Neuropsychological identification of motor problems: can we learn something from the feet and legs that hands and arms will not tell us?

Hand and Foot Selection in Mental Body Rotations Involves Motor-Cognitive Interactions

Action imagery involves the mental representation of an action without overt execution, and can contribute to perspective taking, such as that required for left-right judgments in mental body rotation tasks. It has been shown that perspective (back view, front view), rotational angle (head-up, head-down), and abstractness (abstract, realistic) of the stimulus material influences speed and correctness of the judgement. The present studies investigated whether left-right judgements are more difficult on legs than on arms and whether the type of limb interacts with the other factors. Furthermore, a combined score for speed and accuracy was explored to eliminate possible tradeoffs and to obtain the best possible measure of subjects' individual ability. Study 1 revealed that the front view is more difficult than the back view because it involves a vertical rotation in perspective taking. Head-down rotations are more difficult than head-up rotations because they involve a horizontal rotation in perspective taking. Furthermore, leg stimuli are more difficult than hand stimuli, particularly in head-down rotations. In Study 2, these findings were replicated in abstract stimuli as well as in realistic stimuli. In addition, perspective taking for realistic stimuli in the back view is easier than realistic stimuli in the front view or abstract stimuli (in both perspectives). We conclude that realistic stimulus material facilitates task comprehension and amplifies the effects of perspective. By replicating previous findings, the linear speed-accuracy score was shown to be a valid measure to capture performance in mental body rotations.

The Bias toward the Right Side of Others Is Stronger for Hands than for Feet

As shown by a series of previous studies, ambiguous human bodies performing unimanual or unipedal actions tend to be perceived more frequently as right-handed or right-footed rather than left-handed or left-footed, which indicates a perceptual and attentional bias toward the right side of others’ body. However, none of such studies assessed whether the relative strength of such a bias differs between the upper and lower limbs. Indeed, given that the prevalence of right-handedness is slightly larger than that of right-footedness, and given that hands provide more information than feet as regards both communicative and aggressive acts, it is plausible that the bias toward the right side of human bodies should be stronger for the hand than for the foot. We performed three experiments in each of which participants had to indicate the rotating direction (revealing the perceived handedness/footedness) of ambiguous human figures with either one limb (arm or leg) or two limbs (one arm and the contralateral leg) extended. The hypothesized advantage of the right hand over the right foot was found in both the second and the third experiment.

Cross-lateralisation in children with attention-deficit/hyperactivity disorder and motor skill performance

Cross‐lateralisation and increased motor difficulties have been reported in children with attention‐deficit/hyperactivity disorder (ADHD). Nevertheless, the question of how crossed (i.e. mixed preference) or uncrossed (i.e. same side preference) lateralisation impacts motor performance in children with ADHD has yet to be examined. In this study, previously validated observational measures of hand and foot preference were used to identify right‐handed children with ADHD who display cross‐ (n = 29) and uncross‐lateralisation (n = 31). An uncross‐lateralised typically developing (TD) group (n = 32) was also identified, and included as a control. Motor performance was assessed with seven valid and reliable fine and gross motor tasks performed with both preferred and non‐preferred limbs. Group, task and sex‐related effects were examined. Findings revealed that male (but not female) cross‐lateralised children with ADHD performed significantly worse, respectively, in two of the fine motor tasks (spiral tracing [p < .01], and dot filling [p < .05]). Results suggest that cross‐lateralised hand and foot preference may affect complex motor skills in male children with ADHD. Furthermore, characteristics of ADHD may manifest differently in male and female children. Findings highlight the importance of considering both hand and foot preference when targeting motor interventions for children with ADHD.

Foot preference across the lifespan: Effects of target location and task complexity

This study was designed to determine the factor(s) that influence the choice of the foot throughout the lifespan. To achieve this purpose, 86 right-footed participants (young children (5– 8), adolescents (10–14), young adults (18–25) and older adults (over 50) were tested on two tasks of different levels of difficulty, performed in three spatial locations (left, right, and midline) according to two levels of body posture: sitting and standing. Results revealed that the participants favored their preferred foot when the object was located in the ipsilateral hemispace and at the midline. They selected their non-preferred foot when the object was located in the contralateral hemispace. The participants used their preferred foot to a greater extent during the most complex task than during the easiest one and more often while standing rather than sitting. Finally, we have found a significant age effect. Young children often used the preferred foot more frequently than the other age groups. In conclusion, the findings of this study suggest that foot selection depends on task demand, environmental constraints, and a biological factor associated with motor dominance.

