Arm folding, hand clasping, and Luria's concept of "latent left-handedness"

Are Footedness and Lateral Postures Better Predictors of Hemispheric Dominance Than Handedness: A Cross-sectional Questionnaire-Based Clinical and Pedigree Study

Objective  Approximately 9 out of 10 individuals show right-hand dominance. The remaining 10% include left-hand dominant and mixed handed/ambidextrous individuals. Laterality, lateral postures or lateral preference is defined by various authors as the most comfortable posture that an individual prefers to assume. The current study aims at finding the distribution of these lateral postures and their correlation with handedness/dominant side.

Materials and Methods  The study was done in medical and nursing students in the age group 18 to 22 years. The patients were asked to fill a self-assessment questionnaire to determine handedness and footedness. The laterality traits were observed by asking the patients to do by themselves after an untailored demonstration.

Statistical Analysis  The relationship between study parameters was assessed using Chi-square test. Pearson’s correlation test was done to assess the strength of association between comfort ratings of the various laterality postures.

Results  In our study, 96.5% were right handed and 79.9% of patients were right footed. Also, 50.8% preferred right-hand clasping, 53.9% preferred left-arm folding, and 60.6% preferred right-leg folding. A statistically significant correlation was seen between foot preference and lateral postures and arm folding and hand clasping (p < 0.05). A significant association was also found between handedness and positive history of retraining. Sidedness did not follow any Mendelian pattern of inheritance.

Conclusions  Handedness is affected by genetic and environmental factors. Since cultural and traditional practices can affect the lateral postures and handedness, it is important to know the relationship between laterality postures and sidedness and the impact of retraining on them. These postures are measures of cerebral dominance and are clinically important.

The Role of Dispensing Device and Label Warnings on Dosing for Sunscreen Application: A Randomized Trial

Drug manufacturers are expected to provide labeling information needed to yield safe and effective product use. However, it is not clear that consumers dose sunscreen, an over-the-counter drug, appropriately; in fact, existing evidence suggests underdosing as a common phenomenon. The objective of this study was to evaluate the effect of dispensing device and labeling on self-administered doses of sunscreen in young adults. To investigate those effects, a 2 × 2 factorial laboratory experiment crossing dispensing device (two levels) with labeling treatment (two levels) was conducted. Participants applied sunscreen from each of the four treatments; dosing concentration, measured in mg/cm², served as the response variable. Participants (n = 94) were recruited on the campuses of Michigan State University (East Lansing, MI) and California Polytechnic State University (San Luis Obispo, CA). Each participant applied sunscreen from each unique treatment to sites on their arms and legs (four applications). Postapplication, a survey was completed to characterize demographics, risk perception, and sunscreen use patterns. Results indicate participants applied approximately 30% less sunscreen from the pump bottles than the squeeze bottles (difference estimate of 0.3059 mg/cm², standard error = 0.0607, p < .0001); there was no evidence of a difference based on label treatments. Post hoc recognition tests indicated only 55% of participants were able to recognize the two experimental labels they had viewed immediately following sunscreen application. Sunscreen application density was directly related to level of worry regarding skin cancer and frequency of sunscreen use (α = .05). Our results suggest the dispensing device used to deliver sunscreen impacts the dosage amount consumers apply.

Comparative study of laterality in people with fragile X syndrome, people with intellectual disabilities, and people with typical development

Following on from the studies by McManus and Cornish [(1997). Fractionating handedness in mental retardation: What is the role of the cerebellum? Laterality, 2(2), 81-89] and Cornish, Pigram, and Shaw [(1997). Do anomalies of handedness exist in children with fragile-X syndrome? Laterality, 2(2), 91-101], the aim of this paper was to determine laterality in people with fragile X syndrome (FXS). The sample comprised three study groups: the first with 30 people with FXS (mean age 17.9 years), the second 34 people with various intellectual disabilities (ID, mean age 20.9 years), and the third 160 people with typical development (mean age 14.7 years). Laterality was assessed with a test adapted for this study. The results confirm the preponderance of right-handedness (93.3%) in people with FXS and present new data regarding footedness and sensory dominance (eyedness and earedness), indicating inconsistent footedness and ocular cross-dominance. Almost three-quarters (73.5%) of people with other ID were right-handed. The results corroborate those of McManus and Cornish (1997). People with FXS tend to be right-handed but have ocular cross-dominance.

Hand clasping, arm folding, and handedness: relationships and strengths of preference

We investigated via a survey the relationship between hand clasping, arm folding, and handedness. We aimed to provide new data on degree of preference for each of these lateralities. We also examined the relative importance of thumb position versus interdigitisation of the fingers in determining one's comfort in a hand-clasping position. We explored this in the context of the fact that sensory acuity is greater for the thumb than other fingers, suggesting that preference for how the fingers are intermeshed may be more influenced by thumb than finger position. Lastly we performed an exploratory analysis to determine if self-reported menstrual phase-known to influence turning bias-also influences hand clasping, arm folding or the strength of one's handedness. Our study suggests that lateral preferences for hand clasping, arm folding, and handedness are independent. However, the degrees of lateral preference for hand clasping and arm folding are correlated. Our exploration of the relative importance of thumbs versus fingers to hand clasping revealed some trends that were not statistically significant, but worth future exploration. Our data on menstrual phase showed a reduced strength of preference for arm folding in mid-luteal females versus non-mid-luteal females.