title: Something to sink your teeth into: The presence of teeth augments ERPs to mouth expressions.
abstract: If the whites of the sclera can impact neural processing of eye expressions (Hardee, Thompson, & Puce, 2008; Whalen et al., 1998), do seen teeth affect neural responses to mouth expressions? Twenty participants (10 females; ages 22-31) viewed avatar mouth images depicting grimaces, smiles and open mouth expressions that were presented with and without teeth. A continuous 256 channel electroencephalogram (EEG) was recorded while subjects completed two tasks: an implicit task evaluating stimulus color and an explicit task evaluating mouth expression valence. Event related potential (ERP) peak amplitudes and latencies and area under the curve (AUC) were measured in individual subject averaged ERPs. Statistical testing revealed a main effect of the presence of Teeth for P100, N170, and vertex positive potential (VPP) amplitudes and for slow positive wave (SPW) AUC. Task by teeth interactions occurred for P250 amplitude, underscoring how explicit task demands can influence neural processing. Arousal ratings co-varied with teeth presence, suggesting that low-level visual features such as teeth may drive the saliency of emotional expressions, and lie at the core of differences in neural processing to different emotional expressions.
authors.affiliation: Indiana University-Bloomington, USA.
authors.forename: Elizabeth B
authors.initials: EB
authors.lastname: daSilva
authors.affiliation: Indiana University-Bloomington, USA.
authors.forename: Kirsten
authors.initials: K
authors.lastname: Crager
authors.affiliation: Indiana University-Bloomington, USA.
authors.forename: Danika
authors.initials: D
authors.lastname: Geisler
authors.affiliation: Indiana University-Bloomington, USA.
authors.forename: Powell
authors.initials: P
authors.lastname: Newbern
authors.affiliation: Indiana University-Bloomington, USA.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Orem
authors.affiliation: Indiana University-Bloomington, USA. Electronic address: ainapuce@indiana.edu.
authors.forename: Aina
authors.initials: A
authors.lastname: Puce
mesh_terms: D000328:Adult; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology*; D005149:Facial Expression; D000066499:Facial Recognition / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D009055:Mouth; D010775:Photic Stimulation; D012815:Signal Processing, Computer-Assisted; D014070:Tooth; D055815:Young Adult
keywords: Arousal; Grimace; Low-level stimulus features; Mouth; Smile; Stimulus configuration