Specific phobias have a one-year prevalence of 8.7% in the USA with 21.9% of the cases being severe, 30.0% moderate and 48.1% mild. The usual age of onset is childhood to adolescence. Women are twice as likely to suffer from specific phobias as men.

Evolutionary psychology argues that infants or children develop specific phobias to things that could possibly harm them, so their phobias alert them to the danger.

The most common co-occurring disorder for children with a specific phobia is another anxiety disorder. Although comorbidity is frequent for children with specific phobias, it tends to be lower than for other anxiety disorders.

Onset is typically between 7 and 9 years of age. Specific phobias can occur at any age but seem to peak between 10 and 13 years of age.

Phobias are a common form of anxiety disorders and distributions are heterogeneous by age and gender. An American study by the National Institute of Mental Health (NIMH) found that between 8.7 percent and 18.1 percent of Americans suffer from phobias, making it the most common mental illness among women in all age groups and the second most common illness among men older than 25. Between 4 percent and 10 percent of all children experience specific phobias during their lives, and social phobias occur in one percent to three percent of children and adolescents.

A Swedish study found that females have a higher incidence than males (26.5 percent for females and 12.4 percent for males). Among adults, 21.2 percent of women and 10.9 percent of men have a single specific phobia, while multiple phobias occur in 5.4 percent of females and 1.5 percent of males. Women are nearly four times as likely as men to have a fear of animals (12.1 percent in women and 3.3 percent in men) — a higher dimorphic than with all specific or generalized phobias or social phobias. Social phobias are more common in girls than in boys, while situational phobia occurs in 17.4 percent of women and 8.5 percent of men.

According to Child and Adolescent Mental Health, approximately 5 percent of children suffer from specific phobias and 15 percent seek treatment for anxiety-related problems. In recent years the number of children with clinically diagnosed phobias has gradually increased. Researchers are finding that the majority of these diagnoses come anxiety related phobias or society phobias.

Specific phobias are more prevalent in girls than in boys. Likewise, specific phobias are also more prevalent in older children than younger.

Rachman proposed three pathways to acquiring fear conditioning: classical conditioning, vicarious acquisition and informational/instructional acquisition.

Much of the progress in understanding the acquisition of fear responses in phobias can be attributed to classical conditioning (Pavlovian model). When an aversive stimulus and a neutral one are paired together, for instance when an electric shock is given in a specific room, the subject can start to fear not only the shock but the room as well. In behavioral terms, this is described as a conditioned stimulus (CS) "(the room)" that is paired with an aversive unconditioned stimulus (UCS) "(the shock)", which leads to a conditioned response (CR) "(fear for the room)" (CS+UCS=CR).

For instance, in case of the fear of heights (acrophobia), the CS is heights such as a balcony on the top floors of a high rise building. The UCS originates from an aversive or traumatizing event in the person's life, such as almost falling down from a great height. The original fear of almost falling down is associated with being on a high place, leading to a fear of heights. In other words, the CS "(heights)" associated with the aversive UCS "(almost falling down)" leads to the CR "(fear)".

This direct conditioning model, though very influential in the theory of fear acquisition, is not the only way to acquire a phobia.

Vicarious fear acquisition is learning to fear something, not by a subject's own experience of fear, but by watching others reacting fearfully (observational learning). For instance, when a child sees a parent reacting fearfully to an animal, the child can become afraid of the animal as well. Through observational learning, humans are able to learn to fear potentially dangerous objects; a reaction which also been observed in non-human primates. In a study focusing on non-human primates, results showed that the primates learned to fear snakes at a fast rate after observing parents’ fearful reactions. An increase of fearful behaviors was observed as the non-human primates continued to observe their parents’ fearful reaction. Even though observational learning has been proven to be effective in creating reactions of fear and phobias, it has also been shown that by physically experiencing an event, chances increase of fearful and phobic behaviors. In some cases, physically experiencing an event may increase the fear and phobia more so than observing a fearful reaction of another human or non-human primate.

Informational/instructional fear acquisition is learning to fear something by getting information. For instance, fearing electrical wire after having heard that touching it will result in an electric shock.

