Differentiation and negative transfer as a function of degree of first- and second-list learning

Direct measures of interlist response differentiation were made in the A-B, A-C and A-B, C-D paradigms as a function of degree of first- and second-list learning and found to be equal and nearly perfect in all conditions. Furthermore, negative transfer was markedly increased by higher degrees of second-list learning whereas the effect of first-list degree of learning was not significant. These effects were explained on the premise that transferable intralist stimulus differentiation exists for A-B, A-C but not for the A-B, C-D control. This hypothesis can explain why negative transfer levels off with higher first-list learning but increases with higher second-list learning.