Transfer of relational stimulus control in conditional discriminations.
Teach two links and the learner will travel the whole chain—just arrange the display so similar items sit side-by-side.
01Research in Context
What this study did
Adults and one child learned simple A→B and B→X matches with colored shapes. The trainer never taught the A→X link. Later probes asked for that untaught match and for the reverse of every link.
The setup was a standard matching-to-sample task in a quiet lab. Correct picks produced points on a screen.
What they found
Every person immediately picked the correct comparison on A→X, X→A, and every other untaught combination. The relations emerged without extra trials or feedback.
In plain words, once the brain learns two steps of a chain, it freely travels the whole chain and walks it backward too.
How this fits with other research
Ayres‐Pereira et al. (2025) now supersedes this method. They showed that when the stimuli look almost identical, you must line them up side-by-side during teaching or equivalence collapses. The 1994 study used easy-to-tell-apart shapes, so it missed this display rule.
Pérez-González et al. (2003) extends the idea by adding contextual cues. They proved that a background color or shape can flip which equivalence class the learner uses, even though the 1994 paper never tested context.
Plazas et al. (2018) extends the pathway. They formed new classes using only exclusion trials and no praise or points, showing that reinforced matching-to-sample is not the only route to emergent relations.
Why it matters
This lab demo is the bedrock of higher-order programming. When you teach letter→sound and sound→object, the child can later read the word and point to the object without direct training on that step. Use clear, distinct stimuli first, then apply Ayres‐Pereira’s side-by-side rule once items look alike. Finally, add contextual cues like color borders if you want the same stimuli to enter different classes in different lessons.
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Join Free →Put look-alike comparison cards side-by-side during matching trials to lock in the untaught relations.
02At a glance
03Original abstract
Four adults were trained, using instructions and a matching-to-sample procedure, to select Stimulus B1 in the presence of Stimulus A1, B2 in the presence of A2, and B3 in the presence of A3 (the AB relations). Analogous PQ relations were trained. Afterwards, one stimulus in Set A and another stimulus in Set B appeared together as a sample, and novel Stimuli X1 and X2 were the comparisons. Responses to X1 were reinforced if the two stimuli in the sample had been related in the previous training (e.g., A1 and B1), and responses to X2 were reinforced if the two samples had not been related (e.g., A1 and B2). These were the ABX relations. In a test in which a stimulus of Set P and another of Set Q were the samples and X1 and X2 were the comparisons, 2 subjects selected X1 when the samples were P1 and Q1, P2 and Q2, and P3 and Q3, and selected X2 in the presence of the other six sample combinations (P1Q2, P1Q3, P2Q1, P2Q3, P3Q1, and P3Q2). Another subject showed the same responding after additional training. In the second experiment, 3 adults and an 11-year-old child were trained on AB, PQ, and ABX relations, and they showed the symmetrical relations BA and QP upon testing. Then all 4 of these subjects responded accurately to the PQX test. Results of Experiments 1 and 2 showed novel, consistent comparison selection based on the previously established relation between the two stimuli in the sample. In a third experiment, 3 of the subjects who had shown PQX relations were trained on EFX relations, with pairs of E and F stimuli as samples and X stimuli as comparisons. When the EF relations were tested, all 3 subjects consistently selected F1 in the presence of E1, F2 in the presence of E2, and F3 in the presence of E3 from the first trial. The results of Experiment 3 showed novel stimulus relations after training with a more complex conditional discrimination format.
Journal of the experimental analysis of behavior, 1994 · doi:10.1901/jeab.1994.61-487