Aversion therapy is a behavioral intervention based on the principle of positive punishment.
In psychological terms, positive punishment means adding an unpleasant stimulus right after an unwanted behavior. This reduces how often the behavior happens.
By creating a negative association, clinicians aim to break harmful habits or compulsive patterns.
Historically, this approach involved applying physical discomfort, such as mild electric shocks, to deter problematic actions.
While these methods were common in the mid-20th century, modern practitioners rarely use them.
Today, cognitive behavioral therapy (CBT) focuses on more ethical and sustainable strategies for change.
Key Takeaways
- Mechanism: Aversion therapy uses classical conditioning to pair an unwanted stimulus, such as alcohol, with an unpleasant reaction like nausea or shock.
- Alcohol Treatment: The emetic and disulfiram procedures are the best-documented clinical use, with roughly half of patients abstinent at one-year follow-up in early trials.
- Weak Evidence: A systematic review of the similar aversive-smoking literature found most supporting studies too methodologically flawed to trust.
- Ethical History: Clinicians once used electric-shock aversion to try to change gay men and women’s sexual orientation, a practice now recognised as ineffective and harmful.
- Clinical Decline: Poor generalisation to daily life, the instructional deficit of punishment-only learning, and ethical concerns have made aversion therapy a last resort today.
How it Works
Aversion therapy pairs the stimulus that can cause deviant behavior (such as an alcoholic drink or cigarette) with some unpleasant (aversive) stimulus, such as an electric shock or nausea-inducing drug.
With repeated presentations, the two stimuli become associated, and the person develops an aversion towards the stimuli which initially caused the deviant behavior.
Aversion therapy is based on classical conditioning. According to learning theory, two stimuli become associated when they frequently occur together (pairing).
An unconditioned stimulus, such as an emetic drug, automatically produces an unconditioned response such as nausea, with no learning required.
Alcohol then becomes a conditioned stimulus. After enough repeated pairings, alcohol alone triggers the same nausea as a conditioned response, even without the drug present.
For example, in addiction, the drug, alcohol, or behavior in the case of gambling becomes associated with pleasure and high arousal.
Aversion therapy uses the same principle but changes the association and replaces the pleasure with an unpleasant state (counterconditioning).
Biological Basis: The Garcia Effect
Alcohol aversion therapy also works because of a well-documented piece of biology called conditioned taste aversion, or the Garcia effect.
Garcia and Koelling (1966) found that animals learn a taste-illness pairing far more readily than other pairings, such as a taste with a light or sound. One pairing can be enough.
Rats learned to avoid a taste that made them sick after a single pairing, even with a long delay before the illness began.
This rapid learning system evolved to stop an animal repeating a dangerous poisoning. It helps explain why the alcohol/emetic procedure conditions efficiently.
But the resulting aversion stays tied mainly to taste and smell, not the wider behaviour of drinking.
Examples
Alcoholism
Aversion therapy has been used in the treatment of alcoholism for decades, though reviews of the evidence have reached cautious conclusions (Davidson, 1974; Elkins, 1991).
Patients are given an aversive drug, which causes vomiting-emetic drug.
They start experiencing nausea; at this point, they are given a drink smelling strongly of alcohol, and they start vomiting almost immediately. The treatment is repeated with a higher dose of the drug.
Another treatment involves the use of disulfiram (e.g., Antabuse). This drug interferes with the metabolism of alcohol.
Normally, alcohol is broken down into acetaldehyde and then into acetic acid (vinegar).
Disulfiram prevents the second stage from occurring, leading to a very high level of acetaldehyde which is the main component of hangovers.
This results in severe throbbing headaches, increased heart rate, palpitations, nausea, and vomiting.
Disulfiram works differently. It only works while a patient keeps taking it, so its value lies mainly in ongoing compliance, not one-off conditioning.
Krampe et al. (2006) followed 180 alcohol-dependent patients for up to seven years. The more consistently they took a deterrent such as disulfiram, the better their drinking outcomes.
Gambling addiction
For behavioral addiction, such as gambling, aversion therapy involves associating such stimuli and behavior with a very unpleasant unconditioned stimulus, such as an electric shock.
These shocks are painful but do not cause damage.
The gambler creates cue cards with key phrases they associate with their gambling and then similar cards for neutral statements.
As they read through the statements, they administer a two-second electric shock for each gambling-related statement.
The patient set the intensity of the shock themselves, aiming to make the shock painful but distressing.
The client then associates the behavior with the shock. A conditioned link replaces the original urge.
Covert Sensitization
Covert sensitization is a variation where the unpleasant consequence occurs entirely within the client’s imagination. Joseph Cautela developed the technique in 1967.
This is used for behavioral excesses like gambling, overeating, or sexual deviations.
The therapist directs the client to visualize themselves engaging in the target habit.
