Reading focus
Syllabus: How Do We Adapt as We Grow Older?
Evaluate Schaie's objection against the actual design and claims of the opening study. Identify what a criticism shows to be uncertain and what evidence would be needed to settle that uncertainty.
A question to consider. Which assumption in Salthouse's approach does this commentary most seriously challenge, and how would you investigate it?
Why this reading
This brief commentary asks whether a study's comparisons justify its developmental claim. It offers an opportunity to evaluate an objection to an inference rather than treat criticism as a competing set of results.
Before you read
The commentary responds to Salthouse's 2009 study of cognitive aging. An age difference compares people; an age change follows a person. A methodological criticism should identify the assumption at issue and explain how it could affect the conclusion.
Read for
- Reconstruct the objection about cohort differences in your own words.
- Examine the concerns about retest intervals, variability, and the abilities represented.
- Separate a limitation of the evidence from a demonstration that the proposed explanation is false.
Consider afterwards
- Which part of the argument would be strengthened by following several birth cohorts over the same ages, and what problem would that design still face?
Editorial context
This is a two-page commentary, not a new empirical study or a correction notice. Salthouse's four-page response rejects a single-cause interpretation of either design. The exchange leaves readers with competing assumptions to investigate, rather than a universal age at which cognition changes.