What concept did Watson demonstrate using a white rat and loud noise?

The concept demonstrated by Watson using a white rat and a loud noise is classical conditioning. Classical conditioning is a learning process in which an initially neutral stimulus becomes associated with another stimulus that elicits a response. In this case, Watson paired the loud noise (an unconditioned stimulus that naturally elicited fear) with the white rat (the neutral stimulus). After repeated pairings, the child began to display fear in response to the rat alone, even without the loud noise.

This experiment highlighted how emotional responses can be conditioned through association, a foundational principle in behaviorism and psychology. Classical conditioning is significant in understanding how behaviors can be learned and modified through environmental interactions, which has implications in various areas, including therapy and education.