Sensory adaptation is a phenomenon in which the body adjusts to external stimuli over time, becoming less sensitive or responsive to that particular stimulus.
For instance, if you were exposed to loud noises for a long time, your brain would gradually grow accustomed and become desensitized because it slowly becomes unresponsive.
Over time, your brain would require a louder noise to respond, similarly to when you first heard the sound.
Sensory adaptation is not limited to hearing – people experience it in all five senses, and it occurs both on a conscious and subconscious level.
For example, you may find that foods that initially tasted salty or sweet begin tasting blander after extended exposure. This is because our taste buds become less sensitive as they adapt to the same flavor over time.
Definition of Sensory Adaptation
Sensory adaptation is a phenomenon in which the body’s sensory responses to an external stimulus decrease over time. It occurs as the brain adjusts to a particular stimulus, becoming less sensitive or responsive to it.
This form of adaptation is found in all five senses and can occur both on a conscious and subconscious level.
According to Harris (2007),
“…sensory adaptation occurs when sensory receptors reduce their responsiveness to a stimulus after repeated or continuous exposure” (p. 41).
For example, if exposed to loud noise for an extended time, the brain will gradually become desensitized to the sound and will require a louder volume to respond as it did initially.
Similarly, through prolonged exposure, certain tastes can become blander as our taste buds adapt over time.
Webster (2012) states that
“…studies of adaptation have a very rich history in perceptual science because the perceptual “aftereffects” of the adaptation can provide clues as to how our senses encode and represent the stimulus” (p. 1).
Simply, sensory adaptation is a process by which human bodies adjust to external inputs, reducing or increasing their sensitivity depending on the stimulus.
10 Examples of Sensory Adaptation
- Hearing: If exposed to loud noise over time, the brain gradually becomes desensitized to the sound and requires a louder volume to respond as it did initially. If you enter a stadium after a loud football game, for example, your ears may adjust, and you will no longer hear the noise of cheering fans.
- Taste: Through prolonged exposure, certain tastes can become blander as our taste buds adapt over time. So, salty food can taste without many flavors if eaten for an extended period.
- Smell: If exposed to a pungent odor for an extended time, the sense of smell gradually becomes less sensitive and eventually reduces or eliminates the detection of that particular scent (known as olfactory fatigue).
- Touch: Human skin’s sensitivity can decrease if in contact with a consistent source of heat or pressure for an extended period, resulting in desensitization. So, a hot water bottle may feel uncomfortable in the first few minutes and then gradually become less noticeable.
- Sight: Prolonged exposure to bright light causes human eyes to be less responsive and more prone to glare due to an adaptation mechanism known as ‘dark adaptation.’ It means that cells in the eye develop greater sensitivity to darker conditions while being less sensitive to bright light sources.
- Pressure/Gravity: Human bodies can adapt to changes in gravity. This is achieved by lengthening muscles, ligaments, and bones. By doing so, people can maintain an upright position and move freely even when not subjected to gravity, such as in weightlessness or in conditions with atypical gravitational forces compared to Earth’s gravity.
- Pain: Pain thresholds vary from person-to-person. But even within individuals, these thresholds may change due to stress levels, lifestyle choices, and other external factors such as temperature. If a person is exposed to constant pain or discomfort, their body may naturally reduce the sensitivity of certain receptors.
- Balance/Equilibrium: Human brains constantly adjust equilibrium between the inner ear’s three semicircular canals. They control our sense of balance based on how we move around in different postures, like standing up or down, moving horizontally, etc. So that we don’t lose our balance when faced with sudden movements like jumping off a trampoline or running up a flight of stairs etc.
- Temperature: When we experience sudden temperature changes, our body adapts by either sweating more or shivering intensely. Sweating helps remove excess body heat in hot temperatures while shivering warms up cold air before it enters our body to regulate our temperature. So, if you keep a hot compress on your skin for a while and then take it off, you’ll be able to feel the cool air much more acutely than before.
- Spatial Orientation/Position Sense: Human bodies will automatically adapt within moments after swapping positions normally via muscle memory. Take, for instance, something as simple as lying on your right side. When you adjust to the new position and become comfortable, your body will naturally shift or stretch its limbs to maintain balance without conscious thought.
Sensory Adaptation vs. Habituation
Sensory adaptation and habituation are two related but distinct processes. Both involve learning to cope with stimuli; however, the main difference is in how quickly each adapts (McBurney & Balaban, 2009).
Sensory adaptation is a process that occurs over a relatively short period (usually milliseconds or less). It results from changes occurring in neural receptor cells, which allow them to become less responsive to stimuli after prolonged exposure.
