Conditioning-specific reflex modification of the rabbit (Oryctolagus cuniculus) nictitating membrane response: Generality and nature of the phenomenon

Conditioning-specific reflex modification (CRM) occurs when classical condi tioning modifies responding to an unconditioned stimulus in the absence of a conditioned stimulus. This form of reflex modification suggests that lear ning modifies the unconditioned reflex pathway. Rabbit (Oryctolagus cunicul us) nictitating membrane responses to 5 intensities and 3 durations of airp uff (AP) or periorbital electrical stimulation (ES) were monitored before a nd after conditioning. AP tests detected strong CRM after conditioning with ES and modest levels of CRM after conditioning with AP. After conditioning with AP, ES tests failed to detect CRM. After conditioning with a stronger AP, CRM was again detected by AP tests. CRM is a general phenomenon but is more readily detected after training with a relatively aversive stimulus; thus, it may be a function of level of arousal.