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Jared Abrams, Taosheng Liu, Marisa Carrasco; Endogenous, sustained attention alters contrast appearance. Journal of Vision 2008;8(6):144. doi: https://doi.org/10.1167/8.6.144.
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© ARVO (1962-2015); The Authors (2016-present)
Goal: Exogenous, transient attention alters appearance along a number of perceptual dimensions including contrast (Carrasco, Ling & Read, 2004). However, it remains unclear whether endogenous, sustained attention also changes appearance. Here we tested the effect of endogenous attention on perceived contrast.
Methods: A central cue prompted observers to direct attention to one of two peripheral locations at eight degrees of eccentricity or to both locations (focused versus distributed attention, respectively). Two RSVP letter streams were shown at those locations for 1.2 s, followed by two independently tilted Gabor patches adjacent to the letter streams (40 ms). For focused-attention trials, observers directed attention to the cued RSVP stream and detected a target letter (‘X’); for distributed-attention trials, observers monitored both streams for the target. A target was presented on 20% of total trials, and observers indicated target detection by pressing a key. The rate of the RSVP stream was dynamically adjusted to maintain a high detection performance (∼90%). When observers did not detect the target, they reported the orientation of the higher contrast Gabor patch. One of the Gabors was the Standard (32% contrast) while the other was the Test, whose contrast was chosen from one of 9 levels around the Standard (13%–77%).
Results and Conclusion: Performance on the RSVP detection task was better for peripheral than neutral trials, indicating that attention was effectively deployed to the cued location. This deployment of attention caused a systematic shift in the psychometric functions for appearance: the stimuli in the cued location were perceived to have higher contrast than stimuli in the uncued location. In addition, attention improved performance on the orientation discrimination task. A control experiment ruled out a cue-bias explanation of the effect. These results indicate that endogenous, sustained attention also alters appearance.
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