Hand Preference for Visually-Guided Reaching in Human Infants and Adults. In: Ward JP, Hopkins WD, editors. Primate Laterality. New York: Springer; 1993. pp. 285-305. [DOI: 10.1007/978-1-4612-4370-0_13]

Planning actions with a magnetic tool: how initial tool orientation and number of functional ends influence motor planning abilities in capuchin monkeys (Sapajus spp.)

The way in which animals grasp objects to perform subsequent action execution allows studying their anticipatory abilities. We examined whether 11 capuchin monkeys (Sapajus spp.) were able to prospectively grasp a magnetic dowel to use it as a tool to retrieve a baited metallic container from a plexiglas box placed in front of them. We investigated whether and how initial dowel orientation (horizontal vs vertical) affected grasping and using the dowel to retrieve the container in two testing conditions: (1) 2-FE condition in which the dowel had two functional magnetic ends; (2) 1-FE condition in which the dowel had only one functional magnetic end. In the 2-FE condition, capuchins had to take into account the initial dowel orientation since both ends were functional, whereas in the 1-FE condition capuchins had also to take into account the initial functional end position when grasping the dowel. Capuchins were trained to grasp the dowel to put one functional end in contact with the metallic container. However, they did not learn to associate the functional end of the 1-FE dowel to successful retrieval. Capuchins showed better anticipatory planning (1) in 2-FE than in 1-FE condition and (2) when the dowel was initially positioned on the horizontal plane than on the vertical one. Moreover, hand preferences affected planning in the 1-FE condition. Results were discussed within the frameworks of primates' abilities to use abstract cues and on their abilities to process functional features and spatial cues and to perform mental rotations.

Effective and Efficient Stand Magnifier Use in Visually Impaired Children

PURPOSE

The main objective of this study was to analyze the effectiveness and efficiency of magnifier use in children with visual impairment who did not use a low vision aid earlier, in an ecologically valid goal-directed perceptuomotor task.

METHODS

Participants were twenty-nine 4- to 8-year-old children with visual impairment and 47 age-matched children with normal vision. After seeing a first symbol (an Lea Hyvärinen [LH] symbol), children were instructed to (1) move the stand magnifier as quickly as possible toward a small target symbol (another LH symbol that could only be seen by using the magnifier), (2) compare the two symbols, and (3) move the magnifier to one of two response areas to indicate whether the two symbols were identical. Performance was measured in terms of accuracy, response time, identification time, and movement time. Viewing distance, as well as hand and eye dominance while using the magnifier was assessed.

RESULTS

There were no significant differences between the two groups in accuracy, reaction time, and movement time. Contrary to the prediction, children with visual impairment required less time to identify small symbols than children with normal vision. Both within-subject and between-subject variability in viewing distance were smaller in the visually impaired group than in the normally sighted group. In the visually impaired group, a larger viewing distance was associated with shorter identification time, which in turn was associated with higher accuracy. In the normally sighted group, a faster movement with the magnifier and a faster identification were associated with increasing age.

CONCLUSION

The findings indicate that children with visual impairment can use the stand magnifier adequately and efficiently. The normally sighted children show an age-related development in movement time and identification time and show more variability in viewing distance, which is not found in visually impaired children. Visually impaired children seem to choose a standard but less adaptive strategy in which they primarily used their preferred hand to manipulate the magnifier and their preferred eye to identify the symbol.

TRIAL REGISTRATION

Registered at http://www.trialregister.nl; NTR2380.

The influence of M. P. Bryden's work on lateralization of motor skill: Is the preferred hand selected for and better at tasks requiring a high degree of skill?

One question of interest to Dr M. P. Bryden was how skilled motor behaviour, task complexity, and the degree of handedness are linked. His research suggested that there would be dissociation between hand preference and performance for skilled versus unskilled actions. The thought was that "simple" or unskilled tasks such reaching or grasping could be performed equally well by either hand, and thus either could be selected. Skilled tasks such as fine manipulation would be performed best by the preferred hand and thus it would be selected more frequently. Over the past two decades, researchers have attempted to determine whether such a definition of skilled action best encapsulates the specialization of the preferred hand. The current paper will review M. P. Bryden's research on skilled motor behaviour, as well as more recent work, and explore the question of whether the preferred hand is actually superior and preferred for actions requiring manipulation.

