Sensitization in Psychology: 10 Examples and Definition

Sensitization is a psychological process where repeated exposure to an event or stimulus leads to increasingly intense psychological or physiological responses.

Both animals and humans can experience this phenomenon, which is marked by a heightened sensitivity or responsiveness towards the same stimulus over time.

For example, someone who has repeatedly experienced trauma may become increasingly anxious each time they are exposed to related cues, such as noises, people, or locations similar to the original traumatic experience.

In addition, exposure to something that wasn’t initially threatening can become increasingly dangerous with repeated use due to sensitization.

Definition of Sensitization

Sensitization is a type of learning where exposure to a stimulus several times causes changes in the sensitivity and responsiveness of cells toward the stimulus.

This often leads to an increased reaction of the cells or organism when exposed to the same stimulus, even after long periods.

According to Clark & Martin (2019), sensitization is:

“…a learning process in which repeated administration of a stimulus results in the progressive amplification of a response” (p. 7).

Collip and colleagues (2007) believe that:

“…sensitization refers to the observation that individuals who are exposed repeatedly to an environmental risk factor may develop progressively greater responses over time, finally resulting in a lasting change in response amplitude” (p. 221).

The process of sensitization happens through alterations in neural networks like synaptic strengthening or plasticity. These alterations are a result of changes in neurotransmitters caused by experience (Bilek et al., 2019).

In other words, the connections between neurons become reinforced due to repeated stimuli, causing more intense reactions when faced with similar events.

10 Examples of Sensitization

• Substance Use: Repeated use of certain substances can cause sensitization, which makes a person more susceptible to their effects. The opposite effect, systematic desensitization, occurs with other types of substances.

• Phobias: Someone with a phobia may become increasingly anxious when exposed to their feared stimulus repeatedly, resulting in associative learning and a heightened reaction each time they are confronted with it.

• Anxiety: People who suffer from anxiety can experience sensitization, where exposure to certain triggers (such as people or environments associated with trauma) results in an increased fear response even after prolonged periods of avoidance or inactivity regarding those triggers.

• Post-Traumatic Stress Disorder (PTSD): Those with this disorder may become more sensitive to things that remind them of the traumatic event. As a result, they may have stronger reactions when exposed to similar reminders, and they may start to avoid anything that triggers the memory of the traumatic experience.

• Eating Habits: People struggling with disordered eating habits can become sensitized over time as they continue engaging in restriction or bingeing behaviors. This can lead to increased self-destructive thoughts each time they face similar situations related to eating and food intake.

• Panic: Sensitization may play a role in the development and cyclical nature of panic. In this case, individuals become increasingly sensitive to personal sensations such as increased heart rate or shortness of breath after facing multiple psychosocial stressors or anxiety-provoking events, leading to eventual avoidance of situations that cause this reaction.

• Aggression: Research has suggested that violent environments often create contexts for increased aggressive behavior due to sensitization. For example, exposure to verbal aggression may lead one person’s response to become increasingly aggressive when faced with similar situations repeatedly over time.

• Social Anxiety: Consistently encountering situations that make one feel uncomfortable and doubtful can worsen symptoms for individuals dealing with social anxiety. Examples of such situations might include public speaking or attending social events with unfamiliar people.

• Attention-Deficit/Hyperactivity Disorder (ADHD): Individuals with this condition might have trouble focusing on tasks and avoiding distractions, especially if they have many things to address at once. If they are repeatedly exposed to situations that require them to do multiple tasks and stay focused, this can lead to sensitization.

• Obsessive Compulsive Disorder (OCD): OCD patients may experience distress due to sensitization effects when they are exposed to negative emotions from images, thoughts, or impulses. This can lead them into cycles of rumination and intrusive behaviors, which can further reinforce compulsive tendencies if not managed properly.

Short-Term vs. Long-Term Sensitization

Whether sensitization occurs in the short term or long term depends on how long and how often someone is exposed to a stimulus (Sadhu et al., 2023).

Short-term sensitization typically refers to simple behaviors that reflect an increase in reactivity for a single or few consecutive trials, such as reflexes and escape responses (Sadhu et al., 2023).

It can be seen with short durations of intense stimulation or even just one trial during which the organism becomes more sensitive to the stimulus than before.

Long-term sensitization generally requires longer periods of repeated exposure and is usually associated with more complex activities like learning and memory formation (Sadhu et al., 2023).

Long-term sensitization has been linked to changes in neuronal plasticity, where alterations in synaptic strength lead to an organism’s response being enhanced over multiple occasions.

Additionally, certain forms of stress have been identified as possible contributing factors leading up to lasting sensitization effects.

So, short-term sensitization is characterized by rapid changes in response to a single stimulus. In contrast, long-term sensitization includes more permanent alterations due to prolonged exposure.

Sensitization vs Cross-Sensitization

Cross-sensitization refers to a condition where an individual experiences an increased response to multiple stimuli, even if those stimuli are not related to each other (Yang et al., 2011).

In other words, it means that encountering one stimulus can enhance the reaction to a different stimulus, even if the latter is unfamiliar.