A conditioned fear response to an object or situation is not always a phobia. To meet the criteria for a phobia there must also be symptoms of impairment and avoidance. Impairment is defined as being unable to complete routine tasks whether occupational, academic or social. In acrophobia an impairment of occupation could result from not taking a job solely because of its location at the top floor of a building, or socially not participating in a social event at a theme park. The avoidance aspect is defined as behavior that results in the omission of an aversive event that would otherwise occur with the goal of the preventing anxiety.

Social anxiety disorder is known to appear at an early age in most cases. Fifty percent of those who develop this disorder have developed it by the age of 11, and 80% have developed it by age 20. This early age of onset may lead to people with social anxiety disorder being particularly vulnerable to depressive illnesses, drug abuse and other psychological conflicts.

When prevalence estimates were based on the examination of psychiatric clinic samples, social anxiety disorder was thought to be a relatively rare disorder. The opposite was found to be true; social anxiety was common, but many were afraid to seek psychiatric help, leading to an underrecognition of the problem.

The National Comorbidity Survey of over 8,000 American correspondents in 1994 revealed 12-month and lifetime prevalence rates of 7.9 percent and 13.3 percent, respectively; this makes it the third most prevalent psychiatric disorder after depression and alcohol dependence, and the most common of the anxiety disorders. According to U.S. epidemiological data from the National Institute of Mental Health, social phobia affects 15 million adult Americans in any given year. Estimates vary within 2 percent and 7 percent of the U.S. adult population.

The mean onset of social phobia is 10 to 13 years. Onset after age 25 is rare and is typically preceded by panic disorder or major depression. Social anxiety disorder occurs more often in females than males. The prevalence of social phobia appears to be increasing among white, married, and well-educated individuals. As a group, those with generalized social phobia are less likely to graduate from high school and are more likely to rely on government financial assistance or have poverty-level salaries. Surveys carried out in 2002 show the youth of England, Scotland, and Wales have a prevalence rate of 0.4 percent, 1.8 percent, and 0.6 percent, respectively. In Canada, the prevalence of self-reported social anxiety for Nova Scotians older than 14 years was 4.2 percent in June 2004 with women (4.6 percent) reporting more than men (3.8 percent). In Australia, social phobia is the 8th and 5th leading disease or illness for males and females between 15–24 years of age as of 2003. Because of the difficulty in separating social phobia from poor social skills or shyness, some studies have a large range of prevalence. The table also shows higher prevalence in Sweden.

Though some fears are inborn, the majority are learned. Phobias develop through negative experiences and through observation. One way children begin to develop fears is by witnessing or hearing about dangers. Ollendick proposes while some phobias may originate from a single traumatizing experience, others may be caused by simpler, or less dramatic, origins such as observing another child’s phobic reaction or through the exposure to media that introduces phobias.

- 2% of parents linked their child’s phobia to a [direct conditioning episode]

- 26% of parents linked their child’s phobia to a [vicarious conditioning episodes]

- 56% of parents linked their child’s phobia to their child’s very first contact with water

- 16% of parents could not directly link their child’s phobia

In addition to asking about the origins of a child’s fear, the questionnaire asked if parents believed that “information associated with adverse consequences was the most influential factor in the development of their child’s phobia.” The results were as followed:

- 0% of parents though it was the most influential factor

- 14% of parents though it was somewhat influential

- 86% of parents though it had little to no influence

BII phobia is one of the more common psychiatric disorders, affecting about 3 to 4% of the general population, and in about 80% of the BII phobia cases, the patient experiences syncope or presyncope. After a random survey was completed in Aligarh, India, with 1648 male and 1613 female, it was found that a significantly higher percentage of females compared to males had BII phobia; 23.36% of females were diagnosed with BII phobia while only 11.19% of males were diagnosed. Females also fainted more often than males, at 64.09% compared to a male rate of 39.4%.

Furthermore, only 5.3% of BII phobia patients reported to have visited the hospital once or twice for consultation about BII phobia, however, without engaging in any kind of treatment.

Another study, involving participants from all 50 states and the District of Columbia, ages 65 years and older, found that a total of 386 participants disclosed having BII Phobia throughout their whole lifetime, 90% of those cases consisted of patients dealing with BII Phobia as well as other lifetime fears.

