Does Luminance Produce Attentional Weighting?

Poster Session F - Tuesday, April 16, 2024, 8:00 – 10:00 am EDT, Sheraton Hall ABC

Nathan Rosen¹ (rosenn@uoguelph.ca), Coleman Olenick¹, Heather Jordan¹, Mazyar Fallah¹; ¹University of Guelph

Models of attention assume a relationship between attentional selection and luminance. Brighter objects are thought to have a greater attentional weight relative to dimmer objects. We investigated this assumption using a saccadic delayed match-to-sample task in which the trajectories of saccades provided a sensitive measure of attentional weights of target and distractor. Previous studies have shown that actively competing distractors have an attractive effect on saccade trajectories, but once competition is resolved the distractors repel the saccade. To examine the hypothesis that luminance is functionally equivalent to attentional weighting, we varied the relative luminance of the target and distractor, ensuring it was irrelevant to the task. Salience-based models of attention would predict saccade trajectory deviations towards the distractor that scale with the relative luminance of the distractor during active competition. Once the competition is resolved, distractors with lower relative luminance should elicit reduced trajectory deviations away from the distractor. Fast reflexive saccades tended to be executed to the brighter object, independent of their target/distractor identity. Once the target was discriminated from the distractor, saccades to the target deviated away from the distractor as predicted. Contrary to the hypothesis, we found no evidence that the magnitude of this deviation varied by relative luminance. Taken together, salience drives the execution of reflexive saccades, but does not affect saccade trajectories after visual discrimination has completed. Therefore, luminance is not synonymous with attentional weighting in saccade target selection. This runs counter to attentional models that suggest attention works via increasing perceived contrast.

Topic Area: ATTENTION: Spatial