Desensitization (psychology)

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Desensitization (psychology)
MeSH D003887

In psychology, desensitization is a treatment or process that diminishes emotional responsiveness to a negative, aversive or positive stimulus after repeated exposure to it. Desensitization also occurs when an emotional response is repeatedly evoked in situations in which the action tendency that is associated with the emotion proves irrelevant or unnecessary. The process of desensitization was developed by psychologist Mary Cover Jones, and is primarily used to assist individuals in unlearning phobias and anxieties. [1] [2] [3] Joseph Wolpe (1958) developed a method of a hierarchal list of anxiety evoking stimuli in order of intensity, which allows individuals to undergo adaption. [4] Although medication is available for individuals suffering from anxiety, fear or phobias, empirical evidence supports desensitization with high rates of cure, particularly in clients suffering from depression or schizophrenia. [5]

Contents

Steps

The hierarchical list is constructed between client and therapist in rank ordered series of steps from the least disturbing to the most disturbing fears or phobias. Secondly the client is taught techniques that produce deep relaxation. It is impossible to feel both anxiety and relaxation at the same time, [6] so easing the client into deep relaxation helps inhibit any feelings of anxiety. Systematic desensitization (a guided reduction in fear, anxiety or aversion [7] ) can then be achieved by gradually approaching the feared stimulus while maintaining relaxation. Desensitization works best when individuals are directly exposed to the stimuli and situations they fear so anxiety-evoking stimuli are paired with inhibitory responses. This is carried out either by clients performing in real life situations (known as vivo desensitization), or, if it is not practical to directly act out the steps of hierarchy, by clients observing models performing the feared behaviour (known as vicarious desensitization). Clients slowly move up the hierarchy, repeating performances if necessary, until the last item on the list is performed without fear or anxiety. [4]

Suggested Mechanisms

Reciprocal Inhibition

The theory that "two opposing states cannot occur simultaneously" i.e. relaxation methods that are involved with desensitization inhibit feelings of anxiety that come with being exposed to phobic stimuli. [8]  Deep muscle relaxation techniques are the primary method used by Wolpe in order to increase parasympathetic nervous system activity, the nervous system the body uses to relax. [8]  

One criticism is that reciprocal inhibition isn’t a necessary part of the process in desensitizing people as other therapies that are along similar lines, such as flooding, work without pre-emptive, inhibitory relaxation techniques. [8] A review of empirical evidence confirmed that therapy without relaxation was equally effective and this gave birth to exposure therapy. [8]

A review of Taylor’s (2002) classification of reciprocal inhibition as being short-term but with long term effects within the understanding of desensitization doesn’t make sense due to it being theoretically similar to reactive inhibition which is longer term as it develops conditioned inhibition. [8]  

Counterconditioning

Counterconditioning suggests that the anxiety response is replaced by a relaxation response through conditioning during the desensitization process. [8] Counterconditioning is the behavioural equivalent of reciprocal inhibition which is understood as a neurological process. [8] Wolpe (1958) used this mechanism to explain the long-term effects of systematic desensitization as it reduces avoidance responses and therefore excessive avoidance behaviours contributing to anxiety disorders. [8] However, this explanation is not supported by empirical evidence. [8] [9]

For similar reasons to reciprocal inhibition, counterconditioning is criticized as the underpinning mechanism for desensitization due to therapies that don’t suggest a replacement emotion for anxiety being effective in desensitizing people. [8] It is to be noted that there would be no behavioural difference between if reciprocal inhibition or counterconditioning were the functioning mechanisms. [9]

Habituation

This theory explains that with increased exposure to stimulus there will be a decreased response from the phobic subject. There is empirical evidence to suggest that overall phobia responses are decreased in people who have specific phobias with in vivo exposure, however, empirical evidence does not support habituation as an explanation of desensitization due to its reversible and short-term nature. [8]

Extinction

Phobic responses are decreased after exposure to stimuli without avoidance and with a lack of a reinforcement. However, this cannot be used as an explanation for why desensitization works as it solely describes the functional relationship between absent reinforcement and phobic responses and lacks an actual mechanism for why such relationship exists. [8]

Wolpe disagreed that extinction could be the explanatory mechanism of how desensitization occurs with therapies based on exposure as he believed that repeated exposure was insufficient and had likely been already happened during the people with specific phobia's lives. [8]

Two-Factor Model

Exposure to phobic stimuli and then a subsequent avoidance response may strengthen the future anxiety as the avoidance response reduces the anxiety which therefore reinforces the avoidant behaviour (prominent feature of specific phobias and anxiety disorders). [10] [8] Therefore, exposure with non-avoidance seen as essential in the desensitization process.