Efficient neuroplasticity induction in chronic stroke patients by an associative brain-computer interface

Brain-computer interfaces (BCIs) have the potential to improve functionality in chronic stoke patients when applied over a large number of sessions. Here we evaluated the effect and the underlying mechanisms of three BCI training sessions in a double-blind sham-controlled design. The applied BCI is based on Hebbian principles of associativity that hypothesize that neural assemblies activated in a correlated manner will strengthen synaptic connections. Twenty-two chronic stroke patients were divided into two training groups. Movement-related cortical potentials (MRCPs) were detected by electroencephalography during repetitions of foot dorsiflexion. Detection triggered a single electrical stimulation of the common peroneal nerve timed so that the resulting afferent volley arrived at the peak negative phase of the MRCP (BCIassociative group) or randomly (BCInonassociative group). Fugl-Meyer motor assessment (FM), 10-m walking speed, foot and hand tapping frequency, diffusion tensor imaging (DTI) data, and the excitability of the corticospinal tract to the target muscle [tibialis anterior (TA)] were quantified. The TA motor evoked potential (MEP) increased significantly after the BCIassociative intervention, but not for the BCInonassociative group. FM scores (0.8 ± 0.46 point difference, P = 0.01), foot (but not finger) tapping frequency, and 10-m walking speed improved significantly for the BCIassociative group, indicating clinically relevant improvements. Corticospinal tract integrity on DTI did not correlate with clinical or physiological changes. For the BCI as applied here, the precise coupling between the brain command and the afferent signal was imperative for the behavioral, clinical, and neurophysiological changes reported. This association may become the driving principle for the design of BCI rehabilitation in the future. Indeed, no available BCIs can match this degree of functional improvement with such a short intervention.

Recognizing familiar objects by hand and foot: Haptic shape perception generalizes to inputs from unusual locations and untrained body parts

The limits of generalization of our 3-D shape recognition system to identifying objects by touch was investigated by testing exploration at unusual locations and using untrained effectors. In Experiments 1 and 2, people found identification by hand of real objects, plastic 3-D models of objects, and raised line drawings placed in front of themselves no easier than when exploration was behind their back. Experiment 3 compared one-handed, two-handed, one-footed, and two-footed haptic object recognition of familiar objects. Recognition by foot was slower (7 vs. 13 s) and much less accurate (9 % vs. 47 % errors) than recognition by either one or both hands. Nevertheless, item difficulty was similar across hand and foot exploration, and there was a strong correlation between an individual's hand and foot performance. Furthermore, foot recognition was better with the largest 20 of the 80 items (32 % errors), suggesting that physical limitations hampered exploration by foot. Thus, object recognition by hand generalized efficiently across the spatial location of stimuli, while object recognition by foot seemed surprisingly good given that no prior training was provided. Active touch (haptics) thus efficiently extracts 3-D shape information and accesses stored representations of familiar objects from novel modes of input.

Motor skills in Czech children with attention-deficit/hyperactivity disorder and their neurotypical counterparts

Attention-deficit/hyperactivity disorder (ADHD) is the most commonly diagnosed neurobehavioural disorder. Characterized by recurring problems with impulsiveness and inattention in combination with hyperactivity, motor impairments have also been well documented in the literature. The aim of this study was to compare the fine and gross motor skills of male and female children with ADHD and their neurotypical counterparts within seven skill assessments. This included three fine motor tasks: (1) spiral tracing, (2) dot filling, (3) tweezers and beads; and four gross motor tasks: (1) twistbox, (2) foot tapping, (3) small plate finger tapping, and (4) large plate finger tapping. It was hypothesized that children with ADHD would display poorer motor skills in comparison to neurotypical controls in both fine and gross motor assessments. However, statistically significant differences between the groups only emerged in four of the seven tasks (spiral tracing, dot filling, tweezers and beads and foot tapping). In line with previous findings, the complexity underlying upper limb tasks solidified the divide in performance between children with ADHD and their neurotypical counterparts. In light of similar research, impairments in lower limb motor skill were also observed. Future research is required to further delineate trends in motor difficulties in ADHD, while further investigating the underlying mechanisms of impairment.

