Detection of visual-tactile contingency in the first year after birth

It is well documented that in the first year after birth, infants are able to identify self-performed actions. This ability has been regarded as the basis of conscious self-perception. However, it is not yet known whether infants are also sensitive to aspects of the self when they cannot control the sensory feedback by means of self-performed actions. Therefore, we investigated the contribution of visual–tactile contingency to self-perception in infants. In Experiment 1, 7- and 10-month-olds were presented with two video displays of lifelike baby doll legs. The infant’s left leg was stroked contingently with only one of the video displays. The results showed that 7- and 10-month-olds looked significantly longer at the contingent display than at the non-contingent display. Experiment 2 was conducted to investigate the role of morphological characteristics in contingency detection. Ten-month-olds were presented with video displays of two neutral objects (i.e., oblong wooden blocks of approximately the same size as the doll legs) being stroked in the same way as in Experiment 1. No preference was found for either the contingent or the non-contingent display but our results confirm a significant decrease in looking time to the contingent display compared to Experiment 1. These results indicate that detection of visual–tactile contingency as one important aspect of self-perception is present very early in ontogeny. Furthermore, this ability appears to be limited to the perception of objects that strongly resemble the infant’s body, suggesting an early sensitivity to the morphology of one’s own body.     

Dissociation and association of the embodied representation of tool-use verbs and hand verbs: An fMRI study

Embodied semantic theories suppose that representation of word meaning and actual sensory-motor processing are implemented in overlapping systems. According to this view, association and dissociation of different word meaning should correspond to dissociation and association of the described sensory-motor processing. Previous studies demonstrate that although tool-use actions and hand actions have overlapping neural substrates, tool-use actions show greater activations in frontal–parietal–temporal regions that are responsible for motor control and tool knowledge processing. In the present study, we examined the association and the dissociation of the semantic representation of tool-use verbs and hand action verbs. Chinese verbs describing tool-use or hand actions without tools were included, and a passive reading task was employed. All verb conditions showed common activations in areas of left middle frontal gyrus, left inferior frontal gyrus (BA 44/45) and left inferior parietal lobule relative to rest, and all conditions showed significant effects in premotor areas within the mask of hand motion effects. Contrasts between tool-use verbs and hand verbs demonstrated that tool verbs elicited stronger activity in left superior parietal lobule, left middle frontal gyrus and left posterior middle temporal gyrus. Additionally, psychophysiological interaction analyses demonstrated that tool verbs indicated greater connectivity among these regions. These results suggest that the brain regions involved in tool-use action processing also play more important roles in tool-use verb processing and that similar systems may be responsible for word meaning representation and actual sensory-motor processing.     

Communicative hand‐waving gestures facilitate object learning in preverbal infants

The theory of natural pedagogy has proposed that infants can use ostensive signals, including eye contact, infant‐directed speech, and contingency to learn from others. However, the role of bodily gestures, such as hand‐waving, in social learning has been largely ignored. To address this gap in the literature, this study sought to determine whether 4‐month‐old infants exhibited a preference for horizontal or vertical (control) hand‐waving gestures. We also examined whether horizontal hand‐waving gestures followed by pointing facilitated the process of object learning in 9‐month‐old infants. Results showed that 4‐month‐old infants preferred horizontal hand‐waving gestures to vertical hand‐waving gestures, even when featural and contextual information were removed. Furthermore, horizontal hand‐waving gestures induced identity encoding for cued objects, whereas vertical gestures did not. These findings highlight the role of communicative intent embedded in bodily movements and indicate that hand‐waving can serve as a new type of ostensive signal.     

Influences of handedness and gender on the grooved pegboard test

We studied performance on the Grooved Pegboard Test upon repeated trials and transfer of training between the hands in the first trial. The classification of handedness was based on the writing hand. We employed three trials for each hand and two different protocols for the order in which the hands started the test. For the three trials combined, women were faster than men. From the first to the second trial, there was an improvement in performance for both sexes. Within the first trial, sex differences reached significance and the protocol interacted with handedness. In this trial, only left-handed men were found to benefit from previous opposite-hand performance. It is speculated that a larger corpus callosum in left-handed men allows for the greater transfer of training between the hands.     

A multiple-schedule evaluation of immediate and subsequent effects of fixed-time food presentation on automatically maintained mouthing

The purpose of this study was to evaluate the immediate and subsequent effects of fixed-time (FT) food presentations on mouthing. The effects of FT food presentations were analyzed within a three-component multiple schedule in which baseline conditions were implemented during the first and third components and treatment conditions were implemented during the second component. Results indicated that FT food reduced mouthing and that levels of mouthing during post-FT components were reliably lower than pre-FT components. Behavioral mechanisms responsible for treatment effects are discussed.     

