Marylyn Annett

A subgroup classification of handedness, ordered for degrees of relative hand skill, was linearly related to the probability of nonright preference for foot and eye in a volunteer sample of 263 people from the general public. Percentages of people with a nonright-handed parent also differed over groups as expected but not significantly.

This paper explains how combinations of asymmetries for pairs of laterality variables may be predicted. It shows that many pairs combine as expected by chance, plus the influence of the RS+ gene hypothesised by Annett (1978, 1985). These include: eye dominance with writing hand, with throwing hand, and with foot for kicking; nonright handedness wit...

The reported therapeutic benefits of nonsteroidal anti-inflammatory drugs (NSAIDs) in slowing periodontal disease progression appear intimately linked to the effective inhibition of local prostaglandin synthesis. This randomized, partially double-blind, controlled trial was conducted to evaluate the pharmacodynamic effects of the NSAID, ketoprofen...

The right shift (RS) theory (Annett, M., 1972. The distribution of manual asymmetry. Br. J. Psychol. 63, 343-358; Annett, M., 1985. Left, Right, Hand and Brain: The Right Shift Theory. Lawrence Erlbaum, London) suggests that the typical pattern of human cerebral and manual asymmetries depends on a single gene (RS+) which impairs speech-related cort...

The right shift (RS) theory of handedness and cerebral dominance (Annett, 1972, 1985) suggested that individual differences for patterns of cerebral dominance may be associated with different types of risk to cognitive functions. The higher prevalence of dextrality than sinistrality in humans depends on a single gene (RS+) which facilitates left he...

The right-shift (RS) theory suggests that sex differences for handedness are due to the displacement of a chance distribution of asymmetry farther to the right in females than males by about 20%. An analysis of studies in the literature shows that when handedness is assessed by self-report, paired samples of males and females differ for incidence o...

This clinical trial used a randomized, partially double-blind, controlled parallel design to evaluate the pharmacokinetics and safety of the NSAID, ketoprofen (KTP), in gel formulations. Forty-two subjects, ages 35 to 57 years, with generalized, moderate to advanced adult periodontitis were recruited and randomized to one of 5 treatments over a 14...

Alexander and Annett (Brain and Language, in press) described new cases of atypical cerebral specialization, and suggested that these observations and others in the literature could be explained by the right shift (RS) theory. The theory generates specific predictions as to the prevalence of different patterns of cerebral dominance and their distri...

Anomalous lateralization of cognitive functions is observed in a small percentage of right-handed patients with unilateral brain damage, either crossed aphasia (aphasia after right brain damage) or "crossed nonaphasia" (left brain damage without aphasia but with visuospatial and other deficits typical of right brain damage). No comprehensive theory...

The prediction of the right shift theory that there are two types of dyslexia with different distributions of handedness was examined in a large cohort of school children. Dyslexics with poor phonology were less biased to dextrality than controls, while dyslexics without poor phonology tended to be more dextral than controls on measures of hand pre...

The right shift (RS) theory of a gene for left-cerebral dominance which increases the probability of right-handedness is outlined, together with two proposed alternatives, the 1985a genetic theory of McManus and the 1993 developmental instability theory of Yeo and Gangestad. Similarities and differences among the three theories are reviewed. Both o...

The question whether there is an association between handedness and dyslexia has been investigated in many studies spanning more than 50 years. In 1990, Bishop reviewed studies which met stringent methodological criteria and concluded that there was little support for an association. A reanalysis of the same studies using newer procedures of meta-a...

Questions about twin birth, sex, age and handedness for writing were asked as part of a survey of hearing disability (Davis, 1989) in a large sample of the adult population. The findings show unequivocally that the prevalence of left handedness is higher in twins than in the singleborn, in males than in females and in younger than in older adults....

Percentages of left-handed relatives were compared between subgroups of left-handers and of right-handers to test the prediction that the subgroups are ordered for probability of carrying the rs +/gene (hypothesized by the right-shift theory of handedness). Data included families of undergraduates and Open University students who described their ch...

The fallacy of the argument for reduced longevity in left-handers depends on the use of the writing hand in the assessment of the present generation of elderly people, when writing was not used as a criterion in the early years of the century. A 'thought' experiment demonstrates that a sample of left-handers is likely to be younger than a sample of...

