Abstract
We propose a way of understanding form perception that emphasizes the changes in eye movements relative to changes in firing on the retina; a critical ratio is formed between the frequency of retina ganglion cell firing and the frequency of extraocular muscle contractions (i.e., the muscles controlling eye movements). In Experiment 1 we asked if changes in eye movement frequencies would alter perceived forms and their perceived movement by altering the critical ratio between eye movement and retinal firing frequencies. We manipulated participants’ eye movements by spinning them around in a chair (Jacobson & Shepard, 2007). Participants judged whether a repeating complex dot pattern appeared the same before and after being spun. Twenty-six out of twenty-seven participants reported drastic changes in the image after being spun, suggesting the importance of eye movements in form perception. In Experiment 2, we examined whether critical ratios varied in stability for perceptions of form consistent with a phase locking formula (i.e., Farey sequence). According to the Farey sequence, the most stable ratio is 1:1, where the eye movement frequency and the retinal firing frequency are the same followed by 1:2, 1:3 and so forth following a specific hierarchy of ratios. Participants identified forms in an image, then adjusted the frames per second (fps) at which the image was displayed until they no longer saw the same form. The initial fps of the image was varied to create different critical ratios. Stability was defined as the range of fps for which participants indicated seeing the same form. The results revealed an increase in the stability of the form perceived by participants as the stability of the critical ratio also increased. Together, these experiments suggest that the perception of form is related to the critical ratio formed between retinal firing frequencies and extraocular muscle contraction frequencies.
Meeting abstract presented at VSS 2012