Lateral biases are evident in a number of behaviors across many organisms. The present work was concerned with the particular lateral phenomenon known as handedness. Previous research has suggested that handedness is not a one-dimensional trait. This study evaluated handedness using two factors: hand preference and hand performance. Hand preference refers to the hand chosen to carry out a given action whereas hand performance refers to each hand’s ability, or skill, at carrying out that action. The relationship between hand preference and hand performance has been studied extensively in adults, but the larger body of work with human infants has only assessed hand preference. The goals of this study were to develop a methodology to measure infant hand performance and to begin to examine the relationship between hand preference and hand performance in development. To this end, thirty-six 11-month-old infants were videotaped completing three tasks. The first task assessed hand preference and consisted of a free-play period during which infants were presented with a series of toys that afforded different types of manipulation. The second and third tasks were novel measures of infant hand performance. The second task assessed the infant’s gross motor skills and involved fitting a ball into the top aperture of a toy. The third task assessed the infant’s fine motor skills by requiring infants to retrieve a Cheerio from a stationary plastic cup. Overall, the majority of infants were found to be right-preferent. This was in agreement with previous studies of hand preference in 11-month-olds as well as the pattern of hand preference seen in adults. There was no group-level asymmetry on either measure of hand performance. Hand preference was regressed on hand performance in an overall model of handedness. The right hand’s performance on each task significantly predicted hand preference scores. This was the first study to demonstrate that hand preference can be predicted by hand performance in infants. Future work will examine infant hand proficiency in greater detail as well as the relationship between hand preference and hand performance in nonhuman primate infants.

No description available.

Handedness is a widely studied behavioral asymmetry that is commonly measured as a preference for using one hand over the other. Right hand preference in humans occurs at a ratio of 9:1, whereas left hand preference in rhesus monkeys has been estimated at 2:1. Despite differences in the direction and degree of hand preference, this dissertation investigated whether primates share common underlying factors for the development of handedness. Previous work in human infants has identified a predictive relationship between rightward supine head orientation and later right hand preference. Experiment 1 examined the relationship between neonatal head orientation and later hand use in rhesus monkey infants (N=16). A leftward supine head orientation bias was found that corresponded to greater left hand activity for hand-to-face movements while supine; however, neonatal head positioning did not predict later hand use preference for reaching or manipulation on a coordinated bimanual task. A supine posture is common for human infants, but not for rhesus monkey infants, indicating that differences in early posture experience may differentially shape the development of hand use preference. Movement quality is an additional factor that may affect how the hands are used in addition to neonatal experience. 2-D and 3-D kinematic analyses were used to examine the quality of reaching movements in rhesus monkey infants (N=16), human infants (N=73) and human adults (N=12). In rhesus monkey infants, left hand reaches were characterized as ballistic as compared to right hand reaches independent of hand use preference (Experiment 2). Left hand ballistic reaching in rhesus monkeys may be a carryover from earlier primates that relied on very fast reaches to capture insect prey. Unlike monkey infants, reach quality was a function of hand preference in human infants (Experiment 3). By contrast, a right hand advantage for reaching was observed in human adults regardless of left or right hand preference (Experiment 4). Differential hand experience due to hand preference in early infancy may in part be responsible for the hand preference effects on movement quality observed in human infants but not monkey infants. Motor control may become increasingly lateralized to the left hemisphere over human development leading to the right hand advantage for reaching observed in human adults, as well as over primate evolution leading to right hand use preferences in higher primates like chimpanzees. An underlying mechanism such as a right shift factor in humans and a left shift factor in rhesus monkeys may be a common basis for primate handedness. Environmental and experiential factors then differentially shape this mechanism, including species-typical development. Further work examining the ontogeny of hand preference and hemispheric specialization in various primate infants will lead to a greater understanding of how different factors interact in the development of hand use across primate species.

