Neurobiology of the Eye
Control of fixational eye movements by luminance and spatial frequency content of the viewing target
Fixational eye movements are small amplitude irregular deviations of the fixation axes from the point of fixation that consist of tremor, drift and micro-saccades. It was assumed that their major function is to prevent fading because photoreceptors exposed to a constant luminance signal will rapidly adapt, resulting in a fading image. Recently, Kuang, Poletti, Victor and Rucci (Current Biology 22, 510-514, 2012) have shown that there is much more – the pattern of fixational eye movements is such that they enhance contrast sensitivity at higher spatial frequencies (SF), thereby “whitening” the SF spectrum. There is normally less contrast with higher SFs (contrast is roughly inversely correlated to SF in natural scenes).
We would like to know whether fixational eye movements are adaptable and how much they are interaction with the visual scene. We would also know whether they are also driven by rods. Currently, Ulrich Wildenmann studies whether gaze tracker outputs are confounded by changes in centration of the pupil with changing pupil diameter.
European community, ITN OpAL