Practical Issues
• The fact that the systematic desensitization technique can be applied to images means that many of the practical disadvantages involved in vivo exposition with this type of phobia can be eliminated.
• One weakness of in vitro exposition is that it relies on the client’s ability to be able to imagine the fearful situation. Some people cannot create a vivid image, and thus systematic desensitization is not always effective (there are individual differences).
• Systematic desensitization is a slow process, taking 6-8 sessions on average. Although, research suggests that the longer the technique takes, the more effective it is.
• The progressive structure of systematic desensitization allows the patient to control the steps he/she must make until fear is overcome. This absence of disturbing elements makes this technique less likely to provoke abandonment of the therapy.

Theoretical Issues
• Systematic desensitization is highly effective where the problem is learned anxiety of specific objects/situations, e.g., phobias (McGrath et al., 1990). However, systematic desensitization is not effective in treating serious mental disorders like depression and schizophrenia.
• Studies have shown that neither relaxation nor hierarchies are necessary and that the important factor is just exposure to the feared object or situation.
• Systematic desensitization is based on the idea that abnormal behavior is learned. The biological approach would disagree and say we are born with a behavior, and therefore it must be treated medically.
• Treats the symptoms, not the cause(s) of the phobia. Systematic desensitization only treats the observable and measurable symptoms of a phobia. This is a significant weakness because cognitions and emotions are often the motivators of behavior, and so the treatment is only dealing with symptoms, not the underlying causes.
• Social phobias and agoraphobia do not seem to show as much improvement. Could it be that there are other causes for phobias than classical conditioning?