How does the embodied metaphor affect creative thinking?

Highlights

• Virtual reality technology was applied to realize the embodiment of “breaking the rules”.

• Better creative performance was observed in the “break-wall” condition.

• The proportion of novel answers increased more rapidly in the “break-wall” condition.

• Deactivation of the frontopolar area, DLPFC and somatosensory association cortex were found in the “break-wall” condition.

Abstract

This study aimed to explore the neural correlates of the embodied metaphor “breaking the rules” and how it affects creativity by using functional near-infrared spectroscopy (fNIRS). To embody the metaphor “breaking the rules,” we created a circumstance in which participants can experience “breaking the walls” through virtual reality (VR) technology. Participants were randomly assigned to three conditions: the “break-wall” condition, where they broke the walls to move forward; the “auto-wall” condition, where the barrier wall opened automatically; and the “no-wall” condition, where no barrier walls appeared. While walking in the virtual scenes, participants were asked to solve a creativity-demanding problem and to wear the fNIRS device to record their neural activities. It was found that participants showed better creative performance in the “break-wall” condition than in the other conditions. Weaker activations were found in the frontopolar cortex, the dorsolateral prefrontal cortex, and the somatosensory association cortex under the “break-wall” condition, which may be associated with rule-breaking behaviors, creative performance, and sense of embodiment. These findings may indicate that physical actions of “breaking the wall” activate the conceptual metaphor of “breaking the rules,” which triggers brain activities related to rule-breaking, thus affecting creative performance.

Introduction

You have probably encountered the following scenarios in science fiction: a brain in a nutrient medium or a sophisticated computer with extraordinary and mature cognitive skills. Is this possible? Research on embodied cognitive science has raised doubts. Supporters of embodied cognition emphasize the role of sensory and motor functions in cognition itself, meaning that systems for sensing, acting, and thinking are constitutively interdependent (Barsalou, 1999; Foglia and Wilson, 2013). Along with much evidence, this interactive relationship between the human mind and body has been widely accepted (Thelen et al., 2001; Shapiro, 2010). For instance, one of the most classic studies showed that compared to recalling experiences of being accepted, individuals felt much colder when they recalled experiences of being rejected (Zhong and Leonardelli, 2008). Moreover, participants who held a heavy clipboard judged a problem to be more important compared to those who held a light clipboard (Jostmann et al., 2009). To summarize, our cognition is a collective of our mind and body.

As an important human capacity, creativity is defined as the ability to produce work that is novel and useful (Runco and Jaeger, 2012; Sternberg and Lubart, 1993). In recent years, the study of creativity under the perspective of embodied cognition has drawn more and more attention. Leung et al. (2012) reported that compared to walking in a fixed route, individuals who walked freely performed better on creative tasks. Slepian and Ambady (2012) found that tracing fluid drawing—in other words, fluid arm movements—can facilitate creative cognition. A neuromodulation study showed that using transcranial direct current stimulation (tDCS) to activate the M1 region increased musical improvisation performance, which indicated that the primary motor cortex contributes to musical creativity (Anic et al., 2018).

In addition to sensations and movements, metaphors have also been recognized as another bridge that connects the human mind and body. Higher-order, abstract, mental representations are ultimately grounded in bodily states, and our everyday language is full of metaphors (Lakoff and Johnson, 1980). For instance, in the phrase “rising star,” “rising” implies “progressive and successful; ” in the sentence “I’m very down today,” “down” implies “sad.” Recently, researchers have been more and more interested in the effects of embodied metaphors on creativity. Kim (2015) asked participants to squeeze balls to embody the metaphor “squeeze your head” and found that squeezing a soft, deformable ball can enhance divergent thinking, whereas squeezing a hard ball can facilitate convergent thinking. Intriguingly, Leung et al. (2012) found that standing outside a box to embody the metaphor “thinking outside of the box” could enhance participants’ creative performance. “Breaking the rules” is another common metaphor. It is an everyday Chinese idiom that is often used to encourage people to solve problems in novel ways, rather than using traditional approaches. Moreover, in both Chinese and English language contexts, the symbolic meanings of “walls” could be rules, traditions, constraints, or even confinements. In this sense, the implication of “breaking the walls” could be equal to “breaking the rules.” Wang et al. (2018) used virtual reality (VR) technology to simulate a scenario in which participants could break through walls. It was found that participants showed better creative performance in the break-wall condition than in the no-wall condition. All of these studies have shown that embodying specific metaphors can influence cognitive processes and outcomes, even unconsciously.

