An odd effect: lengthened reaction times for judgments about odd digits.

Eight experiments are reported that first establish and then explicate a serendipitous finding that judgments about whether digits are odd or even take longer for odd than for even digits. The slowing of judgments about odd digits is more pronounced when digit pairs or triples are used, but is still weakly present when a single digit must be classified. A similar effect is seen when judgments of nouns are based on whether the nouns are the names of living or dead objects. Nouns that name dead objects are judged more slowly than ones that name living objects. The concept "alive" is linguistically marked. Past research has shown that unmarked concepts are processed more rapidly than marked ones. The similarity in the pattern of results when digits and words are judged is used to argue that the slower judgments about odd digits are due to the fact that "odd" is a linguistically marked and "even" a linguistically unmarked concept.