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Does photographic memory exist?

"Photographic" or eidetic memory is said to occur in some 8% of children, but almost all of these grow out of it. The phenomenon is extremely rare in adults, and indeed the very existence of photographic memory is still somewhat contentious. However, it may be that particular brain abnormalities can lead to ways of processing information that are dramatically different from the normal (see the case of Kim Peek).

I’ve discussed on a number of occasions the effects that stereotypes can have on our cognitive performance. Women, when subtly reminded that females are supposedly worse at math, do more poorly on math tests; African-Americans, when subtly reminded of racial stereotypes, perform more poorly on academic tests. And beliefs about the effect of aging similarly affect memory and cognition in older adults.

Distributed practice more effective than massed practice

It has long been known that spacing practice (reviewing learning or practicing a skill at spaced intervals) is far more effective than massed practice (in one heavy session). An interesting example of this comes from a study that aimed to find the best way of teaching postmen to type (this was at the request of the British Post Office). The researchers put postmen on one of four schedules:

Brain tissue is divided into two types: gray matter and white matter. These names derive very simply from their appearance to the naked eye. Gray matter is made up of the cell bodies of nerve cells. White matter is made up of the long filaments that extend from the cell bodies - the "telephone wires" of the neuronal network, transmitting the electrical signals that carry the messages between neurons.

The volume of gray matter tissue - a measure you will see cited in various reports - is a measure of the density of brain cells in a particular region.

Frances Yates described the memory strategy valued by the ancient Greeks and Romans as the "Art of Memory" in her widely quoted and seminal book The Art of Memory. Today we know it as the method of loci. But the Art of Memory, as those of the ancient world and those of the medieval world practiced it, is far richer than is implied by that title.

A general distinction you can make is that between:

  • direct study, and
  • learning from context

Direct study is more important when you're learning a non-cognate language. It's also more important in the initial stages of learning a language. Learning from context is particularly useful for cognate languages.

Of course learning a language requires both approaches, but the relative proportions will vary.

I recently reported on a finding that memories are stronger when the pattern of brain activity is more closely matched on each repetition, a finding that might appear to challenge the long-standing belief that it’s better to learn in different contexts. Because these two theories are very important for effective learning and remembering, I want to talk more about this question of encoding variability, and how both theories can be true.

Brain autopsies have revealed that a significant number of people die with Alzheimer’s disease evident in their brain, although in life their cognition wasn’t obviously impaired. From this, the idea of a “cognitive reserve” has arisen — the idea that brains with a higher level of neuroplasticity can continue to work apparently normally in the presence of (sometimes quite extensive) brain damage.

The use of worked examples

We're all familiar, I'm sure, with the use of worked-out examples in mathematics teaching. Worked-out examples are often used to demonstrate problem-solving processes. They generally specify the steps needed to solve a problem in some detail. After working through such examples, students are usually given the same kind of problems to work through on their own. The strategy is generally helpful in teaching students to solve problems that are the same as the examples.

Alzheimer's disease currently affects one in 10 people over age 65 and nearly half of those over age 85.

More than 19 million Americans say they have a family member with the disease, and 37 million say they know somebody affected with Alzheimer's.

In the United States, the average lifetime cost per Alzheimer patient is US$174,000. (These figures are from the U.S. Alzheimer's Association).