The brain creates our core sense of reality, and we can learn a lot about that by noticing what happens when it is damaged by aging, accident, or illness. For example, sometimes an injury or a stroke alters neural structures that help constitute our experience of reality, including concepts of front and back, left and right, clockwise and counterclockwise. Then it’s as if one of the stage sets for our personal Truman Show has suddenly collapsed. (See “Your own little Truman Show,” December 8, 2014.)
In rare cases after a stroke, a patient’s visual experiences become a mirror image of normal experiences. As a result, books can be read only if they’re held up to a mirror. Such individuals write the mirror image of their signature and want to drive on the left-hand side of the road! That’s a fairly basic reality shift.
Or consider hemineglect, in which people ignore half of their world as if it isn’t there (usually the left half). When asked to copy a drawing of a flower they only draw the right side. They still realize that every object has two sides, but the brain modules which structure their experience of the world in terms of left and right have been damaged.
Neurologist Oliver Sacks tells of a stroke patient who would only eat the right half of a plateful of food. She could, of course, have turned the plate around after eating half of her meal. Then the neglected left half would have become the effortlessly-noticed right half. But since it was so hard to focus on “leftness,” she would physically move, turning around in a circle to the right. Looking at the plate again she would see the remaining food – or at least the right side of what was “left” over. She would do this several times, consuming one half after another until only crumbs remained.
This patient was highly intelligent and could even joke about the conceptual predicament of hemineglect. “It may look funny, but under the circumstances what else can I do?” When she tries to rotate the plate rather than rotating herself, “it is oddly difficult, it does not come naturally, whereas whizzing round in her chair does, because her looking, her attention, her spontaneous movements and impulses, are all now exclusively and instinctively to the right.” “‘It’s absurd,’ she says. ‘I feel like Zeno’s arrows – I never get there’” (The Man Who Mistook His Wife for a Hat, pp. 77-78).
In mentioning Zeno, she was referring to a Greek philosopher who asked how an arrow could ever arrive at its target. After all, before the arrow lands it has to go halfway, before going halfway it has to go 1/4 the distance, before that 1/8, and so on ad infinitum. Thus the stroke patient consumed half of her food, 1/4 more, and so on. So even though she knew she was succumbing to an illusion, her compelling inner sense of the way things are overwhelmed her intellectual insight.
So when the brain changes, reality changes – or seems to.
Roger Christan Schriner