Auditory rhythm facilitates perception and action in children at risk for developmental coordination disorder.

Developmental Coordination Disorder (DCD) is a common neurodevelopmental disorder featuring deficits in motor coordination and motor timing among children. Deficits in rhythmic tracking, including perceptually tracking and synchronizing action with auditory rhythms, have been studied in a wide range of motor disorders, providing a foundation for developing rehabilitation programs incorporating auditory rhythms. We tested whether DCD also features these auditory-motor deficits among 7-10 year-old children. In a speech recognition task with no overt motor component, modulating the speech rhythm interfered more with the performance of children at risk for DCD than typically developing (TD) children. A set of auditory-motor tapping tasks further showed that, although children at risk for DCD performed worse than TD children in general, the presence of an auditory rhythmic cue (isochronous metronome or music) facilitated the temporal consistency of tapping. Finally, accuracy in the recognition of rhythmically modulated speech and tapping consistency correlated with performance on the standardized motor assessment. Together, the results show auditory rhythmic regularity benefits auditory perception and auditory-motor coordination in children at risk for DCD. This provides a foundation for future clinical studies to develop evidence-based interventions involving auditory-motor rhythmic coordination for children with DCD.

The development of rhythmic categories as revealed through an iterative production task.

Both humans and non-humans (e.g. birds and primates) preferentially produce and perceive auditory rhythms with simple integer ratios. In addition, these preferences (biases) tend to reflect specific integer-ratio rhythms that are common to one's cultural listening experience. To better understand the developmental trajectory of these biases, we estimated children's rhythm biases across the entire rhythm production space of simple (e.g., ratios of 1, 2, and 3) three-interval rhythms. North American children aged 6-11 years completed an iterative rhythm production task, in which they attempted to tap in synchrony with repeating three-interval rhythms chosen randomly from the space. For each rhythm, the child's produced rhythm was presented back to them as the stimulus, and over the course of 5 such iterations we used their final reproductions to estimate their rhythmic biases or priors. Results suggest that regardless of the initial rhythm, after 5 iterations, children's tapping converged on rhythms with (nearly) simple integer ratios, indicating that, like adults, their rhythmic priors consist of rhythms with simple-integer ratios. Furthermore, the relative weights (or prominence of different rhythmic priors) observed in children were highly correlated with those of adults. However, we also observed some age-related changes, especially for the ratio types that vary most across cultures. In an additional rhythm perception task, children were better at detecting rhythmic disruptions to a culturally familiar rhythm (in 4/4 m with 2:1:1 ratio pattern) than to a culturally unfamiliar rhythm (7/8 m with 3:2:2 ratios), and performance in this task was correlated with tapping variability in the iterative task. Taken together, our findings provide evidence that children as young as 6-years-old exhibit simple integer-ratio categorical rhythm priors in their rhythm production that closely resemble those of adults in the same culture.

The complexity-aesthetics relationship for musical rhythm is more fixed than flexible: Evidence from children and expert dancers.

The urge to move to music (groove) depends in part on rhythmic syncopation in the music. For adults, the syncopation-groove relationship has an inverted-U shape: listeners want to move most to rhythms that have some, but not too much, syncopation. However, we do not know whether the syncopation-groove relationship is relatively sensitive to, or resistant to, a listener's experience. In two sets of experiments, we tested whether the syncopation-groove relationship is affected by dance experience or changes through development in childhood. Dancers and nondancers rated groove for 50 rhythmic patterns varying in syncopation. Dancers' and nondancers' ratings did not differ (and Bayesian tests provided substantial evidence that they were equivalent) in terms of mean groove and the optimal level of syncopation. Similarly, ballet and hip-hop dancers' syncopation-groove relationships did not differ. However, dancers had more robust syncopation-groove relationships (higher goodness-of-fit) than nondancers. Children (3-6 years old) completed two tasks to assess their syncopation-groove relationships: In a 2-alternative-forced choice task, children compared rhythms from 2 of 3 possible levels of syncopation (low, medium, and high) and chose which rhythm in a pair was better for dancing. In a dance task, children danced to the same rhythms. Results from both tasks indicated that for children, as for adults, medium syncopation rhythms elicit more groove than low syncopation rhythms. A follow-up experiment replicated the 2-alternative-forced choice task results. Taken together, the results suggest the optimal level of syncopation for groove is resistant to experience, although experience may affect the robustness of the inverted-U relationship. RESEARCH HIGHLIGHTS: In Experiment 1, dancers and nondancers rated groove (the urge to move) for musical rhythms, demonstrating the same inverted-U relationships between syncopation and groove. In Experiment 2, children and adults both chose rhythms with moderate syncopation more than low syncopation as more groove-inducing or better for dancing. Children also danced more for moderate than low syncopation, showing a close perception-behavior relationship across tasks. Similarities in the syncopation-groove relationship regardless of dance training and age suggest that this perceptual and behavioral groove response to rhythmic complexity may be quite resistant to experience.