Motor planning and execution in left- and right-handed individuals during a bimanual grasping and placing task

The issue of handedness has been the topic of great interest for researchers in a number of scientific domains. It is typically observed that the dominant hand yields numerous behavioral advantages over the non-dominant hand during unimanual tasks, which provides evidence of hemispheric specialization. In contrast to advantages for the dominant hand during motor execution, recent research has demonstrated that the right hand has advantages during motor planning (regardless of handedness), indicating that motor planning is a specialized function of the left hemisphere. In the present study we explored hemispheric advantages in motor planning and execution in left- and right-handed individuals during a bimanual grasping and placing task. Replicating previous findings, both motor planning and execution was influenced by object end-orientation congruency. In addition, although motor planning (i.e., end-state comfort) was not influenced by hand or handedness, motor execution differed between left and right hand, with shorter object transport times observed for the left hand, regardless of handedness. These results demonstrate that the hemispheric advantages often observed in unimanual tasks do not extend to discrete bimanual tasks. We propose that the differences in object transport time between the two hands arise from overt shifting visual fixation between the two hands/objects.

Handedness and footedness: relations to differences in sprinting speed and multiple sprints performance in prepubertal boys

Physical performance and movement skills are differentiated by brain hemispheric dominance. Relations of handedness and footedness to differences in sprint speed and multiple sprints performances were investigated in 362 prepubertal, male, novice wrestlers. Participants with two months of irregular training experience were grouped by hand and foot preferences and matched on age and anthropometry. Mean running speed was associated with the number of sprints and handedness, but not with footedness. The decrease in sprint speed was less for right-handed subjects, who also had better sprinting speed and multiple sprint performance. Symmetrical arm and leg strength development for left-handers should be emphasized.

Foot Laterality in Children, Adolescents, and Adults

This investigation reviewed 14 studies describing the trichotomous distribution of foot preference behaviour spanning early childhood to adult years. Findings suggest that a substantially greater percentage of children are mixed-footed in comparison to older individuals. A significant shift towards right-sidedness appears to occur sometime during late childhood, after which, behaviour remains relatively stable. The incidence of left-footedness is similar across the lifespan. In comparison to handedness, substantially more (about twice as many) young children are mixed-footed compared to mixed-handed. A similar pattern is noted during adolescence and adulthood, but the differences are smaller. Values for leftsidedness (upper and lower limbs) are comparable across the lifespan. Of the existing theoretical models, Annett's Right-shift hypothesis with additional propositions related to environmental influences (Collins, 1977; Porac, 1993; Provins, 1992) provides partial explanation for the findings.

Midline-crossing Inhibition: An Indicator of Developmental Delay

In normal development midline crossing integration is usually attained by eight or nine years of age. The inability to attain this developmental milestone is called midline crossing inhibition (MCI). A new method to detect MCI was used to examine the presence of MCI in a group of subjects with mental retardation. Seventeen subjects with mental retardation and an equal number of non-disabled peers participated in the study. Choice response time measurements consisting of reaction time and movement time were the dependent variables. These variables were recorded when subjects executed ipsilateral, midline and contralateral movements with each leg. Analysis of data revealed for both dependent variables significant differences between the two groups of subjects. Only the group with mental retardation exhibited contralateral times that were significantly slower than ipsilateral times. Midline crossing inhibition was evident with these developmentally delayed subjects. This new method shows promise for assessing developmental and neurological anomalies.

AGILITY, GNOSIS, AND GRAPHAESTHESIA FOR THE TOES AND FINGERS IN CHILDREN: NORMATIVE DATA (AGES 7-14 YEARS)

The differential representation of the toes/feet and fingers/hands along the medial and lateral surfaces of the cerebral cortices, respectively, may have diagnostic utility. Normative data for errors for toe and finger graphaesthesia and gnosis, as well as foot and finger agility, were collected for 86 children (ages 7 to 14). The fingers were more agile than the feet, and the right side of the body was more agile than the left side, regardless of age. A marked improvement in toe gnosis, but not in finger gnosis occurred in children after 11-12 years of age. A statistically significant interaction between laterality and gender was due to the greater numbers of errors for both toe and finger gnosis, displayed by girls for the left sides of their bodies compared to their right sides. This discrepancy was not significant for boys.

