Evaluating the Effects of Compound Stimuli on Stimulus Control during Match-to-Sample Procedures

Grey et al. (2024) built a quick check for match-to-sample programs. They used compound stimuli, like a picture plus a word, during teaching. Then they tested each part alone to see which piece the learner really used.

The paper is a case study, so it walks through one learner step by step. The goal was to spot "restricted stimulus control," where the child picks the match based on only one part of the cue.

The study did not report final outcome numbers. Instead it showed the probing method: separate trials for picture alone, word alone, and the pair together. This layout lets you see if the compound cue is treated as one signal or as two split cues.

Allan et al. (1991) did the first post-training probe trick. They tested single versus paired stimuli after teaching and found that some kids lost control by one part. Grey’s method copies that logic inside match-to-sample.

Perez et al. (2015) ran a close cousin study. They taught children with disabilities to listen to compound cues, then checked which part controlled the response. Three kids showed full control, two showed over-selectivity, matching Grey’s worry.

Bergmann et al. (2023) flip the coin. They showed that adding a picture to an auditory tact speeds up learning. Grey warns us to probe, Bergmann shows the payoff can be real when control is true.

Cariveau et al. (2022) and Sundberg (2016) found the same risk in intraverbal drills. The first word in a compound pair often overshadows the second. Grey moves that same spotlight to matching tasks.

Before you trust that a picture-word card is "one stimulus," run a few solo probes. Present the picture alone, then the word alone. If the learner fails either probe, you have restricted control, not real equivalence. Adjust by teaching each part separately or fading the salient cue. This five-minute check saves weeks of faulty generalization.