Transfer of stimulus control: measuring the moment of transfer.

Three boys with intellectual disability learned color discriminations. The trainer showed a red key first, then added a second color.

Each new reversal started with the red key alone. The delay before the second color grew bit by bit. This let the boys switch to the new correct color without making errors.

All boys reached errorless performance. The cool part: later reversals took fewer trials. The boys got faster at shifting to the new correct color each time.

Tantam et al. (1993) and Shawler et al. (2022) extend the idea. They show that once stimuli are linked through equivalence, the control can jump to new items without any extra training.

Attwood et al. (1988) used a different trick. They stripped away extra features instead of adding a delay. Both methods kept errors low, showing there are many roads to errorless learning.

Fantino (1969) reminds us to check what the learner actually sees. Even with the same setup, different boys may latch onto different cues.

You can cut errors by starting with one clear cue and slowly bringing in the new one. Try fading in the new stimulus a little later each session. Watch for fewer trials needed as the learner practices; that tells you the skill is solid and flexible.