Factors Involved in Visual Fixation

While there has been significant research into the subject of vision and the way in which our eyes work, visual fixation is still a rather blurry spot for scientists (Barash et al., 1998). Visual fixation is the ability of the eye to take in, process, and rest on one particular scene without moving for a period of time (Bear, Connors, & Paradiso, 2007). This phenomenon raises the question of why exactly our eyes fix on one scene? Why do we stop to stare at the things we do? What factors determine whether our eyes will fix on one particular scene over another?

Research by Barash et al. (1998) done on macaque monkeys revealed that visual fixation depends on background illumination, dark scenes cause the eye to shift upward in position implying that the background illumination of a scene determines whether or not the eye will fix on that particular scene. This factor in visual fixation is also noted Goldstein (2010) who explains that stimulus salience aids in determining whether we will fix on a particular scene. Stimulus salience is the prominence of the stimulus in the environment, thus the more prominent the stimulus is, the more likely we're going to fixate on it. Factors in stimulus salience include color, illumination, contrast, and patterns (Goldstein, 2010). One study done with individuals with Autism showed the overwhelming effect of stimulus salience on the developmentally disordered brain, concluding that the influence of stimulus salience caused study subjects to over-select a particular response (two cards with different colors on each). Subjects of the test continually choose the more prominent when prompted to choose a card, and it was only after the over-selected (more prominent) color was tossed out as a choice for another less prominent color, than the "previously under-selected color emerged to control behavior" (Leader et al., 2008).

Memory of a certain scene also seems to have something to do with whether we fix on a scene or not. A study by De Fockert et al. (2001) noted the importance of memory on how much attention we give a particular scene, and thus fixate on it. Goldstein (2010) notes that one's fixation depends a great deal on how much we recognize something, what we know about it, and if we find the specifics of the scene interesting, contrasting, or familiar.

This last point leads us to the third factor in visual fixation. As we can all relate to, we often focus on one particular scene or object due to the fact that we simply must. We cannot continuously look out the window while trying to do the dishes or focus on the bird on the other side of the street while skateboarding. Sometimes what we choose to focus on depends on what we're doing at the time. In short, the nature of our task determines what we will fixate on and for how long (Goldstein, 2010). Obviously we cannot always allow colors and contrast, or an object that catches our eye to distract us, so we must have some level of control over what we fixate on. Task fixation is one example of how we control what we fixate on and why.

References:

Barash, S., Melikyan, A., Sivakov, A., & Tauber, M. (1998). Shift of visual fixation dependent on background illumination. Journal of Neurophysiology, 79, 2766-2781. doi: 0022-3077/98

De Fockert, J. W., Rees, G., Frith, C. D., & Lavie, N. (2001). The role of working memory in visual selective attention. Science 2, 291, 1803-1806. doi: 10.1126/science.1056496.

Goldstein, E. B. (2010). Sensation and perception, 8th ed. Belmont, CA: Wadsworth.

Leader, G., Loughnane, A., McMoreland, C., Reed, P. (2008). The effect of stimulus salience on over-selectivity. Journal of Autism and Developmental Disorders.