Differential derived stimulus relations across probe-trial versus adduction testing are not a function of...

The present research assessed whether unreliable derivation of three-node equivalence relations in adduction testing is due to the absence of comparison-stimulus presentation. College students first learned arbitrary-matching-to-sample discriminations (AB, BC, CD, and DE) with Arabic numbers (A), nonsense syllables (B, C, D), and nonrepresentational forms (E) as stimuli. Participants then were exposed to either probe-trial testing or adduction testing. In probe-trial testing, each trial involved one of the four E stimuli (e.g., E1) as a sample and each of the four A stimuli (A1, A2, A3, A4) as comparisons. Successful performance involved participants selecting the corresponding A stimulus in the absence of differential consequences (e.g., A1 in the presence of E1). In adduction testing, each trial involved an arithmetic equation such that successful performance involved combining derived EA relations with simple math skills. Critically, unlike in typical adduction testing, participants were presented with four response options to select from (i.e., comparison stimuli). In probe-trial testing, each participant derived the EA relations, whereas no participant performed successfully in adduction testing. The present findings suggest that the unreliable derivation of three-node equivalence relations in adduction testing is not due to the typical absence of comparison stimuli. The present research challenges experimental psychologists to clarify the role of testing context in identifying the necessary and sufficient conditions that control emergent learning.