British Survey of Left-handedness

Copyright 1992 by Nigel Bradley

In order to assess the incidence of left-handedness in the United Kingdom a representative sample of the British population was questioned. The results are summarised and discussed in relation to other published papers.

This article first appeared in the British Institute of Graphologists journal: The Graphologist 1992 (Winter), 10(4) Issue 37, 176-182).

Method

RSL-Research Services Ltd. is an independent market research agency with interviewers spread throughout the country. This field force uses laptop computers to administer questionnaires in respondents’ own wwws. This methodology is known as CAPI (Computer-assisted personal interviewing). The present study was conducted using RSL’s weekly omnibus known as CAPIBUS. A two stage random location design was used. The Post-code Address File (PAF) was used as a sampling frame and addresses were selected using the geo-demographic segmentation tool ACORN. 180 start points were randomly selected and at each point interviewers had to achieve tight interlocking quotas within a small area. Approximately 2000 interviews are achieved each week. This task was undertaken in March and April 1992 and covers several weeks of fieldwork. The question used was ‘Do you normally use your left hand to write with?’ This was put to 8435 people.

The results by handedness and gender are shown in Table 1, where it is shown that approximately 10 per cent of the population are left-handed, and slightly more among men than women.

Table 2 shows the same information by age. The left-handed percentage is roughly the same up to age 54, and then falls off noticeably. One interpretation of this, which has appeared in the popular press, could be that left-handers die earlier than right-handers.

An alternative view, however, is that older people were at school during the period when children were often being forced into the right-handed mould, and left-handedness was suppressed. The wisdom of this unnaturalness was being questioned at the time, and so not all children were subjected to it, but it took time for the more liberated view to prevail completely.

The next step was an examination of regional differences in handedness. Table 3 reports on a smaller sample of 6280 respondents. It also groups ambidextrous people together with left-handers. Most of England has 11-12 per cent of the people left-handed or ambidextrous while the Celtic fringe of Wales and Scotland has 8 per cent. If this is a genetic difference it suggests that many Scottish genes are present in the North of England, where the percentage is a similar figure of 8 per cent.

Table 3 REGIONAL DISTRIBUTION OF LEFT-HANDEDNESS

A very different hypothesis is that, perhaps, older teaching methods prevail in Wales, Scotland and the North, persuading more natural left-handers into right-handedness. Another suggestion is that, for some reason, left-handed people are more likely to migrate away from these areas. Neither of these cultural explanations account for the abrupt discontinuity as well as does the existence of a broadly different gene pool, and this has been tested by asking left-handers and ambidextrous people whether any member of their family was also left-handed (Table 4).

Father also left-handed #9; 9

Mother also left-handed 9

More than half of the left-handers questioned had some known family members left-handed also. As this figure is much larger than the 10 per cent that would be expected purely by chance, it seems clear that there is a genetic factor of family likeness in operation. The differential may even be a little understated, as some without apparent left-handedness in the family may have relatives who were compelled to be right-handed in the past. This masking effect could hardly work in the opposite direction, so we are probably safe to regard 56 per cent as a minimum figure.

Left-handers were asked what they believed to be the advantages and disadvantages of their handedness. Table 6 shows clearly that the latter are thought to outweigh the former. While two-thirds of the respondents saw no particular advantage, only 39 per cent had met no disadvantage, and the list of disadvantages specified is much longer than the list of advantages. Sport was their most frequently mentioned item.

Although over one-third find no problem, the remainder have concerns. Relevant for graphology is the fact that 17 per cent complain that they cannot perform the writing process satisfactorily, and that their writing becomes smeared. They also find difficulties with desks made for right-handers. A range of utensils and skills pose problems and it is disturbing to think that such basic behaviour as eating or opening doors is likely to cause difficulties for about 56,000 people in Britain today, due simply to left-handedness.

Piggott (1958) collected 25,000 samples of handwriting dating from 1956-7 and found that 5 per cent were left-handed. This percentage is the same as that found in people over 65 years in the 1992 study, who would then have been over 36. Macfarlane Smith’s study (1964) found a slightly higher percentage than seven to eight years previously. There was a sex difference, with 7 per cent of males left-handed but still only 5 per cent of females.

Patterson, working in 1967 and 1970, analysed 500 questionnaires from members of MENSA, whose members score highly on intelligence tests. She found 7 per cent were left-handed, but this is a minimum figure as 12 per cent had unknown handedness, including some who were ambidextrous. It seems that the percentage was increasing over time.

Norman Geshwind and Albert Galaburda, at the Harvard Medical School in Boston suggested that left-handedness may be created by a higher level of testosterone in the mother, which may slow the development of the left side of the brain and allow the right side to become dominant, leading to a left-hander. As the male foetus also has more testosterone, this hypothesis would account for the greater frequency of left-handedness in boys than girls. Women naturally have lower levels of male hormones and are less often left-handed.

Coren (1992) offers another important viewpoint: "...the right hemisphere of the brain develops earlier. If the foetus is deprived of oxygen during pregnancy, left brain damage is much more likely to happen than right brain damage. The left hemisphere requires more energy than the right for its normal functioning. It is at greater risk of having its blood supply and oxygen temporarily stopped by the pressure on the head and the arteries during delivery.’’

Coren contacted four thousand families to discover whether there is a direct relationship between birth stress and left-handedness, and found that the age of the mother is important. The older the mother, the greater the chance of a left-handed child. Maternal smoking also predisposed to left-handedness, and furthermore, premature and Caesarean babies are more likely to be left-handed than others.

These various influences suggest that environmental conditions can affect left-handedness as well as the genetic ones implied by regional differences, and supported by international comparisons. West Africa has been reported as having a common problem of stutterers, a high incidence of twins, and frequent left-handedness. Compare this with Japan which apparently has the world’s lowest level of stuttering and left-handers, in stark contrast to China, where at least 18 per cent of the population is left-handed (Teng, 1976). There seems a clear difference in handedness from place to place.

Like British left-handers, those studied elsewhere are not able to see major benefits from their predicament. There are well documented advantages in baseball, in that better swings can be made to hit and then run in the same direction. In fencing, opponents are confused, as the left-hander does it all backward, and other sports such as tennis have similar stories. The right-hander has more clockwise strength, but the left-hander can apply more force turning anti-clockwise, which helps to open tightly screwed jars.

Disadvantages, however, are more common. Paul (1992) mentions turning on computers, and operating microwave ovens, fax machines, car phones, electric sewing machines, cameras, videos and television sets. Coren (1992) mentions soup ladles, saws, hockey sticks, fishing rods and even the reading of books. He asserts that left-handers are more common among individuals with a history of alcoholism, suicide attempts, epilepsy and migraine, and are more likely to suffer from asthma, insomnia, allergies and diabetes. Similar information is not available from the 1992 United Kingdom Survey, but case studies would be possible.

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