Arbitrary Eye Movement Strategies in Global-Local Processing Experiments

Perceptual organization is one of the most hotly debated issues in visual perception. Human adults, in normal conditions, process global features faster than local details, the effect that is called “Global Precedence”. Researches have shown that as stimulus eccentricity gets more distant from the fovea, the perceptual decisions of local details become more delayed. This even happens when the gaze is fixated on the center of the field of view and the stimulus location is manually adjusted. The present study aims to explore the eye movement strategies in the process of global and local features, when the gaze point is not restricted to a particular fixation point. Fourteen participants were asked to respond to Matching and Similarity Judgment tasks. The data was recorded using EYELINKII™, with a sampling frequency of ۱۰۰۰Hz. The Global Precedence Effect (GPE) was observed in the two tasks. Additionally, a higher average of “arbitrary eccentricity” in global trials was observed as compared to local trials. Arbitrary eccentricity was referred to as the eccentricity individuals unconsciously choose to perceive the stimuli. Furthermore, the number of fixations were significantly greater in local trials.  From our findings, we speculate that in daily life we can perceive the world globally with peripheral vision and not always need eye-movements and only decide to focus foveally when selectively attending to local details seems necessary.

کلیدواژه ها:

Eye movement strategy ، Global precedence ، Global-Local processing ، Visual perception