What does this mean?

Whereas 20 per cent of submitted manuscripts are rejected by physics journals, this rate reaches 80 per cent in psychology.
Adair, J.G. & Vohra, N. (2003).The explosion of knowledge, references, and citations: Psychology?s unique response to a crisis. American Psychologist, 58(1), 15?23.

Perhaps it means that psychology journals have higher standards? Or that that psychologists submitting papers have lower standards? Both seem unlikely, especially since the authors and the reviewers are often the same people. Does an incoherent intellectual culture make the business of publishing research more problematic? Answers on a postcard please…