Equating context conditioning in Pavlovian incubation of US signal value

• The present study showed that subjects that received four conditioning and four extinction trials showed significantly greater responding than subjects that received only four conditioning trials.
• Importantly, the present study had two important modifications that were absent in Goddard (2013).
• First, the present study included a control condition in which rats received unpaired conditioning trials.
• Second, the present study equated the number of food pellets delivered in conditioning and extinction.
• The present study suggests trial number may not be the fundamental unit of learning.

The present study replicated the finding by Goddard (2013), that when a single food pellet unconditioned stimulus (US) signaled the delivery of three additional pellets, responding after the single US was significantly greater on a delayed, compared to an early, test. Importantly, the present study equated context conditioning by delivering the identical number of food pellets in both conditioning and testing and showed that responding was significantly reduced in control subjects that had received unpaired single food–triple food presentations. Implications for theories of conditioning are considered.