Simultaneously, the client imagines a repulsive event, such as becoming violently nauseous or facing public ridicule.
This mental “punisher” can eventually translate into real-world behavior change without the need for physical pain.
The Unethical Use Against Homosexuality
Aversion therapy also has a documented history of use against homosexuality. Clinicians used the same electric-shock methods described above in an attempt to change a person’s sexual orientation.
This is now recognised as one of the clearest cases of psychology being used to enforce prejudice rather than treat genuine illness.
MacCulloch and Feldman (1967)
- Aim: To evaluate anticipatory-avoidance electric aversion therapy in gay men who had sought treatment to change their sexual orientation.
- Method: 43 gay men were shown a slide of an attractive man and had eight seconds to switch it off before receiving an electric shock.
- Results: About 58% of patients showed improvement, defined by the researchers as a shift toward heterosexual responsiveness, though the change varied in size and durability.
- Conclusion: The authors presented this method as more effective at changing homosexual behaviour than earlier, simpler aversion techniques.
This outcome measure was defined entirely by the clinicians, not by patients’ own wellbeing, and there was no untreated comparison group to judge the result against.
Later critiques found the weakest results among men who reported no heterosexual arousal to begin with. Its apparent successes were concentrated exactly where change was least likely.
Why This Is Recognised as an Ethical Failure
Davison (1976) argued that treatments like this could never rest on free, uncoerced consent.
Gay men and women faced intense social and family pressure to become heterosexual, so a patient’s request for treatment was not straightforward evidence of free choice. This logic still applies today.
Davison also argued that research effort spent on eliminating same-sex feelings was itself a value judgement, not a neutral scientific choice.
Decades later, Bartlett, Smith and King (2009) surveyed UK mental-health professionals.
They found that 17% had tried to help a lesbian, gay or bisexual client change their same-sex feelings, despite no credible evidence that this works.
Professional bodies have since reversed position.
Both the Royal College of Psychiatrists and the American Psychological Association now hold that homosexuality is not a disorder. Any resulting distress reflects prejudice and discrimination, not something wrong with the person.
A Survivor’s Account
The writer Garrard Conley has spoken publicly about the conversion-practice tradition this research gave rise to.
Boy Erased, his 2016 memoir, recounts the experience.
At nineteen, after being outed to his conservative Baptist parents, he faced a choice. He could attend a Christian ‘ex-gay’ programme called Love in Action, or lose contact with his family and college funding.
As Conley recalled in a 2021 interview, explaining why he agreed to attend: “I can’t leave my family and I can’t leave this community and the God that I’ve prayed to every day since I was old enough to pray.”
Conley has described the experience as pushing him to the brink of suicide. He has since become a public advocate against conversion practices.
Contemporary Research
The research has moved in two directions since 2015. One strand documents the harm; the other documents recovery.
Tran et al. (2024), publishing in The Lancet Psychiatry, surveyed 4,426 LGBTQ+ adults in the United States. They compared mental-health symptoms between those who did and did not recall exposure to conversion practice.
Depression and PTSD symptoms were more severe among those who recalled exposure. The pattern was stark. Participants targeted over their gender identity reported the highest symptom levels of any group studied.
The study’s authors concluded that conversion practice carries a measurable mental-health burden, regardless of who delivers it or what it targets.
Recovery research is newer. Dromer et al. (2022) interviewed 20 Canadian adults who had experienced these practices, using thematic analysis to identify how they rebuilt their lives afterward.
Three recovery pathways emerged: reconnecting with LGBTQ-affirming community, accessing affirming healthcare providers, and managing relationships with those who had originally pushed the practice on them.
Critical Evaluation
The decline of aversion therapy is due to both ethical problems and practical limitations. Many practitioners now view these methods as outdated or even inhumane.
Limitations and Risks of Punishment
Modern behavioral therapy prioritizes positive reinforcement, which involves providing rewards to strengthen healthy, adaptive behaviors.
Several factors contribute to the decline of punishment-based models:
-
Emotional Side Effects: Aversive stimuli can trigger disabling anxiety, aggression, or a desire to retaliate against the therapist.
-
Relationship Erosion: The use of pain or discomfort fosters deep mistrust and may lead to the dehumanization of the client.
-
Lack of Generalization: These techniques are often impractical to implement in a client’s natural, day-to-day environment.
-
Instructional Deficit: Punishment only teaches a person what not to do. It fails to guide them toward better, healthier alternatives.
Ethical Issues and Compliance
Clinicians have largely abandoned physical aversion methods due to equivocal effectiveness, meaning the results are inconsistent or uncertain.
Furthermore, these techniques often produce severe negative side effects.
Using such methods can lead to the dehumanization of the client, where the individual is treated more like an object than a person.
Other significant risks include:
-
Increased aggression in the patient.
-
Development of fear or mistrust toward the therapist.
