Higher intraindividual variability is associated with more forgetting and dedifferentiated memory functions in old age

► Older adults whose choice reaction times varied more from trial-to-trial also forgot more of the encoded pictures over 1 week. ► Older adults whose choice reaction times varied more from trial-to-trial showed dedifferentiation of working memory and episodic memory. ► Slower reaction time speed is associated with lower episodic memory performance in older adults, but is unrelated to forgetting.