Curiously, just last night I came across some interesting material about left-handedness.
K.S. Bowers "Sex and Susceptibility as Moderator Variables in the Relationship of Creativity and Hypnotic Susceptibility." Journal of Abnormal Psychology 78 (1971) - cited by H. B. Gibson in "hypnosis" London: Peter Owen, 1977.
Bowers matched 36 men with 36 women for degree of hypnotizability, taking subjects at all levels of susceptibility, and tested them on measures of "creativity." It was found that for men creativity was slightly negatively related to hypnotic susceptibility, but for women there was quite a strong positive association.
Further experiment with most of the same subjects showed quite striking differences between the two sexes. Among all subjects whose susceptibility to hypnosis was relatively high, the relationship between creativity and hypnotizability was especially high for women and especially low for men.
If creativity is tapping into the subconscious mind, and hypnosis is supposed to help to do that - inducing a state of intense dissociation - how is it that it works for women, but creative men are resistant to hypnosis?
Apparently, this sort of thing turns up here and there in the literature but few serious studies have been done in this direction. Ernest Hilgard, in his book "Divided Consciousness: Multiple Controls in Human Thought and Action (New York: Wiley, 1977), reports a significant correlation between a favorable attitude to hypnosis and susceptibility to hypnosis in women, but no in men. In other words, if you approve of hypnosis and are female, there is a strong chance that you will be a good hypnotic subject; but if you approve of it and are male, no such assumption can be made.
Back to Gibson:
Weitzenhoffer {"Hypnotism" New York: Wiley 1963} reviewed a number of studies on the sex difference in hypnotizability, later than Hull, and noted regular slight superiority of females. We may wonder, therefore, why some authors state that there is no difference between the sexes. Here we come upon the point that may vex the lay reader and convince him of the old saying that there are lies, bloody lies, and statistics. Some writers have the habit of saying that there is "no difference" when they have shown a difference that is "not significant." ...
The fact is that if a certain tendency, however small, occurs again and again in the same direction in different studies, one can be pretty sure that there is a real tendency and in need of some explanation...
Gibson makes the point that this comment is also valid in reference to a lot of other data, including the incidence of neurosis and psychosis in men and women respectively. Apparently, neurosis is more common among females and psychosis is more common in males. Unfortunately, the last study done on this was in 1943. Why is no one interested in this? Gibson suggests that this is due to "feminist" pressure, but I wonder if it is not really that psychopaths planted that idea because it really is a protective mechanism for their "kind"?
The bottom line is: sex differences exist in correlates of hypnotizability, and this should be studied so that we can understand the implications of the differences between male and female brains/minds.
Then, we come to Ruben and Raquel Gurs work on "Handedness, Sex and Eyedness as Moderating Variables in the Relation between Hypnotic Susceptibility and Functional Brain Asymmetry" from the Journal of Abnormal Psychology 83 (1974). Gur thought that the inconclusiveness of the studies that connected hypnotizability with different functions of the two cerebral hemispheres was due to conceptual naivete of the experimental protocols. Other workers had not only ignored sex differences, but had also ignored the handedness of their subjects and the "eyedness" as well. (This does not refer to which eye you prefer to use when using a telescope or microscope, but something more akin to what is nowadays utilized in NLP.)
Experimental studies have shown that when asked to concentrate on a mental problem individuals will habitually glance to the left or to the right while thinking. Contrary to earlier assumptions, it seems that it is NOT the type of question (math, language, etc) that influences the direction of the glance, but which cerebral hemisphere the individual is employing at that moment.
Glancing to the right indicates employment of the left "Major" hemisphere and glancing to the left indicates the use of the right "Minor" hemisphere. Note that "left major" and "right minor" applies to right handed people.
However, not even all right-handed people glance to the right most of the time! Some right-handed individuals looked more often to the left. At the same time, some left-handers glanced more often to the right; and yet others (both left and right-handed) glanced equally to the right and left. In other words, handedness and eyedness did not necessarily agree.
More than that, ALL females are (according to the study) "less well lateralized for hemispheric functions" than all males, and left-handed males also more closely resemble the females in the bilateral representation than they do right-handed males, particularly in respect of language function.
Gur reports that individuals who were strongly left-handed AND glanced to the left when thinking more than 70% of the time, tended to be more readily hypnotizable that pure right handers. Between moderate left-handers and right-handers he found no differences. He also found a high negative correlation between number of eye movements to the right and hypnotizability for right-handed males; slight negative correlation between number of eye movements to the right and hypnotizability for left-handed males; slight positive correlation between number of eye movements to the right and hypnotizability for right-handed females, and hight positive correlation between number or eye movements to the right and hypnotizability for lef-handed females.
In other words: right-handed males who glance often to the right are hard to hypnotize as a rule, but right-handed females who do the same - glance often to the right - have a more positive tendency to hypnotizability. BUT, left-handed females who glance often to the right (which they should not be doing by handedness) are SIGNIFICANTLY more hypnotizable.
What does it mean aside from the obvious implication that male and female brains work differently and this can definitely have strong influences on many things?
Well, one thing that stands out is this: men become less creative or it is less creative men who tend to dissociate easily. Men who do not dissociate easily are apparently more creative. The reverse is true for women. So obviously, there are different roles that each play in the creative process and perhaps this is Nature's way of saying that creativity requires male/female cooperation in a way we do not fully understand.
ADDED: I am right-handed, but use my left hand for a number of tasks preferentially. I tend to glance to the left when thinking (started making note of this) and also habitually tilt my head to the left when thinking or listening. I preferentially use my left ear when on the telephone. (I used to think that this was due to the fact that my right ear was severely damaged when I was a child, but really, there is not that much difference in hearing capacity.)
