The theory that physiological and emotional changes occur simultaneously in response to a stimulus (as opposed to the earlier James-Lange theory).

Example: A woman is hiking in the forest when she stumbles upon a bear. All at once, she starts sweating, trembling, and feeling extremely afraid.

I think this link explains the theory in the greatest detail, It has diagrams  to illustrate the main idea such as this one:  http://en.academic.ru/dic.nsf/enwiki/1716266

STIMULUS (Bear) –> EMOTION (Fear) –> REACTION/RESPONSE (Run Away)

    Last reviewed: By John M. Grohol, Psy.D. on 6 Aug 2010