Self-Efficacy

This is the view that a persons' belief in themselves of being able to cope increases, especially when moving up the exposure hierarchy and having confirmatory experiences of being able to cope from the lower levels. [8] The increase in self-efficacy then explains fear reduction i.e. desensitization to stimuli. [8]

This mechanism as an explanation for desensitization lacks an explanation for how increased expectation of fear reduction actually leads to reduced fear responses and how if a person didn't actually experience a reduced fear response whether desensitization will have occurred as their anxiety response will reaffirm their phobia. [8]

Expectancy Theory

This theory suggests that because people expect that the therapy is going to work and change their view on how they are going to receive the phobic stimuli after speaking with the therapist, their responses will align with that and display reduced anxiety [8] [11] Marcia et al (1969) found that those with high expectancy change (receiving full expectancy treatment) had comparable results to those who had systematic desensitization therapy suggesting its just a change in expectancy that reduces fear responses. [11]

Emotional Processing Theory

R.J McNally explains "fear is represented in memory as a network comprising stimulus propositions that express information about feared cues, response propositions that express information about behavioural and physiologic responses to these cues, and meaning propositions that elaborate on the significance of other elements in the fear structure". [12] Excessive fear such as phobias can be understood as a problem in this structure which lead to problems processing information leading to exaggerated fear responses. [12] Using this information about fear networks, desensitization can be achieved accessing the fear network using matching stimuli to information in the fear network and then having the person engage with the stimuli to input new information into the network by disconfirming existing propositons. [12]

Neuroscience

Medial Prefrontal Cortex

The medial prefrontal cortex works with the amygdala and when damaged, a phobic subject will find desensitization more difficult to achieve. [12] Neurons in this area aren't fired during the desensitization process despite reducing spontaneous fear responses when artificially fired suggesting the area stores extinction memories that reduce phobic responses to future stimuli related to the phobia (conditioned) which explains the long-term impact of desensitization. [12]

N-methyl-D-aspartate Glutamatergic Receptors

NMDA receptors have been found to play a key role in extinction of fear and therefore the use of an agonist would accelerate the reduction in fear responses during the process of desensitization. [12]

Criticism and Developments

With the widespread research and development of behavioural therapies and experiments being conducted in order to understand the mechanisms driving desensitization, a consensus often arises that exposure is the key element of desensitization. [8] [12] This suggests the steps leading up to the actual exposure such as relaxation techniques and the development of an exposure hierarchy are redundant steps for effective desensitization. [8] [12]

Effects on animals

Horses have a natural fear of unpredictable movement. Pictured is a horse being desensitized to accept the fluttering skirt of a lady's riding habit. Horsemanship for Women 056.png
Horses have a natural fear of unpredictable movement. Pictured is a horse being desensitized to accept the fluttering skirt of a lady's riding habit.

Animals can also be desensitized to their rational or irrational fears. A race horse who fears the starting gate can be desensitized to the fearful elements (the creak of the gate, the starting bell, the enclosed space) one at a time, in small doses or at a distance. Clay et al. (2009) conducted an experiment whereby he allocated rhesus macaques to either a desensitization group or a control group, finding that those in the desensitization group showed a significant reduction in both the rate and duration of fearful behavior. This supports the use of PRT training. Desensitization is commonly used with simple phobias like insect phobia. [13] [14] In addition, desensitization therapy has been shown to be a useful tool in training domesticated dogs. [15] Systematic desensitization used in conjunction with counter-conditioning was shown to reduce problem behaviours in dogs, such as vocalization and property destruction. [15]

Effects on violence

Desensitization also refers to the potential for reduced responsiveness to actual violence caused by exposure to violence in the media, although this topic is debated in the scientific literature on the topic. [16] Desensitization may arise from different sources of media, including TV, video games and movies. Some scholars suggest that violence may prime thoughts of hostility, with the possibility of affecting the way we perceive others and interpret their actions. [17] [18] [19]

It is hypothesized that initial exposure to violence in the media may produce a number of aversive responses such as increased heart rate, fear, discomfort, perspiration and disgust. However, prolonged and repeated exposure to violence in the media may reduce or habituate the initial psychological impact until violent images do not elicit these negative responses. Eventually the observer may become emotionally and cognitively desensitized to media violence. In one experiment, participants who played violent video games showed lower heart rate and galvanic skin response readings, which the authors interpreted as displaying a physiological desensitization to violence. [20] However, other studies have failed to replicate this finding. [21] [22] Some scholars have questioned whether becoming desensitized to media violence specifically transfers to becoming desensitized to real-life violence. [23]

See also

Related Research Articles

Arachnophobia Fear of spiders and other arachnids

Arachnophobia is the intense and irrational fear of spiders and other arachnids such as scorpions.

