Evaluation of some tasks used for specifying handedness and footedness

Healthy men (n = 42) and women (n = 45) who were right-handed and men (n = 21) and women (n = 20) who were left-handed were studied. Men's mean age was 21.1 +/- 3.5 yr. and women's 20.7 +/- 3.1 yr. These students in various faculties reported they were right- or left-handed. Then their hand and foot preferences (handedness and footedness) were ascertained by asking each of the subjects to perform 11 tasks for handedness and 9 tasks for footedness. A discriminate function analysis test showed that each of the 11 tasks used for assessing their self-reported handedness was significant, but, of the 9 tasks used for assessing self-reported footedness, only 7 were significant. Strength of the hand or foot played no role in reports of handedness or footedness. A combination of four tasks, such as pulling a door, pushing a door, holding an object, and hammering a nail, on which the maximum number of subjects performed with the right or left hand, depending upon their self-reported handedness, would be ideal for ascertaining handedness. A combination of three tasks, namely, kicking a football, pushing an object with the foot, and stamping on the ground, would be ideal for ascertaining footedness.     

The role of sensorimotor experience in the development of mimicry in infancy

During social interactions we often have an automatic and unconscious tendency to copy or ‘mimic’ others’ actions. The dominant view on the neural basis of mimicry appeals to an automatic coupling between perception and action. It has been suggested that this coupling is formed through associative learning during correlated sensorimotor experience. Although studies with adult participants have provided support for this hypothesis, little is known about the role of sensorimotor experience in supporting the development of perceptual‐motor couplings, and consequently mimicry behaviour, in infancy. Here we investigated whether the extent to which an observed action elicits mimicry depends on the opportunity an infant has had to develop perceptual‐motor couplings for this action through correlated sensorimotor experience. We found that mothers’ tendency to imitate their 4‐month‐olds’ facial expressions during a parent‐child interaction session was related to infants’ facial mimicry as measured by electromyography. Maternal facial imitation was not related to infants’ mimicry of hand actions, and instead we found preliminary evidence that infants’ tendency to look at their own hands may be related to their tendency to mimic hand actions. These results are consistent with the idea that mimicry is supported by perceptual‐motor couplings that are formed through correlated sensorimotor experience obtained by observing one's own actions and imitative social partners.     

The whole picture: Holistic body posture recognition in infancy

Holistic processing is tied to expertise and is characteristic of face and body perception by adults. Infants process faces holistically, but it is unknown whether they process body information holistically. In the present study, infants were tested for discrimination between body postures that differed in limb orientations in three conditions: in the context of the whole body, with just the isolated limbs that changed orientation, or with the limbs in the context of scrambled body parts. Five- and 9-month-olds discriminated between whole-body postures, but failed in the isolated-part and scrambled-body conditions, demonstrating holistic processing of information from bodies. These results indicate that at least some level of expertise in body processing develops quite early in life.     

The role of posture in sound localization

Studies of auditory localization revealed that where a subject hears a sound is dependent on both his perceived head position and the auditory cues at his ears. If an error is induced between his true and registered head posture, then errors in his auditory localizations of corresponding size and time course result. The presence of visual information prevents the development of postural errors and, consequently, prevents the development of errors in auditory localization, too. These observations are related to the oculogravic illusion and are interpreted as one aspect of the functioning of a spatial reference system involved in the maintenance of the constancies of auditory and visual detection.     

The handedness of imagined bodies in action and the role of perspective taking

Past research at the nexus of motor control and perception investigated the role of perspective taking in many behavioral and neuroimaging studies. Some investigators addressed the issue of one's own vs. others' action imagination, but the possible effects of a front or a back view in imagining others' actions have so far been neglected. We report two 'single trial' experiments in which a total of 640 participants were asked to imagine a person performing a manual action - either in a front or in a back view - and then to indicate the hand used by the imagined person during movement execution. In such a task, we assume the existence of two distinct biases: a perceptual-mnemonic bias due to subjects' visual experience of others' actions, encouraging them to imagine right-handed movements, and a motor bias due to subjects' experience of self-made actions, encouraging them to imagine movements performed with the same hand as their dominant hand. We hypothesized that a greater involvement of motor representations in the back view compared to the front view could result in an increased correspondence between one's own manual preference and the hand used by the imagined agent in the former condition. The results of both experiments were consistent with this hypothesis, suggesting that while imagining others' actions we employ motor simulations in different degrees according to the perspective adopted.     

