The environment is filled with emotionally significant information. On a walk in a forest, an individual might encounter a friendly dog or a disgruntled bear. In nearly every social interaction, an individual might be confronted with facial, vocal, and postural signs of emotion. Thus, spouses smile, colleagues frown, children pout, babies gurgle, and students tremble with anxiety or giggle with joy. Even computers deliver “just joking” faces by e-mail whereas stores and snacks lure with smiley faces. The importance of such information is now well documented: Emotionally charged objects can capture attention, bias perception, modify memory, and guide judgments and decisions (for an overview, see Eich, Kihlstrom, Bower, Forgas, & Niedenthal, 2000; Winkielman, Knutson, Paulus, & Trujillo, 2007).
Even abstract symbols that refer to emotional events, such as language, can rapidly shape an individual's behavior and trigger physiological responses. For example, most children learn through language rather than direct emotional experience that they should not put their fingers in electrical outlets or stand under a tree in a storm. Such information retains its heat in thought and language, and can be generalized to novel events (Olsson & Phelps, 2004). In adults, simple words like “the next tone will be followed by a shock” elicit a fear reaction (Phelps, O'Connor, Gateby, Grillon, Gore, & Davis, 2001) whereas terms of endearment trigger positive arousal (Harris, Ayçiçegi, & Gleason, 2003).