Introduction Restorative sleep is crucial for cognitive, emotional and behavioral performance and general human well-being. Handedness has been discussed as one factor affecting sleep among various others including age, body mass index (BMI) and sex. Being the preferred use of one hand over the other, handedness has been linked to physiological traits like memory function and pathological conditions like psychiatric disorders. While several studies investigated potential associations between handedness and (mostly subjective) sleep, large-scale studies including a broad age span of participants and studies analyzing women and men separately are lacking. In addition, there are only few studies determining objective sleep. These studies provided inconsistent results. Objectives Therefore, the aim of this study was to examine associations between handedness and both objective and subjective sleep in a large cohort with a broad age range from 18 to 80 years. In addition, the aim was to address potential endocrine effects by comparing associations in women and men as well as in premenopausal and postmenopausal women. Methods A subset of the approximately 10,000 participants from the population-based study “LIFE-Adult” (Leipzig Research Center for Civilization Diseases – adult group) was analyzed with regard to their handedness, objective and subjective sleep and important co-factors. Objective sleep data were determined using at-home actigraphy from 1764 healthy participants (18 to 80 years, 908 women), averaging five consecutive nights. 1024 individuals receiving acticraphy had been previously excluded for not meeting any of the in- and exclusion criteria. Only data collected in nights prior to work days were used. In addition, subjective sleep-related data were captured by self-report diaries, the Pittsburgh Sleep Quality Index (PSQI), the Epworth Sleepiness Scale (ESS) and the Morningness-Eveningness-Questionnaire (MEQ). Handedness was determined using the Edinburgh Handedness Inventory (EHI). The EHI provides information on the direction (i.e. left vs right) and the degree of handedness (i.e. strong vs weak). To address potential endocrine effects, premenopausal women (≤45 years) and postmenopausal women (≥55 years) were analyzed separately. This was also done for men, leaving four subgroups: young females (N=190), young males (N=137), female seniors (N=511) and male seniors (N=519) in order to compare pre- and postmenopausal age groups. Subgroups were compared using t-Test and correlations between sleep parameters and handedness were calculated using Spearman rank correlations. Results The degree and direction of handedness were correlated with “wake after sleep onset” (WASO) in the total sample and all women (the more right-handed/lateralized the shorter WASO). In postmenopausal women, additionally, time in bed (TIB) and total sleep time (TST) were positively correlated with right-handedness/higher lateralization. There were no other significant associations between an objective sleep variable and handedness. In both premenopausal women and >55-year-old men subjective quality of sleep (PSQI) was correlated with direction and degree of handedness, i.e. the more right-handed/lateralized the better. In the total sample and postmenopausal women, the degree and the direction of handedness were negatively correlated with daytime sleepiness, i.e. the less right-handed/lateralized the higher the daytime sleepiness. The chronotype was not associated with handedness in any group. 91% of participants were classified as RH with a very high degree of lateralization that was lower in non-RH participants. 