Second-order discrimination in humans: the roles of explicit instructions and constructed verbal responding.

In two experiments, university students were trained on a conditional discrimination task (second-order matching to sample) involving various types of stimulus presentations and experimenter-provided instructions. The students' acquisition of conceptual behavior was assessed during transfer tests defined at the intramodal, extramodal and extrarelational levels. On each transfer trial, subjects had to construct their own verbal description of the stimulus being chosen and of the stimulus relation controlling their current choice. The main finding was that conceptual behavior during test trials developed largely independently of the training conditions. The acquisition of conceptual behavior in these experiments may be attributed to the subjects' constructing their own verbal descriptions on each transfer trial. These findings are discussed in relation with the notions of problem solving, generalized responding, and rule-governance.