Sorry, Monica ("I wish, for once, a study would be done thoroughly, with all that is necessary to avoid confusion and holes"). Doing a thorough study accounting for all variables is something the Psych Dep't at Brown doesn't have the stomach, budget, or math ability for. I worked in the computer center there, and only the Sociologists and Physicists used sophisticated statistics. The psychologists were way too interested in extrapolating what they could "determine" by looking at infants' sucking rates (whoa! they have some cognitive ability! Well, many species' newborns can gallop!) or else being politically correct to "bother" with making their work too close to actual science; there's no profit in that! (Please excuse my rather tortured sentence structure; no time to edit.)