Tilted lines as complex stimuli.

Fantino (1969) worked with three adults who had intellectual disabilities.

Each person sat at a panel with two buttons and a screen.

Tilted lines flashed on the screen: one angle meant press left, another meant press right.

The team wanted to see if the learners would use the tilt cue and not some other part of the picture.

All three adults learned to pick the correct button.

But probes showed they did not all use the tilt.

One man pressed by the width of the line, not the angle.

Another watched brightness.

Only the third truly used tilt.

Same lesson, different controlling stimulus for each learner.

Tantam et al. (1993) later showed that once a feature controls behavior, that control can jump to new, untrained stimuli through equivalence classes.

Haimson et al. (2009) added brain data: after people form equivalence classes, their EEG waves change even to the untrained links.

Together these papers say stimulus control can emerge in ways you did not directly teach, so check what the learner is actually watching.

O’Connor et al. (2020) applied the same idea to kids with autism, teaching emotion–person links through equivalence.

Their success fits E’s warning: test which cue is really in charge, or you may think you taught emotion when the child is really looking at shirt color.

Before you run more trials, run a quick probe.

Cover, brighten, or rotate the target feature and see if the response stays.

If it drops, you just saved hours of useless drilling.

Use the real cue in teaching and fade the rest.