In this instance, giggling and squirming is a conditioned response (CR).
A CR is a learned automatic response that occurs when a neutral stimulus is repeatedly followed by an unconditioned stimulus, till the neutral stimulus by itself elicits a conditioned response. In this scenario, the CR is Grace whistling, the unconditioned stimulus is the tickling, and the response is Khaleel giggling and squirming. After the repeated pairing of Grace's whistling followed by tickling, Grace's whistling alone creates the conditioned response in Khaleel.
