Intrauterine Influences

Several theories postulate intrauterine influences on handedness. In contrast to the pathology hypotheses, intrauterine hypotheses do not necessarily imply (minor) brain damage that changes the standard pattern of cerebral dominance. Rather, the intrauterine models explain variation in handedness as the consequence of subtle developmental mechanisms that affect lateralization. There are two theories about the role of the intrauterine environment in the origin of handedness, the testosterone...

Testosterone And Grasp Reflex

Total sample Table 3 presents the mean testosterone levels for the right-, left-, and mixed-handed participants for the grasp reflex in human neonates (unpublished observations). For the free testosterone levels, the difference between groups did not reach a traditional level of significance, F (2, 55) 2.56, p < .10. The left-handers had the lowest mean testosterone level, which was significantly less than that of the right-handers, t (35) 2.23, p < .OS, and mixed-handers, t (31) 2.01, p...

The Cerebral Theory And Hemispheric Asymmetry

The cerebral, or more specifically the 'hemispheric asymmetry', account of the cradling bias has its origin in a body of evidence on the lateralization of emotion that became increasingly well-developed during the 1970's and 1980's. Specifically, the theory reminds us that the right hemisphere (in those with conventional cerebral dominance) is specialised for the perception and expression of emotion (see Campbell, 1982 for an early review). Based on this well-established finding, it appeared...

Skilled Behaviour And Its Classification

Previous researchers have suggested that skill might be an underlying factor in both preference and performance (e.g., Steenhuis, 1996), based on evidence that the preferred hand is not only more often chosen to perform complex tasks, but also outperforms the non-preferred hand at such tasks (Flowers, 1975). Before reviewing the literature on the influence of skill on preference and performance behaviours, one should perhaps define skill. At a simplistic level, skill can be used to denote...

Males and females

The mean free testosterone levels were found to be 5.9+3.6 ng dL and 7.8+4.2 ng dL for the female (N 35) and male (N 47) neonates, respectively. The difference between males and females was statistically significant, t (80) 2.15, p < .05. The mean total testosterone levels were found to be 112.5+58.9 ng dL and 142.2+ 69.2 ng dL for the female (N 35) and male (N 47) neonates, respectively. The difference was statistically significant, t (80) 2.05, p < .05. In females, the mean total...

References

Aboitiz, F., Scheibel, A., & Zaidel, E. (1992). Morphometry of the sylvian fissure and the corpus callosum with emphasis on sex differences. Brain, 115, 1521-1541. Absoud, E.M., & Harrop, S.N. (1984). Hand injuries at work. Journal of Hand Surgery, 9, 21 1-215. Aggleton, J. P., Kentridge, R.W., & Good, J.M.M. (1994). Handedness and musical ability a study of professional study of professional orchestral players, composers and choir members. Psychology of Music, 22, 148-156. Alexander,...

Methods Of Handedness Measurement And Quantification

There are two general methods used to assess handedness 1) recording hand preference for everyday tasks, usually by interview or self-report on a handedness questionnaire, and 2) measuring hand performance for a specific manual task, such as moving pegs. The cross-correlations of preference and performance measures have been studied and reviewed (Bishop, 1989 Chapman & Chapman, 1987 Johnstone, Galin & Herron, 1979 Provins & Magliaro, 1993 Raczkowski, Kalat, & Nebes, 1974 Rigal,...

Factor Structures of Hand Preference Questionnaires Are Skilled and Unskilled Factors Artifacts

Mandal and M.P. Bryden ' lOsaka Gakuin Junior College, Japan 2 Indian Institute of Technology, India University of Waterloo, Canada The selection of activities to be included in a handedness questionnaire is of critical importance in the classification of handedness (see also Chapter 6, this volume). This is especially true when comparing data from different cultures, became the same activity may or may not be a good item for a hand preference questionnaire in different...

Neurodevelopmental Explanation

From a neurodevelopmental perspective, Previc (1991) poses arguments that stimulate differing thoughts from the typical operational definition concerning foot dominance (see also Chapter 2, this volume). Tracing its origins to asymmetric prenatal development of the ear and labyrinth and position of the fetus (cephalic-leftward, right ear facing out) during the final trimester, Previc hypothesizes that in most humans, about two-thirds, there is a left-otolithic advantage that underlies a...

Examining The Notion Of Foot Dominance

As mentioned in the introduction, it appears that in order to grasp the notion of foot dominance, a different perspective is required One that includes identifying and understanding the distinctive anatomical and physiological characteristics and behavioural features that are unique to this form of functional asymmetry. Actions of the lower limbs involve three alternative motor functions stability, mobility, and the combination of stability mobility. These functions are most typically described...

