Adverse visual suppressions are frequently an important complication of visual problems, while normal suppressions of visual and other input are advantageous. Suppressions facilitate the processing of information by filtering distracting stimuli. Suppression of extraneous stimuli is essential for sustained, selective attention. It is not possible to be consciously aware of all of the external and internal input that bombard our visual system.
Our eyes send more data to the brain than all of our other senses combined and there are as many nerve fibers from the brain to the eyes as there are from the eyes to the brain. These guide what the eyes look for and also influence the processing of input at the retinal level. Without suppressing non-essential stimuli, accurate visual perception would not be possible.
Adverse suppressions are caused by sensory mismatches. This is usually a binocular dysfunction in which the two eyes are not sending coordinated data to the brain. These occur when the two eyes do not focus equally or when they do not align precisely. Adverse suppressions reduce confusion to enable the individual to function, albeit with compromised efficiency and visual processing. Adverse suppressions can lead to prolonged maladaptations such as amblyopia and difficulty processing print.
Suppression of vision during rapid eye jumps is critical to visual function and comfort. Our eyes move four times a second even when we think that we think that we are locked onto a target. This is how the brain constructs our view of the world since our vision is only clear in the central 5o of our visual field. If vision is not suppressed during rapid eye movements the individual sees a smear. The brain fills in during rapid eye movements as it does when our eyes close during a blink.
These saccadic suppressions are critical for reading. When the timing of these suppressions is off, it makes it very difficult to get information from print. If it is a developmental visual problem, and the person has never seen any other way, they assume that this is what everyone experiences. When it happens as a result of a concussion, the individual is aware of the changes and is disabled and sickened by the effects.
Most people are aware of the fallacy of multi-tasking; that we cannot actually do two separate cognitive tasks at the same time. Alex Pang explains that this is over-generalized. If we are listening to someone and texting something else, we cannot process both simultaneously and must be switching back-and-forth rapidly. This impairs performance compared to doing each task separately. Alex Pang describes this as “switch-tasking” not multi-tasking. On the other-hand, being able to multi-task efficiently is essential to many things we do such as driving a car. Efficient reading is another example of what appears to be a unitary task it that requires a great deal of multi-tasking.
Vision must coordinate with other systems for us to function well. When they do not, when the systems are overloaded, adverse suppressions and sensory processing disorders occur. These include poor eye-hand coordination, dizziness, spatial disorientation, affective disorders, reading problems, attention disorders, and clumsiness.