Sensory Adaptation and Response Fatigue Compared to Habituation
The most important characteristic of habituation is a declining response to a previously elicited stimulus. There are other reasons why a response to a particular stimulus would decline other than habituation. In order to understand the difference, we must reconsider reflexes.
Sensory or afferent neurons that send messages to the brain may become temporarily "insensitive" to stimulation due to a blinding light or temporary hearing loss after attending a rock concert. These decreases in sensitivity are referred to as sensory adaptation.
The motor or efferent neurons responsible for sending messages away from the brain and spinal cord and controlling muscles may become ineffective due to response fatigue. Both sensory adaptation and response fatigue impede response, acting outside the nervous system in "sense organs and muscles," and for this reason are different from habituation (Domjan, 2003).
It is assumed neurophysiological changes prevent or assist communication of the sensory neurons to the motor neurons through habituation or sensitization. Even though an organism is able to respond to a stimulus using the appropriate muscles they fail to respond due to habituation, which apparently blocks the sensory neural impulses to the motor neurons (Domjan, 2003).
Sensory adaptation is distinguished from habituation when it can be determined that habituation is "response-specific" and "an organism may stop responding to a stimulus in one aspect of its behavior while continuing to respond to the stimulus in other ways" says Domjan (2003).
Sensitization is the opposite of habituation in that it produces increases in responsiveness, rather than decreasing responses. However, like habituation sensitization does not usually have lasting effects. According to Domjan (2003), "in all response systems the duration of sensitization effects is determined by the intensity of the sensitizing stimulus" with the greater the stimulus the greater responsiveness and the more intense the stimuli, the longer the duration the sensitizing effects will persist.
The Dual-Process theory suggests sensitization processes take place in the "state system" (Domjan, 2003). This system is responsible for other parts of the nervous system, maintaining arousal levels, and activated by arousing stimuli and emotional experiences. Drugs "such as stimulants or depressants" are able to alter the state system changing levels of response. The highly emotional state of fear is controlled by the state system.
Applying a sensitization process to dog training might include relaxation training; establishing hierarchies of stimulus presentations beginning with the least intrusive, as we slowly increase the level of tolerance, at the same time applying counter-conditioning using a reinforcer. Understanding the short duration associated with a sensitization process, a fearful dog for example should be continually exposed to a previous fearful stimulus to maintain the newly established positive response and to generalize the behavior to multiply conditions.
Habituation and sensitization are respondent conditioning processes, and related to biology and reflexes and sometimes overlapped by operant learning. When working with dogs and fear issues, we are commonly working with respondent conditioning, because fear responses are reflexive changing one’s biological condition and reflected by increased heart rate and respiration. However, these responses may also be due to some type of operant learning experience, causing avoidance behavior associated with fear and anxiety.
Finally, both habituation and sensitization processes are limited in their application and only involve responses already in the animals behavioral repertoire and do not include "learning new responses or responses to new stimuli" and usually involve just one type of stimuli, according to Domjan (2003).
Burch, Mary R., & Bailey, Jon S. (1999). How Dogs Learn.
New York: Howell
Taflinger, M., & Wilkinson, J. (Eds.). (2003). The Principles of Learning and Behavior . (5th ed.).
Reid, Pamela J. (1996). Excel-erated Learning .
CA: James & Kenneth
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