Abstract
Perceived size is a function of perceived viewing distance, retinal images size, and various contextual cues such as linear perspective and the size and location of neighboring objects. We have recently shown that adding dynamic components to classic visual illusions can significantly alter the influence of contextual elements, and thus enhance or reduce illusion magnitudes. Interestingly, motion dynamics greatly enhance the effects of the Dynamic Ebbinghaus illusion (size contrast), whereas they reduce the effects of the Dynamic Corridor illusion (size constancy). Here, across three experiments, we explore further differences in the nature of these two dynamic illusions to identify the key dynamic components that enhance or reduce illusion magnitude. In particular, in our previous studies of the Dynamic Corridor illusion, the context itself (i.e., the corridor) was static, whereas for the Dynamic Ebbinghaus illusion, the contextual elements (i.e., the inducers) were dynamic in terms of their size and motion. In Experiment 1, a simplified Dynamic Corridor illusion led to a weak illusion, even when the corridor background was translating. In Experiment 2, a dynamically changing context (i.e., the corridor was only partially visible at any one time) led to a strong illusion. These results were replicated in Experiment 3 using a dynamic version of the classic Ponzo illusion, further limiting potential influences of size contrast from differently sized elements of the corridor background. This pattern of results indicates that a combination of a moving target and a dynamically changing context leads to a particularly strong influence of contextual cues on perceived size.