Date of Award

Winter 12-18-2013

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Psychology

First Advisor

Gwen Frishkoff, Ph.D.

Second Advisor

Tricia King, Ph.D.

Third Advisor

Erin Tone, Ph.D.

Fourth Advisor

David Washburn. Ph.D.

Fifth Advisor

Michael Owren, Ph.D.

Abstract

Laughter is a socioemotional cue that is characteristically positive and historically served to facilitate social bonding. Like other communicative gestures (e.g., facial expressions, groans, sighs), however, the interpretation of laughter is no longer bound to a particular affective state. Thus, an important question is how basic psychological mechanisms, such as early sensory arousal, emotion evaluation, and meaning representation, contribute to the interpretation of laughter in different contexts. A related question is how brain dynamic processes reflect these different aspects of laughter comprehension.

The present study addressed these questions using event-related potentials (ERP) to examine laughter comprehension within a cross-modal priming paradigm. Target stimuli were visually presented words, which were preceded by either laughs or environmental sounds (500 ms versions of the International Affective Digitized Sounds, IADS). The study addressed four questions: (1) Does emotion priming lead to N400 effects? (2) Do positive and negative sounds elicit different neurocognitive responses? (3) Are there laughter-specific ERPs? (4) Can laughter priming of good and bad concepts be reversed under social anxiety? Four experiments were conducted. In all four experiments, participants were asked to make speeded judgments about the valence of the target words. Experiments 1-3 examined behavioral effects of emotion priming using variations on this paradigm. In Experiment 4, participants performed the task while their electroencephalographic (EEG) data were recorded. After six experimental blocks, a mood manipulation was administered to activate negative responses to laughter. The task was then repeated.

Accuracy and reaction time showed a small but significant priming effect across studies. Surprisingly, N400 effects of emotion priming were absent. Instead, there was a later (~400–600 ms) effect over orbitofrontal electrodes (orbitofrontal priming effect, OPE). Valence-specific effects were observed in the early posterior negativity (EPN, ~275 ms) and in the late positive potential (LPP, ~600 ms). Laughter-specific effects were observed over orbitofrontal sites beginning approximately 200 ms after target onset. Finally, the OPE was observed for laughs before and after the mood manipulation. The direction of priming did not reverse, contrary to hypothesis. Interestingly, the OPE was observed for IADS only prior to the mood manipulation, providing some evidence for laughter-specific effects in emotion priming.

These findings question the N400 as a marker of emotion priming and contribute to the understanding of neurocognitive stages of laughter perception. More generally, they add to the growing literature on the neurophysiology of emotion and emotion representation.

Share

COinS