There is a strong agreement in the scientific community that there is no specific cause of emetophobia. Some emetophobics report a traumatic experience with vomiting, almost always in childhood, but many do not. Some suggest that sufferers are victims of childhood abuse – sexual or physical. While this is occasionally true, it seems to be no more prevalent than in the general population. (Christie, 2004) Some experts believe that emetophobia may be linked to worries about lack of control. Many people try to control themselves and their environment in every possible way, but vomiting is difficult or impossible to control.

There are many factors that can cause a legitimate case of emetophobia. It can affect the minds of young children, but emetophobia can also affect a person at any age. While some emetophobics are indeed severely mentally ill, many are not and have been diagnosed as such and treated inappropriately.

Dr. Angela L. Davidson "et al". conducted an experiment where it was concluded through various surveys that people suffering from emetophobia are more likely to have an internal locus of control pertaining to their everyday life as well as health-related matters. A locus of control is an individual's perception of where control comes from. Having an internal locus of control means that an individual perceives that they have their own control over a situation whereas an external locus of control means that an individual perceives that some things are out of their control.

She explains how this phobia is created through the locus of control by stating, "Thus far, it seems reasonable to stipulate that individuals with a vomiting phobia deem events as being within their control and may therefore find it difficult to relinquish this control during the act of vomiting, thus inducing a phobia."

In an internet survey conducted by Dr. Joshua D. Lipsitz et al. given to emetophobic people, respondents gave many different reasons as to why they became emetophobic. Among some of the causes listed were severe bouts of vomiting as children and being firsthand witnesses to severe vomiting in others due to illness, pregnancy, or alcoholism.

There are three major categories of driving phobia, distinguished by their onset.

The first and most common cause of a fear of driving is traffic accidents. These situations cause PTSD driving phobia, where the fear develops in response to a traumatic event. Usually, situations like these trigger a fear of driving in only specific situations related to the original cause, though it also can trigger a fear of driving entirely.

The second most common form is driving phobia as a specific phobia. Because driving does involve some danger and the possibility of a collision, there does exist some fear or caution in many rational people. However, for some the fear of crashing, losing control over the car, being criticized or being in a dangerous situation will cause panic. It is classified as a phobia when the anxiety does not rationally reflect the amount of danger.

The least common category is an extension of agoraphobia, the anxiety of having a panic attack while being in crowds or public places. One manifestation of agoraphobia is the inability to travel long distances away from home. When driving, an agoraphobe may feel that he is putting himself into a fearful situation, and driving phobia may develop.

A specific phobia is any kind of anxiety disorder that amounts to an unreasonable or irrational fear related to exposure to specific objects or situations. As a result, the affected person tends to avoid contact with the objects or situations and, in severe cases, any mention or depiction of them. The fear can, in fact, be disabling to their daily lives.

The fear or anxiety may be triggered both by the presence and the anticipation of the specific object or situation. A person who encounters that of which they are phobic will often show signs of fear or express discomfort. In some cases, it can result in a panic attack. In most adults, the person may logically know the fear is unreasonable but still find it difficult to control the anxiety. Thus, this condition may significantly impair the person's functioning and even physical health.

Specific phobia affects up to 12% of people at some point in their life.

It has been shown that there is a two to threefold greater risk of having social phobia if a first-degree relative also has the disorder. This could be due to genetics and/or due to children acquiring social fears and avoidance through processes of observational learning or parental psychosocial education. Studies of identical twins brought up (via adoption) in different families have indicated that, if one twin developed social anxiety disorder, then the other was between 30 percent and 50 percent more likely than average to also develop the disorder. To some extent this 'heritability' may not be specific – for example, studies have found that if a parent has any kind of anxiety disorder or clinical depression, then a child is somewhat more likely to develop an anxiety disorder or social phobia. Studies suggest that parents of those with social anxiety disorder tend to be more socially isolated themselves (Bruch and Heimberg, 1994; Caster et al., 1999), and shyness in adoptive parents is significantly correlated with shyness in adopted children (Daniels and Plomin, 1985).

