Right-handed Persons Research Articles

Left-handedness and field-independence

Left-handed persons have been reported to show less field-independence than right-handed persons. Using a large sample of left-handers (96), a replication attempt was made and the opposite result was obtained. Left-handers were found to be more field-independent than right-handers. Results from previous studies were probably due to the use of extremely small samples of left-handers (four and 10). Different instrumentation was ruled out since the Embedded Figures Test and the Group Embedded Figures Test are essentially the same.

Failure to replicate the Scott et. al. finding of reversed ear dominance in the native American Navajo

The apparent universality of left hemisphere language specialization in neurologically normal right-handed persons has been questioned by S COTT et al. ( Neuropsychologia 17, 89–92, 1979). They found that Native American Navajos had a significant left ear advantage on the dichotic C-V task, while Anglo Ss had a right ear advantage. We attempted to replicate this finding with essentially the same task, more Ss and four times as many trials. Results showed a very clear right ear advantage in Navajos. While we had previously questioned the Scott et al. conclusion on the basis of visual laterality test findings, present results directly contradict those of Scott et al.

Right-left asymmetry in anterior speech region.

The extent of the anterior speech region (defined as pars opercularis and pars triangularis of the third frontal convolution) and of the planum temporale was measured in 12 brains belonging to strictly right-handed persons. When the portion of the anterior speech region visible on the hemispheric surface was measured, no interhemispheric difference was found. By contrast, when both the extrasulcal and intrasulcal portions of cortex were considered, the anterior speech region in the left hemisphere was found to be significantly larger than the homologous areas in the right hemisphere. The planum temporale was significantly larger on the left than on the right, but there was no necessary correspondence between the presence of a larger right planum and a larger right anterior speech region.

Handedness and Temperament

Answers to a questionnaire from members of the Tecumseh Community Health Study showed a relationship of handedness and temperament, especially for younger persons. Left-handed persons rated themselves more emotional than right-handed persons, and younger sinistral males appear less extraverted than dextrals.

Evidence against the hypothesis of right hemisphere language dominance in the native American Navajo

The hypothesis that the Native American Navajo possess a reverse (right hemisphere) language function dominance was tested, using the Lateralized Object Naming Latency Task as a measure of hemispheric language specialization. Navajo performances were indistinguishable from those of “Anglo” university students. The Navajo appear no less consistently left hemisphere dominant for language than other neurologically-normal right-handed persons.

Seating preference, hypnotizability, and imagery ability.

The effects of a specific hemispheric mode of functioning as indexed by lateralized seating preference was tested separately for male and female subjects in terms of their performance on the Harvard Group Scale of Hypnotid Susceptibility, Form A, the Creative Imagination Scale, and Betts' Questionnaire Upon Mental Imagery. Males, but not females, who preferred right-side seating scored higher on the Harvard scale but not on the Creative Imagination Scale or Betts' imagery questionnaire. Findings provide some support the notion that hypnotizability is associated with the right hemisphere for right-handed persons.

Dual Task Performance during Bimanual Coordination

Right-handed men and women tapped two mechanical keys in time to an entraining metronome, using each hand alone and the two hands in alternation. Concurrently, they recited familiar nursery rhymes or read unfamiliar text out loud. The direction of interference from the language-based tasks on manual performance was measured relative to baseline performance. Magnitude and direction of interference from both language tasks were greater during bimanual alternation than unimanual performance. However, the direction of interference during bimanual alternation differed significantly between right-handed men and women, and the sex differences in direction of interference differed according to the characteristics of the language-based secondary task. Right-handed subjects with a family history of sinistrality showed less overall and less lateralized dual task interference than right-handed persons without a family history of sinistrality.

Einseitige Taubheit ? Neuropsychologische Untersuchungen

Forty righthanded persons with unilateral deafness-congenital or acquired in the first years of their life — underwent in average 25 years later a neuro-psychological examination. The main purpose was to investigate if the missing auditory input to the contralateral hemisphere caused changes in hemispheric specialization, memory and so-called intelligence. Ten women were deaf on the left side, 10 on the right side, and 10 men were deaf on the left side and 10 on the right side. Especially man with deafness on the right side scores poorer results in the tests than the other three groups. Half of the persons indepently of sex and side of deafness showed impaired memory function. The intelligence was found inside the normal material.

Cerebral laterality and verbal processes.

Research suggests that we process information by way of two distinct and functionallly separate coding systems. The localization of these two processing systems appears to be somewhat dependent on cerebral laterality, which has been shown to vary in right-handed and left-handed persons. To test the dual coding model, right-handed and left-handed subjects learned lists of abstract and concrete words under various conditions of visual and tactile interference. Right-handed subjects showed a significant superiority in the remembering of highly concrete items, while total recall did not differ reliably between groups.

