1. Concepts of Habituation and Sensitization
Habituation and sensitization are two fundamental ways that all organisms respond to previous experience with an eliciting stimulus
Habituation effects: Decrease in responsiveness with repeated exposure to a particular eliciting stimulus
Sensitization effects: Increase in responsiveness with repeated exposure to a particular eliciting stimulus
Sensitization and Habituation help us organize and focus our behavior by reducing the number of stimuli to respond to and which not to respond to

2. Characteristics of Habituation and Sensitization
Habituation to startle Figure 2.10
Time Course of Habituation
Habituation does not always persist for extended periods of time (weeks or months)
Short-term Habituation
response decreases within minutes
from frequent presentation of stimulus over short time
Spontaneous recovery is usually complete
Long-term Habituation
can persist for many days
from infrequent presentation of stimuli over longer time (many days)
spontaneous recovery is usually incomplete

3. FIGURE 2.10 Spontaneous Recovery
Startle response of rats to a tone presented once a day in Phase 1, every 3 seconds in Phase 2, and once a day in Phase 3. (Based on “Long-Term Retention of the Habituation of Lick Suppression and Startle Response Produced by a Single Auditory Stimulus,” by R.N. Leaton, 1976, Journal of Experimental Psychology: Animal Behavior Processes, 2, pp. 248–259.)
The Principles of Learning and Behavior, 7e by Michael Domjan
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4. Characteristics of Habituation and Sensitization
Time Course of Habituation
Spontaneous recovery after a period of time (days) without repeated stimulus presentation
when stimulus is again presented
response to the stimulus returns
size of spontaneous recovery
depends on characteristics of the stimulus and frequency of the repeated stimulus
fast simple reflexes (eye blink) have very robust recovery
short-term habituation has more robust recovery
Spontaneous recovery video

5. Characteristics of Habituation and Sensitization
Sensitization and the Modulation of Elicited Behavior
Typically (but not always) short-lived
With only a repeated stimulus
salivation reflex seen in Figure 2.5
visual attention seen in Figure 2.7
With loud background noise which increases arousal
repeated stimulation elicited more vigorous startle reactions in Fig 2.1
Common in movies and at concerts
Eyeblink startle response modulated by threat of shock and type of picture
group 1: threat of shock during pleasant pictures
group 2: threat of shock during unpleasant pictures
threat of shock produces more response
pleasant pictures without threat of shock produces the least response
Figure 2.12
Emotional disorders such as anxiety, depression or PTSD

6. FIGURE 2.11
Magnitude of the startle response of rats to successive presentations of a tone with a background noise of 60 or 80 dB. (Based on “Sensitization of the Rat Startle Response by Noise,” by M. Davis, 1974, Journal of Comparative and Physiological Psychology, 87, pp. 571–581.)
The Principles of Learning and Behavior, 7e by Michael Domjan
Copyright © 2015 Wadsworth Publishing, a division of Cengage Learning. All rights reserved.

7. The Principles of Learning and Behavior, 7e by Michael Domjan
Copyright © 2015 Wadsworth Publishing, a division of Cengage Learning. All rights reserved.

8. Discrete and Recurrent Traumatization in PTSD
Symptoms of PTSD include hyperarousal and exaggerated startle
Potentiated startle (eyeblink) reflex using trauma imagery was larger in PTSD patients compared to control participants
Patients with a single, discrete trauma showed extreme startle potentiation to their fear memories
Patients with recurrent traumatization
had the least startle potentiation to their fear memories
more extensive comorbidity such as major depression and anxiety disorders as well as longer enduring PTSD
Individuals with a history of repeated trauma such as childhood physical and/or sexual abuse are the most vulnerable

9. Dual-Process Theory
The most prominent theory developed to explain Habituation and Sensitization
Habituation and sensitization processes have different underlying neural mechanisms
The same stimulus can activate both underlying neural processes
These processes compete for control of behaviour

10. Stimulus-Response (S-R) system versus the State system
Habituation processes occur in the S-R system
activated every time an eliciting stimulus is presented
shortest path (circuit) between sense organs and muscles
Sensitization processes occur in the state system
emotional and motivational states
activated only by arousing events such as fear or hunger
Involve other pathways (circuits) that relate to organisms general level of readiness or responsiveness
Actual behaviour reflects the combined actions (summation) of the S-R and state systems