Growing up with overprotective and hypercritical parents has also been associated with social anxiety disorder. Adolescents who were rated as having an insecure (anxious-ambivalent) attachment with their mother as infants were twice as likely to develop anxiety disorders by late adolescence, including social phobia.

A related line of research has investigated 'behavioural inhibition' in infants – early signs of an inhibited and introspective or fearful nature. Studies have shown that around 10–15 percent of individuals show this early temperament, which appears to be partly due to genetics. Some continue to show this trait into adolescence and adulthood, and appear to be more likely to develop social anxiety disorder.

Phobophobia is the fear of phobia(s) and, 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 (free floating fears) 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 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.

Phobophobia differentiates itself from other kind of phobias by the fact that there is no environmental stimulus per se, but rather internal dreadful sensations similar to psychological symptoms of panic attacks. The psychological state of the mind creates an anxious response that has itself a conditioned stimuli leading to further anxiety, resulting in a vicious cycle. Phobophobia is a fear experienced before actually experiencing the fear of the feared phobias its somatic sensations that precede it, which is preceded by generalized anxiety disorders and can generate panic attacks. Like all the phobias, the patients avoids the feared phobia in order to avoid the fear of it.

Bruce and Sanderson also state that animal phobias are more common in females than males. Furthermore, Dr. B.K. Wiederhold, a psychiatrist investigating virtual reality therapy as a possible method of therapy for anxiety disorders, goes on to provide data that although prevalent in both men and women, 75% to 90% of patients reporting specific phobias of the animal subtype are women.

Mental health professionals often distinguish between generalized social phobia and specific social phobia. People with generalized social phobia have great distress in a wide range of social situations. Those with specific social phobia may experience anxiety only in a few situations. The term "specific social phobia" may also refer to specific forms of non-clinical social anxiety.

The most common symptoms of specific social phobia are glossophobia, the fear of public speaking and

the fear of performance, known as stage fright. Other examples of specific social phobia include fears of intimacy or sexual encounters, internet phobia, using public restrooms (paruresis), attending social gatherings, and dealing with authority figures.

Specific social phobia may be classified into performance fears and interaction fears, i.e., fears of acting in a social setting and interacting with other people, respectively. The cause of social phobia is not definite.

Symptoms of social phobia can occur in late adolescence when youths highly value the impressions they give off to their peers. Clinical experience of the prognosis of social phobia shows that it can prolong for many years but that it improves by mid life.

In 2007 scientists found astraphobia is the third most prevalent phobia in the US. It can occur in people of any age. It occurs in many children, and should not be immediately identified as a phobia because children naturally go through many fears as they mature. Their fear of thunder and lightning cannot be considered a fully developed phobia unless it persists for more than six months. In this case, the child's phobia should be addressed, for it may become a serious problem in adulthood.

To lessen a child's fear during thunderstorms, the child can be distracted by games and activities. A bolder approach is to treat the storm as an entertainment; a fearless adult is an excellent role model for children.

The cause of BII phobia is not well known. Some studies show that specific genes make one more vulnerable to the phobia. Other studies suggest that just like any other phobia, BII phobia could be caused by a traumatic experience (Chapman). It has been proved that social stress amplifies BII symptoms, however, it is not a main cause.

Jeanette M. Bruce and William C. Sanderson, in their book "Specific Phobias", concluded that the age of onset for animal phobias is usually early childhood, between the ages of five and nine. A study done in South Africa by Drs. Willem A. Hoffmann and Lourens H. Human further confirms this conclusion for patients suffering from cynophobia and additionally found dog phobia developing as late as age 20.

Though scopophobia is a solitary disorder, many individuals with scopophobia also commonly experience other anxiety disorders. Scopophobia has been related to many other irrational fears and phobias. Specific phobias and syndromes that are similar to scopophobia include erythrophobia, the fear of blushing (which is found especially in young people), and an epileptic's fear that being looked which may itself precipitate such an attack. Scopophobia is also commonly associated with schizophrenia and other psychiatric disorders. It is not considered indicative of other disorders, but is rather considered as a psychological problem that may be treated independently.