-
Extreme difficulty applying these methods in real-world settings.
Ethical Guidelines for Use
Because the research base supporting positive punishment procedures is highly limited and largely restricted to a small number of behavior domains, contemporary ethical guidelines strictly govern their use.
If an aversive procedure is ever to be considered in an applied setting, it must only be used if:
-
Functional Assessment: A rigorous analysis must identify the specific variables maintaining the problem behavior.
-
Exhaustion of Alternatives: Clinicians must first attempt less restrictive procedures, such as negative punishment (removing a pleasant stimulus) or positive reinforcement.
-
Specialized Training: The practitioner must have specific, expert training in aversive protocols.
-
Oversight: A review panel must provide supervision. If monitoring shows the treatment is ineffective, it must be discontinued immediately.
Punishment-based models only inform individuals about what not to do; they do not guide them toward what they should do instead. Because of this instructional deficit, they are viewed as a last resort in modern clinical practice
Generalization and Relapse
A significant hurdle is the lack of generalization, which is the ability of a learned behavior to transfer from the clinic to the real world. The fear is context-specific.
A patient may avoid alcohol in a room where they expect a shock. However, they know that drinks at a local pub will not trigger an electric current.
Consequently, relapse rates are high once the patient leaves the controlled environment of the therapist’s office.
The Holistic Deficit
Aversion therapy is often criticized for being reductionist, meaning it simplifies a complex problem into a basic stimulus-response loop.
It treats the outward behavior but ignores the underlying etiology, or the root cause of the addiction. The symptom fades; the cause remains.
If a person drinks to cope with trauma or anxiety, removing the urge to drink through fear does not solve the initial distress.
A more holistic approach targeting biological, cognitive, and social factors is usually necessary for lasting recovery.
Comparison with Alternative Treatments
Aversion therapy has been largely replaced by approaches that do not rely on inducing pain or sickness.
Exposure-based methods are one example. For phobias and anxiety, treatments such as systematic desensitisation gradually build tolerance to a feared stimulus instead of attaching a new unpleasant reaction to it.
For addictive behaviour specifically, cognitive behavioral therapy has become the dominant approach. It teaches patients what to do differently, not just what to stop doing.
Pharmacological options also exist. Streeton and Whelan (2001) meta-analysed randomized controlled trials of naltrexone for alcohol dependence.
They found it reduced relapse to heavy drinking compared with placebo, by blunting alcohol’s rewarding effects rather than conditioning an aversive reaction to it.
Empirical Validation of Aversion Therapy
Research into the effectiveness of these methods provides mixed results. While some early studies showed promise, modern reviews are more skeptical.
Meyer and Chesser (1970)
-
Aim: To investigate the long-term abstinence rates of alcoholics undergoing aversion therapy.
-
Procedure: Researchers tracked a group of patients who received aversive conditioning for alcohol addiction over one year.
-
Findings: The study found that 50% of the participants remained abstinent for at least twelve months.
-
Conclusions: Aversion therapy can be more effective than no treatment at all for certain individuals.
Hajek and Stead (2001)
Aversive conditioning for smoking often involved electric shocks or a technique known as rapid smoking. In rapid smoking, a client takes a puff every few seconds to induce dizziness and nausea.
-
Aim: To evaluate the overall quality of evidence supporting aversion therapy for smoking cessation.
-
Procedure: The researchers conducted a systematic review of twenty-five separate studies on aversive methods.
-
Findings: They discovered that twenty-four of the twenty-five studies contained significant methodological flaws.
-
Conclusions: The current evidence is insufficient to prove that these methods promote long-term abstinence.
References
Davidson, W. S. (1974). Studies of aversive conditioning for alcoholics: A critical review of theory and research methodology. Psychological Bulletin, 81 (9), 571.
Elkins, R. L. (1991). An appraisal of chemical aversion (emetic therapy) approaches to alcoholism treatment. Behavior research and therapy, 29 (5), 387-413.
Hajek, P., & Stead, L. F. (2001). Aversive smoking interventions for smoking cessation. Cochrane Database of Systematic Reviews, (3).
Krampe, H., Stawicki, S., Wagner, T., Bartels, C., Aust, C., Rüther, E., … & Ehrenreich, H. (2006). Follow-up of 180 alcoholic patients for up to 7 years: Combined Antabuse treatment of alcoholism (CATA). Psychopharmacology, 187(1), 115-127.
Meyer, V., & Chesser, E. S. (1970). Behaviour therapy in clinical psychiatry. Penguin.
Skinner, B. F. (1953). Science and human behavior. Simon and Schuster.
Streeton, C., & Whelan, G. (2001). Naltrexone, a relapse prevention maintenance treatment of alcohol dependence: a meta-analysis of randomized controlled trials. Alcohol and Alcoholism, 36 (6), 544-552.