Functional asymmetry in the face.

The possible existence of one-sided dominance in the face, similar to the phenomena of handedness and footedness, has been investigated by studying smiling pattern, movements of the angles of mouth, winking, platysma contraction, raising and everting the upper lip with dilatation of the nostril, and vertical wrinkling of the forehead, on 300 right-handed and 30 left-handed persons. The conclusions are as follows: 1. The large majority of persons investigated do not use the two sides of face equally. 2. Facial ambilaterality is a rare feature. 3. There is no clear-cut correlation between handedness and the dominant side of the face. 4. The greater percentage (58.66%) of right-handed persons show a left-sided smile and find it more convenient to perform almost all exercises with the left side of the face. A still greater percentage (73.33%) of left-handed persons shows a right-sided smile and a better performance of all exercises with the right side of the face. The contralateral relationship of handedness to the dominant side of the face is significant in the right-handed and more so, in the left-handed persons.

The objectivation of verbal discrimination ability further investigation

The aim of this investigation was to observe basic variables which might be of significance for objective speech audiometry. Contrary to our former experiments, the near-threshold stimulation with indicative test words leads to contingent negative variation (CNVs) which are equal to or even smaller than the CNVs after supra-threshold stimulation. Thus the CNV can be used for objective testing of verbal discriminatory ability only as a qualitative, but not as a quantitative parameter.Independent of whether the presentation was monaural or binaural, the distribution of CNV and the complementary waves were symmetrical over the two hemispheres. Selective concentration of attention on one ear produced particularly strong but symmetrical CNV. No evidence was found for a hemispheric predominance in either right-handed or left-handed persons; but it is still possible that predominance might occur in pathological conditions.The CNV may be used very well as a qualitative test, e.g. in examining cases of aphasia, bu...

Alula Removal Technique for Identifying Wings of Released Waterfowl

A technique for marking waterfowl ducklings less than 1 day old was developed to permit subsequent identification in the hand. Marking was accomplished by removing the alulae from wings of mallard (Anas platyrhynchos) ducklings with a small scissors or clipper. No differences in growth rate, behavior, or flight capability were noted between clipped and nonclipped birds. Thirty-five hun- dred ducklings were clipped when less than 1 day old, and 1,880 of these birds were subsequently examined at 41/2 weeks of age. Significant (P <0.01) differences in successful removal of right and left alulae indicate that right-handed persons should exercise more care when clipping left wings than when clipping right wings. Alula removal appears to be effective for marking the wings of waterfowl. The Duck Wing Survey of the U. S. Bu- reau of Sport Fisheries and Wildlife is con- ducted annually throughout the nation to gather data on the species, age, and sex of ducks harvested by licensed waterfowl hunters ( Carney and Geis 1960 ) . Duck wings received from cooperating hunters are collected and identified at regional cc . 1 ,,

The effect of the operator's handedness on some directional stereotypes in control-display relationships.

Recommendations about preferred directions of movement for controls and displays are based almost exclusively on right-handed persons. This experiment has studied some common control-display movement stereotypes to find out if these stereotypes are equally valid for left- and right-handed subjects. Our apparatus presented a scale that could be oriented horizontally or vertically. The numbers on the scale increased either right-to-left or left-to-right for the horizontal scales, or up-to-down or down-to-up for the vertical scales. The linkage between the movement of a control knob and the movement of the hairline on the scale was reversible so that a clockwise rotation of the knob could be made to move the hairline toward either end of the scale. We recorded (1) the direction of the first movement made by the subject on each trial, (2) the total number of reversal movements made on each setting, (3) the time taken to make a setting, and (4) the actual setting made (and so, of course, setting errors). We tested 64 subjects, 32 left-handed and 32 right-handed, each using his preferred and non-preferred hands. Significant differences were found in the time to make settings, the number of reversal movements, and errors in initial direction of movement as functions of handedness and the various apparatus relationships. In addition to overall differences between the performance of the left- and right-handed subjects, the two groups behaved differently on some measures when using their preferred and non-preferred hands.

Functional disorganization of the left limbs in a tumour of the corpus callosum infiltrating the hemispheres.