Investigating the stabilising and mobilising features of footedness

This study investigated lower limb laterality for stabilising and mobilising actions in 10 right- and 10 mixed-footed participants by determining, via the Waterloo Footedness Questionnaire--Revised (WFQ-R), the preferred foot in carrying out a range of stabilising and mobilising activities and by recording foot performance on standing balance and ball juggling. The log odds ratio (lambda score) was used to quantify the degree of laterality in task performance. Differences between the stability and mobility scores and the two groups were analyzed using a 2 (Group) x 2 (Task) ANOVA model with repeated measures on Task. Right- and mixed-footed participants differed significantly in the stability but not in the mobility items of the WFQ-R. No significant between-group differences were noted in either ball-juggling or standing balance performance. Mixed-footed participants had a significant right-left foot difference in standing balance, whereas both groups had a significant right-left foot difference in ball juggling. It is concluded that preference is not a steady attribute across the mobility and stability items of the WFQ-R and appears to be dependent on the behavioural context of a particular task. Results further indicated a lack of concordance between questionnaire and performance-based measures suggesting that these two methods of measuring laterality may be indicators of different underlying factors.

The relationship of movement time to hand-foot laterality patterns

Asymmetries in movement times of the hands in 60 healthy participants with different patterns of hand-foot dominance were investigated. Handedness and footedness were assessed by means of questionnaires and verified by simple motor tasks. Psychomotor performance was evaluated by the use of selected tests from the computerised Vienna Test System (VST, Vienna, Austria). Movement time (MT) was assessed separately for dominant and non-dominant hands in a unimanual simple reaction task. Participants performed significantly better with their preferred hand, and differences in performance between right- and left-handers were not significant, neither was there a main effect of foot dominance on MT of the hands. However there was a significant effect of laterality pattern in hand-foot combination on hands MT: participants with cross-lateral dominance patterns of hands and feet performed significantly better than those with congruent hand-foot dominance. No significant interaction with sex was found. These results provide evidence for a lack of independence of hand and foot dominance in motor performance, suggesting the functional significance of limb laterality pattern in the motor control system. The results support the hypothesis that the quality of human hand movements may be influenced not only by central information processing (hemispheric specialisation) but also by other structures and processes of motor control, such as central pattern generators (CPGs) and biomechanical factors.

How Good People are at Estimating their Own Performance? A Study of the Relationship between Hand Preference and Motor Performance

This article examines the relationship between the awareness of hand preference and hand and foot performance among right-, left- and mixed-handers (n = 224). The hand preference was assessed using a handedness inventory. Hand and foot performances were measured using rapid index finger or toe tapping. A significant interaction between hand preference and the tapping rate indicated that in left-handers, left tapping was faster than right tapping and in right-handers, right tapping was faster than left tapping regardless of effector, finger or toe. The mixed-handers, however, did not show differences between left and right tapping performance. Correlations between performances were highest between hands or between feet. Also, hand performance was more strongly positively associated to foot performance in the mixed- and left-handers than right-handers. Similar inter-limb performance in mixed-handers tends to implicate inconsistent or undeveloped cerebral lateralisation. The results indicate that self-awareness of the pattern of hand use significantly relates to hand and foot performance.

Cultural and environmental influences on footedness: cross-sectional study in urban and semi-urban Malawi

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 left-foot preference was lower than that on left-hand preference (57% vs. 75%) and a smaller proportion of volunteers suggested that left-footers should be forced to change the foot (63.5% vs. 87.6%). In total, mobilizing and stabilizing tasks scored similar proportions of negative responses. Expectation of inferior performance of the left foot than the right one was the major reason for negative views on left-foot preference. Gender and driving experience had significant but weak effect on the view on left-foot preference. Most of the responders (74%) suggested that left-footers should change the foot in early family environment.

Lower extremity response time performance in boys with ADHD

OBJECTIVE

Children with ADHD have been labeled as "uncoordinated" and "inefficient movers"; however, a paucity of research has systematically examined "stimulant-free" motor processing in this population.

METHOD

In the present investigation, the authors employ a cross-lateral integration task to assess the attainment of a motor milestone in a corpus of 16 adolescents with ADHD acutely removed from their daily medication routine (methylphenidate) and 19 age-matched peers. Participants perform a choice response time task involving the lower extremity to targets located at midline and in ipsilateral and contralateral space.

RESULTS/CONCLUSION

This investigation finds that children with ADHD have slower lower extremity reaction and movement times compared to controls, and all preadolescent children demonstrate an inhibition in processing movements that require crossing the midline of the body.

Effect of stimulant medication on lower extremity response time of boys with attention deficit hyperactivity disorder

Children with attention deficit hyperactivity disorder (ADHD) have been labeled as "inefficient movers"; however, little research has examined the effect of stimulant medication on lower extremity movements. 16 boys, 11 to 13 years old, with ADHD performed a lower-limb choice-response time task, both on and off medication. When nonmedicated, children had significantly slower reaction times to all three targets and significantly slower movement times for the contralateral and midline movements. For both conditions, children had significantly faster movement time when using the right leg than the left leg. These findings suggest that movement characteristics of children with ADHD are different under medicated and nonmedicated situations.

