This image was acquired from
wikimedia. It was marked as Public Domain or CC0 and is free to use. To verify, go to the source and check the information there.
Keywords from Image Description:
KrugDavisGlover. This image shows results from series of three experiments on massed versus distributed reading reported by Krug Davis and Glover The red bars show the mean idea units recalled by groups who read passage twice with no intervening interval The blue bars show the mean idea units recalled by groups who read the same