SENSORY PRECONDITIONING AND 2ND-ORDER CONDITIONING OF ALARM REACTIONS IN ZEBRA DANIO FISH (BRACHYDANIO-RERIO)

A pheromone, alarm substance, passively emitted by injury to the skin of zebra danio fish (Brachydanio rerio), induces an unlearned antipredator alarm reaction in nearby conspecifics. Exposing the fish to alarm substance and initially innocuous olfactory (morpholine) and visual (red light) stimuli transformed the stimuli into learned elicitors of alarm behavior from the fish. It was found that the red light and morpholine also become learned releasers of alarm behavior from more complex relationships as in sensory preconditioning and 2nd-order conditioning. After preconditioning of all fish to light and morpholine together, the fish were exposed to pheromone and 1 of the 2 stimuli, half light, half morpholine. This resulted in learned alarm transferred from the 2nd stimulus to the 1st, the stimulus that had never been paired with pheromone, and thus sensory preconditioning was clearly demonstrated. The results from 2nd-order conditioning were highly comparable.