Kendler, H. H., Hirschberg, M. A., & Wolford, G. (1971). Spence's prediction about reversal-shift behavior. Psychological Review, 78(4), 354.
http://dx.doi.org/10.1037/h0020288
Comments on K. W. Spence's (see record 1936-05785-001) original discrimination-learning model in animals. Spence's theory, depending on the initial start vectors, can predict faster reversal or extradimensional shifts. But when it comes to counterbalanced designs, with no overtraining, the model is unequivocal; reversals should be slower than extradimensional shifts. (PsycINFO Database Record (c) 2016 APA, all rights reserved)