CUED Publications database

Visual search near threshold: Some features are more equal than others.

Hannus, A and van den Berg, R and Bekkering, H and Roerdink, JBTM and Cornelissen, FW (2006) Visual search near threshold: Some features are more equal than others. J Vis, 6. pp. 523-540.

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While searching for objects, we combine information from multiple visual modalities. Classical theories of visual search assume that features are processed independently prior to an integration stage. Based on this, one would predict that features that are equally discriminable in single feature search should remain so in conjunction search. We test this hypothesis by examining whether search accuracy in feature search predicts accuracy in conjunction search. Subjects searched for objects combining color and orientation or size; eye movements were recorded. Prior to the main experiment, we matched feature discriminability, making sure that in feature search, 70% of saccades were likely to go to the correct target stimulus. In contrast to this symmetric single feature discrimination performance, the conjunction search task showed an asymmetry in feature discrimination performance: In conjunction search, a similar percentage of saccades went to the correct color as in feature search but much less often to correct orientation or size. Therefore, accuracy in feature search is a good predictor of accuracy in conjunction search for color but not for size and orientation. We propose two explanations for the presence of such asymmetries in conjunction search: the use of conjunctively tuned channels and differential crowding effects for different features.

Item Type: Article
Uncontrolled Keywords: Adult Color Discrimination (Psychology) Female Humans Male Models, Biological Photic Stimulation Saccades Sensory Thresholds
Divisions: Div F > Computational and Biological Learning
Depositing User: Cron Job
Date Deposited: 17 Jul 2017 19:25
Last Modified: 24 Apr 2018 02:08