Seeing the world through a third eye: Developmental systems theory looks beyond the nativist-empiricist debate

A Commentary on Whitall and Colleagues’ 2020 Article “Motor Development Research: II. The First Two Decades of the 21st Century Shaping Our Future”

This commentary reflects on the discussions of Whitall et al.’s paper “Motor Development Research: II. The First Two Decades of the 21st Century Shaping Our Future.” Comments focus on (a) the emergence and importance of the Developmental Systems approach to motor development, (b) the perceived ambiguity between Dynamic and Developmental Systems approaches, and (c) a case for the evolution of Developmental Motor Neuroscience from the field of Developmental Cognitive Neuroscience.

Sleep as a mirror of developmental transitions in infancy: the case of crawling

The associations between the onset of crawling and changes in sleep were examined in 28 infants who were followed from 5 to 11 months-of-age. Motor development and sleep (actigraphy) were assessed at 2- to 3-week intervals. Along with the overall improvement in sleep consolidation, periods of increased long wake episodes were also manifested; the rise in sleep disruption was temporally linked to crawling onset. The results of the study highlight the dynamic interrelations between domains of development, indicate that emerging motor skills may involve periods of disrupted sleep, and point to the moderating effect of age. Clarifying the factors involved in the interplay between developmental milestones and sleep remains a challenge for future research.

Further Development and Validation of the Affordances in the Home Environment for Motor Development-Infant Scale (AHEMD-IS)

BACKGROUND

Affordances in the home environment may play a significant role in infant motor development.

OBJECTIVE

The purpose of this study was to further develop and validate the Affordances in the Home Environment for Motor Development-Infant Scale (AHEMD-IS), an inventory that measures the quantity and quality of motor affordances in the home.

DESIGN

A cross-sectional study was conducted to evaluate criteria for content validity, reliability, internal consistency, floor and ceiling effects, and interpretability of the instrument.

METHODS

A pilot version of the inventory with 5 dimensions was used for expert panel analysis and administered to parents of infants (N=419). Data were analyzed with Cronbach alpha, intraclass correlation coefficients (ICCs), ceiling and floor effects, and item and dimension interpretability analyses for creation of a scoring system with descriptive categories for each dimension and total score.

RESULTS

Average agreement among the expert panel was 95% across all evaluation criteria. Cronbach alpha values with the 41-item scale ranged between .639 and .824 for the separate dimensions, with a total value of .824 (95% confidence interval [95% CI]=.781, .862). The ICC values were .990 for interrater reliability and .949 for intrarater reliability. There was a ceiling effect on 3 questions for the Inside Space dimension and on 3 questions for the Variety of Stimulation dimension. These results demonstrated the need for reduction in total items (from 41 to 35) and the combination of space dimensions. After removal of questions, internal consistency was .766 (95% CI=.729, .800) for total score. Overall assessment categories were created as: less than adequate, moderately adequate, adequate, and excellent.

LIMITATIONS

The inventory does not determine specific use (time, frequency) of affordances in the home, and it does not account for infants' out-of-home activities.

CONCLUSIONS

The AHEMD-IS is a reliable and valid instrument to assess affordances in the home environment that promote infant motor development.

Effect of the home environment on motor and cognitive behavior of infants

Although information is sparse, research suggests that affordances in the home provide essential resources that promote motor and cognitive skills in young children. The present study assessed over time, the association between motor affordances in the home and infant motor and cognitive behavior. Thirty-two (32) infants were assessed for characteristics of their home using the Affordances in the Home Environment for Motor Development--Infant Scale and motor and cognitive behavior with the Bayley Scales of Infant and Toddler Development--III. Infant's home and motor behavior were assessed at age 9 months and 6 months later with the inclusion of cognitive ability. Results for motor ability indicated that there was an overall improvement in performance from the 1st to the 2nd assessment. We found significant positive correlations between the dimensions of the home (daily activities and play materials) and global motor performance (1st assessment) and fine-motor performance on the 2nd assessment. In regard to cognitive performance (2nd assessment), results indicated a positive association with fine-motor performance. Our results suggest that motor affordances can have a positive impact on future motor ability and speculatively, later cognitive behavior in infants.

The Biological Implausibility of the Nature-Nurture Dichotomy & What It Means for the Study of Infancy

Since the time of the Greeks, philosophers and scientists have wondered about the origins of structure and function. Plato proposed that the origins of structure and function lie in the organism's nature whereas Aristotle proposed that they lie in its nurture. This nature/nurture dichotomy and the emphasis on the origins question has had a powerful effect on our thinking about development right into modern times. Despite this, empirical findings from various branches of developmental science have made a compelling case that the nature/nurture dichotomy is biologically implausible and, thus, that a search for developmental origins must be replaced by research into developmental processes. This change in focus recognizes that development is an immensely complex, dynamic, embedded, interdependent, and probabilistic process and, therefore, renders simplistic questions such as whether a particular behavioral capacity is innate or acquired scientifically uninteresting.

Opportunities for early intervention based on theory, basic neuroscience, and clinical science

Therapeutic approaches in the pediatric population have generally been less aggressive than those implemented for younger and older adults. Several factors contribute to this, starting with the challenge of engaging infants in the "goal" of therapy, their resistance to initiating behaviors that are uncomfortable or fatiguing, the desire to make therapy as functionally relevant as possible when many functional skills have yet to emerge, and residual history of outdated theoretical concepts. On the practical side of who will pay for this more aggressive approach, there is limited empirical evidence based on randomized controlled trials to convince third-party payers to fund more extensive services. This article outlines a theoretical perspective prominent in developmental science that argues not only for the importance of frequent bouts of functionally relevant activity on the self-organization of behavioral patterns, but also for the impact that should be expected from the use of rigorous interventions on underlying subsystems, such as neural organization, that support these outcomes. In order to propose some future opportunities for clinical research and application, examples from recent activity-based clinical studies are presented, along with theoretical principles, neuroscience, and other tissue science data concerning mechanisms that contribute to behavioral changes. One such opportunity is to increase the structured engagement of caregivers, guided by therapists, in administering well-defined activity intervention programs focused on the development of specific functional skills. Such an approach may be one of the few financially feasible options for generating sufficient therapy that adheres to principles for optimizing development of neuromotor control.