Discerning equivalence relations from displayed but not previously learned stimulus pairs

A method was devised to determine whether participants could discern stimulus equivalence (SE) relations between stimuli without prior training, but simply via visual inspection of an array of premise pairs. On each of a series of slides nine circles containing different colours were paired together in boxes in different ways on each slide to embody three 3-member equivalence classes. Below this “study” array of boxes were two “choice” boxes, with two colours derived from the same equivalence class in one, and colours from two different classes in the other. Participants were instructed to choose the box in which the colours were seemingly combined “according to the pairs above”. Then on a final “sort” slide they were asked, in relation to its array, to allocate the nine colours into groups of their own choosing. Twenty-two undergraduate students, some naïve and some with some prior experience of standard equivalence experiments, participated in this experiment. Participants 1–11, in addition to trials in which the within-class choice was a symmetric or transitive pair, were given extra “baseline” trials with a simple copy of one of the array pairs in the within-class choice box. Such “baseline” trials were omitted for the remaining participants. On the choice trials about half of the participants systematically selected the within-class alternatives. There was some indication that prior experience made this more likely, whereas inclusion of “baseline” trials seemingly had a negative effect. Participants who systematically selected the within-class alternatives mostly also sorted the colours into the appropriate three equivalence groups. Some methodological refinements and extensions of this “plain sight” procedure are proposed, and the analytical potential of comparing performance on these with that on standard MTS procedures is discussed.