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Tuesday, April 21, 2015

Dual process theory

Dual process theory

According to the dual-process theory, which explains responses that occur as a result of two different processes, habituation and sensitization are opposite dynamics that relate to our reaction to stimuli.
Habituation, which may result in a habit or learning, is a decreased response to stimulus as opposed to its antithesis in sensitization: a heightened response to stimulus.
These two reactions are results of different processes, the S-R system and the state of arousal system, and originate in different areas of the human brain. When we habituate, we no longer respond to either the negative or the positive factors of the stimulus. We adapt in a way that we perform a function without stimulus response. Habituation is the result of changing neurons that moderate our level of response. Sensitization occurs when the state of arousal is greater in the excitation of stimulus response. Since habituation and sensitisation stimulus responses have two different results and function through two different systems (S-R and state), they are not said to be related to each other.
An example of habituation is eating in shift-workers who have a set time for their hunger stimulus that is not the same as that of regular workers. The shift-workers' schedules habituate their bodies to change the original bio-clock stimulus. Keep in mind that habituation can be either short or long term differentiating between short-term habituation and long-term habituation.

Sensitization is the excitation of sensory response towards a stimulus. In the example of animal trainers, sensitization is the best conduit to instill trust and motivation in the animal who is being behaviorally conditioned. Hence, a piece of food is often used as a reward for performing the expected response as part of the heightened sensitization process.

Learning that occurs as the result of the presentation of a single stimulus.
1.  Habituation:   Decrease in the strength of a response following repeated presentations of a single stimulus.  Stimulus initially results in a STARTLE RESPONSE (orientation, increased awareness & attention, fight or flight) which dissipates after a few trials.

Alternative Explanations
      a.  muscle fatigue:  muscles unable to respond?  change stimulus or intensity of stimulus
      b.  sensory adaptation: fatigue of sensory system?  reintroduce stimulus when not expected
 2.  Sensitization:   Increase in the strength of a response following repeated presentations of a stimulus -- "opposite" of habituation.
3.  Groves & Thompson (1970)
dominant theory of how HABITUATION & SENSITIZATION works is called the DUAL PROCESS THEORY proposed by GROVES & THOMPSON (1970) 
• DUAL PROCESS THEORY hypothesizes that there are 2 processes that underlie the increase in responsiveness seen in SENSITIZATION and the decrease in responsiveness seen in HABITUATION.
• There's the SENSITIZATION PROCESS and the HABITUATION PROCESS and these processes are not mutually exclusive -- that is, they can BOTH be activated at the same time.
a. HABITUATION NEURAL PROCESSES occur in what Groves & Thompson call the S-R SYSTEM which is analogous to the REFLEX ARC.  EVERY presentation of a stimulus activates this system.
b. SENSITIZATION NEURAL PROCESSES occur in the STATE SYSTEM which determine's the Animal's general level of responsiveness or "AROUSAL".  Only arousing events activate this system.
The S-R SYSTEM works together with the STATE SYSTEM and the net result is behavior. .  The outcome -- whether we habituate or sensitize -- will depend upon which is stronger in any given set of circumstances.
3.  Davis (1974)
Rats in an apparatus with movable floors called stabilimeter chambers, repeated pairings of loud tone (110dB) = habituation, loud tone over 60db background noise = habituation, loud tone over 80db background noise = sensitization.

Results support GROVES & THOMPSON (1970)
They would say that when the rats were tested with a relatively quiet background noise, there wasn't much to produce changes in the STATE SYSTEM so the S-R SYSTEM won out and the rats habituated.
When the rats were tested in a loud background noise, the background noise probably increased arousal (the STATE SYSTEM) and the rats increased responding, that is they sensitized.

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