5.4% of the women and 4.1% of the men were left-handed, 3.6% of the women and 4.8% of the men were ambidextrous as defined by the EHI-Score (EHI > 50 as RH, EHI < -40 as LH). Discussion To my knowledge, this is by far the largest study investigating the association between handedness and objective and subjective sleep. Most essential findings are, that right-handedness and higher lateralization both are associated with the following: a) less WASO in the whole group, all women and postmenopausal women b) more TIB and TST in postmenopausal women c) better subjective quality of sleep in premenopausal women and >55-year old men d) less daytime sleepiness in the total group and postmenopausal women Thus, overall, while associations were not consistently found in all groups, right-handedness tended to be associated with better sleep and less daytime sleepiness. Overall, associations were weak, though. The finding, that direction and degree of handedness showed similar correlations, is plausible, since the vast majority of participants were right handed and showed a high degree of lateralization. Results of this study are met by a relatively small body of literature, as only 11 studies were conducted on the association between handedness and sleep so far. Out of these, four used objective measuring techniques on young participants exclusively (mean ages from 20.5 to 22.4 years), delivering a rather inconsistent picture. For example, while longer or shorter TST was found to be associated with right-handedness, other studies could not find an association at all. Also findings from our study do not show a homogenous picture. Overall, however, direction and degree of handedness (the more right-handed and the more lateralized) were associated with better objective sleep, being roughly in line with most of the studies. In contrast to these, however, our study is the first one to include participants over 30 years of age. Comparably, out of the seven studies focusing on subjective sleep, all but one included participants younger than 30 years. Findings here mostly indicated, that right-handedness or higher lateralization are associated with better subjective sleep (e.g. longer TST, less WASO, fewer sleep problems). The only study targeting older participants did not find differences in the proportion of individuals agreeing to the question, whether they “can get enough rest and sleep”. Thus, our study is overall in line with the studies in younger adults. Importantly, our study is the first to explore the relationship between handedness and daytime sleepiness. Here, right-handedness and higher lateralization were associated with less daytime sleepiness. This finding is in line with the idea that it may be more stressful and exhausting for non-RH coping in a right-handed world. While we did not find striking differences between women and men or between pre- and postmenopausal women, several indications might suggest endocrine influences: For example, TIB and TST were positively correlated in postmenopausal but negatively in premenopausal women. Such findings warant further research on the influence of sex hormones on both handedness and sleep. Conclusion Although associations found in this study were not consistent in all subgroups, a trend towards right-handedness and higher lateralization being associated with aspects of better objective and subjective sleep as well as less daytime sleepiness became apparent. Seemingly differing associations between women and men are in line with endocrine interactions. Degree and direction of handedness seem to be equally important and should both be considered in future research.

