Magical Contagion (Law of Contagion)

Characteristics of Contagion

Magical contagion is the belief that contact transfers an essence from a person or object to something else. The following features are illustrated mainly through historical studies of American participants’ reactions to objects associated with people with AIDS. Participants sometimes treated an object, or even a former home, as negatively marked by that association (Nemeroff, Brinkman, & Woodward, 1994; Rozin, Markwith, & Nemeroff, 1992). These findings concern perceived contamination and stigma, not evidence that such contact transmits HIV.

Physical Contact Is Critical

In magical contagion, actual physical contact (as opposed to mere proximity) – whether direct or indirect – is critical in accomplishing transmission of essence. People are more concerned about wearing a sweater that had been worn but was not owned by someone with AIDS (and then washed) than about a sweater owned but never worn by someone with AIDS (Nemeroff et al., 1994; Rozin et al., 1992). A cockroach that runs near one’s plate is not nearly as contaminating as one that runs over one’s food.

Once in Contact, Always in Contact

A core feature of the law of contagion is that once joined through direct or indirect physical contact, a transfer of essence occurs that is often permanent; hence “once in contact, always in contact.” Consider a bowl of mashed potatoes that a cockroach briefly runs across. After 1 year in a freezer, someone who remembers the contact may still regard the potatoes as inedible. With respect to AIDS, 92% of the negative 1-day effect remains after 1 year. Similar results are obtained with a piece of silverware that had been used 1 day or 1 year ago by someone with AIDS (Nemeroff et al., 1994; Rozin et al., 1992).

The Holographic or Metonymic Nature of Essence

All of the properties of the source pervade the entire source and are contained in its essence. Magical contagion is “holographic” in the metonymic sense of the whole being equivalent to the part (“the part equals the whole”). As a result, contact with any part of the source transfers essence, including fingernail parings or a lock of hair. Within this belief, Hitler’s fingernails can seem as contaminating as his brains. This property, which can be called route insensitivity, is illustrated by the fact that 43% of subjects reported that there was no place at all on the body of a person with AIDS (including elbow and lock of hair) that they would feel as comfortable touching as the corresponding place on the body of a healthy stranger (Nemeroff et al., 1994).

Dose Insensitivity

Minimal contact is usually sufficient to transmit near maximal amounts of essence. A sweater worn for 5 minutes by a person with AIDS (and then washed) yields a drop in desirability that is 71% of the effect of use for 1 full year; similar results hold for a fork vehicle (Rozin et al., 1992). We have also found that, in the view of 68% of our subjects, the relationship between their perceived probability of developing AIDS and the number of HIV particles entering the body is flat (dose independence). According to these subjects, a single HIV particle that enters the body has a potency of infection (measured as probability of induction of AIDS) that is the same as 10,000 or 1,000,000 viruses (Nemeroff, Brinkman, & Woodward, 1994). Depending on the way the holographic principle is construed, one might consider dose insensitivity a consequence of the holographic nature of essence. Even a fraction of a hologram contains information sufficient to recreate the whole image.

Negativity Bias

We argued for a general principle, applying across many human domains, that negative effects are stronger than positive effects; we call this general phenomenon negativity bias (Rozin & Royzman, 2001; see also Baumeister, Bratslavsky, Finkenauer, & Vohs, 2000). In one manifestation of negativity bias, which we call negativity potency (related to loss aversion), negative events are more negative than corresponding positive events are positive. This principle is illustrated with particular clarity in the domain of contagion. There is no positive entity that is as strongly positive as a cockroach, poison, or Hitler is negative. That is, contact with a butterfly, vitamin, or Mother Teresa does not produce positive effects as strong or reliable as the negative effects produced by the previously mentioned negative entities (Nemeroff & Rozin, 1994; Rozin, Nemeroff, Wane, & Sherrod, 1989). Furthermore, in what we describe as negativity dominance, combinations of contact with negative and positive entities (e.g., touching the target with a cockroach and an antibiotic or a valued object; touching of the target by a disliked and a liked person) result in a net effect more negative than would be expected from the sum of the negativity and positivity of the sources (Rozin et al., 1989; Rozin & Royzman, 2001).

The cited ethnographic reports describe a similar asymmetry. Meigs’s account of the Hua of Papua New Guinea (Meigs, 1984) includes many beliefs in positive contagion but describes negative contagion as stronger. Reports of Hindu caste practices describe contact with a lower caste as regarded as polluting, without an equivalent purifying effect from contact with a higher caste. These are accounts of social beliefs, related to Stevenson’s (1954, p. 50) claim that “pollution overcomes purity” (see also Appadurai, 1981). In studies of American undergraduates and a general sample of American adults, although almost everyone showed negative contagion effects, only about one-third showed positive contagion effects (Rozin et al., 1989, Nemeroff & Rozin, 1994).

A Wide Range of Properties of the Source Are Potentially Contagious

Questionnaire (e.g., Rozin et al. 1986, Rozin et al., 1989; Nemeroff & Rozin, 1994), laboratory (Rozin et al., 1986, 1999) and ethnographic data (e.g., Meigs, 1984) indicate that physical attributes (e.g., size, growth rate, color, illness), abilities (strength, coordination, visual acuity), dispositions (personality characteristics), and moral qualities are believed to be subject to transmission by contact. Intentions may also be thought to be transmitted in the sense that contact with a source person who has a harmful intent toward the target can bring bad luck to the target.

Backwards Action

In what has been described up to this point, influence flows from a contagious source to a recipient in much the same way that germs are transmitted from one individual to another. Backward contagion reverses the causal arrow, and challenges the normal sense of causation. Thus, in traditional magic, a target is believed able to harm a source by burning a lock of the source’s hair or fingernail parings, or to attract a source by placing these items in a love potion. We obtained substantial evidence for such backward contagion in American college students. A substantial number (approximately one-third, but not the virtual unanimity of response we get for forward contagion) were uncomfortable about the prospect that their hairbrush or a lock of their hair (neither to be seen again) came into the possession of a personal enemy (Rozin et al., 1989). The reluctance of many Americans to donate blood since the beginning of the AIDS epidemic might conceivably be accounted for by backward contagion.

We envision two types of explanation of backward contagion: One is that the same types of transferred essence analysis holds in both types of contagion. On this view, backward contagion would require an additional assumption: that essence remains unitary in contact, even when physically separated. Thus, the essence in the cut lock of hair remains forever connected with its source, allowing action on the hair to affect its source. Alternatively, it is possible that an important component of contagion is mere association, in time or space, between target and source. In forward contagion, this association is supplemented by the forward transmission of essence by contact. However, in backward contagion, it could just be the association. This would account for the fact that backward contagion is weaker and less frequent than forward contagion, but leaves many questions unanswered. One, of course, is why contact is so important in backward contagion?