11. Implications of the Dual-Process Theory
S-R system always involved in processing stimuli so habituation is always possible
State system modulates the response depending on amount of arousal
Stimulus specificity
Habituation is specific to the stimulus that is repeatedly presented
A change in the stimulus will interrupt A difference in a critical feature of the stimulus
Change in taste stimulus (sweeter)
Change in sound (different source of sound or louder sound)
Sensitization is not highly stimulus-specific, Footshock increases sensitivity to auditory and visual cues

12. Application of the Dual Process Theory
Infant attention to complex 12X12 pattern shows more arousal (State system) then 4X4 pattern (see figure 2.7)
With a background noise of 80 db rats have more arousal (state system) (see figure 2.11)
Discrete and Recurrent Traumatization in PTSD

13. Extensions to Emotions and Motivated Behavior
Stimuli “your romantic partner” can elicit complex emotional responses such as love
Stimuli “drinking alcohol” can elicit complex physiological responses
These complex emotional and physiological responses can habituate with repeated exposure

14. Opponent-Process Theory (Solomon & Corbit, 1974)
 Three features of emotional reactions to various stimuli
1. Biphasic- primary reaction to the eliciting stimulus and the opposite “after-reaction” when exposure is discontinued
2. With repeated exposure to the stimulus, the primary reaction becomes weaker
3. With repeated exposure to the stimulus, the “after-reaction” becomes stronger
Habituation of primary drug reaction is partially responsible for drug tolerance
Decline in effectiveness (amount of response) of drug with repeated exposure
Enjoyment decreases and crashes or hangovers more severe
Habituation of Love:
Infatuation (initial reaction) declines over time
grief at the loss of partner even after initial affection has declined is very intense (after effect)

15. The Opponent-Process Theory of Motivation
Primary process or "a" process: An emotional reaction :to presentation of emotion-arousing stimulus pushes us away from emotional equilibrium
Opponent reaction or "b" process: Opposite emotional reaction elicited by primary or a process to bring emotions back into equilibrium Opponent process "b" lags the onset of the primary process "a"
Strength of the opponent process "b" subtracts from the strength of the primary process "a"
After the stimulus is remove "a" process ends so Opponent process "b" dominates the response
The pattern represents the net effect of the two opponent processes or forces Fig. 2.15

16. FIGURE 2.15 Primary After Reaction
Opponent process mechanism during the initial presentation of an emotion arousing stimulus. The observed emotional reactions are represented in the top panel. The underlying opponent processes are represented in the bottom panel. Notice that the b process starts a bit after the onset of the a process. In addition, the b process ends much later than the a process. This last feature allows the opponent emotions to dominate after the end of the stimulus. (From “An Opponent Process Theory of Motivation: I. The Temporal Dynamics of Affect,” by R. L. Solomon and J. D. Corbit, 1974, Psychological Review, 81, pp. 119–145.)
Primary
After Reaction
The Principles of Learning and Behavior, 7e by Michael Domjan
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17. The Opponent-Process Theory of Motivation
Opponent Mechanism After Extensive Stimulus Exposure
initial "a" process is little changed
Opponent process "b" becomes strengthened with repeated activation
Opponent process "b" dominates the response
So after response is very large becasue "b" process is large and unopposed by the "a" process (Fig 2.16)
Opponent Aftereffects and Motivation Pleasure of drugs gone for habitual users and negative effects of withdrawal is much stronger
Drug addiction is theorized to be an attempt to minimize the aversiveness of the negative aftereffects (i.e., to reduce withdrawal not obtain pleasure )

18. FIGURE 2.16 Primary After Reaction
Opponent process mechanism that produces the affective changes to a habituated stimulus. The observed emotional reactions are represented in the top panel. The underlying opponent processes are represented in the bottom panel. Notice that the b process starts promptly after the onset of the a process and is much stronger than in Figure In addition, the b process ends much later than the a process. Because of these changes in the b process, the primary emotional response is nearly invisible during the stimulus, but the affective after-reaction is very strong. (From “An Opponent Process Theory of Motivation: I. The Temporal Dynamics of Affect,” by R. L. Solomon and J. D. Corbit, 1974, Psychological Review, 81, pp. 119–145.)
Primary
After Reaction
The Principles of Learning and Behavior, 7e by Michael Domjan
Copyright © 2015 Wadsworth Publishing, a division of Cengage Learning. All rights reserved.