Stimulus equivalence occurs when a learner correctly identifies a symbolic relationship between two or more non-identical stimuli without specific training on that relationship. There are 3 types of stimulus equivalence: reflexivity, symmetry, and transitivity.
Reflexivity – when in the absence of training and reinforcement, a learner will select a stimulus that is matched to itself (A=A). This is like identical matching but with untrained materials.
Symmetry – after learning A=B, the learner demonstrates that B=A without direct training on that relationship. For example, the learner matches the spoken word “car” (A) with the picture of the car (B). And then without formal training, matches the picture of the car (B) with the correct spoken word for “car” (A).
Transitivity – after learning A=B and B=C, the learner demonstrates that A=C without training. So, when A (e.g., spoken word “car”) = B (e.g., picture of car) AND B (e.g., the picture of car) = C (e.g., the written word car); THEN without formal training the learner identifies that the spoken word “car” (A) matches with the written word car (C). It’s nice to visualize a triangle for this process and how each component connects. When drawing this example out - put each letter for every corner of the triangle to better visualize!
Hopefully this gives you support in answering the questions about the student learning the written word “horse” and the picture of a horse from last week. Let me know any questions or feedback!