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Biological Preparedness

By Charlotte Nickerson, published Nov 08, 2021

Key Takeaways

  • Biological preparedness postulates that organisms are evolutionarily predisposed to developing associations between certain stimuli and responses. For example, people can be more predisposed to fearing things (such as heights or snakes) which have historically presented a mortal threat to humans.
  • Martin Seligman proposed preparedness theory as a way of explaining fears and phobias as providing an evolutionary advantage and therefore be passed on by natural selection. Although biological preparedness spawned from research examining fear, researchers have since used the theory to explain phenomena ranging from taste aversion to industrial design.
  • Following criticism of the original preparedness theory experiments, theorists have created several theories which attempt to explain how people form fears around stimuli that did not historically threaten humans.

Definition and Background

Biological preparedness is the idea that organisms are biologically predisposed to quickly learning associations between stimuli, responses, and reinforcers (Seligman, 1971).

This quick learning can be explained by an organism’s fit with genetic traits that evolved to increase the species’s chances of survival. For example, people may be averse to certain foods associated with gastrointestinal illness — such as rotting meat — even if they have never eaten them before.

Seligman suggests that humans have a biological preparedness to develop certain phobias rather than others, because they were adaptive (i.e. helpful) in our evolutionary past. For example, individuals that avoided snakes and high places would be more likely to survive long enough and pass on their genes than those who did not.

Seligman's Preparedness theory is one of the most influential ideas in explaining the existence of particular phobias (Åhs et. al, 2018).

Martin E. P. Seligman (1971) proposed the preparedness theory of fears and phobias. Seligmana’s article, Phobias and Preparedness, represented a break from traditional conditioning theories of fear and inspired a line of research integrating evolutionary theory with learning theory which continues to this day (McNally, 2015).

This research has spawned adjacent theories of selective sensitization, expectancy, and nonassociative theories.

Seligman trained as an experimental psychologist specializing in animal learning and motivation, however, he soon acquired clinical training which expanded his reach to psychopathology.

Perhaps his best-known contributions are the learned helplessness theory of depression (Seligman, 1975) and his work in the field of positive psychology (Seligman and Csikszentmihalyi, 2000).

Seligman used preparedness theory to make phenomena that traditional conditioning theories could not explain or test testable (McNally, 2015). Prior to Seligman’s work, there was a growing emphasis on phylogenetics — the study of evolutionary relationships between species — in learning and conditioning research.

In particular, John Garcia’s taste aversion research found that rats rapidly learn to avoid sweetened water when its ingestion is accompanied by radiation-induced gastric district, but not with a foodstock.

Indeed, Garcia and Koelling (1967) used “natural selection” to explain why taste cues could be easily associated with gastrointestinal distress, while audiovisual cues were more likely to be associated with footshock-induced pain (McNally, 2015).

Seligman would adopt Garcia and Koelling’s evolutionary invocation to argue that evolution shapes organisms’ propensity for learning certain behaviors over others.

Seligman’s article would go on to have a major impact in anxiety disorders, and in the years following Seligman’s publication, laboratory experiments testing preparedness theory began to appear.

Biological Preparedness Working With Classical Conditioning

The most prominent psychophysiologist to experiment with preparedness theory was the Swede Arne Öhnman. Öhnman conducted a series of classical conditioning experiences where he attempted to facilitate participants in learning and unlearning fears associated with colored photographs of stimuli which Öhnman believed people would be biologically prepared to acquire fear-eliciting properties to.

For example, snakes, spiders, and men with angry facial expressions. Öhnman showed one group of people a series of fear-relevant stimuli, and another group fear-irrelevant stimuli, such as pictures of flowers or circles and triangles.

At random, he assigned one picture category so that participants would receive an “uncomfortable, but not painful” electric shock whenever they saw it (McNally, 2015).

Öhnman associated increased skin conductivity as increased fear, as it reflects sweating in the palm of the hand. Öhnman found that, while people acquired fears of the non-fear stimulating and fear-stimulating photos at a similar rate, fear of the fear-stimulating photos persisted long after each set of photos was no longer associated with an electric shock.

In fact, even when the researchers instructed participants that no further shocks would happen and physically removed the shock electrodes, fears of the fear-relevant images still persisted.

Åhs etc. al. (2018) conducted a systematic review of 32 fear conditioning experiments. In these experiments, researchers attempted to decondition participants’ fear of spiders and snakes through showing them a series of pictures. 22 of these 32 experiments were able to decondition the fear of spiders, which Åhs et. al. argues weakens preparedness theory as an explanation for fear.

Other studies have shown that instructions can quickly diminish fear-responses to fear-relevant stimuli (Dawson, Schell, and Tweddle-Banis, 1986), and others have failed to replicate the resistance to fear deconditioning described in Ohman’s original study (McNally and Foa, 1986).

Studies such as McNally and Reiss (1982) have also shown that people can be conditioned to believe that fear-related stimuli are non-shock safety signals just as easily as they can with non fear-related stimuli.

All in all, studies have shown deeply ambivalent empirical support for preparedness theory. Scholars have also questioned how Seligman (1971) interpreted phobias.