Quantifying hand preference using a behavioural continuum

Bishop, Ross, Daniels, and Bright (1996) proposed a novel approach to quantifying hand preference (QHP) using a single behavioural measure. The extent to which individuals used their dominant hand to reach across the midline to pick up cards discriminated subgroups of right-handers, similarly categorised by their scores on the Edinburgh Handedness Inventory. This study aimed to investigate whether (1) the QHP approach was able to differentiate subgroups within the left-handed as well as right-handed populations, (2) left-handers behave like mirror-image right-handers, and (3) if interacting with the environment in extrapersonal space is influenced by the level of fine motor skill demanded by the task. Results support the use of the QHP to discriminate subgroups of both left- and right-handers, particularly when the task demands very fine motor skill or very little. Left-handers behaved as mirror-images of the right-handers except when performing the unskilled motor task in which they showed greater readiness to use the nonpreferred hand. These results suggest that interaction with the environment in extrapersonal space may be a key factor contributing to manual dominance and that the lateralisation of fine motor skill interacts with this attentional bias.

Lateralized effects on reaching by children

This study examined the limb selection profiles of children for a reach-to-grasp task presented in various positions of hemispace. Underlying questions focused on the use of attentional information and lateralized effects in motor programming for reaching movements. As expected, both right- and left-handed groups used their dominant limb more frequently at the midline and in their own ipsilateral hemispace. However, in response to stimuli presented in contralateral (to the dominant limb) hemispace, both groups switched to using their nondominant limbs at significant levels. As a general comparison, right-handers exhibited greater use of their dominant limb, but arguably, motor dominance in this context may have intervened with the participant's ability to use attentional information to produce a more efficient response. Overall, these findings address the phenomenon associated with motor dominance and use of attentional information in programming.

Stress correlates of hand preference in rhesus macaques

In this research we examined stress-related correlates of hand preference in monkeys. Specifically, we tested the hypothesis that stress reactivity and plasma levels of the stress hormone cortisol are developmentally related to handedness in rhesus macaques (Macaca mulatta). We found a significant positive correlation between cortisol levels sampled in juveniles and the frequency of right- versus left-hand use sampled in these same animals during adulthood. Right-hand preference was negatively correlated with stress reactivity. These data are consistent with the view that stress functioning and reactivity are associated with the development of hemispheric specialization in primates.

The Relation Between Hand Preference and Hand Performance: What You Get Depends on What You Measure

In the present investigation, we addressed the relation between manual preference and performance. A total of 52 right-handers and 48 left-handers were tested for manual proficiency and preferences using a range of tasks. Self-professed right-and left-handers showed greater preference for, and superior performance with, the preferred hand. Left-handers use their nonpreferred hand more often and in some instances are more skilled with it than right-handers. There was a subgroup of persons with mixed handedness, who identified themselves as left-handed, wrote with the left hand, and were more skilled with the left hand on dot-filling, but who were otherwise right-handed. Overall, the data indicated that a complete description of handedness will only be provided by careful consideration of the nature of the preference and performance measures one uses.

Early lateral bias in tufted capuchins (Cebus apella)

We investigated the development of lateral bias in infant tufted capuchins (Cebus apella) by recording head orientation during the first 2 postnatal weeks and hand preference during Weeks 23 to 24 and 47 to 48. We found that lateral bias for head orientation at 1 to 2 weeks was negatively related to hand preference at 23 to 24 weeks. Further, we found population-level left-hand preferences at both 23 to 24 and 47 to 48 weeks, and that hand preference at 23 to 24 weeks is positively correlated with hand preference at 47 to 48 weeks. We also noted a trend toward a sex difference in the direction of neonatal head orientation, with males exhibiting a left-side preference and females exhibiting a lack of preference toward either side. Our findings differ from those obtained in studies with developing humans and chimpanzees in two important ways. First, the trend for head orientation and hand preference in infant capuchins was to the left rather than to the right. Second, we found a negative relation between direction of early head orientation and subsequent hand preference. It seems likely that research examining cerebral development in capuchins will help us to better understand the occurrence of left-handedness and the development of cerebral dominance in humans.

Hand preference in infant rhesus macaques (Macaca mulatta)

In this research we examined hand preference in infant rhesus macaques (Macaca mulatta). The subjects were 20 Macaca mulatta, each aged between 4 and 11 months. We assessed hand preference using both a unimanual reaching task and a bimanual coordination task. In the unimanual reaching task, we presented subjects with raisins and noted which hand the animals used to retrieve the food. In the bimanual coordination task, we presented the same subjects with plastic tubes filled with raisin paste and noted which hand the animals used to hold the tubes and which hand the animals used to remove the food. We noted a population-level bias toward use of the left hand for both tasks. These results suggest early right hemisphere advantage for reaching and bimanual coordination in Macaca mulatta, although we acknowledge that this issue needs to be examined more directly through neuroimaging procedures such as Positron Emission Tomography (PET) or functional Magnetic Resonance Imaging (fMRI). We speculate that early right hemisphere advantage contributes to differential patterns of hand preference development for unimanual and bimanual action, and that the development of hand preference for bimanual coordination is related to the emergence of hemispheric specialization for processing species-specific vocalizations.