New Methods for Unraveling Imitation Accuracy Differences Between Children with Autism and Typically Developing Peers.

This study applies methods used in sign language and gesture research to better understand reduced imitation accuracy (IA) of actions and gestures in children with autism spectrum disorder (ASD), and we addressed contrasting theories on IA in ASD and the role of objects and meanings in imitation. Eight male children with ASD with a mean chronological age (CA) of 86.76 months (SD = 10.74, range 70.5-104.4) and 22 male and female peers with typical development (TD) and a mean CA of 85.44 months (SD = 7.95, range 73.4-96.7) imitated videos of an adult performing actions with objects, representational gestures, conventional gestures and meaningless gestures. We measured accuracy as ability to effectively reproduce features (handshape, palm orientation, location, movement direction and type) and timing (speed) of observed actions/gestures, after ruling out cases of specular (i.e., mirror-like) versus anatomical imitation. Results highlighted significantly lower feature and timing accuracy in children with ASD with respect to the TD group across tasks, and these findings supported sensory-motor theories of IA in ASD. Our data also showed the different impact of objects and meanings within groups. Overall, these results suggest validity to our assessment method and suggested the importance of considering both discreet variables (i.e., variables describing action/gesture feature accuracy, e.g. handshape, movement direction) and continuous variables (i.e., kinematic variables, e.g. speed) in evaluating IA in autism.

Do Spoken Vocabulary and Gestural Production Distinguish Children with Transient Language Delay from Children Who Will Show Developmental Language Disorder? A Pilot Study.

The literature on the role of gestures in children with language delay (LD) is partial and controversial. The present study explores gestural production and modality of expression in children with LD and semantic and temporal relationships between gestures and words in gesture + word combinations. Thirty-three children participated (mean age, 26 months), who were recruited through a screening programme for LD. Cognitive skills, lexical abilities, and the use of spontaneous gestures in a naming task were evaluated when the children were 32 months old. When the children were 78 months old, their parents were interviewed to collect information about an eventual diagnosis of developmental language disorder (DLD). According to these data, the children fell into three groups: children with typical development (n = 13), children with LD who did not show DLD (transient LD; n = 9), and children with LD who showed DLD (n = 11). No significant differences emerged between the three groups for cognitive and lexical skills (comprehension and production), for number of gestures spontaneously produced, and for the sematic relationships between gestures and words. Differences emerged in the modality of expression, where children with transient LD produced more unimodal gestural utterances than typical-development children, and in the temporal relationships between gestures and words, where the children who would show DLD provided more frequent representational gestures before the spoken answer than typical-development children. We suggest a different function for gestures in children with T-LD, who used representational gestures to replace the spoken word they were not yet able to produce, and in children with LD-DLD, who used representational gestures to access spoken words.

Exploring Agreement between MB-CDI Short Forms for Evaluating the Language Skills of Italian Children Aged 18-24 Months.

INTRODUCTION: The short forms of MacArthur-Bates Communicative Development Inventories (MB-CDI) are widely used for assessing communicative and linguistic development in infants and toddlers. Italian norms for the Words and Gestures (WG) and Words and Sentences (WS) short forms overlap between 18 and 24 months. OBJECTIVE: To evaluate the agreement between these two forms. METHODS: Parents of 104 children aged 18-24 months filled in both questionnaires. RESULTS: The two questionnaires showed high agreement in measuring expressive vocabulary size and the percentile of lexical production and good agreement in identifying children at-risk for language delay (75% of the cases were accurately identified). Both short forms include a list of 100 words and a set of questions investigating potential risk factors for communication and language disorders. Ten children with an expressive vocabulary <10th percentile were compared to 10 with typical language development. Scores for children <10th percentile were significantly lower than their peers, in addition to scores of lexical comprehension, gesture-word, and 2-word combinations, and phonological accuracy, imitation of new words, and decontextualized use of language. CONCLUSIONS: Short forms of the Italian MB-CDI can be used interchangeably for evaluating lexical production, but each one offers different quantitative and qualitative information on the behaviours related to language acquisition.

Untrivial Pursuit: Measuring Motor Procedures Learning in Children with Autism.

Numerous studies have underscored prevalence of motor impairments in children with autism spectrum disorders (ASD), but only few of them have analyzed motor strategies exploited by ASD children when learning a new motor procedure. To evaluate motor procedure learning and performance strategies in both ASD and typically developing (TD) children, we built a virtual pursuit rotor (VPR) task, requiring tracking a moving target on a computer screen using a digitalized pen and tablet. Procedural learning was measured as increased time on target (TT) across blocks of trials on the same day and consolidation was assessed after a 24-hour rest. The program and the experimental setting (evaluated in a first experiment considering two groups of TD children) allowed also measures of continuous time on target (CTT), distance from target (DT) and distance from path (DP), as well as 2D reconstructions of children's trajectories. Results showed that the VPR was harder for children with ASD than for TD controls matched for chronological age and intelligence quotient, but both groups displayed comparable motor procedure learning (i.e., similarly incremented their TT). However, closer analysis of CTT, DT, and DP as well as 2D trajectories, showed different motor performance strategies in ASD, highlighting difficulties in overall actions planning. Data underscore the need for deeper investigations of motor strategies exploited by children with ASD when learning a new motor procedure.

A new calibration methodology for thorax and upper limbs motion capture in children using magneto and inertial sensors.

Recent advances in wearable sensor technologies for motion capture have produced devices, mainly based on magneto and inertial measurement units (M-IMU), that are now suitable for out-of-the-lab use with children. In fact, the reduced size, weight and the wireless connectivity meet the requirement of minimum obtrusivity and give scientists the possibility to analyze children's motion in daily life contexts. Typical use of magneto and inertial measurement units (M-IMU) motion capture systems is based on attaching a sensing unit to each body segment of interest. The correct use of this setup requires a specific calibration methodology that allows mapping measurements from the sensors' frames of reference into useful kinematic information in the human limbs' frames of reference. The present work addresses this specific issue, presenting a calibration protocol to capture the kinematics of the upper limbs and thorax in typically developing (TD) children. The proposed method allows the construction, on each body segment, of a meaningful system of coordinates that are representative of real physiological motions and that are referred to as functional frames (FFs). We will also present a novel cost function for the Levenberg-Marquardt algorithm, to retrieve the rotation matrices between each sensor frame (SF) and the corresponding FF. Reported results on a group of 40 children suggest that the method is repeatable and reliable, opening the way to the extensive use of this technology for out-of-the-lab motion capture in children.