Handedness and the Body-Specificity Hypothesis

In addition to its relationship with language representation, handedness is also found to be associated with conceptual representation. Casasanto (2009) investigated the links between handedness and mental representation of abstract concepts with positive or negative valence (e.g. intelligence, sadness, bravery). He observed that right-handers tend to associate rightward space with positive ideas while the left-handers with the leftward space. The author argued that people who interact with the physical environments in systematically different ways should form different mental representations accordingly, which he named “the body-specificity hypothesis” (Casasanto, 2009). In one of his experiments, the participants received a piece of paper with a cartoon figure at the center and two boxes at each side of the figure,

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either horizontally or vertically arranged (vertical array being the control) (See Figure 1 adapted from Casasanto, 2009). Participants were instructed that the cartoon figure liked zebras and hated pandas (counterbalanced) and they were to draw the zebra in the box that best represented good things like seeing zebras and the panda in the box representing bad things (or vice versa). Results demonstrated that participants had a tendency to draw the good animal in the box at their dominant side. The results were replicated with Dutch speakers and with oral response instead of hand-drawing, which indicates that this preference was not due to the native language of the subjects or the fact that the hand drawing of the animal was the dominant hand.

Figure 1. The experimental materials adapted from Casasanto (2009)

Another experiment in the series examined whether the left-right position of the stimuli would have an implicit influence on left- and right-handers’ judgements towards positive/negative traits. Participants received a piece of paper with 12 pairs of created alien creatures. The creatures were arranged in two columns, one on each side of a list of questions printed in a center column. The task was to circle one of the creatures in the pair that best fit the question, to indicate a judgement about one of the four personal characteristics (i.e., intelligence, attractiveness, honesty, happiness). Results showed that participants’ directional

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preference was influenced by the right-left location of the creature, even though spatial location was irrelevant to the judgements.

In fact, research has demonstrated that positive emotion (pleasantness) reflects the

“approach motivation” while negative emotion links to the “avoidance motivation”

(Cacioppo & Berntson, 1994; Lang & Bradley, 2010). For example, food and drink provoke one’s motivation to approach, which is a natural instinct for survival and progeny, whereas punishment or danger motivates one to avoid. Approach motivation is thus associated with positive emotion while avoidance motivation with negative valence. Literature also pointed out that the LH is specialized for approach and the RH for avoidance motivation (Davidson &

Fox, 1982; for a review, see Harmon--Jones, Gable & Peterson, 2010). Interestingly, Brookshire and Casasanto (2012) have found that the cerebral lateralization of approach motivation is to the same hemisphere that controls the dominant hand: the hemispheric correlate of approach motivation is lateralized to the LH for the right-handers, but to the RH for the left-handers. In addition to representation of abstract concepts, the body-specificity hypothesis is also exhibited in the interaction between language and action. An fMRI study by Willems, Hagoort & Casasanto (2010) investigated whether the meanings of manual action verbs are grounded in how the particular language users perform the actions. The researchers compared the premotor activation in right- and left-handers during a lexical-decision task on manual-action verbs (e.g. grasp, throw) and non-manual-action verbs (e.g.

kneel, giggle). In the first task, participants viewed the manual-action verbs,

nonmanual-action verbs, pseudowords, and fillers in an fMRI machine. The presentation of a pseudoword or filler stimulus was followed by the screen showing a question of whether the stimulus was an extant word, and the participants should press the key for response as fast as possible.

After the critical stimuli (i.e., manual-action verbs and nonmanual-action verbs) no responses were solicited. In the second task, participants were instructed to mentally imagine

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themselves performing the action denoted by the verb. By comparing the first and the second task, the researchers were able to determine the cerebral activation of viewing the manual-action verbs was not due to the participants’ mental visualization of the verbs. After careful exclusion of the potential confounding factor -- mental imagery, they observed that each group, right- or left-handed, preferentially activated premotor areas in the hemisphere contralateral to their dominant hands, which suggested the body specificity of the motor component in action verb semantics.

In summary, people have implicit preference to their dominant side and that the approach motivation, which is associated with positive emotion, is lateralized to the dominant hemisphere. And since body-specificity has been exhibited in both conceptual representation of positive/negative characteristics and language, it would be informative to see if we can combine the two and explore whether this hypothesis can also be true for emotion word processing.

However, before we move on to the literature about emotion word processing, it is important to note that positive/negative valence has not always been associated with left-right distinction. In fact, in many languages such as English and Chinese, metaphorical expressions tend to associate positive and negative valence with the top and bottom of a vertical spatial continuum (Lakoff & Johnson, 1980, 1999). A happy individual has “high” spirit, but a sad person feels “down.” In Chinese, a smart person has “high” IQ (“高”智商), but a foolish person is “an idiot” (“低”能兒 (literal translation: low ability)). An object of great quality is of “top” class (“頂”級). This High Is Good mapping associates the source domain of physical space with abstract target domain that is of positive valence. These mental metaphors import the inferential structure of source domains like space into target domains, which allows language users to envision, measure and compare the height of excitement or the depth of sadness. (Boroditsky, 2000; Casasanto, 2008; Pinker, 1997)

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It is still under debate as to whether mental metaphors arise from correlations (1) in linguistic experience or (2) in bodily experience. On the first account, it is proposed that mental metaphors are established through experience by using linguistic metaphors. Using spatial words in both literal and metaphorical contexts (e.g., a high shelf, a high standard) in daily life could induce a transfer effect of the structural elements from the concrete source domain to the abstract target domain representations in mind via analogical processes that are not necessarily “embodied” (Boroditsky, 2000; Gentner et al., 2001). For example, in the experiment by Meier & Robinson (2004), participants were faster to judge words like polite and rude as having positive or negative valence when positive words were presented at the top and negative words at the bottom of a computer screen. Linguistic conventions associating valence with vertical space are reinforced by other non-linguistic cultural conventions, such as the “thumbs up” and “thumbs down” gestures signaling approval and disapproval. This account believes that once these linguistic and non-linguistic conventions are part of a culture, they can serve as the basis for metaphorical mappings in the minds of individual learners, diminishing the role of direct bodily experience (Casasanto, 2009).

On the second account, it is said that mental metaphors like Positive Is Up and Negative Is Down could be established as people implicitly learn associations between physical experiences and emotional states that typically co-occur. For instance, people stand tall and raise the chin when feeling proud, slouching and dropping the head when feeling frustrated (Lakoff & Johnson, 1999). Linguistic metaphors later encode the pre-existing mental metaphors developed on the basis of these relationships between different types of bodily experiences. In one experiment, participants assuming an upright posture persisted longer in a puzzle-solving task, as compared to a slouching posture (Riskind & Gotay, 1982), and in another study participants expressed more pride in their test performance after sitting upright during the critical phase of the experiment than after slouching (Stepper & Strack,

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1993). This account proposes that mental metaphors are developed by the implicit reinforcement of the repeated co-occurrence of bodily experience and emotional states.

In sum, although testing the left vs. right preference (i.e. the body-specificity hypothesis) on emotion word processing is the focus of the current study, it is important to note that up vs. down preference might be another interesting topic to pursue to complement the current study.