Co-thought and co-speech gestures are generated by the same action generation process.

Abstract

People spontaneously gesture when they speak (co-speech gestures) and when they solve problems silently (co-thought gestures). In this study, we first explored the relationship between these 2 types of gestures and found that individuals who produced co-thought gestures more frequently also produced co-speech gestures more frequently (Experiments 1 and 2). This suggests that the 2 types of gestures are generated from the same process. We then investigated whether both types of gestures can be generated from the representational use of the action generation process that also generates purposeful actions that have a direct physical impact on the world, such as manipulating an object or locomotion (the action generation hypothesis). To this end, we examined the effect of object affordances on the production of both types of gestures (Experiments 3 and 4). We found that individuals produced co-thought and co-speech gestures more often when the stimulus objects afforded action (objects with a smooth surface) than when they did not (objects with a spiky surface). These results support the action generation hypothesis for representational gestures. However, our findings are incompatible with the hypothesis that co-speech representational gestures are solely generated from the speech production process (the speech production hypothesis).

How do gestures influence thinking and speaking? The gesture-for-conceptualization hypothesis.

“…When complex information (e.g., the shape of a vase) is gesturally expressed, a single gesture may not be able to express all relevant aspects of the information, and each gesture may then focus on a particular aspect (e.g., the shape of the opening, the contour outline from a particular viewpoint). What is expressed by a gesture may be determined by affordances (Gibson, 1979) of the referent (Chu & Kita, 2015;Masson-Carro, Goudbeek & Krahmer, 2015) or by other top-down factors (e.g., an…”

“…The Gesture as Simulated Action framework (Hostetter & Alibali, 2008) holds that the mental representations that underlie gestures are simulated actions and perceptual states. In addition to these theories about co-speech gestures, the Action Generation Hypothesis (Chu & Kita, 2015) extends the same action-based view to co-thought gestures. These theories contrast with theories that embed gesture generation solely within speech production processes (Butterworth & Hadar, 1989;de Ruiter, 2000;McNeill, 1992) The Gesture-for-Conceptualization Hypothesis builds on the idea that gestures are generated from the same process that generates practical actions (cf.…”

“…These theories contrast with theories that embed gesture generation solely within speech production processes (Butterworth & Hadar, 1989;de Ruiter, 2000;McNeill, 1992) The Gesture-for-Conceptualization Hypothesis builds on the idea that gestures are generated from the same process that generates practical actions (cf. Chu & Kita, 2015;Hostetter & Alibali, 2008;Kita, 2000;Kita & Özyürek, 2003). That is, the information encoded in gestures is generated from the action system.…”

“…Chu and Kita (2015) presented participants with two images of a mug, and described how one mug could be rotated into the position of the other. The mugs either had smooth surfaces or had spikes on their surfaces (Figure 7).…”

Co-thought gesturing supports more complex problem solving in subjects with lower visual working-memory capacity

“…More precisely, although there is some evidence that co-thought gestures are more likely to arise when task complexity is high (e.g., Chu & Kita, 2008;Logan et al, 2014), it is not clear yet how they relate to internal cognitive capacities such as working-memory capacity. Furthermore, in contrast to co-speech gestures (e.g., Hostetter & Alibali, 2008), it is still unknown under which conditions co-thought gestures arise (Chu & Kita, 2016). …”