3/20/25 Michael Pratte, Mississippi State: Stimulus-Specific effects in Vision and Visual Memory: Pernicious Noise and Buried Treasure
CCN Brown Bag
Michael Pratte, PhD
Associate Professor, Department of Psychology
Mississippi State University
Date: Thursday, March 20, 2025
Time: 12:10-1:00pm
Location: Wilson Hall 316
Stimulus-Specific effects in Vision and Visual Memory: Pernicious Noise and Buried Treasure
Everyone knows that you shouldn’t average data over people. Ignoring person variability would inject massive amounts of noise into the results, distort conclusions when the path from brain to data is non-linear (which it always is), and would miss out on powerful opportunities for theory building by studying individual differences. Yet very few researchers have a problem with averaging data over the particular stimuli used in a study. This seems especially true in vision studies where any differences in memory performance for different displays of colored squares, or differences in motion perception for different random dot kinematograms, may seem inconsequential. But here I show that for several typical experimental designs there is substantial systematic variability across particular stimuli, and it is often as large as the variability across people. I explore not only the negative consequences of ignoring this variability, but also what can be gained by purposefully designing experiments and models to account for it. Whereas typical modeling techniques are not able to account for differences across people and stimuli simultaneously, I present a novel Bayesian model of continuous report data that allows for several such effects to be incorporated within substantive models of circular data. The results provide for unprecedented accuracy in parameter estimation, and new avenues for testing and developing theories by examining why performance differs so greatly across particular stimuli.