Bridging psychology and biology with animal research.

407 is the same, however: making sense out of the previously unwanted variance in grouped data by relating it to independent measures of other kinds of individual difference. Once one grasps the point that there are almost always individuals who do not follow the group’s mean trend, a fact that may be the result of hidden but nonrandom determinants, the door is open to many exciting new investigative vistas and the broadening of theory.