Toward a better approach for measuring visual-search slopes.

The slope of the function relating response times to the number of stimuli in a visual-search display is commonly considered a measure of search speed and is extensively used to test theories of visual cognition. Unfortunately, this important measure is confounded in multiple ways so that many classical findings in the literature must be called into question. As a way out of this predicament, we here develop a new technique to measure search speed (data collected in 2022 and 2023): Instead of manipulating the number of stimuli that need to be searched via a set-size manipulation, we achieve the intended purpose by placing the search target at different spatial positions with respect to an a-priori-known search order.