Talk:Fixation (visual)

Wiki Education Foundation-supported course assignment
This article is or was the subject of a Wiki Education Foundation-supported course assignment. Further details are available on the course page. Student editor(s): AleksNemo, SEReichert, TSantos, Hphan1719.

Above undated message substituted from Template:Dashboard.wikiedu.org assignment by PrimeBOT (talk) 21:29, 16 January 2022 (UTC)

Merging
Article merged: See old talk-page here — Preceding unsigned comment added by Hphan1719 (talk • contribs) 14:06, 24 April 2016 (UTC)

Retinal Stabilization
"In the absence of retinal jitter (a laboratory condition called retinal stabilization), the visual percept rapidly fades out and may even completely disappear under certain conditions (low contrast, absence of sharp edges, etc.)."

I have read a lot about this topic, and I am pretty confident that this sentence is very misleading. Even high contrast stimuli with sharp edges will (not just "may") fade and completely disappear quite quickly if the stabilization is good enough (perfect stabilization is almost impossible to achieve even today). Using an exceptionally good stabilization technique (but one that, for technical reasons, can only be used with certain special, and, I think, rather low contrast stimuli) Coppola & Purves (1996) found that percepts would disappear completely in less than a tenth of a second (much more quickly than in other experiments using poorer stabilization), but even Pritchard, Heron & Hebb (1960), using a much more primitive stabilization technique, but with high contrast, sharp edged stimuli (black and white drawings) found that the percepts would often quite rapidly disappear. In this case the percepts (or parts of them) tended to reappear after a little more time, but this is now thought to be due to slight shifts of teh image on the retina due to the imperfect stabilization.
 * Coppola, D. & Purves, D. (1996). The Extraordinarily Rapid Disappearance of Entoptic Images. Proceedings of the National Academy of Sciences of the USA, 93, 8001-8004.
 * Pritchard R.M., Heron W., & Hebb D.O. (1960). Visual Perception Approached by the Method of Stabilized Images. Canadian J. Psych., 14, 67-77.  —Preceding unsigned comment added by Treharne (talk • contribs) 11:20, 22 April 2009 (UTC) Treharne (talk) 11:39, 22 April 2009 (UTC)

General
I fixed some grammar issues throughout the article and clarified that the application of Brainstem Biometrics technology is monitoring anesthesia. AleksNemo (talk) 01:33, 25 April 2016 (UTC)

Visual fixation in other animals
The first paragraph presents an overly narrow view of visual fixation as depending on the presence of a fovea. Visual fixation occurs in almost all animals with good vision including fish and invertebrates, many of which lack an acute zone and yet display a strategy of alternating fixation and saccade. Importantly, due to differences in inertia, small animals use body and head movements in a way functionally equivalent to how larger animals use head and eye movements. Taking the narrow view of fovea-dependent fixation ignores a wonderful illustration of convergent evolution across the animal kingdom and a visual principle that applies to humans, mice, flies, and even robots.