1. Facts vs. artefacts (the importance of methodology)
2. Definition of Developmental Psychology:
the study of age-related changes in behaviour, usually in humans, across the life-span.
3. Developmental Research Designs
i) The Longitudinal Design
Advantages: intra-individual change, rate of change, no cohort effects.
Disadvantages: time, expense, dated variables/ measures, attrition, practice/ memory effects, poor generalisation.
ii) The Cross-sectional Design
Advantages: circumvents most of the disadvantages of the longitudinal design.
Disadvantages: only inter-individual differences, confounds age & cohort effects
Additional problems relevant to both designs (esp. if long-term): Selective sampling, selective survival, terminal drop
Conclusion: Dubious internal & external validity
iii) Sequential Developmental Designs
a) Bell’s (1953, 1954) Convergence Approach
Age Samples Longitudinal Yearly Data
4 year-olds 5, 6, 7 7 year-olds 8, 9, 10
10 year-olds 11, 12, 13
An accelerated longitudinal study
b) Schaie’s (1965) Trifactorial Approach
Schaie’s 3 Factors (influencing behavioural performance)
Changes in performance may reflect:
1. *Age – Maturational (biological) changes over time.
Universal across cultural + historical settings e.g. motor responses.
2. Cohort – generational differences resulting from
having been born at different time points and having
experienced different socio-cultural,...