CHAPTER 7 
Aversive Stimuli 
Aversive stimuli (technically termed negative reinforcers) are, by definition, those that an 
organism will avoid or escape. One can evaluate empirically whether a particular stimulus 
(e.g., an electric shock, a loud noise, a cold environment) will serve as a negative reinforcer by 
presenting it and determining whether a laboratory animal will learn a response that prevents 
it, terminates it, diminishes its intensity, or decreases its frequency of occurrence. Stimuli that 
function as negative reinforcers for some individual species are not aversive for others. The 
same is true, of course, for positive reinforcers. As with positive reinforcers, however, it has 
been determined that some stimuli will function reliably as negative reinforcers across a wide 
range of conditions for most organisms. Electric shock is such a stimulus, which partially 
accounts for the prevalence of its use as an aversive stimulus in behavioral research. Other 
aversive stimuli might be critical in some areas of research, such as studies of pain. 
Behavioral studies that use aversive stimuli fall into several broad categories. There are those 
that examine aversively motivated instrumental behavior, such as avoidance, escape, and 
punished responding. Classical fear conditioning is one of the most commonly used 
behavioral paradigms in which aversive stimuli are employed. In fear conditioning, the 
aversive stimulus, usually footshock, is paired with some neutral event, and as a result the 
neutral stimulus acquires the ability to elicit emotional behaviors and physiological 
adjustments that typically occur in the presence of stimuli that cause harm or predict danger. 
Because these responses are hard-wired, they result in species-typical expressions. Fear 
conditioning is often said to be stimulus rather than response learning (i.e., the means by 
which humans and other animals learn about novel dangers). Other researchers focus on 
pain, while some study aversive conditions commonly referred to as "stress." 
AVERSIVELY MOTIVATED BEHAVIOR 
Many different stimuli have been used to study aversively motivated behavior, such as 
deviations from ambient temperature (Carlisle and Stock, 1993; Gordon et al., 1998), a puff of 
air under pressure (Berger and Thompson, 1978; Welsh et al., 1998), a novel cage or an 
unfamiliar animal (Gould et al., 1998; Miczek, 1979; Miczek and O'Donnell, 1978; Weninger 
et al., 1999), strong visual or auditory stimuli (Crofton, 1992), restraint, and electric shock 
(Honig, 1966). Systematic manipulation of an aversive stimulus permits the establishment of 
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