Non-associative learning is when an individual’s response to a stimulus changes in the absence of new stimuli (or changes in circumstances) that might explain the change in response.
We categorize non-associative learning into two categories: habituation and sensitization. Habituation refers to situations where a stimulus no longer causes a strong response; sensitization occurs when the same stimulus causes a stronger response over time.
Associative vs Non-Associative Learning
In Pavlov’s classical conditioning experiment, the dog began to salivate in response to the bell. The sound of the bell was associated with food. This was associative learning: a stimulus causes a direct response.
Associative learning theories have proven valuable in explaining how:
“…animals and humans assess the relationship between events and generate expectations about the future” (Thorwart & Livesey, 2016, p. 1).
However, over time, the dog may stop salivating in response to the bell. The dog’s response to the stimulus changes.
That is non-associative learning.
There are two forms of non-associative learning: habituation and sensitization.
- Habituation occurs when the stimulus no longer evokes the previously conditioned response.
- Sensitization is a psychological behavior that occurs when a very strong response is evoked by a stimulus. This may result in the one-time onset of an extremely strong stimulus. Or, it can occur as a result of repeated presentation of a mild but noxious stimulus.
10 Non-Associative Learning Examples
- Living near an airport for a year and getting used to the sound of airplanes passing overhead ─ Habituation
- Hearing loud thunder when at home alone at night and then becoming easily startled by bright flashes of light ─ Sensitization
- A pet turtle that no longer withdraws its head when touched ─ Habituation
- Watching a scary movie about a lab technician working alone at night. Later, walking down a dark hallway in your office building and being easily frightened by any noise ─ Sensitization
- Knowing your best friend for so many years that you no longer even notice how annoying they can be at the dinner table ─ Habituation
- Being married for so long that even the slightest hint of bossiness from your spouse sets you off ─ Sensitization
- Squirrels in a public park getting so used to seeing people that they no longer run away when one walks near ─ Habituation
- A dripping faucet that keeps you awake at night and becomes increasingly irritating ─ Sensitization
- Being able to read in a crowded cafeteria because you have learned to block out the noise ─ Habituation
- A timid child with angry parents that cries at school if the teacher uses a stern tone of voice ─ Sensitization
1. Cologne in The Elevator
One day, Jackson overheard some colleagues mention that he had a bit of an unpleasant body odor. He ruminated about those comments for weeks until his wife bought him some expensive cologne for his birthday.
Now, every morning he puts a little dab on his fingertip and applies it to both sides of his neck. But, after a while, he thought maybe the cologne was getting weaker. He could no longer smell it, even right after putting it on.
So, he started to squirt a little on his shirt too. His reasoning was that the cologne might stay longer on cloth than skin; it probably wouldn’t evaporate so easily.
Then, he couldn’t believe it, but that stopped working too. So, he started to squirt the cologne on his neck, his shirt as usual, wrists, and a few shots on his back.
That seemed to do the trick. Now, whenever he gets in the elevator, someone always compliments his choice of cologne.
2. Animal Habituation to Humans as an Existential Threat
Deforestation and poaching pose severe threats to many species throughout the globe. For many conservationists, one strategy to combat these destructive forces is to increase public awareness, and appreciation, by conducting tours through exotic lands.
For example, seeing a gorilla just a few meters away is going to create a far stronger emotional impact than watching a documentary on TV.
Of course, it’s not a good idea to just bring a group of sightseers through the jungle and let them start snapping photos of a great silver-back. The first time that happens, he will most likely protect his territory by attacking the tourists immediately.
Therefore, it is necessary for guides to expose the gorillas to human beings very slowly and gradually. It is a long process of habituation.
As the gorillas become more accustomed to seeing human beings, they will become less fearful. Eventually, the gorillas will become habituated and practically ignore their presence.
At that point, it will be safe…most likely.
3. Habituation in Snails
Habituation is a highly adaptive behavior in all species. As a given animal explores its environment, it has to learn which stimuli are life-threatening and which are not. If it were to exhibit a fear response to everything encountered, each and every time, it would be unable to adapt.
Fortunately, when an organism encounters a stimulus repeatedly, without negative consequences, it will no longer exhibit a fear response to that stimulus.
This phenomenon can be easily demonstrated near your home during spring. All you have to do is find a snail.
