The birthdate effect: an extension of the Mere Ownership Effect.

Studies have shown that attributes or variables associated with oneself are liked or preferred more compared to similar attributes unrelated to the self. Nuttin found in 1985 that people tend to prefer the letters that occur in their own names more than the letters that do not occur in their names. This name-letter-effect was later explained as a more general "mere ownership effect." The present purpose was to test whether the Mere Ownership Effect generalizes to a person's evaluation of their birthdate (month and year). 83 participants evaluated a variety of dates and objects. As expected, participants showed a significantly more positive evaluation of their own birth month and year than to their nonbirth months and years.