In order to empirically test progressive complexity and inclusivity assumptions of the taxonomic proposal by Ribes and López, in the present study the effects of different T cycle lengths on behavioral adjustment were evaluated. Three groups of rats were exposed to non-contingent water delivery, contingent water delivery, and a two-choice conditional discrimination situation for water delivery, between successive phases. Between groups of rats the duration of the T cycle was 15, 30, and 60 s long. A generalized adjustment index was calculated in all three conditions of water delivery. It was observed that the generalized adjustment index decreased across water delivery conditions and increased with the cycle length. The results are discussed highlighting the effects of the cycle length.