Four group tests of hand skill, square marking (SQUARES), dotting between targets (DOTS), line drawing between targets (LINES) and punching holes through targets (HOLES), were given to samples of undergraduates and schoolchildren, most of whom were also tested individually on a peg moving task (PEGS). Findings for PEGS were shown to be comparable t...

Two tests of spatial ability, mental paper folding given to 459 14-15-year-olds representative of the secondary school population, and recall of the Rey figure given to 428 undergraduates, found significant relationships between ability and hand preference when preferences were classified in subgroups of left- and right-handers (Annett, 1970a). In...

Relationships between the skill of each hand and differences between the hands are described for a sample of 14-15-year-olds representative of the general population. The description is modelled on the account of Galaburda et al. (Neuropsychologia 25, 853-868, 1987) of relationships between asymmetries of the Planum Temporale (PT) and measures of P...

A phoneme segmentation task requiring Ss to produce deliberate spoonerisms was performed by 78 undergraduates, along with a dichotic monitoring task and tests of hand preference and hand skill. The hypothesis that those performing badly on the speech task would include a higher proportion of individuals with left ear advantage on the dichotic task...

Observations of spontaneous reaching for food in 31 captive lowland gorillas found a full range of hand preferences between strong left and strong right, with most animals showing intermediate levels of preference. There was a high degree of consistency between observations made on different occasions for the same animal, showing that degrees of re...

This review will address three main questions relevant to child psychology and psychiatry: first, what is known about the nature of human cerebral dominance and how it develops; second, what can be said about the exceptions (left handers and those with right hemisphere or bilateral speech); and third, what if any are the implications for intellectu...

The idea that reading ability might vary with right-left hand skill, such that children with mild biases to the right hand have advantages for learning, while children at both left and right extremes have disadvantages, was supported by findings for a large sample of primary schoolchildren. Poor readers tended to have weak left hand skills, giving...

Relationships between arithmetic ability, hand preference and hand skill were investigated in a general population sample of schoolchildren, aged 9-11 years. Incidences of non-right-handedness were highest in the children best at arithmetic and fell progressively through average and below average groups. Strong effects were found for hand skill; le...

The right shift (RS) theory of handedness suggests that the human bias to dextrality has costs as well as benefits. Samples of children from six primary schools were individually tested for hand preference, hand skill and Raven's Matrices. Scores on standardized educational tests recently given by teachers were available for three schools. When chi...

The raised incidences of strong left-handedness and of mixed-handedness in homosexual men, as in dyslexics, are mutually consistent under the normal distribution function, as expected by the right shift theory of handedness. It is argued that atypical laterality in these groups is better described as a "reduction of right shift" than as a "left shi...

Two main approaches to problems of individual differences in hemisphere specialisation are to be found in the literature. The first is avoidance: subjects are restricted to fully right-handed males, with no known left-handed relatives. It is assumed that such subjects are likely to be homogeneous for the typical pattern of cerebral specialisation....

The lateral preferences and L-R skill of 109 male and 20 female dyslexics were as expected if the distribution of lateral asymmetry is shifted less far to the right in dyslexics than in controls. Several aspects of the data were consistent with Annett's hypothesis that some dyslexics lack the left hemisphere speech-organising factor postulated by t...

Hand preference and hand skill were examined in relation to sex and age from 3 1/2 to 50+ years. The data were drawn from several samples which avoided volunteer bias, either by selecting children according to birth-date or by taking complete class groups. The distribution of hand preference and of asymmetry of skill gave no evidence of systematic...

The distribution of differences between the hands (L-R) in skill, as measured by a peg-moving task, was examined for several samples in which volunteer bias was absent or minimal. After comparing the main samples for hand preference and L-R times, they were combined to give 617 males and 863 females, aged 12–63 years. There was also a smaller sampl...

A second sample of children of L × L parents resembled a first sample (Annett, 1974) in the distribution of hand preferences and of hand skill. The mean difference between the hands in skill (L—R) was slightly but not significantly biased in favour of the right hand and 31 per cent were sinistral writers. Three tests were made on the combined sampl...

Directional biases in visual perception were examined for individual differences in sixty-five subjects on two tasks. One task required judgments of the onset asynchrony of pairs of dots presented at random, either one dot in each visual field, or both in the left visual field (LVF), or the right visual field (RVF). The second task required the rec...

