Organisms that can learns from past experiences have adaptive advantages over those that cannot. Memories, such as learning, depend heavily upon emotion, furthermore, memories of past experience tend to shape expectations for the present and future. The affective component of pain fosters adaptation through instrumental (operant) learning as well as classical conditioning (learning by association) (Bromm & Desmedt, 1995). Operant learning requires reinforcers, and reinforcers are events accompanied by emotions. Classical conditioning represents the formation of an association between a normally neutral event and the negative emotion associated with the onset of pain (Bromm & Desmedt, 1995; Carlson, 1998).
Operant learning involves any situation or setting in which the patient is active and reinforcing events take place. A reinforcer event is an event that alters the future likelihood of a behavior recurring when it immediately follows that behavior. There are two types of reinforcer: positive and negative. The former reinforces events that produce a pleasurable outcome (such as rewards), and increases the likelihood that the behavior will reoccur. The latter reinforces events that produce an unpleasant outcome (such as pain), and decreases the likelihood of the behavior being produced again. The positive or negative nature of reinforcers, and their personal significance, occur in conscious awareness as feelings (Bromm & Desmedt, 1995). Hence, reinforcing events are those that are emotionally prominent. Emotion-free events have no reinforcing properties, thus, it does not contribute to adaptive learning (Bromm & Desmedt, 1995).
Classical conditioning on the other hand, involves setting in which a neutral stimuli is given in association with a aversive stimuli, therefore, conditioning the neutral stimulus to elicit the same response that the aversive stimulus evoked. In the case of learning with classical conditioning, it safeguard against dangerous situation. For example, when a person turns on the hair blower to dry his/her hair and hears a buzzing noise, then gets an electrical shock, which causes him/her to drop the hair blower and step away from it. If next time, she turns on a hair blower and hears the same noise again, she;ll immediately drop the hair blower and move away from it, because she has learned and thus, associates the buzzing noise with getting a shock.
Conditioned emotional responses are therefore, essentially sensory-affective association (Bromm & Desmdt, 1995). The amygdala appears to be the primarily structure involved in linking the sensory experience to the emotional arousal and in the conditioning of negative emotional associations (Bromm & Desmdt, 1995, Carlson, 1998). Furthermore, emotion associated with pain also influenced memory. Research in memory shows that both limbic and nonlimbic pathways are involved in memory processes, and evidence exists that the brain preferentially stores information that has strong emotional loading (Bromm & Desmdt, 1995).