This implies that some shared mechanisms may be involved in the process, as opposed to regular sensitization, which is usually limited to one stimulus only.

Cross-sensitization is when conditioning leads to a stronger effect than regular sensitization. This is because cross-sensitization involves learning from multiple experiences rather than just one (McNamara et al., 2021).

In contrast, regular sensitization deals with only a single trigger at any given time, so the response is generally more manageable and easier to control.

Importance of Sensitization

Sensitization is an important concept in psychology because it describes how stimuli can become stronger with repeated exposure, leading to either positive or negative effects depending on the nature of the stimuli.

On a positive note, sensitization helps organisms to learn and adapt quickly to redirect previously wasted energy toward productive activities. 

This could be seen with Pavlov’s dogs, who started salivating at the sight of their food after being conditioned by bells (the bells are the conditioned stimulus). 

When exposed to the bell again, they would not only show signs of anticipation for their food earlier than usual but also start salivating quicker than before.

On the negative side, sensitization can also be associated with anxiety disorders.

Repeated exposure to specific triggers can cause individuals to become overwhelmed easily or experience an intense reaction even from very low levels of stimulation. 

For example, someone with PTSD may feel intensely anxious in response to loud noises that are normally harmless such as fireworks, due to having developed a heightened response from bad experiences or stressors in their past.

The concept of sensitization in psychology is significant as it helps us comprehend how organisms can develop a heightened sensitivity towards stimuli over a period, which may result in favorable or unfavorable consequences.

Who Coined the term “Sensitization?”

Sensitization was first discovered by Eric Kandel, a neuroscience pioneer, in the 1960s while studying sea slugs (Robertson & Walter, 2010).

Through experiments conducted on the creatures, Kandel deduced that repeated exposure to certain stimuli increased their reaction towards it. 

This led him to coin the term “sensitization” and formulate his idea of synaptic strengthening due to experience-dependent modulation. 

Since then, Kandel’s work has been further developed by scientists such as Konrad Lorenz, who studied animal behavior and explored how sensitization could play a role in influencing it (Robertson & Walter, 2010).

Sensitization and its effects on different disorders such as phobias, social anxiety disorder, and PTSD have been extensively researched by psychology experts in recent years.con

Conclusion

Sensitization is a process whereby organisms become more sensitive to particular stimuli over time through short-term or long-term exposure. 

Sensitization can be beneficial, as it allows organisms to learn quickly and adapt. For example, Pavlov’s dogs learned to associate the sound of a bell with their food, resulting in an increased response even when no food was present. 

However, it can also lead to negative outcomes such as increased anxiety or fear in response to previously harmless stimuli. 

Cross-sensitization is another form of sensitization, where exposure to one stimulus increases response to another unrelated stimulus. 

In contrast to regular sensitization, cross-sensitization involves more complex learning mechanisms and has been linked with the development of phobias and anxiety disorders. 

References

Bilek, E., Zang, Z., Wolf, I., Henrich, F., Moessnang, C., Braun, U., Treede, R.-D., Magerl, W., Meyer-Lindenberg, A., & Tost, H. (2019). Neural network-based alterations during repetitive heat pain stimulation in major depression. European Neuropsychopharmacology, 29(9), 1033–1040. https://doi.org/10.1016/j.euroneuro.2019.06.011

Clark, R. E., & Martin, S. (2019). Behavioral neuroscience of learning and memory. New York: Springer.

Collip, D., Myin-Germeys, I., & Van Os, J. (2007). Does the concept of “sensitization” provide a plausible mechanism for the putative link between the environment and schizophrenia?. Schizophrenia Bulletin, 34(2), 220–225. https://doi.org/10.1093/schbul/sbm163

McNamara, H. C., Frawley, H. C., Donoghue, J. F., Readman, E., Healey, M., Ellett, L., Reddington, C., Hicks, L. J., Harlow, K., Rogers, P. A. W., & Cheng, C. (2021). Peripheral, Central, and Cross Sensitization in Endometriosis-Associated Pain and Comorbid Pain Syndromes. Frontiers in Reproductive Health, 3. https://doi.org/10.3389/frph.2021.729642

Robertson, M., & Walter, G. (2010). Eric Kandel and Aplysia californica: Their role in the elucidation of mechanisms of memory and the study of psychotherapy. Acta Neuropsychiatrica, 22(4), 195–196. https://doi.org/10.1111/j.1601-5215.2010.00476.x

Sadhu, A., Badal, K. K., Zhao, Y., Ali, A. A., Swarnkar, S., Tsaprailis, G., Crynen, G. C., & Puthanveettil, S. V. (2023). Short-Term and long-term sensitization differentially alters the composition of an anterograde transport complex in Aplysia. ENeuro, 10(1). https://doi.org/10.1523/ENEURO.0266-22.2022

Yang, P. B., Atkins, K. D., & Dafny, N. (2011). Behavioral sensitization and cross-sensitization between methylphenidate amphetamine, and 3,4-methylenedioxymethamphetamine (MDMA) in female SD rats. European Journal of Pharmacology, 661(1-3), 72–85. https://doi.org/10.1016/j.ejphar.2011.04.035