Phobia Anxiety disorder defined by a persistent and excessive fear of an object or situation

A phobia is a type of anxiety disorder defined by a persistent and excessive fear of an object or situation. Phobias typically result in a rapid onset of fear and are present for more than six months. Those affected will go to great lengths to avoid the situation or object, to a degree greater than the actual danger posed. If the object or situation cannot be avoided, they experience significant distress. Other symptoms can include fainting, which may occur in blood or injury phobia, and panic attacks, which are often found in agoraphobia. Around 75% of those with phobias have multiple phobias.

Acrophobia Extreme or irrational fear of heights

Acrophobia is an extreme or irrational fear or phobia of heights, especially when one is not particularly high up. It belongs to a category of specific phobias, called space and motion discomfort, that share both similar causes and options for treatment.

Joseph Wolpe was a South African psychiatrist and one of the most influential figures in behavior therapy.

Behaviour therapy or behavioural psychotherapy is a broad term referring to clinical psychotherapy that uses techniques derived from behaviourism and/or cognitive psychology. It looks at specific, learned behaviours and how the environment, or other people's mental states, influences those behaviours, and consists of techniques based on learning theory, such as respondent or operant conditioning. Behaviourists who practice these techniques are either behaviour analysts or cognitive-behavioural therapists. They tend to look for treatment outcomes that are objectively measurable. Behaviour therapy does not involve one specific method but it has a wide range of techniques that can be used to treat a person's psychological problems.

Fear of needles, known in medical literature as needle phobia, is the extreme fear of medical procedures involving injections or hypodermic needles.

Systematic desensitization, also known as graduated exposure therapy, is a type of behavior therapy developed by South African psychiatrist, Joseph Wolpe. It is used in the field of clinical psychology to help many people effectively overcome phobias and other anxiety disorders that are based on classical conditioning, and shares the same elements of both cognitive-behavioral therapy and applied behavior analysis. When used by the behavior analysts, it is based on radical behaviorism, as it incorporates counterconditioning principles, such as meditation and breathing. From the cognitive psychology perspective, however, cognitions and feelings trigger motor actions.

Flooding, sometimes referred to as in vivo exposure therapy, is a form of behavior therapy and desensitization—or exposure therapy—based on the principles of respondent conditioning. As a psychotherapeutic technique, it is used to treat phobia and anxiety disorders including post-traumatic stress disorder. It works by exposing the patient to their painful memories, with the goal of reintegrating their repressed emotions with their current awareness. Flooding was invented by psychologist Thomas Stampfl in 1967. It is still used in behavior therapy today.

Social inhibition is a conscious or subconscious avoidance of a situation or social interaction. With a high level of social inhibition, situations are avoided because of the possibility of others disapproving of their feelings or expressions. Social inhibition is related to behavior, appearance, social interactions, or a subject matter for discussion. Related processes that deal with social inhibition are social evaluation concerns, anxiety in social interaction, social avoidance, and withdrawal. Also related are components such as cognitive brain patterns, anxious apprehension during social interactions, and internalizing problems. It also describes those who suppress anger, restrict social behavior, withdraw in the face of novelty, and have a long latency to interact with strangers. Individuals can also have a low level of social inhibition, but certain situations may generally cause people to be more or less inhibited. Social inhibition can sometimes be reduced by the short-term use of drugs including alcohol or benzodiazepines. Major signs of social inhibition in children are cessation of play, long latencies to approaching the unfamiliar person, signs of fear and negative affect, and security seeking. Also in high level cases of social inhibition, other social disorders can emerge through development, such as social anxiety disorder and social phobia.

Phobophobia: “The fear of fear itself”, but more specifically, of the internal sensations associated with that phobia and anxiety, which binds it closely to other anxiety disorders, especially with generalized anxiety disorders and panic attacks. It is a condition in which anxiety disorders are maintained in an extended way, which combined with the psychological fear generated by phobophobia of encountering the feared phobia would ultimately lead to the intensifying of the effects of the feared phobia that the patient might have developed, such as agoraphobia, and specially with it, and making them susceptible to having an extreme fear of panicking. Phobophobia comes in between the stress the patient might be experiencing and the phobia that the patient has developed as well as the effects on his/her life, or in other words, it is a bridge between anxiety/panic the patient might be experiencing and the type of phobia he/she fears, creating an intense and extreme predisposition to the feared phobia. Nevertheless, phobophobia is not necessarily developed as part of other phobias, but can be an important factor for maintaining them.