Introduction Restorative sleep is crucial for cognitive, emotional and behavioral performance and general human well-being. Handedness has been discussed as one factor affecting sleep among various others including age, body mass index (BMI) and sex. Being the preferred use of one hand over the other, handedness has been linked to physiological traits like memory function and pathological conditions like psychiatric disorders. While several studies investigated potential associations between handedness and (mostly subjective) sleep, large-scale studies including a broad age span of participants and studies analyzing women and men separately are lacking. In addition, there are only few studies determining objective sleep. These studies provided inconsistent results. Objectives Therefore, the aim of this study was to examine associations between handedness and both objective and subjective sleep in a large cohort with a broad age range from 18 to 80 years. In addition, the aim was to address potential endocrine effects by comparing associations in women and men as well as in premenopausal and postmenopausal women. Methods A subset of the approximately 10,000 participants from the population-based study “LIFE-Adult” (Leipzig Research Center for Civilization Diseases – adult group) was analyzed with regard to their handedness, objective and subjective sleep and important co-factors. Objective sleep data were determined using at-home actigraphy from 1764 healthy participants (18 to 80 years, 908 women), averaging five consecutive nights. 1024 individuals receiving acticraphy had been previously excluded for not meeting any of the in- and exclusion criteria. Only data collected in nights prior to work days were used. In addition, subjective sleep-related data were captured by self-report diaries, the Pittsburgh Sleep Quality Index (PSQI), the Epworth Sleepiness Scale (ESS) and the Morningness-Eveningness-Questionnaire (MEQ). Handedness was determined using the Edinburgh Handedness Inventory (EHI). The EHI provides information on the direction (i.e. left vs right) and the degree of handedness (i.e. strong vs weak). To address potential endocrine effects, premenopausal women (≤45 years) and postmenopausal women (≥55 years) were analyzed separately. This was also done for men, leaving four subgroups: young females (N=190), young males (N=137), female seniors (N=511) and male seniors (N=519) in order to compare pre- and postmenopausal age groups. Subgroups were compared using t-Test and correlations between sleep parameters and handedness were calculated using Spearman rank correlations. Results The degree and direction of handedness were correlated with “wake after sleep onset” (WASO) in the total sample and all women (the more right-handed/lateralized the shorter WASO). In postmenopausal women, additionally, time in bed (TIB) and total sleep time (TST) were positively correlated with right-handedness/higher lateralization. There were no other significant associations between an objective sleep variable and handedness. In both premenopausal women and >55-year-old men subjective quality of sleep (PSQI) was correlated with direction and degree of handedness, i.e. the more right-handed/lateralized the better. In the total sample and postmenopausal women, the degree and the direction of handedness were negatively correlated with daytime sleepiness, i.e. the less right-handed/lateralized the higher the daytime sleepiness. The chronotype was not associated with handedness in any group. 91% of participants were classified as RH with a very high degree of lateralization that was lower in non-RH participants. 5.4% of the women and 4.1% of the men were lefthanded, 3.6% of the women and 4.8% of the men were ambidextrous as defined by the EHI-Score (EHI > 50 as RH, EHI < -40 as LH). Discussion To my knowledge, this is by far the largest study investigating the association between handedness and objective and subjective sleep. Most essential findings are, that righthandedness and higher lateralization both are associated with the following: a) less WASO in the whole group, all women and postmenopausal women b) more TIB and TST in postmenopausal women c) better subjective quality of sleep in premenopausal women and >55-year old men d) less daytime sleepiness in the total group and postmenopausal women Thus, overall, while associations were not consistently found in all groups, righthandedness tended to be associated with better sleep and less daytime sleepiness. Overall, associations were weak, though. The finding, that direction and degree of handedness showed similar correlations, is plausible, since the vast majority of participants were right handed and showed a high degree of lateralization. Results of this study are met by a relatively small body of literature, as only 11 studies were conducted on the association between handedness and sleep so far. Out of these, four used objective measuring techniques on young participants exclusively (mean ages from 20.5 to 22.4 years), delivering a rather inconsistent picture. For example, while longer or shorter TST was found to be associated with right-handedness, other studies could not find an association at all. Also findings from our study do not show a homogenous picture. Overall, however, direction and degree of handedness (the more right-handed and the more lateralized) were associated with better objective sleep, being roughly in line with most of the studies. In contrast to these, however, our study is the first one to include participants over 30 years of age. Comparably, out of the seven studies focusing on subjective sleep, all but one included participants younger than 30 years. Findings here mostly indicated, that righthandedness or higher lateralization are associated with better subjective sleep (e.g. longer TST, less WASO, fewer sleep problems). The only study targeting older participants did not find differences in the proportion of individuals agreeing to the question, whether they “can get enough rest and sleep”. Thus, our study is overall in line with the studies in younger adults. Importantly, our study is the first to explore the relationship between handedness and daytime sleepiness. Here, right-handedness and higher lateralization were associated with less daytime sleepiness. This finding is in line with the idea that it may be more stressful and exhausting for non-RH coping in a right-handed world. While we did not find striking differences between women and men or between preand postmenopausal women, several indications might suggest endocrine influences: For example, TIB and TST were positively correlated in postmenopausal but negatively in premenopausal women. Such findings warant further research on the influence of sex hormones on both handedness and sleep. Conclusion Although associations found in this study were not consistent in all subgroups, a trend towards right-handedness and higher lateralization being associated with aspects of better objective and subjective sleep as well as less daytime sleepiness became apparent. Seemingly differing associations between women and men are in line with endocrine interactions. Degree and direction of handedness seem to be equally important and should both be considered in future research.

