This post was updated Oct. 19 at 7:30 p.m. Cady Heron from “Mean Girls” famously said that in “girl world,” Halloween is the one night a year when girls can dress in sexy costumes and no other girls ...

Extrinsic motivation is motivation that come from outside oneself. Examples include doing something for financial gain, promotion, praise or approval, or to win a competition. Depending on the ...