Ageing and midline crossing inhibition

Age-related deficits of lower extremity lateral movements were investigated to identify a specific age range for the reappearance of midline crossing inhibition (MCI) along a developmental continuum. Ten individuals (five men and five women) representing each decade between the ages of 40 and 89 (five age groups) performed 108 seated trials on a lower extremity apparatus that measured choice reaction time and movement time. Midline crossing inhibition was operationally defined as statistically slower contralateral reaction times when compared to ipsilateral reaction times. The two eldest age groups (70- and 80-year-olds) exhibited MCI only on the first day of testing. Practice may facilitate cross lateral integration in normal ageing adults, even those of advanced age. There were no significant differences for movement times across age groups.

Age differences and changes in midline-crossing inhibition in the lower extremities

BACKGROUND

The effects of crossing the body midline on the lower extremities of individuals 65 years of age and older was investigated.

METHODS

The subjects were 10 individuals 65-79 years of age, 10 individuals 80 years and older, and 10 individuals 20-35 years. The total testing phase consisted of 2 sets of 30 trials per leg on 2 days. The subjects performed trials that involved movements ipsilaterally, contralaterally, and directly in front of the anterior superior iliac crest of the leg being tested. Reaction time and movement time scores were recorded.

RESULTS

Individuals 65 years of age and older were found to exhibit slower reaction times to movements in a contralateral direction when compared with movements made in the ipsilateral direction whereas individuals 80 years of age and older were also found to exhibit slower reaction times to movements in a contralateral direction when compared with movements made in the midline and ipsilateral direction.

CONCLUSIONS

These findings indicate that the effects of midline-crossing inhibition on the lower extremities reemerge in individuals 65 years and older, whereas in early development this effect disappears by 8 or 9 years of age.

Earedness and handedness: distribution in a German sample with some family data

There are only few data on the relative contribution of genetical factors to ear preference ("earedness"). We studied the distribution of earedness and handedness in a sample of 292 families and 36 offspring pairs. The incidence of nonright-earedness was found to be 35% and was not related to age or gender. In the same sample the incidence of nonright-handedness amounted to about 9% and was characterized by a significant prevalence in men. The distribution of handedness did not differ significantly between parents and children. We found that children's earedness and handedness were related to parental preferences. However, no paternal or maternal effect was found. The frequency of left-earedness and left-handedness of children is directly proportional to the number of left-sided parents. These results suggest that the direction of ear preference and handedness is genetically determined. But there is no genetic association between handedness and earedness.

Comparisons of psychomotor performance between the upper and lower extremities in three age groups

Decreasing speed of foot movement is a serious perceptual-motor impairment for older individuals such as in walking and driving. The present study examined the relationship between age and psychomotor performance for upper vs lower extremities. A visual stimulus was used to measure the speed of finger and foot movement responses, i.e., choice reaction time and total response time. 32 healthy persons, ranging in age from 9 to 75 years, were divided into three groups: ages 9-10, ages 20-30, and age 60 and above. A 3 (age group) x 2 (test: finger vs foot) two-way analysis of variance on converted Z scores indicated a significant effect on age group and an interaction between test and age group. While the elderly group showed poorest over-all performance, their lower extremity response was identified to be relatively slower than their upper-extremity response.

A question of foot dominance

It is suggested that the popular definition of foot dominance (i.e., the limb preferred to execute a manipulative or mobilizing action while the other [nondominant] foot provides stabilizing support, e.g., kicking a ball) be reconsidered in light of understanding the functional characteristics of footedness and selected theoretical explanations. Relevance to future research designs and assessment methodology is discussed.

Lower-limb speed and foot preference in children

Foot preference and performance characteristics of gross-motor lower-limb speed of tapping were examined in 606 4- to 6-yr.-olds. Analysis indicated no effect for gender; however, speed of foot tapping increased significantly across the three ages, suggesting an association with selected developmental (neuromuscular) processes. Contrary to earlier reports on handedness, there was no statistical evidence that mixed- or left-footers were at a performance disadvantage compared to right-footers. All groups performed best with the right foot, limb differentiation (right versus left) being significant for the right- and mixed-footed groups. Speculation about maturational and environmental influences is given.