The hypothesis that special ability in mathematics is associated with a reduction in bias to dextral preference and skill was examined in several samples of students and in 97 male and 27 female teachers of mathematics, mainly in Universities and Polytechnics. The math students and math teachers differed from controls, both general and academic, in...

Left-handed and right-handed parents in personally visited families were asked about the perinatal history of themselves, and their children. Reported birth stress (RBS) was as frequent for right-handers as for left-handers. The children of left-handed mothers were not more likely to have RBS than the children of right-handed mothers. The incidence...

The nature of the difference in skill between the preferred and non-preferred hands was investigated using a peg-board task. The first experiment examined the effects of varying movement amplitude and target tolerance on performance. The difference between hands was found to be related to tolerance rather than movement amplitude. The second study a...

Experiments designed to check the absence of effects for hands and handedness in simple and two-choice reaction time found unexpected individual differences related to stimulus laterality. The majority of subjects responded faster to the stimulus on the left and a substantial minority responded faster to the stimulus on the right in any choice pair...

The hand preferences of Open University (OU) students and their relatives, including children, are described. As in earlier series, estimates of heritability are higher for mothers than fathers. There is no evidence of smaller heritability for paternal than maternal grandparents. The distribution of left-handedness in families is examined in the li...

A brief review of theories of the causes of handedness shows why the major determinant is probably accidental variation, modified in man by a genetic factor inducing dextral bias. Levy's (1976, 1977) criticisms of Annett (1973) are answered by a detailed consideration of Chamberlain's (1928) report and by the presentation of an alternative analysis...

Annett (1970a) described 283 subjects classified for hand preference and measured for the movement time of each hand on a peg moving task. A new sample of 804 subjects has been examined and classified as before. The mean differences between hands for each preference group are very similar in both samples. Hand preference can be regarded as anchored...

A theory of the origins of hand preferences (Annett, 1972) is outlined and its implications for the distribution of cerebral speech in handedness groups are examined. Five studies of dysphasia in right and left handers with unilateral cerebral lesions are compared and found surprisingly consistent. Data from three series found alike in all essentia...

Measures of manual speed on a peg moving task were repeated after intervals ranging from 7 weeks to 18 months. Significant test-retest correlations were found for each hand and for the difference between hands. In a second experiment, with this task, practice was found to improve the speed of each hand but not to eliminate the difference between th...

Tests of naming and visual discrimination given during recovery from unilateral ECT show poorer naming after left sided than after right sided treatments. No systematic differences could be demonstrated for the visual task. The time needed for the psychological examination was longer after left sided than after right sided treatment, and this diffe...

Measures of hand speed in 45 children having two sinistral parents showed an equal division between children faster with the right hand and children faster with the left hand. The mean difference was very close to zero and the standard deviation was not less than that of unselected samples. These observations are compatible with the theory that the...

. A random sample of right-handed children and a population sample of left-handed children, including over 100 subjects in each group, were assessed for vocabulary, drawing, maze tracing and for laterality of hand, eye and foot. Reading quotients were available for 145 children. The data were examined in two ways. The first compared the abilities o...

The handedness of 3644 yound adults and that of their parents and siblings is described for the incidence of left handedness in children from families classified for parental handedness and also in the relatives of right and left handers. Estimates of heritability are derived for this main sample and also for a smaller sample of parents and grandpa...

The effect of laterality of early brain lesions and the role of familial sinistrality were examined in a population sample of 106 hemiplegic children. Each child was assessed for speed of peg moving by the affected hand and the better hand, for verbal and performance scale IQ and for the presence of epilepsy, speech difficulties and other special d...

Four different descriptions of lateral asymmetry are reviewed and their probable interrelations examined. Two main features are distinguished: first, a normal distribution of relative efficiency of the two sides which probably applies to all species subject to lateral differences; second, a factor specific to humans which induces a shift of the nor...

Hand preference, speed of movement of each hand and vocabulary were examined in a random sample of children aged 3 1/2–15 years. The distributions of preference and relative manual speed were found unchanged during growth. Sex differences in preference and skill indicated that females are more asymmetrical to the right than males. Right-, mixed and...

An association analysis was made of the responses of young adults to a hand-preference questionnaire. Many patterns of preference were distinguished and there were no marked differences between adjacent classes. These findings are believed to demonstrate that hand preference is distributed continuously and not discretely. When it is necessary to cl...