This study was undertaken in an effort to determine whether or not left-handed students achieve as high pro- ficiency as do right-handed students in secondary school subjects which require motor ability. This problem came to the attention of the writer after he had examined the pre- vious writings in the general field of inquiry. It was found that mich of the material contained in these earlier studies had to do with the probable causes of handedness and what the effect would be to change a sinistral indi- vidual to dextral usage. Less material was found concern- ing the relative success of the left-handed student who was permitted to continue using his left hand.

No description available.

No description available.

This investigation was an attempt to replicate and expand previous research which suggested that laterality of electromyographic biofeedback input had a significant effect in lowering frontalis muscle activity. In 1984 Ginn and Harrell conducted a study in which they reported that subjects receiving left ear only audio biofeedback had significantly greater reductions in frontalis muscle activity than those receiving right ear only or both ear feedback. This study was limited to one biofeedback session and subjects were selected based on demonstration of right hand/ear dominance. The purpose of the present study was to determine whether the left ear effect reported by Ginn and Harrell could be replicated. Furthermore, the current investigation sought to extend the previous finding to left handed subjects and explore the stability of the effect, if found, by adding a second biofeedback session. Subjects were 96 students recruited from undergraduate psychology classes. They were screened for handedness by the Edinburgh Handedness Inventory which resulted in identification of 48 right handers and 48 left handers. Subjects were randomly assigned to one of four groups consisting of left ear feedback, right ear feedback, both ears feedback, and controls. This resulted in eight conditions. Analysis of variance of microvolt changes from baseline found no statistically significant differences between groups. An examination of the rank order of the data reveal a left ear group performance in the same direction as those reported by Ginn and Harrell (1984).

Made available in DSpace on 2016-04-28T20:56:45Z (GMT). No. of bitstreams: 1 Priscila Lambach Ferreira da Costa.pdf: 1337763 bytes, checksum: fab2c985ec1fc87b4f1676e037283192 (MD5) Previous issue date: 2014-04-11 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This research aimed to understand how people experience the condition of being left-handed, trying to identify the characteristics of manifestation of laterality, understand the relationship of the person with his family, school and work concerning this condition. Thus, it was possible to locate the difficulties faced by this group, the facilities and advantages of being left-handed, discussing the significance of this difference, and the myths and prejudices faced throughout their lives. A theoretical study was conducted to clarify the concept of handedness what causes a person to be left-handed or right-handed, left-handed throughout history and conceptions about this condition. We worked with non-directive interviews, focusing on the life stories in the pursuit of understanding the constitution of the person, as proposed by Ciampa. Five women between 23 and 82 years old, represented different generations, which allowed us to identify changes in how school and society realized and acted in relation to the left-handed. The data demonstrate varied experiences, with cases of repression of handedness by family and school, and others in which there was no objection. Difficulties remained in the material aspect, such as using scissors and desks, for example. Common form, found that this difference reaches a minority group, even if it involves some difficulties, is not a negative experience. We found that the left-handed accepts and is pleased with his condition, he feels that belongs to a group in which people recognize and value, and although throughout history left-handedness has been considered something allied to evil and negative, today there is a new look. The left-handed like to be different, to stand out among the rest / Esta pesquisa teve por objetivo compreender como as pessoas vivenciam a condição de serem canhotas, buscando identificar as características de manifestação da lateralidade, além de compreender a relação do sujeito com sua família, escola e trabalho frente a essa condição. Dessa forma, foi possível localizar as dificuldades enfrentadas por esse grupo, as facilidades e vantagens de ser canhoto, discutindo o significado dessa diferença, e os mitos e preconceitos enfrentados ao longo de suas vidas. Foi realizado um estudo teórico para esclarecer o conceito de lateralidade, o que leva uma pessoa a ser canhota ou destra, o canhoto ao longo da história e concepções sobre essa condição. Foram realizadas entrevistas não diretivas, com foco nas histórias de vida, em busca da compreensão da constituição do sujeito, tal como proposto por Ciampa. Foram entrevistadas cinco mulheres entre 23 e 82 anos, representantes de diferentes gerações, o que permitiu identificar mudanças na maneira como a escola e a sociedade perceberam e agiram em relação ao sujeito canhoto. Os dados demonstram experiências variadas, havendo casos de repressão da lateralidade pela família e pela escola, e outros em que não houve objeção. As dificuldades se mantiveram no aspecto material, como o uso de tesouras e carteiras escolares, por exemplo. De forma comum, constatamos que essa diferença que atinge um grupo minoritário, ainda que implique algumas dificuldades, não é vivenciada negativamente. Verificamos que o canhoto aceita e se compraz com sua condição, sente-se pertencente a um grupo em que as pessoas se reconhecem e se valorizam e, apesar de ao longo da história o canhotismo ter sido considerado algo aliado ao mal e ao negativo, hoje há uma nova postura. O canhoto gosta de ser diferente, de se destacar entre os demais