How the EYEs function / How the PERSON functions, two points of view

Past Event Date: 


Dr. August Colenbrander

Meeting room: 

Room 204 - Main Conference Room

Event Type: 


I will discuss insights that my work in vision rehabilitation has given me regarding the nature of the visual system. “Vision” can be seen as a black box, the input of which consists of visual stimuli, while the output is visually-guided behavior in a dynamic environment. This means that the perception and recognition of visual stimuli is not the endpoint of visual performance, but only a necessary half-way point. It also means that the usual stationary or time-limited vision tests do not fully reflect the continuing interaction of vision and behavior. One example is letter chart acuity vs. reading. Letter chart acuity (one letter at a time) tests only the retinal area where the letter is projected.  Even for a 20/200 letter, this is less than 1 degree. Reading involves a continuous process of letter and word recognition over a significantly larger area – the visual span. The same visual signals that are used for letter/word/content recognition in the ventral stream, are simultaneously used in parallel in the dorsal stream to guide our eye movements. This part of our vision happens entirely outside our conscious awareness Without word recognition, we could not read. However, without appropriate eye movements, we could not read either. In the clinic, as in research, the conscious processing of visual information has received far more attention than the subconscious part. Both sides need to be studied.  Successful vision rehabilitation must address both.