SENSORY ADAPTATION

a reduction in response to stimuli after a prolonged exposure. This adaptation may be specific or general one.

Contents
What is Sensory Adaptation?Why does Sensory Adaptation Occur?How does Sensory Adaptation Work?How Long does it Take for Sensory Adaptation to Occur?Who Discovered Sensory Adaptation?Examples

What is Sensory Adaptation?

Sensory adaptation, also known as neural adaptation, is:

  • The way our senses adjust and adapt to different stimuli (Sahyouni, 2012).
  • When a sensory receptor or sensory system reduces responsiveness when stimulated repeatedly or for a long time (American Psychological Association, 2023).
  • Not voluntary and physiological (Mlblevins, 2015).
  • Can happen to all five senses (i.e., sight, hearing, smell, taste, touch) and proprioception, our sense of balance (Sahyouni, 2012).

Why does Sensory Adaptation Occur?

Sensory adaptation allows people to change what they are focusing on and what is background information. People adapt to things that are no longer attentionally needed, such as the sound of passing cars outside, the feel of socks on our feet, and others. Without this type of adaptation, senses would be constantly overwhelmed with everything fighting for attention and us being unable to ‘tune’ things out.

How does Sensory Adaptation Work?

Stimuli activate a sensor, which creates an action potential. The signal emanating from the action potential is then sent to the brain (Chung et al., 2002). After a period of time that this signal is active, the sensor will significantly reduce the signals being sent to the brain, until there is a notable change (Chung et al., 2002).

How Long does it Take for Sensory Adaptation to Occur?

It depends, some sensory adaptations happen extremely quickly in a matter of milliseconds (Miller et al., 1999). However, some can also take much longer, ranging from minutes to hours or even days (Greenlee et al., 1991).

Who Discovered Sensory Adaptation?

George M. Stratton first discovered sensory adaptation in vision (Neural Adaptation, 2018). In 1896, he wore inversion goggles, or goggles that flipped his vision upside down, all day for eight days and noticed, after the fifth day, that his vision seemed normal. He coined the term sensory adaptation from this study (Neural Adaptation, 2018).

Examples

  • Sight- Sensory adaptation can happen two ways with sight through up regulation for bright lights or down regulation for darkness.
    • For bright lights: When it is extremely bright outside and lots of light is coming into our eye, our pupils transfer from big and constrict to be smaller. The quickness in this could damage your retina and to protect against retinal damage, sensory adaptation will cause a decreased sensitivity of the rods and cones in your eyes. This makes it so people in high levels of light often (i.e., people who work outside or in settings with an excess amount of light) will not be continuously harming their retina.
    • For dark lights: A similar process occurs as with bright lights. Instead of a constriction of the pupil to be smaller, pupils will increase to get more light to the back of the eyes. In this case, there will be an increased light sensitivity with the rods and cones. This is sensory adaptation which is implemented to account for minimal amounts of lights.
  • Hearing- When loud noises are heard, the inner ear muscle contracts to protect the inner ear from being damaged. This process takes a few seconds so loud and fast noises can, and do, easily damage the inner ear (e.g., a gunshot). However, when sounds are built up to a point of loudness, such as in a rock concert, ears can down regulate and adapt decreasing their sensitivity. This is an effort to protect the ears and tune out non-essential sounds.
  • Smell- In walking into rooms, people often first notice the different smells in the room. This is especially true for restaurants where there are a variety of different food smells. Over time, people stop smelling the initial smells that brought them into the restaurant- this is sensory adaptation. The sense of smell will stop detecting smells when they are repeatedly being activated as a way to focus on other endeavors.
  • Taste- Initially when tasting a new food, there is a medley of different tastes, and the sense of taste can distinguish between the distinctness of each flavor. Over time, when eating that same food, the tastes become less strong as you get more accustomed to the medley of different tastes. This decrease in sensitivity of the sense of taste is sensory adaptation.
  • Touch- When first hopping into a pool, the water feels extremely cold and is a bit of a shock. However, after adjusting our body temperature to the pool, the temperature of the pool starts to feel normal. This is sensory adaptation as the sense of touch with the water has decreased its cold sensitivity.
  • Proprioception- This is our sense of balance and how a person knows where they are in the world. When wearing goggles, our sense of balance is thrown off. To accommodate for the change, the brain will adjust and become less sensitive to the alteration- this is sensory adaptation.

References

American Psychological Association. (2023). Sensory Adaptation. APA Dictionary. https://dictionary.apa.org/adaptation

Chung, S., Li, X., Nelson, S.B. (2002) Short-term depression at thalamocortical synpases contributes to rapid adaptation of cortical sensory responses in vivo. Neuron 34(3) 437-446. https://doi.org/10.1016/S0896-6273(02)00659-1

Greenlee, M.W., Georgeson, M.A., Magnussen, S., Harris, J.P. (1991). The time course of adaptation to spatial contrast. Vision Research 31(2), 223-236. https://doi.org/10.1016/0042-6989(91)90113-J.

Müller, J. R., Metha, A.B., Krauskopf, J., & Lennie, P. (1999). Rapid Adaptation in Visual Cortex to the Structure of Images. Science 285 (5432),1405-1408. https://doi.org/10.1126/science.285.5432.1405

Mlblevins. (2015, April 23). Understanding sensory adaptation with examples. Psychologenie. https://psychologenie.com/understanding-sensory-adaptation-with-examples

Neural Adaptation. Psynso. (2018). https://psynso.com/neural-adaptation/

Sahyouni, R. (2012). Sensory adaptation. Khan Academy. Retrieved May 4, 2023, from https://www.khanacademy.org/test-prep/mcat/processing-the-environment/sensory-perception/v/sensory-adapting

SENSORY ADAPTATION: “Sensory adaptation occurs after a prolonged exposure to a certain wavelength of a stimulus.”
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