Prepared or not prepared: considerations from the behavioural immune system

Preparedness, an evolved adaptive mechanism, is said to mediate the preferential association of fear relevant stimuli with aversive outcomes. Fear conditioned to snakes, spiders or angry faces is resistant to extinguish relative to fear conditioned to non-fear relevant stimuli. Fear conditioned to other race faces or older faces shows similar resistance to extinction, raising the question of whether this is an instance of prepared learning. Alternatively, other race and older faces could present a biological disease threat which facilitates learning. It was hypothesised that fear conditioned to disease cues would resist extinction. Faces disfigured by a port-wine birthmark were used as disease cues to test this hypothesis. A within-participants differential fear conditioning paradigm was used, in which participants viewed two control and two disfigured faces. One set of faces (control and disfigured) was paired with an electric stimulus (CS+) and the other was not (CS-). Conditioning was readily acquired to both sets of faces and no differences between control and disfigured stimuli were revealed. A follow-up was conducted, priming participants with a disease threat. Results replicated the first study, revealing no differences between faces. The findings suggest disease cues do not mediate fear learning that is resistant to extinction. In the absence of a disease threat the most likely explanation for the findings is that socio-cultural learning about negative out-group stereotypes could result in similar conditioning biases as prepared fear. Implications for the results and future research are discussed