Tumours of the corpus callosum (C.c.) are known to be a difficult diagnostic problem. Intellectual and mental disturbances and rapid deterioration in the course of the illness have been observed in most of these cases and are considered by many authors to indicate an involvement of this body (Lévy-Valensi, 1910; Mingazzini, 1922; Ironside and Guttmacher, 1929; Alpers and Grant, 1931; Voris and Adson, 1935; Schlesinger, 1951, Bremer et al., 1956). However, a similar picture may also occur in tumours of other sites; moreover, tumours of the C.c. tend to infiltrate the hemispheres, particularly the cingulum and the frontal lobes, and this might well account for the mental picture. A sign which seems to be more specific for damage of the C.c. is dyspraxia restricted to the left limbs in right-handed persons. Although this dyspraxia has been reported only in a small minority of cases concerned, it has not been observed in lesions other than those of the C.c.

Dupuytren's contracture: Notes on the age at onset and the relationship to handedness

A study of the findings concerning Dupuytren's contracture in the literature and combined with an experience of 154 patients involving 247 hands has led to the following conclusions: 1. 1. Dupuytren's contracture is a disease of the fascia occurring principally in the palm in middle-aged Caucasian males. It is often hereditary, usually painless, insidious in onset and slowly progressive with periods of exacerbation, but seldom regression. In involves the fascias of the palm and principally those pretendinous bands of the aponeurosis to the ring and little fingers. It starts bilaterally in 40 per cent of the patients and has its onset almost equally in the right and left hands. The onset in right-handed persons is almost as frequent in the left hand as in the right. It occurs in the older groups when other diseases of the ligaments and fascias occur. Similar lesions may be found on the dorsum of the middle joints, the foot and in the penis. 2. 2. The etiology is unknown. There is no medical evidence to show that trauma has any relation to the cause or progress of the disease nor that it accelerates it or aggravates it in any way. 3. 3. The disease is not fatal and in many cases the disability is minor and treatment is not required. 4. 4. Medical treatment, physical therapy and local treatment are useless. 5. 5. The symptoms of the disease are due purely to contracture of the fascial bands of the palm and fingers with secondary changes in the other tissues. The tendons and tendon sheaths are never directly involved in the process. 6. 6. Surgical treatment aims to relieve the contracture. It should be as simple and as least disabling as possible and should vary with the age and general condition of the patient, the duration and disability of the disease and the area of involvement. 7. 7. Future case reports should continue to use the classifications set up by Skoog and also attempt to determine the age and site of onset more accurately. The dominant hand of each individual patient should be recorded. 8. 8. The low incidence in women deserves further study. Most cases in women occur after the menopause. A study of this disease and its relation to ovarian function would be important. 9. 9. The relationship to epilepsy as reported by Skoog needs further study.

A Syndrome Associated with Left Hand Paralysis of Central Origin

Certain disturbances of a higher order, e.g. aphasia and agnosia, follow as a rule a lesion of the left hemisphere in right-handed persons and vice versa. This dominance of one hemisphere for certain functions has been well established from abundant material. The Gerstmann Syndrome, recently studied, seems to obey the same rule of dominance; other disorders, such as the attitude toward paralysed limbs and defective functions, appear to be caused by lesions of the non-dominant hemisphere. The relations of the latter group, however, to the hemisphere cannot be regarded as firmly established, since the material presented is still limited.

STUDIES ON THE CORPUS CALLOSUM

On the basis of the concept of a unilateral cerebral dominance in man, Liepmann1postulated that in right-handed persons the left hemisphere, by means of the corpus callosum, exercises a dominating influence on the right hemisphere. Liepmann and Maas2concluded that involvement of the anterior portion of the corpus callosum produced sympathetic dyspraxia in the subordinate hand. According to Lange,3apraxia or dyspraxia occurs most consistently after lesions of the corpus callosum or the gyrus supramarginalis of the dominant hemisphere. The studies of Baldy4and Critchley5on the syndrome of the anterior cerebral artery tend to substantiate the importance of the corpus callosum in the performance of purposeful and complex movements in the subordinate hand. Other investigators, such as Dandy,6Foerster,7Armitage and Meagher8and Barre and associates,9described cases of surgical section of the corpus callosum or destruction of this

INJECTION OF PROCAINE INTO THE BRAIN TO LOCATE SPEECH AREA IN LEFT-HANDED PERSONS

In cases in which it is necessary for the neurosurgeon to remove portions of the premotor area of the brain, he must first assure himself that in so doing he will not render the patient aphasic. In right-handed persons the center for motor speech always is located in the posterior part of the third left frontal convolution, just in front of the motor center for the face. In congenitally left-handed persons the speech functions usually are located in the corresponding area in the right cerebral hemisphere. The more pronounced the left handedness, the more certain it is that the speech function is located on the right side. Persons who acquire left handedness as a result of the occurrence of right hemiplegia early in life also usually will acquire complete right cerebral dominance, with the speech function located on the right side. Occasionally, the neurosurgeon is confronted by the problem of