Abstract

`Motion dazzle’ is the hypothesis that certain types of patterns, such as high contrast stripes and zigzags, can cause misperceptions in the speed and direction perception of moving targets. Motion dazzle is relevant to both ecological questions, including why striped patterning may have evolved in animals such as zebras, and also for camouflage design for human purposes. We have used an interdisciplinary approach to address questions about motion dazzle in human subjects, combining techniques from psychophysics and behavioural ecology. We have focused on what aspects of a target are important in creating motion dazzle effects and what specific perceptual errors are observed, with a view to understanding the phenomena at a mechanistic level. Using touch screen technology, we have replicated work showing that targets with striped markings are amongst the hardest for humans to capture, but that these effects depend upon the orientation of the stripes and whether multiple targets are present. We have also made measurements of speed and direction judgements for targets with different patterning using psychophysical techniques. Subjects show small but consistent speed and direction judgement errors that depend upon static stripe orientation relative to the direction of motion. Motion dazzle may therefore be an effective camouflage strategy caused by several different misperceptions, not all of which have been previously reported.