Irwin R J, Hautus M J, Butcher J C
Department of Psychology, University of Auckland, New Zealand.
Percept Psychophys. 1999 May;61(4):766-9. doi: 10.3758/bf03205544.
If observers in a same-different experiment base their decisions on the absolute difference between observations on a trial, the area under the receiver operating characteristic equals the maximum proportion of correct decisions that an unbiased independent-observations observer could attain. Even though the differencing strategy is suboptimal, the area measure yields an index of optimal performance.