Perceived Depth Modulates Perceptual Resolution

The goal of this thesis was to investigate whether changes to perceived depth affects the resolution of object perception. In a series of four experiments, I used psychophysical methods to examine how perceived depth, defined by 2D pictorial cues in the Ponzo Illusion, modulated perceptual resolution even when it was independent to the task at hand. For Experiments 1-2, participants completed size and orientation discrimination tasks with a pair of lines, where the stimuli were placed either on the "close" or "far" portion of the Ponzo Illusion, as well as a non-Illusory "flat" portion. Across both experiments, more precise and faster discrimination abilities were found for lines perceived as closer to the observer. To rule out a potential confound of surface size, a follow up control experiment was conducted on the orientation task (Experiment 2b) using two size-matched non-illusory version of the Ponzo illusion. The results continued to show a persistent enhancement of close objects even when surface size was controlled for. Lastly, in agreement with previous findings, results of Experiment 3 showed that this close benefit extends even to high level perceptual processing such as a face identification task. Together these findings support the idea that the human visual system may have dedicated processes for closer things.