Classical (respondent) conditioning occurs when a previously neutral stimulus (NS) becomes a conditioned stimulus (CS) after being paired repeatedly with an unconditioned stimulus (US) that naturally evokes an unconditioned response (UR) (Cooper, Heron, & Heward, 2020). One real-life example from my own experience involves developing anxiety around the sound of a dental drill.
Unconditioned Stimulus (US): Pain during a dental procedure
Unconditioned Response (UR): Fear, muscle tension, and increased heart rate
Neutral Stimulus (NS): The sound of the dental drill (before conditioning)
Conditioned Stimulus (CS): The sound of the dental drill (after conditioning)
Conditioned Response (CR): Fear and anxiety in response to the drill sound
Initially, the sound of the dental drill did not produce any fear or discomfort. However, during several dental appointments, the drill sound consistently preceded the painful portion of the procedure. The pain functioned as the unconditioned stimulus (US), naturally producing fear and tension (UR), which, according to Pavlov’s foundational work, is how reflexive responding develops through stimulus pairings (Pavlov, 1927). Over multiple visits, the previously neutral drill sound became predictive of the upcoming pain. As a result, the drill sound transitioned from an NS to a conditioned stimulus (CS), and hearing it alone—even outside of painful procedures—began to evoke the conditioned response (CR) of fear and anxiety.
This process reflects the respondent conditioning principles described by Cooper et al. (2020), where a neutral stimulus becomes capable of eliciting a new response after repeated pairings with an unconditioned stimulus. Pierce and Cheney (2017) similarly explain that classical conditioning transfers control of a reflexive response from an unconditioned stimulus to a conditioned one through repeated temporal pairing. In this example, the conditioning history resulted in the sound of the drill acquiring the ability to evoke the same fear response that was originally elicited only by the painful procedure.
This everyday situation demonstrates how classical conditioning can influence emotional reactions and how neutral environmental stimuli can acquire conditioned effects through repeated associations.
References
Cooper, J. O., Heron, T. E., & Heward, W. L. (2020). Applied behavior analysis (3rd ed.). Pearson.
Pavlov, I. P. (1927). Conditioned reflexes. Oxford University Press.
Pierce, W. D., & Cheney, C. D. (2017). Behavior analysis and learning (6th ed.). Psychology Press.