Cynophobia is the fear of dogs and canines in general. Cynophobia is classified as a specific phobia, under the subtype "animal phobias". According to Dr. Timothy O. Rentz of the Laboratory for the Study of Anxiety Disorders at the University of Texas, animal phobias are among the most common of the specific phobias and 36% of patients who seek treatment report being afraid of dogs or cats. Although snakes and spiders are more common animal phobias, cynophobia is especially debilitating because of the high prevalence of dogs and the general ignorance of dog owners to the phobia. The Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR) reports that only 12% to 30% of those suffering from a specific phobia will seek treatment.

Exposure therapy is a technique in behavior therapy to treat anxiety disorders. Exposure therapy involves exposing the target patient to the anxiety source or its context without the intention to cause any danger. Doing so is thought to help them overcome their anxiety or distress. Procedurally, it is similar to the fear extinction paradigm developed studying laboratory rodents. Numerous studies have demonstrated its effectiveness in the treatment of disorders such as generalized anxiety disorder, social anxiety disorder, obsessive-compulsive disorder, PTSD, and specific phobias.

Dental fear Medical condition

Dental fear is a normal emotional reaction to one or more specific threatening stimuli in the dental situation. However, dental anxiety is indicative of a state of apprehension that something dreadful is going to happen in relation to dental treatment, and it is usually coupled with a sense of losing control. Similarly, dental phobia denotes a severe type of dental anxiety, and is characterised by marked and persistent anxiety in relation to either clearly discernible situations or objects or to the dental setting in general. The term ‘dental fear and anxiety’ (DFA) is often used to refer to strong negative feelings associated with dental treatment among children, adolescents and adults, whether or not the criteria for a diagnosis of dental phobia are met. Dental phobia can include fear of dental procedures, dental environment or setting, fear of dental instruments or fear of the dentist as a person. People with dental phobia often avoid the dentist and neglect oral health, which may lead to painful dental problems and ultimately force a visit to the dentist. The emergency nature of this appointment may serve to worsen the phobia. This phenomenon may also be called the cycle of dental fear. Dental anxiety typically starts in childhood. There is the potential for this to place strains on relationships and negatively impact on employment.

Blood-injection-injury (BII) type phobia is a type of specific phobia characterized by the display of excessive, irrational fear in response to the sight of blood, injury, or injection, or in anticipation of an injection, injury, or exposure to blood. Blood-like stimuli may also cause a reaction. This is a common phobia with an estimated 3-4% prevalence in the general population, though it has been found to occur more often in younger and less educated groups.

Interoceptive exposure is a cognitive behavioral therapy technique used in the treatment of panic disorder. It refers to carrying out exercises that bring about the physical sensations of a panic attack, such as hyperventilation and high muscle tension, and in the process removing the patient's conditioned response that the physical sensations will cause an attack to happen.

Fear of flying Human fear

Fear of flying is a fear of being on an airplane, or other flying vehicle, such as a helicopter, while in flight. It is also referred to as flying anxiety, flying phobia, flight phobia, aviophobia, or aerophobia.

Counterconditioning is functional analytic principle that is part of behavior analysis, and involves the conditioning of an unwanted behavior or response to a stimulus into a wanted behavior or response by the association of positive actions with the stimulus. For example, when training a dog, a person would create a positive response by petting or calming the dog when the dog reacts anxiously or nervously to a stimulus. Therefore, this will associate the positive response with the stimulus.

A driving phobia is a pathological fear of driving. It is also referred to as amaxophobia or vehophobia. Amaxophobia is an intense, persistent fear of participating in car traffic that interferes with the patient’s lifestyle and quality of life, including aspects such as inability to participate in the workforce due to the pathological and self-defeating avoidance of driving. The fear of driving may be triggered by specific driving situations, such as expressway driving or dense traffic. Driving anxiety can range from a mild cautious concern to an irrational phobia.

Safety behaviors are coping behaviors used to reduce anxiety and fear when the user feels threatened. An example of a safety behavior in social anxiety is to think of excuses to escape a potentially uncomfortable situation. These safety behaviors, although useful for reducing anxiety in the short term, might become maladaptive over the long term by prolonging anxiety and fear of nonthreatening situations. This problem is commonly experienced in anxiety disorders. Treatments such as exposure and response prevention focus on eliminating safety behaviors due to the detrimental role safety behaviors have in mental disorders. There is a disputed claim that safety behaviors can be beneficial to use during the early stages of treatment.

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