In psychology, aversives are unpleasantstimuli that induce changes in behavior via negative reinforcement or positive punishment. By applying an aversive immediately before or after a behavior the likelihood of the target behavior occurring in the future is reduced. Aversives can vary from being slightly unpleasant or irritating to physically, psychologically and/or emotionally damaging. It is not the level of unpleasantness or intention that matter, but rather the level of effectiveness the unpleasant event has on changing behavior that defines something as aversive.
Types of stimuli
There are two types of aversive stimuli:
Unconditioned
Unconditioned aversive stimuli naturally result in pain or discomfort and are often associated with biologically harmful or damaging substances or events. Examples include extreme heat or cold, bitter flavors, electric shocks, loud noises and pain. Aversives can be applied naturally or in a contrived manner.
Conditioned
A conditioned aversive stimulus is an initially neutral stimulus that becomes aversive after repeated pairing with an unconditioned aversive stimulus. This type of stimulus would include consequences such as verbal warnings, gestures or even the sight of an individual who is disliked.
Aversives can be used as punishment during applied behavior analysis to reduce unwanted behavior, such as self-injury, that poses a risk of harm greater than that posed by application of the aversive. Aversive stimuli may also be used as negative reinforcement to increase the rate or probability of a behavior by its removal. The use of aversives was developed as a less restrictive alternative to practices prevalent in mental institutions at the time such as shock treatment, hydrotherapy, straitjacketing and frontal lobotomies. Early iterations of the Lovaas technique incorporated aversives during therapy, though the use of aversives in ABA was not without controversy. Over time the use of aversives has become less and less necessary as less and less restrictive alternative treatments have been developed. Lovaas has since stated his disdain for the use of aversives. Applied behavior analysis permits the use of aversives in limited cases, such as when a behavior is dangerous, especially when the reinforcing contingencies that maintain a behavior are unknown. The Behavior Analyst Certification Board Guidelines for Responsible Conduct state that participation in an any behavior plan must be voluntary, by the client or their surrogate, and that clients or families have the right to terminate a particular intervention if they see fit, including aversive treatments. The Behavior Analyst Certification Board issues credentials for behavior analysts nationwide, although state regulations vary as to whether or not a person can represent themselves as a "behavior analyst". The use of aversive treatment is something that practitioners of applied behavior analysis are supposed to take very seriously due to the pain and risks involved and the controversy surrounding their use. Several national and international disability rights groups have spoken against the use of aversive therapies, including TASH and Autism National Committee. Although it has generally fallen out of favor, at least one institution continues uses electric shocks on the skin an aversive. A ruling in 2018 supported its continued use. The FDA has made a commitment to ban its use, but as of January 2019 has not yet done so.