Limb laterality and motor proficiency in children

This investigation examined the premise derived from recent reports, that children who are consistent right-handers are better coordinated than their left- and mixed-sided (inconsistent) peers. The observation of limb laterality was extended to include footedness. Two samples of children (N = 273) (foot laterality/hand laterality), matched for age and sex, were assessed for motor proficiency and compared according to limb preference (right, mixed, left). Overall, results indicated no significant group differences (ps > .05) in composite scores (upper-limb, lower-limb, combination) and total performance, within foot and hand laterality. In view of recent studies (noting differences between laterality groups) and these nonsupportive results, it appears that additional inquiry is warranted before any consensus regarding the association between limb laterality and motor coordination can be established. Suggestions for further inquiry are presented.

Foot agility and toe gnosis/graphaesthesia as potential indicators of integrity of the medial cerebral surface: normative data and comparison with clinical populations

A protocol was designed to identify quantitative indicators of the function of the medial surfaces of the cerebral hemispheres. Normative data were collected from 40 volunteers for foot agility, toe gnosis, and toe graphaesthesia. A total of 100 patients (most of whom had been referred for possible closed-head injuries) completed thorough neuropsychological and cognitive assessments. Deficits for toe graphaesthesia were most consistently correlated with general brain impairment and with scores for tasks whose normal performance requires the integrity of structures within the dorsal half of the medial cerebral hemispheres.

Foot-preference behavior: a developmental perspective

The developmental course of foot-preference behavior was examined in participants spanning early childhood to young adulthood. Results indicated significant age-group differences, with no effect for gender. Evidence suggests that footedness adheres to some variant developmental features characterized primarily by a significant shift toward greater right-footedness between 8 and 11 years, after which preferences remain relatively stable. Complementing this shift is a substantial decrease in mixed-footedness across the same time line. Of the existing models of hemispheric specialization, Annett's (1978, 1985) right-shift hypothesis, which considers cultural and environmental effects, provides a partial explanation for the findings. Hand-preference data were also collected and are contrasted with foot-preference data.

Foot laterality during childhood: a review

Recent reports suggest that footedness warrants consideration as a potentially useful measure of specific aspects of neuropsychological functioning. However, very few data are available concerning its developmental characteristics. This paper presents a review of studies describing the trichotomous distribution of foot laterality spanning the childhood years (ages 3- to 11). When compared to handedness characteristics in the same population, it was noted that right-side dominance (foot preference) was not as pronounced, and about twice as many exhibit no dominant limb (i.e., mixed). The predictable pattern of increasing right-sidedness with advancing age found in handedness was not obvious for foot laterality over this period of time. The mixed-footed phenomenon is addressed using the basic tenets of Annett's Right-Shift hypothesis and the unique cultural factors associated with foot behavior. Applied implications of these observations for neuropsychological assessment and motor skill instruction are discussed.

Associations between hand and foot preference in 3- to 5-year-olds

Associations between foot and hand preference behavior were examined in 3-, 4-, and 5-year-olds. Analysis of the general trichotomous (right, left, mixed) distribution of preferences indicated no sex or age group differences, while noting that 39% were mixed-footed compared to 17% not favoring one hand over the other. Frequency of paired (congruent and cross-lateral) preferences revealed that two patterns, Right-hand/Right-foot (52%) and Right-hand/Mixed-foot (23%) accounted for the vast majority (75%) of subjects. Of the total number of right-handers, most (67%) preferred the right foot, while only 19% of the left-handers were congruent. Thus, supporting findings reported on older populations that right-handers are more consistently right-footed, than left-handers are left-footed. Behavior of the mixed- and right-handed sample was similar, suggesting an overall predominance of these lateral characteristics in young children.

Toe graphaesthesia as a discriminator of brain impairment: the outstanding feet for neuropsychology

Because of the vulnerability of the medial surfaces of the cerebral hemispheres to the consequences of shear forces, we hypothesized that quantitative sensori-motor deficits for the feet would be strong indicators of general brain dysfunction. On the basis of the Halstead-Reitan Impairment Index, 28 adults who had received closed head injuries were assigned to perfectly normal, normal, or (mildly to severely) impaired groups. Foot tap and finger tap as well as agnosia and graphaesthesia for the fingers and toes were measured. Deficits in toe graphaesthesia were the most powerful group discriminator. Potential usefulness of haptic/motor, finger/toe comparisons for recording the progress of degenerative diseases, such as AIDS, is also suggested.