All stimuli are equal, but some are more equal than others: measuring relational preferences within an equivalence class.

Erica and team asked a simple question. After adults learn an equivalence class, do they like some members better than others?

They taught 12 college students four-member classes with abstract shapes. Then they let students pick which shape they wanted to see again.

Each choice pitted two class mates against each other. The computer recorded which one the student clicked.

People picked the transitive stimulus most. That is the one you never directly trained but can still derive.

They picked the baseline stimulus second. That is the one you actually touched during training.

Symmetry and full-equivalence partners were picked least. The preference order stayed the same for every person.

Taylor et al. (1993) showed equivalence can grow from rejected items. Erica shows that once the class is born, learners still favor the items they chose, not the ones they rejected.

Foti et al. (2015) found select-control training makes stronger classes than reject-control. Erica’s data echo this: the baseline (select-trained) stimulus is preferred over the symmetry partner.

Dias et al. (2021) used EEG to prove pronounceable stimuli give classes a semantic feel. Erica proves learners can still rank even meaningless shapes inside the same class.

Your client may have "mastered" an equivalence set, yet still reach for the transitive or baseline item first. Use that high-preference member as the prompt when you teach a new skill. It will grab attention faster and speed up transfer. Swap in the less-liked symmetry or equivalence partner only after the first response is solid. This tiny tweak can cut training time without extra trials.