Moonwalking With Einstein by Joshua Foer Page B
Authors: Joshua Foer
Tags: science, Personal Memoirs, Biography & Autobiography, Psychology, Self-Help, Personal Growth, Life Sciences, Neuroscience, Cognitive Psychology, Memory Improvement, Memory, Mnemonics
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say what he’d had for breakfast or name the current president, there were some things that he could recall. Milner found that he could learn complicated tasks without even realizing it. In one landmark study in 1962, she showed that HM could learn how to trace inside a five-pointed star on a piece of paper while looking at its reflection in a mirror. Each time Milner gave HM the task, he claimed never to have tried it before. And yet, each day his brain got better at guiding his hand to work in reverse. Despite his amnesia, he was remembering.
Subsequent studies of amnesics, including tests conducted on EP, have found that people who lose their memories are still capable of yet other kinds of unremembered learning. In one experiment, Squire gave EP a list of twenty-four words to memorize. As expected, within a few minutes, EP had no recollection of any of the words, or even that the exercise had happened at all. When asked whether he’d seen a given word before, he answered correctly only half the time. But then Squire sat EP in front of a computer monitor and gave him a different test. This time, forty-eight words were flashed on the screen for twenty-five milliseconds each, just long enough for the eye to catch some, but not all, of them (an eye blink, by comparison, happens in 100 to 150 milliseconds). Half the words were from the list that EP had read over and forgotten, and half were new. Squire asked EP to read each word after it flashed on the screen. Surprisingly, EP was far better at reading the words he’d seen before than the ones that were new. Even though he had no conscious recollection of them, somewhere in the recesses of his brain they had left an impression.
This phenomenon of unconscious remembering, known as priming, is evidence of an entire shadowy underworld of memories lurking beneath the surface of our conscious reckoning. Though there is disagreement about just how many memory systems there are, scientists generally divide memories broadly into two types: declarative and nondeclarative (sometimes referred to as explicit and implicit). Declarative memories are things you know you remember, like the color of your car, or what happened yesterday afternoon. EP and HM had lost the ability to make new declarative memories. Nondeclarative memories are the things you know unconsciously, like how to ride a bike or how to draw a shape while looking at it in a mirror (or what a word flashed rapidly across a computer screen means). Those unconscious memories don’t seem to pass through the same short-term memory buffer as declarative memories, nor do they depend on the hippocampal region to be consolidated and stored. They rely primarily on different parts of the brain. Motor skill learning takes place largely in the cerebellum, perceptual learning in the neocortex, habit learning in the basal ganglia. As EP and HM have so strikingly demonstrated, you can damage one part of the brain, and the rest will keep on working. Indeed, most of who we are and how we think—the core material of our personalities—is bound up in implicit memories that are off-limits to the conscious brain.
Within the category of declarative memories, psychologists make a further distinction between semantic memories, or memories for facts and concepts, and episodic memories, or memories of the experiences of our own lives. Recalling that I had eggs for breakfast this morning would be an episodic memory. Knowing that breakfast is the first meal of the day is a semantic memory. Episodic memories are located in time and space: They have a where and a when attached to them. Semantic memories are located outside of time and space, as free-floating pieces of knowledge. These two different types of remembering seem to make use of different neural pathways, and rely on different regions of the brain, though both are critically dependent on the hippocampus and other structures within the medial temporal lobes. EP has lost both types of
Subsequent studies of amnesics, including tests conducted on EP, have found that people who lose their memories are still capable of yet other kinds of unremembered learning. In one experiment, Squire gave EP a list of twenty-four words to memorize. As expected, within a few minutes, EP had no recollection of any of the words, or even that the exercise had happened at all. When asked whether he’d seen a given word before, he answered correctly only half the time. But then Squire sat EP in front of a computer monitor and gave him a different test. This time, forty-eight words were flashed on the screen for twenty-five milliseconds each, just long enough for the eye to catch some, but not all, of them (an eye blink, by comparison, happens in 100 to 150 milliseconds). Half the words were from the list that EP had read over and forgotten, and half were new. Squire asked EP to read each word after it flashed on the screen. Surprisingly, EP was far better at reading the words he’d seen before than the ones that were new. Even though he had no conscious recollection of them, somewhere in the recesses of his brain they had left an impression.
This phenomenon of unconscious remembering, known as priming, is evidence of an entire shadowy underworld of memories lurking beneath the surface of our conscious reckoning. Though there is disagreement about just how many memory systems there are, scientists generally divide memories broadly into two types: declarative and nondeclarative (sometimes referred to as explicit and implicit). Declarative memories are things you know you remember, like the color of your car, or what happened yesterday afternoon. EP and HM had lost the ability to make new declarative memories. Nondeclarative memories are the things you know unconsciously, like how to ride a bike or how to draw a shape while looking at it in a mirror (or what a word flashed rapidly across a computer screen means). Those unconscious memories don’t seem to pass through the same short-term memory buffer as declarative memories, nor do they depend on the hippocampal region to be consolidated and stored. They rely primarily on different parts of the brain. Motor skill learning takes place largely in the cerebellum, perceptual learning in the neocortex, habit learning in the basal ganglia. As EP and HM have so strikingly demonstrated, you can damage one part of the brain, and the rest will keep on working. Indeed, most of who we are and how we think—the core material of our personalities—is bound up in implicit memories that are off-limits to the conscious brain.
Within the category of declarative memories, psychologists make a further distinction between semantic memories, or memories for facts and concepts, and episodic memories, or memories of the experiences of our own lives. Recalling that I had eggs for breakfast this morning would be an episodic memory. Knowing that breakfast is the first meal of the day is a semantic memory. Episodic memories are located in time and space: They have a where and a when attached to them. Semantic memories are located outside of time and space, as free-floating pieces of knowledge. These two different types of remembering seem to make use of different neural pathways, and rely on different regions of the brain, though both are critically dependent on the hippocampus and other structures within the medial temporal lobes. EP has lost both types of
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