How do you feel today? The effect of mood on language processing

Many aspects of cognition, such as memory retrieval, decision-making, and the use of stereotypes, have been found to be sensitive to mood, the diffuse, objectless affective state the person is in (Clore & Huntsinger, 2007). Although the exact mechanisms are hotly debated, the evidence suggests that people in a happy mood are more inclined to rely on heuristic processing strategies than people in a sad mood. Here we investigate whether mood also affects the use of heuristics (or 'educated guesses') to anticipate upcoming language as a sentence unfolds. If it does, this would show that language processing -- a classic example of 'cold' cognitive computation -- is not immune to affective variables. In constructions like "David praised Linda because...", verbs like "praise" heuristically lead readers to expect more information about the person who is praised (in this case, Linda), not the person praising. This so-called implicit causality bias can be so strong that gender-marked pronouns that subsequently disconfirm the expectation -- "he" in "David praised Linda because he..." -- actually elicit a P600 effect in ERPs (Van Berkum et al., 2007), indicating that such pronouns are briefly taken to be problematic. We reasoned that if people process information more heuristically in a happy mood than in a sad mood, and if such mood-dependent shifts in processing strategy can also affect the mechanism involved in language comprehension, a change in mood should modulate the size of this heuristics-based P600 effect. In a two-session EEG experiment, we used short film clips to manipulate the mood of participants just before they read short stories in which verb-based expectations were sometimes confirmed or disconfirmed with a gender-marked pronoun. When readers were in a happy mood, bias-inconsistent pronouns elicited a P600 effect, as in the abovementioned ERP study. However, when the same readers were in a sad mood, no such P600 effect was observed. Importantly, standard morpho-syntactic subject-verb agreement violations (e.g., "The boys was…") elicited a P600 effect in either mood. Our findings support the general idea that mood modulates the degree of heuristic processing, and they reveal that such mood effects also percolate into basic language comprehension mechanisms. A change in mood has selective consequences for language processing: whereas heuristics-based conceptual anticipation can be abolished in a sad mood, more algorithmic syntactic parsing mechanisms continue to do their job