If your right ear burns, someone is talking good about you. If your left ear burns, someone is talking ill of you.
This is one of the hundreds of superstitions that Fletcher Dresslar records in his 1907 book, Superstition and Education. He elicited them from students in California simply by handing out blank pieces of paper and asking them to write down all the superstitions they could think of. Dresslar describes his project as "an attempt to peep into that darkly veiled but interesting mental realm which holds the best preserved remnants of our psychic evolution" (pg. 2).
In taking stock of his colorful catalogue, Dresslar couldn't help but notice some patterns. For one, those superstitions that mentioned the left side of the body—whether the ear, foot, or hand—tended to be dark and foreboding; the ones mentioning the right side were downright cheery. The quantitative data he reports show this asymmetry quite clearly:
The percentages of superstitions mentioning left (n= 275) or right (n= 274) sides of the body that foretell bad or good fortune. Data from Dresslar (1907).
Dresslar attributes this pronounced pattern to "a well developed bias of mind, though for the most part an unconscious one" (pg. 205). His explanation, now more than a century old, basically holds up. The bias he describes has recently been studied in some detail, most notably by Daniel Casasanto, and it is rooted in a simple fact: we experience the world more fluently with one side of our body than with the other. This experience of differential fluency gives rise to positive associations with our dominant side—for most of us, the right—and negative associations with our non-dominant side—for most of us, the left.
If such associations are indeed "unconscious," this prompts a question: How do they become enshrined in our superstitions? Part of the answer likely lies in the nature of cultural transmission. As bits of language and belief get passed from person to person, and from one generation to the next, the fidelity is far from perfect. Bits that conform to our cognitive biases will be more likely to be remembered and repeated, while those that don’t will be forgotten or flubbed. Or, as Dresslar puts it: "Other things being equal, those which are best adjusted to the retentive and reproductive powers of the mind will survive longest and come to the surface most frequently" (pg. 209). This kind of explanation is powerful and very much in vogue, and it can be applied to more than just superstitions. Folk tales, proverbs, nursery rhymes, myths, and idioms—all are products of long chains of transmission and all bear the fingerprints of the minds that have passed them on.
Notes
1. With a nod to Rebecca Onion, whose post on Slate is where I learned of Dresslar's book.
2. Permit me to point out that the digitized version of Dresslar's book I link to belonged to William James.
3. Among the other patterns that Dresslar describes is the fact that odd numbers are much more common in superstitions than one would expect by chance (see pgs. 195-204).
4. Another place this "bias of mind" shows up is in the lexicon, as is well documented. Countless languages associate left with notions like “clumsy”, “sinister”, and “untrustworthy” and right with skill, luck, propriety, and so on. For numerous examples and discussion, see 'Biased semantics for right and left in 50 Indo-European and non-Indo-European languages' (abstract).