Article: Nicholas Humphrey’s Beautiful Theory of Mind

Casual conversation between friends. Anything goes (almost).
Post Reply
User avatar
anjali
Former staff member
Posts: 1662
Joined: Sat Sep 10, 2011 10:33 pm

Article: Nicholas Humphrey’s Beautiful Theory of Mind

Post by anjali »

An interesting article: Nicholas Humphrey’s Beautiful Theory of Mind. "In his new book, “Sentience,” a neuropsychologist argues that consciousness evolved to make us feel that life is worth living."

I was vaguely familiar with the concept of blindsight, but this article went into some anecdotal detail about the phenomenon. An extended quote from near the beginning of the article,
...Humphrey approached the cage of a monkey named Helen. Her visual cortex had been removed by his supervisor, but her superior colliculus was still intact. He sat beside her, waving and trying to interest her. Within a few hours, she began grasping chunks of apple from his hand. Over the following years, Humphrey worked intensely with Helen. On the advice of a primatologist, he took her for walks on a leash in the village of Madingley, near Cambridge. At first, she collided with objects, and with Humphrey; several times, she fell into a pond. But soon she learned to navigate her surroundings. On walks, Helen would move directly across a field to climb a favorite tree. She would reach for fruit and nuts Humphrey offered her—but only if they were within arm’s length, which suggested that she had depth perception. In the lab, she could find peanuts and currants scattered across a floor strewn with obstacles; once, she collected twenty-five currants from an area of fifty square feet in less than a minute. This was not the behavior of an animal without sight.

As Humphrey tried to understand Helen’s condition, he recalled an influential distinction, made by the eighteenth-century Scottish philosopher Thomas Reid, between perception and sensation. Perception, Reid wrote, registers information about objects in the external world; sensation is the subjective feeling that accompanies perceptions. Because we encounter sensations and perceptions simultaneously, we conflate them. But there’s a difference between perceiving the shape and position of a rose or an ice cube and experiencing redness or coldness. Humphrey suspected that Helen was making use of visual perceptions without having any conscious visual sensations—using her eyes to gather facts about the world without having the experience of seeing. His doctoral supervisor, Larry Weiskrantz, soon made a complementary discovery: he observed a human patient, a partially blind man who was missing half his visual cortex, making consistently accurate guesses about the shape, position, and color of objects in the blind region of his visual field. Weiskrantz named this ability “blindsight.”

Blindsight suggested a lot about the workings of the brain. But it also posed fundamental questions about the nature of consciousness. If it’s possible to navigate the world using only nonconscious perceptions, then why did humans—and, possibly, other species—evolve to feel such rich and varied sensations? In the nineteenth century, the biologist Thomas Henry Huxley had compared consciousness to the whistle of a train or the chiming of a clock. According to this view, known as epiphenomenalism, consciousness is just a side effect of a system that works without it—it accompanies, but doesn’t affect, the flow of neural events. At first glance, blindsight seemed to support this view. As Humphrey asks in a new book, “Sentience: The Invention of Consciousness,” “What would be wrong—or insufficient for survival—with deaf hearing, scentless smell, feelingless touch or even painless pain?”
Image
Post Reply

Return to “Lounge”