Sociologist Erving Goffman suggested that shying away from casual glances in the street remained one of the characteristic symptoms of psychosis in public. Many scopophobia patients develop habits of voyeurism or exhibitionism. Another related, yet very different syndrome, scopophilia, is the excessive enjoyment of looking at erotic items.

Scopophobia is unique among phobias in that the fear of being looked at is considered both a social phobia and a specific phobia, because it is a specific occurrence which takes place in a social setting. Most phobias typically fall in either one category or the other but scopophobia can be placed in both. On the other hand, as with most phobias, scopophobia generally arises from a traumatic event in the person's life. With scopophobia, it is likely that the person was subjected to public ridicule as a child. Additionally, a person suffering from scopophobia may often be the subject to public staring, possibly due to a deformity or physical ailment.

According to the Social Phobia/Social Anxiety Association, U.S. government data for 2012 suggests that social anxiety affects over 7% of the population at any given time. Stretched over a lifetime, the percentage increases to 13%.

Driving phobia, also called vehophobia or a fear of driving, can be severe enough to be considered an intense, persistent fear or phobia. It is often great enough that people will avoid driving at all costs, and instead find someone to drive them or use public transportation, regardless of how inconvenient or expensive.

A fear of driving may escalate to a phobia during difficult driving situations, such as freeway driving or congested traffic.

Exposure methods, using video-taped exposure to others vomiting, hypnosis, exposure to nausea and exposure to cues of vomiting Systemic behavior therapy, psychodynamic and psychotherapy have also shown positive effects for the treatment of emetophobia. However in some cases it may cause re-traumatization, and the phobia may become more intense as a result.

Dogs may exhibit severe anxiety during thunderstorms; between 15 and 30 percent may be affected. Research confirms high levels of cortisol - a hormone associated with stress - affects dogs during and after thunderstorms. Remedies include behavioral therapies such as counter conditioning and desensitization, anti-anxiety medications, and Dog Appeasing Pheromone, a synthetic analogue of a hormone secreted by nursing canine mothers.

Studies have also shown that cats can be afraid of thunderstorms. Whilst it is very rare, cats have been known to hide under a table or behind a couch during a thunderstorm.

Generally if any animal is anxious during a thunderstorm or any similar, practically harmless event (e.g. fireworks display), it is advised to simply continue behaving normally, instead of attempting to comfort animals. Showing fearlessness is, arguably, the best method to "cure" the anxiety.

The telephone is important for both contacting others and accessing important and useful services. As a result, this phobia causes a great deal of stress and impacts people's personal lives, work lives and social lives. Sufferers avoid many activities, such as scheduling events or clarifying information. Strain is created in the workplace because use of phones may play a crucial role within a career.

Blood phobia (also AE: hemophobia or BE: haemophobia) is the extreme and irrational fear of blood, a type of specific phobia. Severe cases of this fear can cause physical reactions that are uncommon in most other fears, specifically vasovagal syncope (fainting). Similar reactions can also occur with trypanophobia and traumatophobia. For this reason, these phobias are categorized as "blood-injection-injury phobia" by the DSM-IV. Some early texts refer to this category as "blood-injury-illness phobia."

Autophobia, also called monophobia, isolophobia, or eremophobia, is the specific phobia of isolation; a morbid fear of being egotistical, or a dread of being alone or isolated. Sufferers need not be physically alone, but just to believe that they are being ignored or unloved. Contrary to what would be implied by a literal reading of the term, "autophobia" does not describe a "fear of oneself". The disorder typically develops from and is associated with other anxiety disorders.

Autophobia can be associated with or accompanied by several other phobias such as agoraphobia, and is generally considered to be a part of the agoraphobic cluster. This means that autophobia has a lot of the same characteristics as certain anxiety disorders and hyperventilation disorders. The main concern of people with phobias in the agoraphobic cluster is getting help in case of emergency. This means people might be afraid of going out in public, being caught in a crowd, being alone, or being stranded.

Autophobia is not to be confused with agoraphobia (fear of being in public, or caught in large crowds), self-hatred, or social anxiety although it can be closely related to these things. It is its own phobia that tends to be accompanied by other anxiety disorders and phobias.