{'fraction_non_alphanumeric': 0.03836657169990503, 'fraction_numerical': 0.013485280151946819, 'mean_word_length': 5.383030303030303, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 2, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Co-speech gestures do not originate from speech production processes: Evidence from the relationship between co-thought and co-speech gestures

Co-speech gestures do not originate from speech production processes: Evidence from the relationship between co-thought and co-speech gestures Mingyuan Chu (M.Chu.1@bham.ac.uk) School of Psychology, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK. Sotaro Kita (s.kita@bham.ac.uk) School of Psychology, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK. Abstract When we speak, we spontaneously produce gestures (co- speech gestures). Co-speech gestures and speech production are closely interlinked. However, the exact nature of the link is still under debate. To addressed the question that whether co-speech gestures originate from the speech production system or from a system independent of the speech production, the present study examined the relationship between co-speech and co-thought gestures. Co-thought gestures, produced during silent thinking without speaking, presumably originate from a system independent of the speech production processes. We found a positive correlation between the production frequency of co-thought and co- speech gestures, regardless the communicative function that co-speech gestures might serve. Therefore, we suggest that co-speech gestures and co-thought gestures originate from a common system that is independent of the speech production processes. Keywords: co-thought gestures; co-speech gestures; speech production. People often spontaneously gesture when they speak (co- speech gestures). There is a consensus in the literature that co-speech gesture and speech production are tightly linked. They are highly coordinated semantically and well synchronized temporally (McNeill, 1992). For example, a speaker may draw circles in the air with an extended index finger and say “rotating” simultaneously when describing a rotational movement. When speech is dysfluent, gesture is interrupted as well. Mayberry and Jaques (2000) showed that co-speech gestures were held motionless during stuttering in speech. Furthermore, speaking and gesturing can influence each other. The way people verbally expressed a motion event had an effect on the way they gesturally depicted it (Kita & Ozyurek, 2003) and prohibiting or allowing gesture could alter children’s explanations of Piagetian conservation tasks (Alibali & Kita, under review). However, there is a lack of consensus regarding the exact nature of the link between co-speech gesture and speech production. One class of theories claims that these two systems are inherently inseparable. According to McNeill (1992), speech and gesture are a single-integrated system and they both arise from a “growth point”, which is the speaker’s minimal idea unit that combines image and word. Meanwhile, some other researchers suggest that co-speech gesture originates from subprocesses of speech production. For example, gesture is generated from the lexical retrieval process (Butterworth & Hadar, 1989; Rauscher, Krauss & Chen, 1996) or the “conceptualizer”, which specifies the pre-linguistic message to be verbalized in the next utterance (de Ruiter, 2000). Generally speaking, this class of theories holds that co-speech gesture production is inseparable from the speech production process. An alternative view is that co-speech gesture and speech production are two interactive but independent systems (Kita, 2000; Kita & Ozyurek, 2003). Kita and Lausberg (2008) found that the linguistically non-dominant hemisphere alone in split-brain patients can generate co- speech gestures based on spatial imagery. This result indicates that co-speech gesture and speech production are dissociable processes. In addition, co-speech gestures can express different information from the concurrent speech (e.g., Perry, Church, & Goldin-Meadow, 1988; Garber & Goldin-Meadow, 2002). The semantic mismatch between co-speech gesture and speech indicates that at least some gestures are produced independently of the speech production process. Kita (2000) further proposed that co- speech gesture is generated from spatio-motoric thinking (or an “Action Generator” in Kita & Ozyurek, 2003), which organizes information with action schemas and their modulation according to the environmental information. In other words, co-speech gestures originate from a cognitive system that is independent of the speech production system and responsible for generating body movements in the physical environment. In addition to co-speech gestures, people also spontaneously gesture when they solve problems without speaking (co-thought gestures). Schwartz and Black (1996) asked participants to verbally explain their solutions of some simple gear problems. The authors found that many participants produced co-thought gestures before their verbal response. Furthermore, people spontaneously produce co-thought gestures during problem solving even in a task that does not involve any use of language. Chu and Kita (2008) found that people spontaneously produced co- thought gestures in a mental rotation task, in which participants seated alone in a room and only needed to make left or right judgments by pressing the correspondent foot