Paying attention with your eyes
Blog vol 6.39. Paying attention with your eyes.
The conversation around the Artemis II mission highlighted the discrepancies between machine vision and human vision. The processing of visual information, the integrating of cortical input, and the seeing the forest AND the trees, sets human vision apart. The human visual system is very complex and very finely tuned, and not so easily duplicated.
Attention, the focussing of the eyes and mind, is integral to vision. In an on-line article in The Conversation, Dr. Michelle Spear, Professor of Anatomy at the University of Bristol (Read here), observes that our brains cannot analyze every object in a scene or space simultaneously. The visual system relies on attention, thereby selecting and filtering.
In my own personal experience, my nemesis is the fridge. I am sent to look for the mayonnaise, and after a careful search of all the shelves, I am befuddled; I cannot see it. The next person to look sees the mayonnaise immediately right in plain sight. Why did I not see it?
Visual searching has a method: a series of spotlight sweeps that go across the visual field. Our fovea, the centre of our vision, can only cover a very small area roughly the size of a thumbnail at arm’s length. This “spotlight” sweeps over a scene gathering detail, sacrificing everything outside its purview. Our eyes will also jump across a scene, by saccades, to cover large areas. These pursuit and saccade movements are constantly and unconsciously being performed by our eyes.
That is not all. It is not just about what information reaches the eye, but also about what the brain expects to find. This is called inattentional blindness or perceptual blindness. It occurs when the brain is so intent on seeing one specific thing that it filters out all other input. A good example of this is a video taken of a group of people passing a basketball around (Watch here). In and out of this scene walks a person in a gorilla costume completely unobserved by most viewers. Frankly, somewhat disturbing to find that I did not see something so obvious.
The part of the brain that is crucial to spatial awareness and directing attention is called the parietal lobe. The pathway that runs to this lobe from the eyes is called the dorsal stream. The parietal lobe allows us to see where objects are in space and plays a crucial role in guiding attention during visual search. In the gorilla video, the larger jumps that our eyes perform to track the balls, the saccades, play a part in reducing our attention. This is good when we really want to focus on something yet may be a deadly problem when we are multitasking in say, heavy traffic or when we are texting and driving.
It is important to remember that vision is not only about the eyes but also includes perception and processing. All the more reason to get your eyes and vision checked regularly.
Til next week,
The good doctor