This allows individuals to tune out distractions and focus on more important sensory information. For example, if exposed to it for several hours, one might not notice the sound of their air conditioning running (Harris, 2007).
Habituation, on the other hand, takes longer to occur (minutes, hours, or days) and involves an individual becoming accustomed to a stimulus after repeated exposure.
It helps us learn not to react negatively or be overwhelmed by repetitive events. An example of this would be someone getting used to talking in public after slowly increasing the length of their speeches over weeks or months (McBurney & Balaban, 2009).
So, while both processes help us adapt our responses to environmental stimuli, they do so in different ways and time scales. Sensory adaptation occurs very quickly, while habituation takes longer due to the need for consistent exposure.
History of Sensory Adaptation
Despite its common occurrence, the study of sensory adaptation was made possible only during the 19th and 20th centuries by two prominent figures in psychology – Hermann von Helmholtz and George M. Stratton.
Hermann von Helmholtz was one of the earliest researchers to draw attention to this phenomenon (also known as the ‘sensory fatigue effect’) with his book On the Sensations of Tone, first published in 1863 (Helmholtz & Ellis, 2007).
In this book, Helmholtz discussed how a continued sensation could wear away at perception in an observer. He also suggested that repetition and familiarity might explain why people learn not to react so intensely to repetitive events.
George M. Stratton took Helmholtz’s ideas further by creating what’s now known as “Stratton’s Experiment.” This experiment involved Stratton wearing special prism goggles that flipped his vision upside down (Ursyn, 2015).
After several hours of walking around with these goggles on, he observed that his perception gradually adjusted, and he was eventually able to recognize objects without any difficulty – indicating that sensory adaptation had occurred.
So, Hermann Helmholtz and George M. Stratton were two pioneering figures in understanding sensory adaptation who helped shape our current understanding of this remarkable process.
Main Causes of Sensory Adaptation
Sensory adaptation, also known as neural adaptation, occurs due to changes in the neural receptor cells that receive and process sensory information.
Researchers suggest that sensory adaptation occurs in various stages of perceptual processing. Sensory adaptation can occur at different rates, either slowly or quickly (Gepshtein et al., 2013).
Fast adaptation happens very quickly, in the span of milliseconds. In contrast, slow sensory adaptation can occur over minutes, hours, or even days. Repeated exposure to stimuli may allow people to “learn” how to adapt faster to the changes.
Sensory adaptation serves an essential purpose by helping individuals tune out distractions and focus on the most relevant or important stimuli (Roseboom et al., 2015).
Imagine what it would be like if you didn’t experience sensory adaptation. For instance, you could be overwhelmed by the pungent aroma of onions emanating from the kitchen or the loud volume of a television.
So, the main causes of sensory adaptation are changes in neural receptor cells, stages of perceptual processing, and exposure to stimuli.
Sensory adaptation is an important psychological phenomenon that helps people reduce sensory stimuli’s intensity over time.
Originally developed in the 19th century by Hermann von Helmholtz and George M. Stratton, it is now a well-researched area of psychology.
Sensory adaptation is caused by changes in neural receptor cells, stages of perceptual processing, and repeated exposure to stimuli. It helps to tune out distractions and focus on the most important stimuli.
Without sensory adaptation, people would likely be overwhelmed by everyday sensations, making it more difficult to function daily.
Understanding how sensory adaptation works can help people to navigate their environment better and adjust to changes in their surroundings.
Gepshtein, S., Lesmes, L. A., & Albright, T. D. (2013). Sensory adaptation as optimal resource allocation. Proceedings of the National Academy of Sciences, 110(11), 4368–4373. https://doi.org/10.1073/pnas.1204109110
Harris, L. A. (2007). CliffsAP psychology. John Wiley & Sons.
Helmholtz, H. V., & Ellis, A. J. (2007). On the sensations of tone. Cosimo Press.
McBurney, D. H., & Balaban, C. D. (2009). A heuristic model of sensory adaptation. Attention, Perception & Psychophysics, 71(8), 1941–1961. https://doi.org/10.3758/app.71.8.1941
Roseboom, W., Linares, D., & Nishida, S. (2015). Sensory adaptation for timing perception. Proceedings of the Royal Society B: Biological Sciences, 282(1805), 20142833. https://doi.org/10.1098/rspb.2014.2833
Ursyn, A. (2015). Handbook of research on maximizing cognitive learning through knowledge visualization. Information Science Reference.
Webster, M. (2012). Evolving concepts of sensory adaptation. F1000 Biology Reports, 4(21), 1–7. https://doi.org/10.3410/b4-21