A note on transfer of stimulus control in the delayed-cue procedure: facilitation by an overt differential response.

The team worked with a learner who had an intellectual disability. The learner could not master a simple match-to-sample task even after many delayed-cue trials.

They added one twist: before choosing, the learner had to say the dictated sample name out loud. Then they watched if this small step helped the learner pick the correct picture.

As soon as the learner repeated each sample name, correct matches jumped from near zero to almost perfect. The overt response acted like a bridge that carried stimulus control from the teacher’s word to the picture array.

When the team later removed the repeat step, the accurate choices stayed high, showing real learning had happened.

Older pigeon studies by Lydersen et al. (1974) and Kohlenberg et al. (1976) already showed that making birds peck or flap in special ways during the sample phase sped up conditional discrimination. The 1994 paper extends the same idea to humans with ID and uses spoken words instead of wing movements.

Reed (2012) seems to disagree at first glance. That study found that adding a delay between sample and comparisons hurt kids with ASD by increasing over-selectivity. The key difference is that Phil used delay only, while R et al. filled the delay with an overt mediating response. The response gives the learner something to do and strengthens memory, turning a harmful gap into a helpful cue.

More recent work by Goodwin et al. (2012) also boosts auditory-visual learning, but they used picture prompts instead of spoken repetition. Both tactics work; one adds visual help, the other adds verbal help.

If a client keeps failing delayed-cue trials, ask them to echo the sample before they choose. The echo acts as an extra prompt you can fade later. It costs no materials and takes only a second, yet it can flip failure to success in one session.