Conditioned Emotional Response (CER): An emotional reaction that is learned through classical conditioning. For example, feeling anxious upon entering the classroom where the bad experience occurred.
Unconditioned Stimulus (US): A stimulus that naturally triggers a response without any prior learning. In this case, it could be an event in the classroom that initially caused fear or anxiety.
Neutral Stimulus: A stimulus that does not naturally trigger a response but becomes associated with an unconditioned stimulus through repeated pairings. For example, the physical environment of the classroom becoming associated with anxiety due to its pairing with the bad experience.