Abstract
The purpose of this study was to investigate attentional capture by onset and color singletons in a search task. The contingent involuntary orienting hypothesis (Folk, Remington, & Johnson, 1992) states that attentional capture by a unique singleton is not entirely stimulus-driven, but is contingent on the relationship between the search goal and the properties of the singleton. In this study, we investigated whether a singleton defined by color or onset captured attention when the observer searched for a reddish target defined by an increment in L chromaticity on the cardinal color axis. The singleton's validity to the task was varied in different conditions: valid (singleton always target), invalid (singleton never target), and informative (singleton was target on 50% of trials). Four observers attempted to detect the reddish target in a display of 10 stimuli. Thresholds corresponding to 75% correct were estimated with a yes-no task. Experiment 1 consisted of 3 types of singletons (onset, blue, and bright) assumed to be signaled by a neural mechanism independent of the neural mechanism coding the target increment. Experiment 2 consisted of 2 types of singleton (red and green) assumed to be signaled by the same neural mechanism that signaled the target increment. Results in invalid conditions showed no evidence of attentional capture by color singletons, while results from the valid conditions suggested that these same color singletons could be used to guide attention to the relevant stimulus. Results in the informative condition suggested that attention was directed initially to the red and green color singletons when there was an incentive to attend to both the singleton and the distractors. An abrupt onset of a stimulus captured attention regardless of its validity to the task. Results provide little support for the contingent involuntary attentional capture by color.
FolkC.L.RemingtonR.W.JohnsonJ.C. (1992) JEP:HPP 18, 1030–1044.