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Afrodit Panagopoulos, Michael Grünau; Visual search with irrelevant background: Speeding or slowing search using endogenous cues. Journal of Vision 2002;2(7):529. doi: 10.1167/2.7.529.
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© ARVO (1962-2015); The Authors (2016-present)
When relevant stimuli (target and distractors) are embedded among irrelevant background elements, visual search takes longer than without background elements. We know that cueing exogenously for the shape or size of the set of relevant stimuli can partially overcome the detrimental effect of the background elements. These results have shown that the ‘spotlight of attention’ has both variable shape and size. The question now is “can endogenous cues guide attention to relevant stimuli in a similar way”? Two configurations (horizontal vs vertical) of 4 relevant stimuli, one of which was the target, were presented with or without a matrix of 11x11 background elements. A variable time before the stimuli, either a valid or invalid endogenous cue was given (a letter “V” or “H”). In a second experiment, the configuration was always vertical, and a cue was again given to the subject. This time the cue was an arrow pointing to the left or to the right of fixation. The results suggest that valid cues correctly guide subjects' attention to the relevant stimuli. This means that endogenous cueing can also change shape and location of the ‘attentional spotlight’, but longer delays are needed to process endogenous cues as compared to exogenous cues, which work well with shorter delays. We now know that top-down processes, just like bottom-up processes, can be manipulated. The present experiments have shed more light on the roles that attention plays in perception.
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