IT has been demonstrated that a conditioned response to a peripheral physiological stimulus (CS) can later be evoked when electrical stimulation of the cortical or subcortical centres is substituted for the original conditioning stimulus1–3. The present experiment was designed to examine the degree to which electrical stimulation of the occipital cortex, during the extinction stage of an avoidance conditioning procedure, would elicit conditioned responses (CRs) in an animal previously trained to respond to light (CS).