026-06-25; verification: verified.

Topics

Ranked by relevance to this paper. Hover a topic for its definition.

• attention selective divided
• perceptual processing