Comparison of U.S. and Tajik infants' time in containment devices

Emergence of locomotor behaviors: Associations with infant characteristics, developmental status, parental beliefs, and practices in typically developing Brazilian infants aged 5 to 15 months

Independent locomotion provides autonomy for infants, drastically changing their relationship with their surroundings. From a dynamic systems perspective, the interaction between environment, tasks, and organismic constraints leads to the emergence of new behaviors over time. This 6-month longitudinal study aimed to verify associations between the emergence of locomotor behaviors and infants' characteristics, developmental status, parental beliefs, and practices. This observational study remotely assessed 37 full-term Brazilian infants aged 5 to 15 months, divided into two groups (G1: 5 to 11 months, n = 19; and G2: 9 to 15 months, n = 18). The motor developmental status of infants was closely associated with the emergence of behaviors (p < 0.05). Infants in G2 whose parents agreed with the statement "In typically developing infants, motor development occurs naturally and there is no need to actively stimulate it" started to walk later than those whose parents disagreed. Infants whose parents expected them to walk around 10-11 months walked earlier compared to those expected to walk after 11 months (G2, p = 0.011). Infants in G2 with a high frequency of staying in the supine position started to walk, both with and without support, later than those with a low frequency (p < 0.05). For infants in G1 with a high frequency of playing on the floor, locomotion (p = 0.041) and crawling on hands-and-knees (p = 0.007) started sooner compared to those with a low frequency. Staying in the cradle more frequently was related to a later emergence of supported walk (p = 0.046) among infants in G2. The emergence of locomotor behaviors is associated with motor developmental status, the surfaces where the infant plays, and body position. Parental beliefs and expectations influence how infants are stimulated and, consequently, the emergence of independent walking.

An update of the development of motor behavior

This primer describes research on the development of motor behavior. We focus on infancy when basic action systems are acquired-posture, locomotion, manual actions, and facial actions-and we adopt a developmental systems perspective to understand the causes and consequences of developmental change. Experience facilitates improvements in motor behavior and infants accumulate immense amounts of varied everyday experience with all the basic action systems. At every point in development, perception guides behavior by providing feedback about the results of just prior movements and information about what to do next. Across development, new motor behaviors provide new inputs for perception. Thus, motor development opens up new opportunities for acquiring knowledge and acting on the world, instigating cascades of developmental changes in perceptual, cognitive, and social domains. This article is categorized under: Cognitive Biology > Cognitive Development Psychology > Motor Skill and Performance Neuroscience > Development.

Long-form recording of infant body position in the home using wearable inertial sensors

Long-form audio recordings have had a transformational effect on the study of infant language acquisition by using mobile, unobtrusive devices to gather full-day, real-time data that can be automatically scored. How can we produce similar data in service of measuring infants' everyday motor behaviors, such as body position? The aim of the current study was to validate long-form recordings of infant position (supine, prone, sitting, upright, held by caregiver) based on machine learning classification of data from inertial sensors worn on infants' ankles and thighs. Using over 100 h of video recordings synchronized with inertial sensor data from infants in their homes, we demonstrate that body position classifications are sufficiently accurate to measure infant behavior. Moreover, classification remained accurate when predicting behavior later in the session when infants and caregivers were unsupervised and went about their normal activities, showing that the method can handle the challenge of measuring unconstrained, natural activity. Next, we show that the inertial sensing method has convergent validity by replicating age differences in body position found using other methods with full-day data captured from inertial sensors. We end the paper with a discussion of the novel opportunities that long-form motor recordings afford for understanding infant learning and development.

Gahvora cradling in Tajikistan: Cultural practices and associations with motor development

In Tajikistan, infants are bound supine in a "gahvora" cradle that severely restricts movement. Does cradling affect motor development and body growth? In three studies (2013-2018), we investigated associations between time in the gahvora (within days and across age) and motor skills and flattened head dimensions in 8-24-month-old Tajik infants (N = 269, 133 girls, 136 boys)) and 4.3-5.1-year-old children (N = 91, 53 girls, 38 boys). Infants had later motor onset ages relative to World Health Organization standards and pronounced brachycephaly; cradling predicted walk onset age and the proficiency of sitting, crawling, and walking. By 4-5 years, children's motor skills were comparable with US norms. Cultural differences in early experiences offer a unique lens onto developmental processes and equifinality in development.