What is the shape of developmental change?

Area of Science:

• Developmental psychology
• Behavioral science
• Motor development

Background:

• Developmental trajectories are key to understanding change processes.
• Accurate trajectory characterization relies on frequent observation sampling.

Purpose of the Study:

• To examine how different sampling intervals affect the characterization of developmental trajectories.
• To assess the impact of sampling frequency on identifying variability and onset ages in infant motor skills.

Main Methods:

• Utilized real behavioral data from 32 infant motor skills observed daily for 18 months.
• Simulated larger sampling intervals (2-31 days) by removing daily observations and interpolating.
• Analyzed the effects of varying sampling frequencies on trajectory estimation.

Main Results:

• Infrequent sampling reduced sensitivity to daily fluctuations, making variable trajectories appear as step functions.
• Estimates of skill onset ages became less accurate with larger sampling intervals.
• Sensitivity to variation decreased as an inverse power function of the sampling interval, with significant degradation beyond 7 days.

Conclusions:

• Typical sampling rates in developmental research may be insufficient for accurately depicting developmental variability and change.
• Inadequate sampling regimes can compromise the validity of developmental theories.
• High-frequency data collection is crucial for robust developmental trajectory analysis.