Work by McClenon examined if theories based on evolution would be verified by collecting a large community sample. The researcher examined specific expectations about survival and adaptability based on beliefs in the paranormal. These theories are referred to in this paper as “sheep”, “goat”, and “black sheep” in relation to these evolutionary tests.
The sheep theory claims that believers in the paranormal are mentally ill, but the benefits of hallucination or belief provide advantages in coping or in placebo effects for healing. The goat theory claims that paranormal belief is associated with primarily negative psychological and health for individuals and is not adaptive. The black sheep theory mixes the two and claims that despite disadvantages, paranormal belief can facilitate coping and positive outcomes.
In order to test these theories in the community, McClenon had participants answer many scales about mental functioning, paranormal belief and experience, and health and analyzed them to see what measures related most closely to each other. The results did support a relationship between types of mental illness and paranormal experiences (goat) but also showed that some psychological tendencies were associated with visions and possible healing (sheep). McClennon concludes that evidence for all three theories was present, but comments that evolutionary and biological research in this domain is limited.
McClennon, J. (2013). A community survey of anomalous experiences: Correlational analysis of evolutionary hypothesis. Journal of Parapsychology, 77, 55-78.