A phobia is described as an irrational and persistent that is associated with the presence or anticipation of a specific object or situation.

In addition, avoidance as seen in agoraphobia is an important component of the definition of a phobia. There are three types of phobias, these are specific or simple phobias such as a fear of flying or the dentist, social phobia described as a fear of being humiliated in public, examples of a social phobia include, eating in public or using public toilets.The last type of phobia is agoraphobia, which is described as an intense fear of open or public places, and is often linked with panic attacks. For example, a person may have a fear of leaving their home in case a panic attack occurs while no one is present to help them. Therefore, as a result the person may rarely or in extreme cases never leave their house. Approximately 4 to 7 per cent of the general population is said to develop a specific phobia, such as arachnophobia, whilst only 1 to 2 per cent are said to suffer from a social phobia, such as talking to a large audience, and approximately 2 to 3 per cent suffer from agoraphobia.

A phobia is diagnosed if a person has a persistent, excessive fear, which is accompanied by an anxiety response, which as a result interferes with the person's ability to lead a normal life. The symptoms experienced by a phobic are a feeling of intense anxiety when faced by the phobic stimulus. Other symptoms include an increased heart rate, increased perspiration, dry mouth, increased breathing and tense muscles. This is part of the 'fight or flight' response, which makes the phobic stay and fight their anxiety or run away from it. There are many explanations for the onset of phobias.

One well-supported explanation is the preparedness theory. This theory suggests that we are born with an innate readiness to fear certain creatures or situations, for example, spiders, snakes, being in an enclosed space or heights. We are born with an innate response to things like spiders because in our evolutionary past they could have killed us. Therefore, having an innate fear of spiders, snakes, and so forth, would have been adaptive and would be useful for our survival because it would have led early humans to avoid these potentially life-threatening creatures or situations.

This preparedness theory is supported by research by Bennett-Levy and Marteau (1984) who conducted a correlational study that supported the hypothesis made that we are born with a response to fear certain creatures, objects or situations. In the study participants were given a list of twenty-nine creatures to rate in terms of their perceived ugliness, harmfulness and also their own fear of that creature. The researchers found that the participants' fear of a particular creature was strongly correlated with the animal's appearance.The researchers noted that the more the animal's appearance was different from the human form the more the participants' seemed to fear the animal, such as the creature having more legs or an unpleasant skin texture. Therefore, this research study supports the preparedness theory as the participants feared creatures that may have harmed them in our evolutionary past.

In addition, the research was strongly correlated therefore this suggests to me that we develop phobias of things that may have harmed us in our evolutionary past. However this theory is not conclusive as it does have its limitations.For example, it does not explain why some people develop objects, which would not have been a threat to us in our evolutionary past, for example, clowns. This is a problem for the preparedness theory because if it were true then people would not develop phobias that would not harm us, however, they do, and therefore, it contradicts this theory.

Another criticism is the theory fails to explain why not everybody develops a phobia, as only 4 to 7 per cent do develop one. Therefore, there must be another explanation to why phobias develop.An alternative explanation is the behaviourist theory. This suggests that phobias are learnt, through three ways - classical conditioning, operant (reward) conditioning or observational learning. Classical conditioning suggests that the object becomes associated with fear causing the phobia to develop.

Operant conditioning suggests that a feared object or situation causes anxiety thus the person avoids the anxiety stimulus at all costs and because they are avoiding the stimulus they feel less anxious and this becomes a reinforcement.Lastly, observational learning suggests that phobias can be learnt from other people. There is evidence, which supports this explanation. One example is the study of Little Albert.

Watson and Rayner (1920) introduced Little Albert to a white rat which was used as a neutral stimulus and then paired this with a very loud noise, which frightened Little Albert and eventually he associated the rat with the loud noise which as a result led to a phobia of rats but also other white fluffy objects which he related to the white rat.Therefore, this piece research by Watson and Rayner supports the theory that phobias are learnt; as prior to the experiment he showed no signs of fear towards the rat. In addition, it supports the explanation of classical conditioning, as Little Albert associated the rat and the loud noise, which resulted in a phobia of the neutral stimulus. Therefore, this suggests that phobias are leant.

Unfortunately, the behaviourist explanation cannot account for why people who have phobias cannot remember a fear-provoking experience.This therefore demonstrates that the behaviourist theory is not entirely reliable, and that there must be other explanations to why people develop phobias. In addition, the Watson and Rayner experiment cannot be replicated because of ethical guidelines issued by the British Psychological Society, and therefore, the results might not happen again, in which case their study would become unreliable. There are other explanations for phobias including the faulty gene theory, psychodynamic theory and the cognitive theory. It has to be noted that both biological and psychological explanations have their strengths and weaknesses.

However, in my opinion the most useful explanation is the multi-dimensional approach as there are many different types of phobias. In addition, some people may be born with a genetic predisposition to develop the disorder, and therefore they are more at risk that the general population. It is presumed that a trigger must be present to set off the disorder as not everyone with a genetic vulnerability does develop the disorder, therefore, this explanation is the best explanation as it does take into account the fact that some people with the genetic vulnerability actually develops the disorder.