Over the past few decades, embodied cognition has become one of the most important and representative research orientations in cognitive research under the rise of the second generation of cognitive science. However, like other burgeoning theories, there are still many unresolved controversies within it. If embodied cognition is “a ghost hovering over the cognitive science laboratory” (Goldman and Vignemout, 2009), then repeatability is “the Sword of Damocles” hanging above the embodied cognition laboratory. Bargh et al. (1996) found that after reading words related to “old age,” participants left the lab more slowly than those who read words unrelated to old age, even when the subjects themselves were unaware of this. However, Doyen et al. (2012) completely repeated the experiment and replaced the stopwatch speed measurement in the original experiment with infrared speed measurement and found that there was no significant difference in the walking speed of the subjects. The results of the abovementioned experiment have triggered a large-scale discussion on repeatability indicators in the field of embodied cognitive psychology.

Therefore, research using brain functional imaging technology to reveal the potential neural mechanisms behind embodied cognition is quite necessary. In fact, some studies have demonstrated the beneficial effects of physical activities on the development of brain structures. For instance, Ben-Soussan et al. (2015) reported gray matter volume and fractional anisotropy changes in several brain regions, including the cerebellum after 4-week specific motor training, and these anatomical changes were positively correlated with AUT flexibility scores. However, the neural mechanisms and brain activities by which embodied metaphors affect higher-level cognitive function such as creativity remain unknown.

Under this circumstance, our study aimed to explore the neural correlates of the embodied metaphor “breaking the rules” and how it affects creativity by using a functional near-infrared spectroscopy (fNIRS) device. Unlike fMRI and EEG, fNIRS allows subjects to wear a VR head-mounted display (HMD) and to perform small movements, so we chose it to record the subjects’ brain activities. As walls can symbolize rules, laws, and even imprisonment, we used “breaking the walls” to represent “breaking the rules.” We exploited VR technology to simulate virtual walls as Wang et al. (2018) did and added a more suitable control condition. Thus, the results in the former study could be replicated and expanded.

Previous neuroscience studies have revealed that the prefrontal cortex (PFC), as part of the executive control network, plays an essential role in creative cognition processing (Beaty et al., 2015). For instance, a meta-analysis study reviewed 34 functional imaging studies that reported brain activities during creative thinking tasks and found that the PFC was involved in cognitive processes shared by diverse creativity tasks such as the RAT and AUT (Gonen-Yaacovi et al., 2013). Vartanian et al. (2013) found that the activation of the DLPFC was significantly lower in the working memory training group, which might contribute to fluid intelligence and divergent thinking. In addition, creative idea generation (i.e., divergent thinking) is associated with the deactivation of the right temporal-parietal junction (r-TPJ) (Benedek et al., 2014). The r-TPJ is thought to be a core region of the ventral attention network. It is proposed that sustained deactivation of this region indicates an internal attentional state that can help individuals attend to potentially creative ideas generated in the mind, thus benefiting creative idea generation (Berkowitz and Ansari, 2010; Corbetta et al., 2008; Fink et al., 2012).

Since breaking the rules requires individuals to violate rules and inhibit rule-guided behaviors, the underlying neural correlates of these behaviors may also be involved. Previous studies have found that the PFC, especially the frontopolar cortex, plays an important role in mediating abstract integration in analogy (Green et al., 2006), rule learning (Boschin et al., 2015), and adherence to social norms (O’Callaghan et al., 2016; Moll et al., 2007). Moreover, the activation of the r-TPJ is related to a sense of bodily separation and multisensory conflicts (disembodiment), and the deactivation of the r-TPJ is associated with embodiment (Blanke et al., 2005; Papeo et al., 2010). Based on the abovementioned review, the PFC and r-TPJ are not only correlated with creativity but are also correlated with embodiment and rule-breaking behaviors, so we selected these two regions as the regions of interest (ROI) in the present study.

In this study, to explore the neural correlates of the embodied metaphor “breaking the rules” and how it affects creativity, participants were randomly assigned to three conditions: the “break-wall” condition, in which they had to break the walls to move forward in VR; the “auto-wall” condition, where the barrier walls would open automatically when participants were close enough to them; and the “no-wall” condition, where no barrier walls appeared. While walking in the virtual corridor, participants were asked to solve a creativity-demanding task. During the task procedure, the neural activity of the PFC and r-TPJ regions was recorded using fNIRS. Participants’ openness, emotional state, ideation in daily life, personal need for structure, self-rated enjoyment, and difficulty of the experimental tasks were measured using scales to test whether the observed effects of embodied metaphor on creative performance were independent from these factors.

Three hypotheses were raised: (1) better creative performance would be observed in the “break-wall” condition; (2) no difference in creative performance would be observed between the “auto-wall” and “no-wall” conditions; (3) deactivation of the frontopolar area, DLPFC and the r-TPJ would be observed in the “break-wall” condition, given that the deactivation of these three brain regions were found to be associated with rule-breaking behavior, creativity improvement and embodiment (Benedek et al., 2014; Blanke et al., 2005; Buckholtz et al., 2015; Crescentini et al., 2011).