Habituation occurs when an individual is exposed to repeated constant stimuli causing a decrease of responsiveness to that stimulus and sometimes can cause no response at all. Habituation is considered one of the most basic forms of learning. This can occur in both humans and animals, some common examples of this would be a person who lives by a railroad, overtime they will no longer have a response of hearing the train pass their house because of the repeated amount of times that this may occur in a day. An example of this for animals would be a dog that stops responding to harmless noises such as a trash bag being shaken open, it can also be lights or repeated sounds in their daily life that are neutral.

Historical Background

Willam James laid the foundation for habituation, he mention is finding in a book he wrote in the 19th century call The Principles of Psychology. He described it as be a way to allow the brain to focus on the important task rather than having to constantly respond to repetitive stimuli we come across day to day. The next mention from a prominent figure in psychology was from Ivan Pavlov in the 20th century, though most commonly known for classical conditioning, he notice behaviors in his dogs that seem to reduce when a neutral stimuli was repeated over amount of time which further back the idea of habituation. This then lead to John B Watson who is the father of behaviorism to determine habituation as a basic form of learning, we learn the stimulus no longer needs a reaction. Many more psychologist and researchers have contributed and continue to contribute to the idea of habituation

Mechanisms of Habituation

Neurophysiological Basis

When we come across a stimulus our neurons responded to it by releasing neurotransmitter to communicate what we are perceiving. When there is a neutral stimulus that is repeated it causes a reduction in neurotransmitter release. This will cause the signal to weaken which ultimately will  lead to a decrease in a responsive behavior. There is also a reduction in sensory neuron activity this causes them to become less sensitive to stimulus over time. These changes to the neurons are done by our brain. When a stimulus is detected by our sensory pathway, the three main area it will go to are the thalamus which acts as the sensory relay station, It will reduce how much of the stimulus will get through if shown a repeated amount of times that it is non-threatening. It will get the information about past encounter from the hippocampus which stores information about the stimulus. Our prefrontal cortex is what determines what is important and what are this we can be less responsive to, using a top-down control to filter through repetitive stimuli.

Behavioral Process

1. Initial Response : When a new stimulus is within you environment the first response will be very strong towards It, taking your attention. Called reflexive reaction or orienting response
2. Repeated Exposure : The same stimulus is repeated many of times and has shown to be non-threatening and staying constant our brains will pay less attention towards it.
3. Decreased Response : We will slowly react less to the stimulus over time. We learn the stimulus does not need a reaction.

These 3 steps are the basic steps of habituation, however there are a couple steps after this is the stimulus where to change we would go through a process of dishabituation. There are two way these process can occur

1. Stimulus specificity : When there is a change in the stimulus such as getting louder, brighter, or more exaggerated.
2. Spontaneous Recovery : If we are not exposed to that stimulus for a while and then the stimulus returns our response will temporarily come back.

With both of these form of dishabituation our strong response will return. However,  habituation the second time is a-lot quicker than the first. We will return back to have a reduced response.

Types of Habituation

Short-Term

This type of habituation is more geared to temporary fixes. This can only take minutes or a few hours. This is primarily use for temporary situation such as hear a loud fan in a room. We can decrease the response to that over bearing stimuli so we do not get fatigue have a strong reaction to it. Though it take a short period of time to habituate from it, it will also take a short time to dishabituate to it. Using the same example as the fan, when we leave the room or turn it off it will only take a few minutes or hours to no longer have the weaken neurotransmitter release to reduce a reaction. When fan turn on we will have a strong reaction until the cycle is repeated.

Long-Term Habituation

This type of habituation cause a structural change within our nervous system. This is due to a repeated amount of time the stimulus has occurred. Long-term habituation can take days, weeks and even longer. This type of habituation is more permanent, meaning even if we take a break from the stimulus then exposed we will maintain the reduced reaction. Examples of long-term habituation is living next to a busy road. Due to this stimulus being very constant through out the day and the exposure have last over a long period of time, our brain will use long-term habituation so we can stay focus on important thing we need to do.

Factors Affecting Habituation

Stimulus Characteristics

Intensity : If the stimulus is weaker will have an easier time habituating to it, if the stimulus is strong or more painful the harder and longer it will take to habituate and the easier it will be to dishabituate.

Frequency if Exposure : The more we are exposed to a stimulus the faster we will habituate. If there are large gaps of time between the exposure the longer it will take and sometime not habituating at all

Time Interval : The interval between the stimulus. For example a short interval, would be a fan buzzing because the time interval is very small leading to faster habituation. While longer intervals the slower habituation becomes.

Novelty and Meaning : If the Stimulus is rewarding or dangerous, we will not habituate to it at all. When this types of stimulus occurs it is important for our brain to pay attention

Individual Differences

Age : Infants and older adults have a slower time habituating while adults are more efficient, However habituation can be a form of measurement when it comes to development in an infant. The faster habituation is the more advance the infants cognitive development is.

Temperament : If someone is more sensitive to stimuli around them the longer it will take them to habituate such as people who are anxious or neurotic. While individual who are more relaxed and easy going will have an easier and quicker time habituating.

Attention span : If someone has a short attention span it will be harder to remain unfocused to it. So when habituation will be much slower and be less permanent.

Neurological Health : Many neurological and psychological condition will affect habituation these are just some of the most common. Individuals who are on the autism spectrum, typical those who show atypical will have slower habituation due to sensory overload. Individual who have schizophrenia, research has shown they have impaired habituation due to the filtering information step that happens within the prefrontal cortex and thalamus. Individual who have post-traumatic stress disorder (PTSD) will have a harder time habituating to louder noise or things that bring up trauma, causing them to believe they are in danger again.

Contextual and Environmental Factors

Physical Environment

The environment you are in can many contribution to habituation. If you are in a familiar environment you are less likely to be attentive to your surroundings which will lead to a quicker habituation. While if you were in a new or unpredictable environment you pay more attention to stimulus making it harder to habituate. An example of this is being able to hear a fan in a hotel room much more then in the room at your house.

Social Environment

We are very social human being, so when we are around a group of people and they are attentive to a certain stimuli we are going to follow in their foot steps. This is called social referencing because you are taking cues from the group on what is important to were your attention should go. However this can work in the same is they are ignoring something. If the group is ignoring a stimuli you may habituate faster again taking their cues.

Relevance of Stimulus in Context

If we are in an environment is important to hear a certain stimuli while typically in some other environments we will ignore it the brain will resist habituation in order to hear the relevant noise. With any important stimuli no matter how many times we have been exposed to it we will remain paying attention to it. For example if you hear your phone ding for a notification has been sent. We hear that a repeated amount of times through we do not habituate to because of it relevancy.

Applications Of Habituation in Psychology

Clinical Psychology and Mental Health

One of the main ways we use habituation within clinical psychology is exposure therapy. When a client has a phobia, PTSD, or a anxiety disorder exposing them to a feared stimuli over time they will slowly habituate to it. Which lowers the feared response when coming into contact with that stimuli. This also used for Obsessive-Compulsive disorder (OCD), they are exposed to a stimuli that is an obsessive trigger without being able to complete their usual compulsion. Slowing habituating so over time they no longer need to fulfill their usual compulsions.

Neuropsychology and Brain Injury

Habituation is one of the simplest forms of learning. So it can be a very good measure for how the brain is developing or if there are any brain injuries. People who have strokes or blows to their head will be assessed for habituation pattern, this can give us another clue to have serve the injury is. One of the test that is given involves a. repeated amount of task or stimuli. If there is failure to habituate is a sign there are problems with sensory gating, working memory or executive function.