Do establishing operations alter reinforcement effectiveness?

Michael (this issue) defines an establishing operation (EO), such as food deprivation, as (a) altering the effectiveness of reinforcement as well as (b) evoking behavior. Although this dual role for EOs is compelling, it is possible that such operations have only evocative effects (i.e., function only in the form of antecedent control). The main question raised here is how the reinforcement-altering function can be experimentally analyzed. Evolutionary and conceptual implications of the two-function EO are also considered.