Facial asymmetry and emotional valence

Although much of the current literature suggests left facedness, that is, superiority of the right hemisphere in the expression of facial emotion, some evidence (e.g., Ehrlichman, 1987 Sackeim, Greenberg, Weiman, Gur, Hungerbuhler, & Geschwind, 1982) suggested a differential facial involvement for emotion as a function of emotional valence. The valence hypothesis proposes that negative emotions are predominantly associated with the right hemisphere and positive emotions with the left...

Asymmetries in Portraits Insight from Neuropsychology

On casual inspection, the human face appears to be very nearly symmetrical. Although individual features, such as a part in the hair, or a mole on the skin may vary within an individual, these individual differences cancel one another when they are considered as part of a larger population. Despite this apparent symmetry, it appears that we choose to portray ourselves asymmetrically. Giovanni Bellini's portrait of Leonardo Loredan, Doge of Venice (c. 1501) provides a good example of four...

Salks Cardiac Theory

The first closely argued explanation for the lateral cradling bias stressed the importance of the lateral position of the heart (Salk, 1960). Lee Salk appears to have first developed the theory when observing a mother rhesus monkey in the Central Park Zoo in New York (see Salk, 1973). Visiting the Zoo repeatedly, Salk observed the mother showing a left-sided cradling preference on 40 of 42 observed occasions. Salk reports wondering whether the phrase 'close to a mother's heart' was more than...

The measurement and expression of foot preference

Although the majority of research conducted on lateral preference has focused on handedness, research examining foot preference has recently come to be popular (see Chapter 10, this volume). The reason for this renewed interest in foot preference perhaps originates in the notion that foot preference may be a less biased measure of lateral preference than hand preference. Specifically, the preferred hand has had years of practice performing complex unimanual tasks such as writing. This is not...

Skilled Behaviour Task Complexity And Lateral Performance

Not only might skill be an important determinant of lateral preference, but it also appears to be an important factor in determining the degree of asymmetry in lateral performance. Instead of using the terms skilled and unskilled to refer to different classes of tasks, it may be more appropriate to discuss task complexity or task difficulty in relation to performance measures. Very little research has been conducted concerning foot performance and task complexity. Kauranen and Vanharanta (1996)...

Review Of Literature

In 1872, Darwin pointed out that the two sides of human face are not equally expressive. However, the first systematic study of facial asymmetry was conducted by Lynn and Lynn (1938, cited in Borod, Haywood, & Koff, 1997). These authors used the term 'facedness' to characterize facial asymmetry during emotional or nonemotional expression. About the same time, Wolff (1943, cited in Sackeim, Gur, & Saucy, 1978) studied facial asymmetry from an emotional quality point of view. Wolff noted...

Attentional And Intentional Factors In Pseudoneglect

Although most of the clinical studies reviewed above included control participants, pseudoneglect is obviously not as profound as hemispatial neglect, and studies designed for patients have neither enough trials nor enough participants to reliably detect any lateral biases. Control participants are also matched to patients for age and therefore do not reflect the primarily young population of undergraduates that are employed in studies of pseudoneglect. Age differences have been reported in...

The Fate Of Salks Theory

Salk's argument certainly represents an interesting proposal, with obvious implications for child care, especially in the immediate post-partum period. As a scientific theory it is also clearly open to empirical test in several areas, it has served to begin a series of cradling-bias investigations that has continued for several decades, and has been widely cited in the literature. However, the theory has not fared as well as might have been expected from the dramatic results of Salk's study....

Handedness And Hand Function In Musicians

Hand preference has been assessed in a number of studies of musicians (e.g., Aggleton, Kentridge, & Good, 1994 Byrne, 1974 Christman, 1993 Hassler & Gupta, 1993 Hering, Catarci & Steiner, 1995 Oldfield, 1969). Such studies have usually been carried out with a view to drawing inferences regarding the role of the right hemisphere in musical function. Despite differences in the methods of assessing hand preference, there are indications that among at least some sub-groups of musicians...

Motor Lateralization In Lower Vertebrates

Each side of the brain controls the musculature on the opposite side of the body and receives sensory input for the opposite side of the body. Thus use of a limb, or limbs, on the left side of the body engages the right hemisphere and vice versa. The same may be said of the body musculature used in turning in animals without limbs or with vestigial limbs. In species with well developed limbs it is possible to look for lateralized limb use in touching or holding objects or performing other acts...