How Our Minds Trick Us Into Overlooking Signs of Dementia
There is a deceptively simple optical illusion that consistently fools us. The Müller-Lyer illusion consists of two parallel lines, one with fins pointing inward and the other with fins extending outward. The lines are of equal length, yet no matter how many times we measure them, the one with the fins diverging will always appear longer. This tension between what we know conceptually and what we perceive instinctively is built into us and is, I believe, at the heart of the caregiver’s dilemma.
Caregivers may realize their parents or spouses suffer from dementia, but in many cases it does not inhibit them from reacting emotionally and erratically to their patient’s misconduct or delusions. Knowing better does not necessarily make caregivers behave better. I encountered this phenomenon so often (even with well-informed caregivers) that I began to wonder if there wasn’t a neurological component to a family member’s inability to accept the full implications of cognitive impairment.
In Thinking, Fast and Slow, the psychologist Daniel Kahneman explains what’s at work here. He postulates two modes of thinking. System 1 is our automatic mode of thinking; it runs effortlessly, forms immediate impressions, and produces visceral and emotional reactions. This unconscious process, which Kahneman dubs “fast thinking,” is almost impossible to suppress. System 1 recruits our intuitions, biases, and assumptions and makes us susceptible to various visual and cognitive pitfalls, such as the Müller-Lyer illusion. System 2 is our more deliberate mode of thinking; it works at a conceptual remove and is slower to pronounce judgment. We can think of System 1 as the loud-mouthed uncle who knows the answer to everything and System 2 as the egghead professor given to murmuring, “I’m afraid I don’t know about that,” or “Maybe we should think things over.” And perhaps if System 2 had more sway over us, it would help us see what we know to be true. Although dementia does not play with lines and angles, it does something even trickier to disguise itself.