Mental rotation studies examine how subjects determine whether two stimuli differing in orientation have the same-handedness. Handedness recognition tasks require the subject to determine whether forms are identical, differing only in degree of angular displacement. Four experiments involving 160 undergraduates demonstrate that mental…

This study of 11 3-generation families supported the hypothesis of autosomal dominant inheritance with reduced penetrance. Data did not support an increased frequency of males, left-handedness, or autoimmune disorders in dyslexics. Severity was greater in males. Long-term outcome was comparable in dyslexics and nondyslexics. (JDD)

Explains the evolution of the hand and its relation with culture and art. Points out the importance of the hand as anatomy and genetic control of development. (Contains 15 references.) (YDS)

Background: Attention-deficit/hyperactivity disorder (ADHD) is strongly influenced by heritability. Identifying heritable vulnerability traits (endophenotypes) that mark a relatively high risk of developing the disorder can contribute to the identification of risk genes. A fruitful area for the search for such endophenotypes may be motor control…

Gray matter volumes of Heschl's gyrus (HG), planum temporale (PT), pars triangularis (PTR), and pars opercularis were measured on MRI in 48 healthy right-handers. There was the expected leftward PT asymmetry in 70.8%, and leftward PTR asymmetry in 64.6% of the sample. When asymmetry patterns within individuals were examined, there was not one…

Functional brain imaging has overshadowed traditional lesion studies in becoming the dominant approach to the study of brain-behavior relationships. The proponents of functional imaging studies frequently argue that this approach provides an advantage over lesion studies by observing normal brain activity in vivo without the disruptive effects of…

Individuals differ in the number of corpus callosum (CC) nerve fibers interconnecting their cerebral hemispheres by about threefold. Early reports suggested that males had smaller CCs than females. This was often interpreted to support the concept that the male brain is more "lateralized" or "specialized," thus accounting for presumed male…

The present study was designed to assess cultural and environmental pressure against left-foot preference in urban and semi-urban Malawi. The findings demonstrated that, when compared to handedness, footedness appeared to be less biased behavioral laterality in culturally restrictive communities. The percentage of responders with negative views on…

Occurrence and type of articulatory speech disorders were studied in 157 7-year-old Finnish children referred for treatment and 130 control group children. About one-third of the control group had articulation impairments. Occurrence did not vary systematically with sex or with handedness. (Author/JDD)

Fifty nonspeaking or minimally speaking subjects with moderate, severe, or profound mental retardation underwent evaluation of handedness. Results confirmed increased prevalence of non-right handedness and the occurrence of a large subtype of ambiguous handedness. Results suggest that incidence of atypical hand preference is not closely linked to…

The purpose of the present study was to replicate and extend to word recognition previous findings of reduced magnitude and reliability of laterality effects when exogenous cueing was used in a dichotic listening task with syllable pairs. Twenty right-handed undergraduate students with normal hearing (10 females, 10 males) completed a dichotic…

Previous research has revealed a lack of planum temporale (PT) asymmetry in adults with autism. This finding is now extended to children and adolescents with the disorder. MRI scans were obtained from 12 children with autism and 12 gender, handedness and age-matched comparison participants. The volume of gray matter in the PT and Heschl's gyrus…

The authors used a modified Simon task (J. R. Simon, 1969) to assess the automatic recognition of handedness. Participants responded to the color of a circle in the center of the photograph of a right or a left hand, displayed in the center of the computer screen. A regular Simon effect was found for back views, whereas a reverse Simon effect was…

The neurophysiological and neuroanatomical foundations of developmental language disorder (DLD) are still a matter of dispute. A main argument is that children with DLD show atypical anatomical asymmetries of speech-relevant brain areas, which possibly affect efficient language processing. In contrast to previous anatomical studies in DLD…

The present study examined the relationship between word concreteness and word frequency using event-related potential (ERP) measurements during a lexical decision task. Potential effects of concreteness in the processing of verbs were also examined. ERPs were recorded from 119 scalp electrodes in 23 right-handed participants. The results showed…