Illusory hand ownership in a patient with personal neglect for the upper limb,but no somatoparaphenia

The symptoms of patients with left personal neglect are characterized by inattention towards contralesional (left) body parts while at the same time explicitly ascertaining ownership for the neglected hemibody. It is currently unknown if personal neglect is associated with more subtle or implicit disturbances of own body perception and body ownership as measured with the rubber hand illusion. In this study, we report data from a patient with a right hemispheric lesion and personal neglect, without associated somatosensory deficits. We administered to the patient (and to 12 age‐matched controls) the rubber hand illusion paradigm to the right and left hands, to elicit illusory ownership for a fake hand, before and after recovery from personal neglect for the left arm. In a first session, run when the patient showed personal neglect affecting the left arm, he experienced a significantly enhanced subjective illusion of embodiment for the left fake hand as compared to the right hand (as assessed through a standard questionnaire). After recovery from personal neglect for the left arm (second session), the results of the left and right rubber hand illusion experiments were comparable, with no modulation of hand ownership. We argue that personal neglect may consist not only in an inattentional disorder, but also in a deficit of multisensory body representation characterized by a high sensitivity to experimental manipulations of subjective aspects of body ownership.     

身体意象可塑吗?——同步性和距离参照系对身体拥有感的影响

身体意象是个体在意识层面对与身体有关的知觉、态度及信念,它的稳定性与可塑性一直存在争论。本研究使用方位追踪仪、数据手套及投影仪,通过2个实验考查虚拟手错觉中距离参照系对身体拥有感的影响。实验1在虚拟环境中采用经典橡胶手错觉的变式,考察同步性和虚拟手位置对拥有感的影响;实验2引入距离参照系,考察在不同参照条件下被试对同一个位置的虚拟手在不同同步情况下的拥有感错觉。研究结果发现:(1)无论是同步性还是距离都会对虚拟手错觉中的拥有感产生影响,即同步比不同步条件下、距离近比距离远条件下拥有感显著;(2)不同的距离参照系对同一位置的拥有感体验影响差异显著,先近后远的呈现方式会减弱错觉而先远后近的呈现方式则会加强错觉。这一发现与身体拥有感是受稳定的身体意象调节的假设并不一致。     

Detecting and predicting changes

When required to predict sequential events, such as random coin tosses or basketball free throws, people reliably use inappropriate strategies, such as inferring temporal structure when none is present. We investigate the ability of observers to predict sequential events in dynamically changing environments, where there is an opportunity to detect true temporal structure. In two experiments we demonstrate that participants often make correct statistical decisions when asked to infer the hidden state of the data generating process. However, when asked to make predictions about future outcomes, accuracy decreased even though normatively correct responses in the two tasks were identical. A particle filter model accounts for all data, describing performance in terms of a plausible psychological process. By varying the number of particles, and the prior belief about the probability of a change occurring in the data generating process, we were able to model most of the observed individual differences.     

The role of gamma band oscillations and synchrony on rubber hand illusion and crossmodal integration

The rubber hand illusion represents an illusory experience during the mislocalization of own hand when correlated visuotactile stimuli are presented to the actual and fake hands. The visuotactile integration process appears to cause this illusion; the corresponding brain activity was revealed in many studies. In this study, we investigated the effect of the rubber hand illusion on the crossmodal integration process by measuring EEG. The participants who experienced less intensive illusion showed greater congruency effect on reaction time (RT), greater power increase at the parietal zero electrode (Pz) and smaller interelectrode synchrony of the gamma band activity. On the other hand, the participants who experienced more intense illusion showed greater interelectrode synchrony. The results suggested that the gamma band activity in the parietal area reflects the visuotactile integration process and that its synchrony causes the illusory intensity.     

Imitation of body postures and hand movements in children with specific language impairment

Within the domain-general theory of language impairment, this study examined body posture and hand movement imitation in children with specific language impairment (SLI) and in their age-matched peers. Participants included 40 children with SLI (5 years 3 months to 6 years 10 months of age) and 40 children with typical language development (5 years 3 months to 6 years 7 months of age). Five tests were used to examine imitation and its underlying cognitive and motor skills such as kinesthesia, working memory, and gross motor coordination. It was hypothesized that children with SLI show a weakness in imitation of body postures and that this deficit is not equally influenced by the underlying cognitive and motor skills. There was a group effect in each cognitive and motor task, but only gross motor coordination proved to be a strong predictor of imitation in children with SLI. In contrast, hand movement imitation was strongly predicted by performance in the Kinesthesia task in typically developing children. Thus, the findings show not only that children with SLI performed more poorly on the imitation tasks than their typically developing peers but also that the groups’ performances showed qualitative differences. The results of the current study provide additional support to the view that the weaknesses in children with SLI are not limited to the verbal domain.