SYSTEMATIC DESENSITISATION
A BEHAVIOURAL THERAPY FOR TREATING PHOBIAS

Remember Watson & Rayner (1920)? John Watson intended to cure Baby Albert of the fear of white furry animals but never got the chance, because Albert's mother withdrew from the study.

In the 1950s, South African psychologist Joseph Wolpe perfected a technique called systematic desensitisation for curing phobias.

Systematic desensitisation is based on classical conditioning and has two components:

1. Counter-conditioning: this involves learning to associate the thing you fear with something relaxing or pleasant
   
2. Graduated exposure: this involves introducing you to the thing you fear in stages, starting with brief and remote encounters (a photograph, at a distance, for a second) and building up to longer, closer and more immediate encounters
   

Sometimes there's a third component:

• Participant modelling: a role model demonstrates being relaxed and calm in the presence of the feared object
  

This video refers to graduated exposure as 'systematic desensitisation' but it's more helpful to think of the whole therapy as systematic desensitisation and the step-by-step introduction of the feared object as graduated exposure

Counter-conditioning

This involves pairing the object, activity or creature that produces the fear response with something else that produces an incompatible response, like pleasure, relaxation or humour.

Wolpe taught his patients relaxation techniques like controlling breathing. Larry Ventis uses humour therapy as a type of counter-conditioning (Ventis et al., 2001).

Notice how Ventis helps Sarah learn new, harmless associations for spiders

The idea is that instead of their old Conditioned Response (CR) of fear, the patient learns a new CR, like relaxing or laughing.

Graduated Exposure

The therapist and the patient work out a STIMULATION HIERARCHY - a list of encounters with the feared thing, going from the least intense to the most intense.

Less intense encounters tend to be:

• pictures or imitations rather than real
• far away rather than close-up
• brief rather than long-lasting
  

Example of a stimulation hierarchy for someone with a fear of spiders (arachnophobia)

It's very important that the stimulation hierarchy is created by the patient not the therapist. This is for two reasons:

• The patient knows best what makes them anxious. Having control over how the therapy proceeds is itself relaxing.
• It would be unethical to expose patients to distressing situations if they hadn't given informed consent to every step in the process first. Ethical guidelines emphasise the importance of respecting people's autonomy (control over what happens to them)

During systematic desensitisation, the patient works their way through the stimulation hierarchy, starting with the least intense encounters and building up to the most intense.

• It's important that the patient can stop at any point. The procedure is voluntary. You don't have to go onto to the next step in the stimulation hierarchy until you feel ready.
• Biofeedback is often used. This involves taking the patient's pulse or measuring breathing as a way of telling how anxious they are.

Drew uses systematic desensitisation to overcome a fear of heights (acrophobia)

Participant Modelling

Systematic desensitisation is based on classical condition, but Social Learning Theory can also be used to improve the therapy.

Douglas Bernstein (1979) calls this participant modelling. A first step on the stimulation hieraarchy would be to watch someone else model the relaxation techniques and encounter the feared object before trying it yourself.

With really severe phobias, the patient can't even bear to watch someone else encounter the feared object. In these cases Richard Sharf (2000) recommends covert modelling. This is where the first step on the stimulation hierarchy is to imagine someone else encountering the feared object.

SYSTEMATIC DESENSITISATION
CODA

Behavioural therapies in general are evaluated on Therapies for Phobias. Flooding is another therapy with its own page.

CREDIBILITY

Systematic desensitisation is based on classical conditioning, which is a well-established psychological theory supported by a huge amount of research (eg Pavlov's dogs, Baby Albert). Research suggests that phobias are learned in the first place through association and can be un-learned by forming different associations.

Since this research has been carried out in controlled laboratory conditions, it also provides a strict scientific basis for systematic desensitisation. This makes it possible to measure the effectiveness of the therapy. It is easy to tell if systematic desensitisation is succeeding by observing how far down the stimulation hierarchy the patient can proceed, compared to the last session.

Gilroy et al. (2003) studied 42 patients who had been treated for their fear of spiders (arachnophobia) in three 45-minute sessions of systematic desensitisation. The phobia's strength was measured by a questionnaire and by observing the patient when they encountered a spider. A Control group was taught relaxation techniques without gradual exposure to the spider. After 3 months and again after 33 months, the treatment group were less fearful than the Control group. This shows that systematic desensitisation reduces the power of a phobia and that the effects are long-lasting. 

OBJECTIONS

It can be unethical to expose a patient to something they find distressing. In fact, it could backfire and make the patient even more frightened of that thing.

However, if systematic desensitisation is done properly, the patient decides on the stimulus hierarchy and only moves on to the next stage of the hierarchy when they feel ready. This respects the patient's autonomy and helps them feel less anxious.

A problem might be that, in real life, sufferers do not get to choose when and how they encounter the object of their fear (a spider might drop on you unexpectedly!) and they might have no control over a real life situation. This means that the benefits of the therapy might not generalise to real life situations.

Another weakness is that systematic desensitisation works best for phobias of objects or animals. It's not so effective for phobias of situations or concepts, like the fear of crowds, foreigners, the number 13, flying or germs.

This is because it's hard to re-create these things in the therapy session and hard to manipulate these things into a stimulus hierarchy. With a fear of flying (aerophobia), you're either flying or you're not. The sufferer isn't frightened of aeroplanes or films set on aeroplanes; it's actually being up in the air themselves that they find frightening.

In the past, in vitro techniques involved the patient imagining themselves to be in the frightening situation. These days, virtual reality is helping to apply systematic desensitisation to situations that used to be difficult to set up in a therapy session.

I want to play "Skyrim" this way

DIFFERENCES

Systematic desensitisation involves gradual exposure to the object you fear, but with flooding you are completely exposed to it, all at once. It's like going directly to the end of the stimulus hierarchy and skipping all the stages in between.

Systematic desensitisation is much more ethical than flooding, because the participants are only exposed gradually to the thing that they fear and they only move on to greater exposure when they feel ready. With flooding, the patient is exposed to the object they fear all at once, in a very intense way. This can be distressing.

Both therapies can be carried out in vitro rather than in vivo. Imagining exposure to the feared object is less distressing. However, in vitro flooding is still more upsetting that in vitro systematic desensitisation.

Neither systematic desensitisation nor flooding tackle the possible underlying problem behind the phobia. They are both behavioural therapies that only deal with the symptoms, not the cause. If there is an underlying problem behind the phobia (like trauma in the patient's past), then that will still be there and will carry on causing difficulties, even if the phobia is temporarily eased.

APPLICATIONS

Rothbaum et al. (1995) created a virtual-reality helmet worn by the patient which displays a phobic situation which is controlled  by the therapist. The scene might be one of driving a car over a high bridge. The pulse rate is monitored by the therapist. When the pulse rate gets too high, the scene is frozen in frame. The therapist then uses counter-conditioning to replace the fear with relaxation techniques.

This sort of technology is replacing in vitro therapy, making systematic desensitisation more ethical without losing its effectiveness; it also enables systematic desensitisation to be applied to phobias of things other than animals or objects.