Stimulus control: part II.

The paper is a plain-language tutorial, not an experiment. It walks readers through the levers you can pull when you want clean stimulus control.

It names two big levers: stimulus disparity (how different the S+ and S- look or sound) and stimulus salience (how much each one pops out).

Examples show how these levers apply to everyday discrimination drills and to higher-order concept training.

No new data are given. Instead, the article organizes decades of pigeon and human work into a checklist.

The checklist says: widen the gap between S+ and S- early on, then narrow it in gradual steps, and pick stimuli that are easy to notice.

Neuringer (1973) had already shown pigeons exactly what the tutorial preaches. Birds trained with two click rates (fast vs slow) formed sharp discrimination, while birds given only "clicks present vs absent" showed flat, sloppy control. The tutorial turns that single-case result into a rule of thumb for clinicians.

SLOANE (1964) added the warning that each new S- you place on a continuum can shove responding toward the opposite end. The 1995 paper folds that finding into its advice on planning S- sequences.

Griffee et al. (2002) extends the same rules to children with developmental delays. They used layered contextual cues plus equivalence training to build hierarchical categories, proving the levers work outside the pigeon lab.

Evenhuis (1996) one year later supplied more pigeon data showing disparity and reinforcer rate jointly guide choice. The tutorial and the experiment treat disparity as an active variable, not a background detail.

Next time a learner struggles to tell two pictures apart, check the gap first. Make the pictures more different, or make the key feature brighter, bigger, or louder. After responding stabilizes, fade the difference back in small steps. This simple two-step recipe—start wide, then narrow—can save hours of trial-and-error and reduce learner frustration.