Supine Body Position Reduces Neural Response to Anger Evocation

Abstract

Body movements affect emotional processes. For example, adopting the facial expressions of specific emotions (even via unobtrusive manipulations) affects emotional judgments and memories (Laird, 2007). Manipulated body postures can affect behavior: slumped postures lead to more ‘‘helpless behaviors’’ (Riskind & Gotay, 1982). Simple body postures may also affect other emotive responses and the neural activations associated with them. Lying flat on one’s back may be antithetical to approach motivation (i.e., the urge to move toward something). We sought to address this issue, which has implications not only for the study of embodiment, but also for the study of neural processes, because some neuroscience techniques rely on individuals being in supine positions. More than 15 studies using electroencephalographic (EEG) and repetitive transcranial magnetic stimulation (rTMS) methods have suggested that the left prefrontal cortex is more activated than the right prefrontal cortex during the experience of anger, particularly anger associated with approach motivational inclinations (Carver & Harmon-Jones, 2009; van Honk & Schutter, 2006). Tomarken and Zald (2009), however, questioned these effects when they reviewed some functional magnetic resonance imaging (fMRI) studies that failed to find greater relative left prefrontal cortical activations during anger. One possible explanation of the divergence of the EEG-rTMS and fMRI studies on anger is that the fMRI studies did not evoke anger associated with approach motivation. Research has shown that mild anger cues only evoke greater relative left frontal cortical activation when approach motivation is also activated (Harmon-Jones, Lueck, Fearn, & Harmon-Jones, 2006). Another possibility for the diverging findings is that the EEGrTMS studies test participants in an upright body position, whereas fMRI studies test participants in a supine body position. We measured relative left frontal EEG activity to an angerinducing insult while participants were upright or reclined. We expected the reclined position to produce less relative left frontal cortical activation than the upright position because a supine position may be antithetical to approach motivation.