Motivation and Motor Control: Hemispheric Specialization for Approach Motivation Reverses with Handedness

Abstract

BackgroundAccording to decades of research on affective motivation in the human brain, approach motivational states are supported primarily by the left hemisphere and avoidance states by the right hemisphere. The underlying cause of this specialization, however, has remained unknown. Here we conducted a first test of the Sword and Shield Hypothesis (SSH), according to which the hemispheric laterality of affective motivation depends on the laterality of motor control for the dominant hand (i.e., the “sword hand," used preferentially to perform approach actions) and the nondominant hand (i.e., the “shield hand," used preferentially to perform avoidance actions).Methodology/Principal FindingsTo determine whether the laterality of approach motivation varies with handedness, we measured alpha-band power (an inverse index of neural activity) in right- and left-handers during resting-state electroencephalography and analyzed hemispheric alpha-power asymmetries as a function of the participants' trait approach motivational tendencies. Stronger approach motivation was associated with more left-hemisphere activity in right-handers, but with more right-hemisphere activity in left-handers.ConclusionsThe hemispheric correlates of approach motivation reversed between right- and left-handers, consistent with the way they typically use their dominant and nondominant hands to perform approach and avoidance actions. In both right- and left-handers, approach motivation was lateralized to the same hemisphere that controls the dominant hand. This covariation between neural systems for action and emotion provides initial support for the SSH.

Different bodies, different minds: The bodyspecificity of language and thought

“…In left-handers, the pattern was reversed: Approach-motivational tendencies predicted more neural activity in the right hemisphere. (Figure reproduced from Brookshire & Casasanto, 2011. ) 382 Casasanto they encourage should be stable over time; to the extent that they change, mental representations may change accordingly.…”

Motor experience influences object knowledge.

“…These results suggest that body-specific experience can influence many aspects of cognition including memory (Apel, Cangelosi, Ellis, Goslin, & Fisher, 2012), language comprehension (Willems et al, 2010; Willems, Labruna, D’Esposito, Ivry, & Casasanto, 2011), mental imagery (Willems et al, 2009), and word learning (de Nooijer, van Gog, Paas, & Zwaan, 2013). Hand dominance has been shown to shape the mental representation of even some abstract concepts such as the notions of good and bad (see Casasanto, 2009; Casasanto & Chrysikou, 2011; de la Fuente, Casasanto, & Santiago, 2015), and the neural representation of abstract personality traits like ambition and pride (Brookshire & Casasanto, 2012). …”

The Neural Basis of Optimism and Pessimism

“…RH) of left-handers [310]. Similarly, approach motivation tendencies are associated with LH activation in right-handers and with RH activation in left-handers [311, 312]. However, some studies on left-handers' emotional lateralization show that it is not a symmetric reverse of right-handers [e.g.…”