Decreasing influence of arbitrarily applicable verbal relations of recreational gamblers: A randomized controlled trial.

Twenty-one recreational gamblers were randomly assigned to two groups; one group was exposed to a conditional discrimination relational training task to bias choice allocation to a black machine presented concurrently with a red machine, and the other group underwent the same relational training task immediately followed by a defusion procedure, designed to expand upon the relations developed in the initial relational task. Both groups completed a simulated slot-machine task before and after the relational training task, with or without the defusion procedure. Results showed that 9 of 11 participants in the relational training only group showed an increased bias toward the black machine, compared to only 4 of 10 in the relational training plus defusion group; this latter group also showed greater matched responding. Results suggest that expanding verbal-relational networks may reduce the influence of any single verbal relation on gambling choice behavior.