Ambidextrous Tendencies May Mean Better Memory

Having a close left-handed relative makes right-handers better at remembering events than those from exclusively right-handed families, new research suggests. There is a downside, however, as members of these ambidextrous families may be relatively impaired in their ability to recall facts.

According to the study, having a left-handed sibling or parent means the organisation of your brain is intermediate between a pure 'lefty' and a pure 'righty'.

Specifically, Stephen Christman and Ruth Propper at the University of Toledo, Ohio claim that people with 'lefties' in the family have a larger corpus callosum - the connection between the brain hemispheres. This makes you better at certain memory tasks, but worse at others, they believe.

Two types of memories are involved. Episodic memories are those with a context that is separate from the information itself - for example, where you parked your car or where you left your keys. Semantic memories on the other hand are things 'you just know', such as the dates of the First World War or the recipe for apple pie.

The researchers showed 180 right-handed subjects lists of words. Some of this group was asked to recall as many of the words as possible once the list had been taken away. This tests episodic memory because the subjects have to remember the words they were taught.

Others from the group were given fragments of words with a letter missing and asked to fill in the gaps. This semantic test simply relies on knowing how the correct word should be spelt. Subjects with close left-handed relatives did better at the first 'remember' task, but worse at the second 'know' task.

"The key difference is not whether you are right handed, but whether you are strongly or weakly handed," explains Christman.

A definitive explanation for the results is still some way off, says Christman. But he suspects that it might involve the roles that different brain hemispheres play in memory. He believes the information itself tends to be stored in the left hemisphere, while the place and time context resides in the right.

Both these components will be useful in episodic memories, so he suspects that people with a large corpus callosum linking their hemispheres - such as those from more ambidextrous families - will do better at these tasks. Semantic memory requires only one hemisphere, so it may be that those with fewer connections between the hemispheres have less interference and perform better.

Chris McManus, an expert in handedness at University College London, agrees that people with left-handed relatives have a brain that is "slightly more like that of a left-hander".

But he is sceptical about Christman's explanation. The link between a weak-handedness and a large corpus callosum is "distinctly controversial", he says

(Another report on the same study)

"Date: Posted 10/22/2001

The Brain's Halves Cooperate To Help Us Remember Events, Giving "Lefty Family" Members Better Episodic Memory

WASHINGTON — Does coming from a family full of “lefties” tend to make a person better at remembering events? The data from two recent experiments answer in the affirmative. What’s more, psychologists may finally be able to explain why kids don’t remember events until they are about four years old. This recent research is reported in the October issue of Neuropsychology, published by the American Psychological Association (APA).
Stephen D. Christman, Ph.D., and Ruth E. Propper, Ph.D., of the University of Toledo in Ohio, studied memory as a function of family handedness. Interestingly, people don’t have to be personally left-handed to share a unique trait: There is evidence that the two brain hemispheres of even right-handers with left-handed relatives share functions more equally, interact more and are connected by a larger corpus callosum (the bundle of mediating fibers) than the hemispheres of people with right-handed relatives. Although it is not well understood, there is a hereditary component to handedness.

Christman and Propper studied two types of memory -- episodic (the recall and recognition of events) and non-episodic (factual memory and implicit memory, the latter of which concerns things people “just know”). Strength or weakness in either, says Christman, “may not have much effect in educational settings, as we can recall things we have learned by ‘remembering’ them (episodic memory) or by ‘knowing’ them (implicit memory). The main difference is that people who ‘remember’ can also recall details about the time and place at which they first learned this fact.”

In the first experiment, which studied 180 right-handed Air Force recruits at Lackland Air Force Base in San Antonio, Christman and Propper found that for different types of word-memory tasks, participants with left-handed relatives had superior episodic memory and inferior implicit memory, at a rate greater than chance. The researchers therefore speculate that a higher level of inter-hemispheric interaction facilitates episodic memory.

In the second experiment, the authors studied episodic and semantic (factual) memory in 84 right-handed undergraduates, studying what happened when they presented words and letter strings to either one part of the brain or to both. When Christman and Propper presented stimuli to one part of the brain, participants remembered facts better. When the researchers presented stimuli to both halves of the brain, participants remembered events better -- again supporting the role of inter-hemispheric processing in episodic memory.

Christman and Propper conclude that because our brains’ two halves work together to help us remember events, people whose brains’ halves work together more actively (people with left-handedness in their families) remember events better than they remember facts. As a result, the authors say that memory studies should factor in the familial and probably personal handedness of participants (having a weak versus strong hand preference may also matter). Further research may help explain why episodic memory benefits from the two halves working together, whereas factual/implicit memory is better processed in one half alone.

The researchers stress that memory performance has nothing to do with so-called “brain dominance.” “While the notion of people being right-brained or left-brained is common in the popular press,” says Christman, “it has received very little support in the scientific literature. Both hemispheres of all people are going to be involved in virtually all tasks.”

Finally, the findings shed light on why children have no episodic memories until about age 4. The onset of episodic memory roughly coincides with the corpus callosum’s maturation and myelinization, the growth of fatty protective sheaths around nerve fibers. In light of the findings, it would mean that a functional corpus callosum is critical in the formation of event memories and therefore explain why its maturation in early childhood is at least partly responsible for the emergence of episodic memory.

5-"I can never remember a bloody thing, let alone where I put the house keys, etc."

To remember where you put your keys, pick a place, a single place, and always put them there.

Form a habit. It takes about 3 weeks to form a habit by habitually doing the same thing (it takes work to remember it at first) every time you do it.

For example, my keys are always in my right front pants pocket, no matter what, (except when they are in the car ignition of course). Even if I am working on the car in my shorts, the keys go back into my pants pocket until I am finished working on it (or alternatively, in the igntion if I am doing mechanical work).

For my wife, I built a small shelf near the front door, so she could deposit them as she came in, or grab them going out. Otherwise they would be where she landed after arriving, ie in the bathroom, in the kitchen, at the telephone, etc. (somehow they never would land in her purse like they should).

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