Eccentricity-dependent influence of amodal completion on visual search

Shirama, Aya; Ishiguchi, Akira · 2009 · Crossref

DOI: 10.4992/jjpsy.80.114

archive: archived pipeline: cataloged verified

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

Summary

This study investigates whether amodal completion—the perceptual process of filling in occluded parts of an object—occurs uniformly across the visual field or is influenced by target eccentricity. Previous research by Rensink and Enns (1998) suggested that amodal completion disrupts efficient visual search by making targets resemble distractors, implying a rapid, field-wide process. However, it remained unclear if this effect persists in the peripheral visual field, where spatial resolution is lower. The authors aimed to determine if the visual system’s basis for rapid completion extends across the visual field and how stimulus representations constructed through amodal completion vary with eccentricity. The researchers conducted two experiments using visual search tasks with five participants. In Experiment 1, they utilized stimuli from Rensink and Enns (1998): Task 1A involved separated elements (efficient search), while Task 1B involved elements forming an occlusion contour (inefficient search due to amodal completion). To compensate for peripheral resolution loss, they applied M-scaling (stimulus size magnification based on cortical magnification factors) up to 17 degrees of eccentricity. Experiment 2 simplified the stimuli to isolate the salience of the target feature (a missing square) from the configuration effects, removing the occluding circle or altering its position to prevent amodal completion. Performance was measured using miss rates in short-duration presentations to prevent eye movements. The results demonstrated that amodal completion disrupted efficient search even at high eccentricities (up to 17 degrees) when M-scaling was applied. In Task 1B, the configuration effect causing amodal completion increased with eccentricity, whereas the same target was detected efficiently at the lowest eccentricity (3.4 degrees). Notably, this eccentricity effect persisted despite M-scaling, unlike previous findings where M-scaling neutralized eccentricity effects in simpler search tasks. Experiment 2 confirmed that the target feature itself remained salient and efficiently searchable in the periphery; the disruption in Task 1B was specifically due to the occlusion configuration triggering amodal completion. These findings indicate that while the visual system possesses a basis for rapid amodal completion across the visual field, the resulting stimulus representations have eccentricity-dependent properties. The study suggests that amodal completion is not homogeneous; rather, the perceptual impact of occlusion contours varies with location. This challenges the assumption of uniform internal representation construction and highlights the complex interaction between spatial resolution, eccentricity, and higher-level perceptual processes like amodal completion in visual search.

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 2026-06-26; verification: verified.

Topics

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

• visual search