For example, noting that rather than having acquired fears through Pavlovian conditioning, many people have recounted having feared stimuli, such as snakes, for as long as they can remember.

Rather than remembering experiencing active harm from the stimulus — such as being bitten by a snake — those who cannot remember the onset of their fear report experiencing intense fear when encountering the stimulus.

In addition, researchers have questioned why some people develop fears, but not others. For example, dog bites and falls from high places occur as frequently in the pasts of those who do not have intense fears of dogs and heights and those that do (Di Nardo et. al, 1988; Menzies and Parker, 2001).

There have also been questions about the origins of fears related to modern technology, for example, whether or not the fear of flying on airplanes originates from a biologically prepared height phobia or contemporary society (McNally and Louro, 1992).

Critical Evaluation

Jeffrey Gray (1987) wrote a notable critique of preparedness and Öhnman’s experiments. This critique had three main points:

  • That the slower deconditioning to fearing fear-related stimuli that Ohman demonstrated was a result of participants being better able to discriminate between fear-related stimuli that provided or did not provide shocks than non-fear related stimuli.
  • Gray argued that the preparedness effect would actually entail that there would be larger responses overall to fear-related stimuli that provided shocks than those irrelevant to fear.
  • Secondly, Gray argued, the participants in Ohman’s experiment did not necessarily have a heightened fear response, but were better able to orient themselves according to the fear-related pictures.
  • Lastly, Gray cited research where participants experienced greater fear responses to fear-relevant stimuli than non-relevant stimuli when they were told that they may receive shocks that never occurred (Öhnman et. al., 1974). From this, Gray hypothesized that Ohman’s experiments did not test Pavlovian conditioning but selective sensitization to fear cues. Lovibond, Siddle and Bond’s (1993) experiment subsequently bolstered this supposed selective sensitization effect (McNally, 2015).

Expectancy Theory, Nonassociative Theory, and Covariation Bias

Following Gray’s critique, scientists pivoted their focus from the role of Pavlovian conditioning in fear formation to theories consistent with Grey's selective sensitization. The three most notable of these pilots were expectancy theory, nonassociative theory, and covariation bias.

Expectancy theory, as formulated by Davey (1992) holds that ontogenetic, or cultural factors, shape expectations of which stimuli are likely to be associated with adverse events (such as shocks) in the laboratory.

Consistent with biological preparedness, snakes and spiders incited larger fear responses than, say, flowers. However, guns only elicited a higher fear response when the picture showed it pointed at the participant.

Essentially, Davey’s work argues, both evolution and social expectations play into how people develop fear responses (McNally, 2015).

Nonassociative theory, meanwhile, maintains an emphasis on evolution (Menzies and Clarke, 1995). According to nonassociative theory, people respond, particularly during childhood, to different stimuli with different amounts of fear depending on the threats that these stimuli have provided throughout history (for example, snakes and heights) (McNally, 2015).

These fears are nonassociative in that they do not require painful experiences with stimuli. Meenzies and other theorists claimed that nonassociation is one of four ways that people develop fears.

The others are Pavlovian conditioning, observational learning, and verbal transmission of threatening information (Rachman, 1977). Lastly, covariation bias sprung out of researchers such as Tomarken, Mineka and Cook, who found that people were more likely to associate pictures of common fear stimuli with negative outcomes in the lab.

However, a further study showed that this only seemed to apply to phylogenetic (evolutionarily-backed) fear-stimuli, and not ontogenetic (man-made) stimuli (Tomarken, Sutton, and Mineka, 1995).


One of the most notable lines of research in biological preparedness is taste aversion. Biological preparedness argues that organisms are more likely to become averse with foods traditionally associated with sickness and gastrointestinal distress.

Besides Garcia and Knoelling’s (1966) study on how sweetened water inspired taste aversion in rats when paired with radiation-induced gastrointestinal distress, other researchers have researched the effect.

For example, Bernstein and Webster (1980) examined learned taste aversion in humans. The researchers exposed adults receiving chemotherapy to one of two distinct, novelty flavored ice creams and found that these participants favored the ice cream flavor they received far less than the other in subsequent experiments.

Previously, Bernstein had conducted a similar experiment in children receiving a treatment that would induce nausea and vomiting (1982). Bernstein and Webster explained this phenomenon along evolutionary lines.

Purucker, Sprott, and Herrmann (2014) elicited biological preparedness in investigating how participants reacted to the design of car fronts. The researchers showed participants pictures of car fronts designed to appear anthropomorphically threatening (such as those resembling an angry human face) and measured responses through eye-tracking.

Ultimately, the researchers found that automotive stimuli both elicited self-reported affective responses and led to automatic responses “explained by evolutionary theory.”

In line with the so-called “threat advantage effect,” for example, the researchers showed that threateningly designed cars initially drew the attention of participants but tended to be ignored over time.

About the Author

Charlotte Nickerson is a student at Harvard University. Coming from a research background in biology and archeology, Charlotte currently studies how digital and physical space shapes human beliefs, norms, and behaviors and how this can be used to create businesses with greater social impact.

How to reference this article:

Nickerson, C. (2021, Nov 08). Biological Preparedness. Simply Psychology.


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