Development of hand preference for object-directed actions and pointing gestures: a longitudinal study between 15 and 25 months of age

The development of hand preferences for object-directed actions and pointing gestures was investigated in toddlers sampled bimonthly between 15 and 25 months of age. Language level was also assessed, in an attempt to examine the relationship between handedness and language development. Results did not reveal any changes over the study period in the mean Handedness Index of the whole sample, both for bimanual manipulative activities and pointing gestures. However, the categorization of participants as left-handers, right-handers, or non-lateralized revealed that most of children presented nonlinear individual trajectories in the development of hand preference. Moreover, the only significant correlations observed between hand preferences for manipulation and pointing were negative correlations between the strength of hand preferences at 19 and 21 months of age, suggesting that manipulative actions and communicative gestures are controlled by different networks in the left cerebral hemisphere. These findings are discussed in relation to the development of speech-gesture links in infancy.     

The interplay between gesture and speech in the production of referring expressions: investigating the tradeoff hypothesis

The tradeoff hypothesis in the speech-gesture relationship claims that (a) when gesturing gets harder, speakers will rely relatively more on speech, and (b) when speaking gets harder, speakers will rely relatively more on gestures. We tested the second part of this hypothesis in an experimental collaborative referring paradigm where pairs of participants (directors and matchers) identified targets to each other from an array visible to both of them. We manipulated two factors known to affect the difficulty of speaking to assess their effects on the gesture rate per 100 words. The first factor, codability, is the ease with which targets can be described. The second factor, repetition, is whether the targets are old or new (having been already described once or twice). We also manipulated a third factor, mutual visibility, because it is known to affect the rate and type of gesture produced. None of the manipulations systematically affected the gesture rate. Our data are thus mostly inconsistent with the tradeoff hypothesis. However, the gesture rate was sensitive to concurrent features of referring expressions, suggesting that gesture parallels aspects of speech. We argue that the redundancy between speech and gesture is communicatively motivated.     

Social cues, mentalizing and the neural processing of speech accompanied by gestures

Body orientation and eye gaze influence how information is conveyed during face-to-face communication. However, the neural pathways underpinning the comprehension of social cues in everyday interaction are not known. In this study we investigated the influence of addressing vs. non-addressing body orientation on the neural processing of speech accompanied by gestures.While in an fMRI scanner, participants viewed short video clips of an actor speaking sentences with object- (O; e.g., shape) or person-related content (P; e.g., saying goodbye) accompanied by iconic (e.g., circle) or emblematic gestures (e.g., waving), respectively. The actor's body was oriented either toward the participant (frontal, F) or toward a third person (lateral, L) not visible.For frontal vs. lateral actor orientation (F > L), we observed activation of bilateral occipital, inferior frontal, medial frontal, right anterior temporal and left parietal brain regions. Additionally, we observed activity in the occipital and anterior temporal lobes due to an interaction effect between actor orientation and content of the communication (PF > PL) > (OF > OL).Our findings indicate that social cues influence the neural processing of speech-gesture utterances. Mentalizing (the process of inferring the mental state of another individual) could be responsible for these effects. In particular, socially relevant cues seem to activate regions of the anterior temporal lobes if abstract person-related content is communicated by speech and gesture. These new findings illustrate the complexity of interpersonal communication, as our data demonstrate that multisensory information pathways interact at both perceptual and semantic levels.     

Neural integration of speech and gesture in schizophrenia: Evidence for differential processing of metaphoric gestures

Gestures are an important component of interpersonal communication. Especially, complex multimodal communication is assumed to be disrupted in patients with schizophrenia. In healthy subjects, differential neural integration processes for gestures in the context of concrete [iconic (IC) gestures] and abstract sentence contents [metaphoric (MP) gestures] had been demonstrated. With this study we wanted to investigate neural integration processes for both gesture types in patients with schizophrenia. During functional magnetic resonance imaging‐data acquisition, 16 patients with schizophrenia (P) and a healthy control group (C) were shown videos of an actor performing IC and MP gestures and associated sentences. An isolated gesture (G) and isolated sentence condition (S) were included to separate unimodal from bimodal effects at the neural level. During IC conditions (IC > G ∩ IC > S) we found increased activity in the left posterior middle temporal gyrus (pMTG) in both groups. Whereas in the control group the left pMTG and the inferior frontal gyrus (IFG) were activated for the MP conditions (MP > G ∩ MP > S), no significant activation was found for the identical contrast in patients. The interaction of group (P/C) and gesture condition (MP/IC) revealed activation in the bilateral hippocampus, the left middle/superior temporal and IFG. Activation of the pMTG for the IC condition in both groups indicates intact neural integration of IC gestures in schizophrenia. However, failure to activate the left pMTG and IFG for MP co‐verbal gestures suggests a disturbed integration of gestures embedded in an abstract sentence context. This study provides new insight into the neural integration of co‐verbal gestures in patients with schizophrenia. Hum Brain Mapp, 2013. © 2012 Wiley Periodicals, Inc.     