The role of domain-specific practice, handedness, and starting age in chess

The respective roles of the environment and innate talent have been a recurrent question for research into expertise. The authors investigated markers of talent, environment, and critical period for the acquisition of expert performance in chess. Argentinian chess players (N = 104), ranging from weak amateurs to grandmasters, completed a questionnaire measuring variables including individual and group practice, starting age, and handedness. The study reaffirms the importance of practice for reaching high levels of performance, but it also indicates a large variability: The slower player needed 8 times as much practice to reach master level than the faster player. Additional results show a correlation between skill and starting age and indicate that players are more likely to be mixed-handed than individuals in the general population; however, there was no correlation between handedness and skill within the sample of chess players. Together, these results suggest that practice is a necessary but not sufficient condition for the acquisition of expertise, that some additional factors may differentiate chessplayers and nonchessplayers, and that starting age of practice is important.     

Handedness and footedness in Korean college students

This study was conducted to obtain normative data on foot preference and to compare footedness and handedness in a large sample (N = 866) of college students in Korea, where left-hand use for writing and other public acts is severely restricted (Kang & Harris, 1993). Based on scores from Korean-language versions of the Edinburgh Handedness Inventory (EHI; Oldfield, 1971) and the Waterloo Footedness Questionnaire Revised (WFQ-R; Elias, Bryden, & Bulman-Fleming, 1988), 11% of the subjects were left-footed but only 4.2% as left-handed. A significantly higher percentage of left-handers than right-handers showed crossed lateral preference, that is, for preference of the opposite-side foot. Of the left-handers with crossed preference, the majority were inconsistent left-handers (ILH; Peters & Servos, 1989), whereas most of those with uncrossed preference were consistent left-handers (CLH). Factor analysis of the EHI and WFQ-R revealed 2 handedness factors and 2 footedness factors. The footedness factors for skilled unipedal actions and for balancing-stabilizing varied in direction, strength, and relation to handedness in mixed-footers and left-handers, consistent with the possibility that the division of footedness into these categories might be neuropsychologically meaningful.     

Sex-typing in infancy: The role of the father

Recent research on mother-infant interaction has provided little empirical support for the role of environmental factors in early sex-role development. In this paper, considerable support for the father's role is presented. Specifically, the research on mother- and father-infant interaction patterns is reviewed in order to describe developmental changes in the nature of differential treatment of the sexes during the first two years of life. Together, the studies reviewed highlight the importance of the father in early sex-role socialization, delineate a developmental model of the early differential treatment of the sexes, and provide clues as to the origins of later childhood sex differences in verbal and visual-spatial abilities.     

Selective attention to a talker's mouth in infancy: role of audiovisual temporal synchrony and linguistic experience

Previous studies have found that infants shift their attention from the eyes to the mouth of a talker when they enter the canonical babbling phase after 6 months of age. Here, we investigated whether this increased attentional focus on the mouth is mediated by audio‐visual synchrony and linguistic experience. To do so, we tracked eye gaze in 4‐, 6‐, 8‐, 10‐, and 12‐month‐old infants while they were exposed either to desynchronized native or desynchronized non‐native audiovisual fluent speech. Results indicated that, regardless of language, desynchronization disrupted the usual pattern of relative attention to the eyes and mouth found in response to synchronized speech at 10 months but not at any other age. These findings show that audio‐visual synchrony mediates selective attention to a talker's mouth just prior to the emergence of initial language expertise and that it declines in importance once infants become native‐language experts.     

The influence of previous movement and posture on subsequent posture

An experiment with 21 subjects has confirmed the findings of other investigators that previous posture affects subsequent posture—the phenomenon of postural persistence. There seems also to be a tendency for the arm to be judged horizontal when in fact above the horizon, no matter which posture has been previously adopted—a “constant upwards effect.” It has also been found that the direction of previous movement affects subsequent posture. After movement, an overshooting effect adds to a “constant upwards effect.”

Various explanations of the phenomenon are discussed, and persistence is considered as an anomaly of postural recognition.     

The otolaryngologist's role in management of hearing loss in infancy and childhood

This article reviews the role of the otolaryngologist-head and neck surgeon-in the diagnosis and treatment of hearing loss in infants and young children. The otolaryngologist is well-versed in the anatomy, physiology, and pathophysiology of the auditory system, as well as the craniofacial syndromes that can involve the head and neck in combination with deafness. In this paper, the various causes of congenital hearing loss are described, as well as the steps required for proper diagnosis. Finally, surgeries used by otolaryngologists to treat childhood hearing loss, their indications, and outcomes, are discussed.     

