Unpleasantness—pain's salient dimension

Abstract

General approaches, specific techniques, and new ideas for how to control pain are inextricably woven into the fabric of our existing knowledge about how we perceive pain. Information about the underlying physiological mechanisms that transform a noxious stimulus into the perception of a particular pain, with unique attributes of quality, location, duration, intensity, and aversiveness, provides the essential framework for developing and refining pharmacological and nonpharmacological interventions. Yet, as Drs. Price and Harkins emphasize in their focus article, fundamental questions about the nature and mechanisms of pain-related affect remain unanswered. The authors have provided a compelling justification for integrating the physiological and psychological information on the infrastructure of the nociceptive system to provide a theoretical framework for understanding how pain unpleasantness is processed. The rationale for a sequential processing model of pain affect is consistent with results from both experimental and clinical pain studies. Experimental pain studies, in which brief noxious stimuli are administered in a well-controlled and safe context, may reveal only a minimum level of pain affect; subjects' recognition that the painful sensations have no adverse implications for them nullifies any cognitive loading due to potentially adverse consequences. In contrast, studies of clinical pain, in which patients experience various acute or chronic pains in an often uncertain context, may reveal maximum levels of pain affect. Like subjects, patients attend to the immediate intensity of the painful sensation, but unlike subjects, the greater overall meaning associated with their clinical pain (e.g., its cause and consequences) increases their affect. In summary, Drs. Price and Harkins have provided a unique and timely contribution to the field. However, their proposed model of two discrete stages of pain-related affect, one closely linked to nociceptive sensation and arousal and the other based on more complex meanings, may inadvertently focus more attention on the existence of separate levels of affective processing than on the critical sensory, contextual, and cognitive factors that truly mediate affective processing.