The parallel nature of early visual processing in visual search

Visual search is a process that is ubiquitous in daily life. Some are relatively easy – looking for a red sock among black socks – while others are extremely difficult – looking for tumors in x-ray images. Classic theories and models of search have long assumed that these easy searches, referred to as efficient search, occur in parallel and without attention and thus should not be affected by factors such as the number of items or the features of the distractors. However, there has been recent evidence that systematic variability exists even inefficient search. This led to the development of the Target Contrast Signal Theory, which proposed a different mechanism for parallel processing in visual search. In contrast to the pre-attentive process of saliency detection and generation proposed by classic theories, Target Contrast Signal Theory proposes that parallel processing in early vision involves an evidence accumulation process that is aimed at rejecting items as non-targets. In this thesis, I present a series of studies that examined the nature of the parallel process in detail. Chapter 2 examines the output of parallel processing and provides evidence in support of the mechanism described in Target Contrast Signal Theory. Chapter 3 examines the fate of the items that have been discarded in parallel processing. Lastly, Chapter 4 examines the influence of scene context on the parallel evidence accumulation process.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Psychology

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2021

Author dc:creator

• Ng, Gavin JP

Contributors dc:contributor

• Lleras, Alejandro
• Buetti, Simona
• Beck, Diane M
• Christianson, Kiel
• Hummel, John E

• visual search
• parallel processing
• target contrast signal theory

Statement dc:rights

• Copyright 2021 Gavin Ng

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/110529

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/110529