The functional role of central and peripheral vision in the control of posture

Three experiments were conducted to investigate the role of central and peripheral vision (CV and PV) in postural control. In Experiment 1, either the central or peripheral visual field were selectively stimulated using a circular random dot pattern that was either static or alternated at 5 Hz. Center of foot pressure (CoP) was used to examine postural sway during quiet standing under both CV and PV conditions. The results showed that, when the visual stimulus was presented in the periphery, the CoP area decreased and more so in the anterior-posterior (AP) than in the medio-lateral (ML) direction, indicating a characteristic directional specificity. There was no significant difference between the static and dynamic (alternating) conditions. Experiment 2 investigated the directional specificity of body sway found in Experiment 1 by having the trunk either be faced toward the stimulus display or perpendicularly to it, with the head always facing the display. The results showed that the stabilizing effect of peripheral vision was present in the direction of stimulus observation (i.e., the head/gaze direction), irrespective of trunk orientation. This suggested that head/gaze direction toward the stimulus presentation, rather than a biomechanical factor like greater mobility of the ankle joint in AP direction than in ML direction, was essential to postural stability. Experiment 3 further examined whether the stabilizing effect of peripheral vision found in Experiments 1 and 2 was caused because more dots (500) were presented as visual cues to the peripheral visual field than to the central visual field (20 dots) by presenting the same number of dots (20) in both conditions. It was found that, in spite of the equal number of dots, the postural sway amplitudes were larger for the central vision conditions than for the peripheral vision conditions. In conclusion, the present study showed that peripheral rather than central vision contributes to maintaining a stable standing posture, with postural sway being influenced more in the direction of stimulus observation, or head/gaze direction, than in the direction of trunk orientation, which suggests that peripheral vision operates primarily in a viewer-centered frame of reference characterized by the head/gaze direction rather than in a body-centered frame of reference characterized by the anatomical planes of the body.     

The role of language in acquiring object kind concepts in infancy

Four experiments investigated whether 9-month-old infants could use the presence of labels to help them establish a representation of two distinct objects in a complex object individuation task. We found that the presence of two distinct labels facilitated object individuation, but the presence of one label for both objects, two distinct tones, two distinct sounds, or two distinct emotional expressions did not. These findings suggest that language may play an important role in the acquisition of sortal/object kind concepts in infancy: words may serve as "essence placeholders". Implications for the relationship between language and conceptual development are discussed.     

Skull asymmetry and handedness in adults: a possibility of their association with lateral head turning in infancy

During the first two to three months after delivery infants when placed in the supine position commonly turn their heads laterally. This posture has been linked to the intrauterine orientation of the fetus. Skulls of adults were expected to bear a mark of this predominant head position in the form of occipital flattening. A blind examination of computerized axial tomography (CT) scans of 35 normal subjects assessed for handedness (20 right- and 15 mixed-handers) confirmed this prediction for the latter group only. Mixed-handers showed a slight, but reliable flattening of the right occiput. Also, there was a small but significant inverse association between the size of the petrous ridge and handedness. Examining subtle variations in skull shape of adults may provide a glimpse into some aspects of pre- and early postnatal development.     

The role of visual information in control of a constrained locomotor task

The nature of visually guided locomotion was examined in an experiment where subjects had to walk to targets under various conditions. Target distance was manipulated so that subjects had to (a) lengthen their paces in order to hit the target; (b) shorten their paces; (c) make no adjustments to their standard pace length at all. They did this under four visual conditions: (a) normal vision; (b) with vision restricted to a "snapshot" each time the foot that was to be placed on the target was on the ground; (c) with a snapshot each time the foot to be placed was in the swing phase; and (d) no vision after departure fro the target. The results show that the subjects succeed in reaching the target in most cases. However, the smoothness and fluidity of their movements vary significantly between conditions. Under normal vision or where visual snapshots are delivered when the pointing foot is on the ground, locomotion is smoothly regulated as the subjects approach the target. where snapshots are delivered when the pointing foot is in the swing phase, regulation becomes clumsy and ill coordinated. Where no vision is available at all during the approach, adjustments are made, but these are least coordinated of all. The results show that well-coordinated visual regulation does not require continuous visual guidance but depends on intermittent information being available at the appropriate times in the action sequence. Such timing is often more important than the total amount of information that is available for guidance.