Clinical Features Associated with Suicide Attempts versus Suicide Gestures in an Inpatient Sample

The objective of this study was to test whether suicide attempters and suicide gesturers can be clinically differentiated. A total of 150 subjects who had attempted suicide at least once, had made a suicide gesture, had suicidal ideation, and/or had engaged in non-suicidal self-injury were recruited from the inpatient service of the Jiménez Díaz Foundation (Madrid, Spain). A multinomial regression analysis was conducted. Histrionic and antisocial personality disorders were risk factors specific to suicide gestures. Narcissistic personality disorder was specifically associated with suicide attempts. Borderline personality disorder was associated with both suicide gestures and attempts. A high level of impulsiveness was a risk factor specific to suicide attempts. Conclusion: Suicide attempters and suicide gesturers are two distinct, although partially overlapping, populations.     

The Good Nurse: A True Story of Medicine,Madness and Murder

Eyewitnesses’ memory reports can be altered when ambiguous post-event information is presented verbally during interviews. Although recent research has identified that gestures can also act as a source of influence in eyewitness interviews, it is unknown whether nonverbal suggestions can exert an influence to the same extent as those made verbally. To investigate this, 92 adults were interviewed about a crime video and provided with either verbal (speech) or nonverbal (gesture) suggestions during questioning that provided either factual or misleading information about the scene. The results revealed that both differed from controls, and that gestures exerted a similar level of influence as speech. As with speech, gestures led participants to giving both correct and incorrect responses. These results highlight that misinformation can be conveyed covertly through gestures as a form of suggestion in a way that is comparable to overt verbal influence.     

Hello and Goodbye: A Study of Social Engagement in Autism

We videotaped 24 children, adolescents, and young adults with autism, individually matched for chronological age and verbal mental age with 24 nonautistic persons with mental retardation, for their spontaneous and prompted greetings and farewells towards an unfamiliar adult. Compared with control subjects, those with autism were less likely to offer spontaneous verbal and nonverbal gestures of greeting and farewell, and were less likely to establish eye contact even when they were offered a greeting. There were also fewer autistic subjects who smiled, or who waved goodbye. Results corresponded with raters' subjective judgments of participants' interpersonal engagement with the stranger. One interpretation of the findings is that they reflect a relative lack of intersubjective engagement by autistic individuals.     

Cerebral blood flow velocity changes during meaningful and meaningless gestures – a functional transcranial Doppler study

The aim of the study was to use functional transcranial Doppler to investigate the possibility of revealing different activation patterns during healthy subjects' performance of meaningful and meaningless actions. Mean flow velocity (MFV) changes were recorded in middle cerebral arteries (MCAs) of 26 normal subjects during a rest phase and during performance of meaningful and meaningless actions. The meaningful task consisted of pouring sugar into a cup with a teaspoon. The meaningless action was an arm movement similar to that necessary for pouring sugar in a cup but without any tool and thus without a goal. Performing actions with or without meaning was associated with different patterns of MFV changes, as documented by the triple interaction condition x performing arm x side of recording [F(1, 25)=10.977; P=0.003]. During the meaningful action, MFV in MCAs increased significantly more than during the meaningless action. During the meaningless action, the MFV increase was significantly higher in the contralateral than in the ipsilateral MCA to the arm performing the task and the meaningful action determined a bilateral MFV increase only when the task was performed with the left arm. When the same task was performed with the right arm, the MFV increase was significantly higher in the contralateral than in the ipsilateral MCA. These findings suggest that the content of an action can influence MFV changes and further confirm the usefulness of transcranial Doppler in neuropsychological investigation.