Stimulus generalization along a dimension based on a verbal concept.

The researcher asked adults to sort photos of men into two piles: high-status jobs or low-status jobs. After the adults learned the labels, they were tested with new photos that slowly shifted from high to low status.

The photos formed a line from doctor to janitor. The adults never saw the middle jobs during training. The question was: would their choices slide smoothly along the line, or jump where the labels changed?

People split the job line into two sharp groups. They picked one response for high-status photos and the other for low-status photos. The switch happened near the learned label boundary.

There was no smooth slide. The verbal labels acted like a wall. Once the photo crossed the wall, the response flipped.

SLOANE (1964) saw the opposite with pigeons. Birds trained to peck for fast flicker and not for slow flicker showed a smooth drop-off in responding. The gradient slid along the physical light continuum instead of breaking into two classes.

The difference is the dimension. Flicker rate is sensed directly by the eye. Job status is sensed only after the person puts it into a word category. Words create cliffs where physical scales create ramps.

Mello (1966) showed that punishment also needs clear labels. Birds given S- training produced tidy generalization curves; birds without it gave flat lines. Together these studies say: whether the cue is punishment, flicker, or job title, discrimination training turns a fuzzy world into neat groups.

If you want clean stimulus control, teach the learner the name of the class. A child who knows "red" versus "orange" will sort crayons sharply. A child who only sees gradual shades may mix them. When you design programs for safety signs, social cues, or emotion cards, first give the client a clear verbal category. The label becomes the boundary.