Adding interesting but irrelevant material to a lesson reduces how much of the relevant material is learned.
Garner and colleagues named it in 1989. Harp and Mayer's 1998 experiments added vivid anecdotes about people struck by lightning to a lesson on how lightning forms, and students remembered the anecdotes and understood less of the mechanism. Sundararajan and Adesope's 2020 meta-analysis found a small-to-moderate negative effect across dozens of studies.
In practice
- A training deck opens each section with a funny stock photograph, and the feedback praises the photographs while the quiz scores fall.
- A museum label leads with the curator's anecdote about the discovery, and visitors leave knowing the anecdote and not what the object was for.
- Standing
- Most of the studies used short sessions, so whether the interest such details add pays for itself over a whole course is less tested. Compare the Dr. Fox effect.
- Further reading
- Wikipedia
- Subject
- Learning & Education
- Essay
- What works in learning, and what schools can and cannot change