Tailoring of painful stimuli used for exploring transfer of function

Abstract

Fifteen college students rated the degree of painfulness of six images showing needle injections to different parts of a human hand. The images were rated on a scale ranging from 1 (not painful) to 5 (severely painful). Next, the participants were trained six conditional discriminations with abstract shapes as stimuli and tested for the formation of three 3-member equivalence classes in a one-to-many (OTM) training structure (AB/AC). The test for emergent relations were followed by training a novel set of stimuli (D) to the A stimuli. The needle injection images rated with the highest and lowest perceived degree of painfulness were used as stimulus D1 and D2, respectively. An image where the needle was replaced with a Q tip was used as stimulus D3 and assumed to be perceived as not painful. The DA training was followed by a matching-to-sample (MTS) test for the formation of three 4- member classes, and the participants were asked to choose one out of three identical bottles with water labelled with the B stimuli. Finally, the participants were asked to rate the degree of painfulness of the B stimuli. The main findings were that the B and D stimuli were not rated significantly different, indicating a transfer of function in the ratings from D to B stimuli. In addition, participants avoided choosing bottle B1 over B2 and B3, but they did not differentiate between B2 and B3.