Toward a cumulative science of expertise: commentary on Moxley, Ericsson, and Tuffiash (2017).

In a recent Psychological Research article, Moxley, Ericsson, and Tuffiash (2017) report two studies of SCRABBLE expertise. The results revealed that the average SCRABBLE rating was higher for males than for females. Moreover, correlational and structural equation analyses revealed that activities that the authors refer to as "purposeful practice" accounted for a substantial amount of the variance in SCRABBLE ratings. The authors generalize their findings concerning SCRABBLE to STEM careers. We believe this generalization is unjustified, as is their argument that SCRABBLE can be used to understand the gender gap in STEM fields. Moreover, the authors' conclusions are undermined by inconsistencies and contradictions in their arguments. We discuss these problems with Moxley et al.'s article in terms of their impact on the cumulative science of expertise.