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. Reliably inducing such a search order is the main achievement of the present study, but we also report several additional data patterns that might turn out instrumental for future research on visual attention. Public Significance Statement: We have developed and validated a new approach to measure the speed at which people can search through a set of visual stimuli. This method will be of use to study visual search and to estimate the difficulty of visually processing certain types of objects, and hopefully, it will replace the traditional, but invalid, approach of measuring search speed by manipulating the number of stimuli in the search array. Our method might eventually also become useful for diagnostical purposes in clinical, educational, or occupational settings. [ABSTRACT FROM AUTHOR]