Responses compete and collaborate, shaping each others' distributions: Commentary on Boakes, Patterson, Kendig, and Harris (2015).

Boakes, Patterson, Kendig, and Harris (2015) showed that schedule-induced drinking (SID), typically concentrated in the first half of the interpellet interval, is not moved there exclusively by competition from magazine entries, and that not all arbitrary responses can be maintained by adventitious reinforcement. They attribute such inferences to Killeen and Pellón (2013) and Patterson and Boakes (2012), and on that basis reject their explanation for the excessive nature of many adjunctive responses as a result of reinforcement. It is a mistaken attribution, as Killeen and Pellón emphasized that reinforcers act on many competing interim and terminal responses. That attribution is a minor oversight on the authors' part; their return to a discredited motivational account is, however, a major blunder. It discards the seminal recent advances in understanding the nature of schedule-induced responses (e.g., those of Patterson and Boakes), and even the positive contributions of their own article: Their data show very strong correlations between magazine entries and drinking, providing much more evidence for response competition than their microanalysis provides against it.