Human Development Research Methods

Human Development Overview

• Human development refers to the changes occurring with age.
• Age cannot be experimentally assigned or manipulated (e.g., cannot assign toddlers to a study group).
• Developmental psychologists often do not use random assignment or experimental designs due to this limitation.

Research Methods in Human Development

Cross-Sectional Studies

• Cross-sectional studies involve assessing people of different ages at one point in time.
• Example: Assess people from age groups (children, adolescents, adults, elderly) on characteristics (e.g., happiness, IQ).
• By comparing results across age groups, researchers examine relationships between age and measured characteristics.
• Key Limitation: Age differences observed may not indicate developmental changes due to cohort effects.
  • Cohort: Generational groups born in the same time period.
  • Cohort Effects: Differences due to historical and social contexts, not merely due to age.
• Example from research: A study cited (Yang, 2008) noted that happiness increases with age:
  • 33% of participants aged 88 reported high happiness compared to 24% of younger participants.
  • Conclusion: This suggests correlation but does not confirm causation; younger individuals might face different stressors affecting happiness.

Longitudinal Studies

• Longitudinal studies assess the same participants multiple times over an extended period.
• Example: Measure IQ of a group of adolescents every 10 years.
• Benefits:
  • Determine individual changes over time.
• Limitations of Longitudinal Studies:
  • Time-consuming and costly.
  • Influences other than age affect results (e.g., technology improvements, social changes).
  • Attrition: Participants may drop out over time due to various reasons (health issues, loss of interest).
  • Remaining participants may become a biased sample, as those who drop out may not represent the original group (e.g., healthier individuals remaining in an older adults study).

Importance of Longitudinal Research

• Many developmental changes require longitudinal studies for accurate conclusions.
• Understanding the complexities of human development often rests on the findings of these longitudinal designs.