The above video provides an excellent description on how to conduct an experiment on habituation in snails.
The first time the snail is touched, it instantly retracts. This is an adaptive response, built-in, in case the thing touching it happened to be a bird or some other predator.
However, after repeated prodding, the snail habituates to the touch and no longer retracts.
4. The Stress Sensitization Model
Research over several decades has revealed that psychosocial stressors are some of the strongest predictors of psychopathology (Harkness, et al., 2015). Stress-related psychopathology can include major depression and bipolar disorder. Moreover, adversity in childhood is also strongly linked with the onset of psychiatric disorders (McLaughlin, et al, 2012).
However, not everyone responds to stress in the same manner. Individuals vary in terms of resiliency and reactions to stressful events.
Therefore, it is important to understand the role of stress sensitivity in individuals that may better inform prevention and treatment options.
The Stress Sensitization Model provides a framework for understanding how individuals differ in their reactions to stress, which may then carry forward to have long-term and more severe mental health implications.
“The model posits that individuals become sensitized to stress over time, such that the level of stress needed to trigger episode onsets becomes increasingly lower with successive episodes” (Stroud, 2020, p. 349).
The Neurobiological Basis of Sensitization
Sensitization is often discussed in a psychological context, such as when an individual becomes more easily upset at even a slight provocation. Examples of how a spouse’s mannerisms ultimately become unbearable come to mind easily. However, there are very real and concrete neurobiological mechanisms behind sensitization.
Post (1992) argues that psychological stressors can lead to changes in neurotransmission. Those changes can increase reactivity, or sensitivity, to events that would ordinarily not be perceived as traumatic.
As a result of experiencing certain stressors over time, enduring changes to neurotransmitters and receptors can lead to “…long-term synaptic adaptations and memory that could last indefinitely” (p. 1002).
Post (2016) suggests that an individual can develop a sensitization to mild stressors that are exaggerated due to “memory-like mechanisms” (p. 315). These changes “are likely the basis for long-term alterations in behavioral responsivity to recurrent events in sensitization” (p. 316).
The above biological explanation for sensitization helps us understand how life events in childhood can have a very real impact throughout the lifespan.
Non-associative learning occurs when an organism changes its response to a stimulus over time. Habituation and sensitization are two forms of non-associative learning that can be observed in nearly all animal species.
For a person, being able to shut out the noisy chatter of a crowded room and focus on reading is an example of habituation to noise (see also: selective attention). For a snail, learning to ignore the prodding of a foreign object that doesn’t involve a predator is an example of habituation to touch.
Sensitization occurs when an individual has a heightened reaction to a stimulus. When a person becomes easily frightened after watching a scary movie, it’s because they have become sensitized.
Sensitization can also explain how trauma in childhood has a prolonged effect on how we interpret and respond to events later in life. This phenomenon has a biological basis that can produce a “memory-like” alteration that is long-lasting.
Harkness, K. L., Hayden, E. P., & Lopez-Duran, N. L. (2015). Stress sensitivity and stress sensitization in psychopathology: an introduction to the special section. Journal of Abnormal Psychology, 124(1), 1-3.
McLaughlin, K. A., Green, J. G., Gruber, M. J., Sampson, N. A., Zaslavsky, A. M., & Kessler, R. C. (2012). Childhood adversities and first onset psychiatric disorders in a national sample of adolescents. Archives of General Psychiatry, 69, 1151–1160.
Pavlov, I. P. (1927). Conditioned Reflexes: An Investigation of the Physiological Activity of the Cerebral Cortex. Oxford: Oxford University Press.
Post, R. M. (1992). Transduction of psychosocial stress into the neurobiology of recurrent affective disorder. American Journal of Psychiatry, 149, 999–1010.
Post, R. M. (2016). Epigenetic basis of sensitization to stress, affective episodes, and stimulants: Implications for illness progression and prevention. Bipolar Disorders, 18(4), 315–324. https://doi.org/10.1111/bdi.12401
Stroud, C. B., Harkness, K. L., & Hayden, E. P. (2020). The stress sensitization model. The Oxford Handbook of Stress and Mental Health, 349-370.
Thorwart, A., & Livesey, E. J. (2016). Three ways that non-associative knowledge may affect associative learning processes. Frontiers in Psychology, 7, 2024. https://doi.org/10.3389/fpsyg.2016.02024