erian" argument, and never seen an overt statement of that plain logical equivalence. I'd be happy to know if anyone alse ever has.
Humberstone, L. (1994), "Hempel meets Wason", Erkenntnis, 41 (1994), pp. 391–402.
Johnson-Laird, P.N. & Wason, P.C. (1977), "A theoretical analysis of insight into a reasoning task", in P.N. Johnson-Laird & P.C. Wason (eds.), Thinking: Readings in Cognitive Science, Cambridge University Press, Cambridge, pp. 143-157.
Oaksford, M. & Chater N. (1994), "A rational analysis of the selection task as optimal data selection", Psychological Review, 101 (1994), pp. 608–631.