Rachel Pitman¹, Daryl Wilson¹; ¹Queen's University

In prior research, we found that motion impaired change detection for orientation but not for colour changes – an unexpected finding, as previous research has shown that motion can interfere with colour perception (Suchow & Alvarez, 2011) and memory (Chung et al., 2023). The absence of any motion effect on colour suggested that motion’s impact on change detection may not stem from disruptions to attention or memory, but rather to characteristics of the features themselves. Therefore, we conducted follow-up experiments to determine whether motion affects change detection differently across features. Across experiments, participants viewed an array of task-relevant triangles and task-irrelevant circles that were either stationary, moving synchronously, or moving asynchronously. In each trial, one task-relevant stimulus gradually changed while participants attempted to identify the change target. In Experiment 1, we used a staircase procedure to replicate our previous findings and determine the change magnitude required for 50% detection accuracy for colour and orientation changes under high (3 task-relevant stimuli) or low (9 task-relevant stimuli) perceptual load. In Experiment 2, we tested whether motion selectively disrupts change detection for spatial features by testing detection accuracy for size (spatial) versus luminance (non-spatial) changes. Detection accuracy was measured directly (no staircase design) as a function of Motion Type (Stationary, Synchronous, Asynchronous) and Load (3, 6, 9, 12 task-relevant stimuli). Across experiments, motion consistently impaired detection for spatial features (orientation and size) under high load, producing both a Pure Motion Effect (Synchronous > Static) and a Chaotic Motion Effect (Asynchronous > Synchronous). In contrast, motion had no impact on non-spatial features (colour and luminance), although detection of both declined with increasing load. These results challenge the assumption that motion impairs change detection by disrupting attention or memory, instead supporting a feature-specific mechanism in which motion selectively impairs detection for spatial-related features.