Acquired equivalence in human discrimination learning: the role of propositional knowledge

The current study investigated the role of propositional knowledge in human acquired equivalence effects. Across 5 experiments, human adults were trained to associate different visual stimuli. Subsequent procedures presented training that was either consistent or inconsistent with the previous associations. More accurate responding in the consistent versus inconsistent condition reflected an acquired equivalence effect. The results of Experiment 1 indicated that a previously reported divergence between verbal and associative processes was likely due to instructional control. Experiments 2-5 further examined the role of verbal processes and demonstrated that acquired equivalence may be produced with verbal instructions alone and critically through a combination of instructions and actual stimulus pairings. The current data not only challenge a purely associative account but actively support an interaction between verbal and associative processes in producing the acquired equivalence effect in humans.