What triggers a gesture? Exploring affordance compatibility effects in representational gesture production

What are the mechanisms responsible for spontaneous cospeech gesture production? Driven by the close connection between cospeech gestures and object-related actions, recent research suggests that cospeech gestures originate in perceptual and motoric simulations that occur while speakers process information for speaking (Hostetter & Alibali, 2008). Here, we test this claim by highlighting object affordances during a communication task, inspired by the classic stimulus-response compatibility paradigm by Tucker and Ellis (1998). We compared cospeech gestures in situations where target objects were oriented toward the speakers' dominant hand (grasping potential enhanced), with situations where they were oriented toward the nondominant hand. Before the main experiment, we conducted a replication attempt of Tucker and Ellis' (1998: Experiment 1) to (re)establish the effect of stimulus compatibility, using contemporary items. Contrary to expectations, we could not replicate the original findings. Furthermore, compatibly with our replication results, the gesture data showed that enhancing grasping potential did not increase the amount of cospeech gestures produced. Vertical orientation nevertheless did, with upright objects eliciting more cospeech gestures than inverted ones, which does suggest a relation between affordance and gesture production. Our results challenge the automaticity of affordance effects, both in a classic stimulus-response compatibility experiment as well as in a more interactive dialogue setting and suggest that previous findings on cospeech gestures emerge from thinking and communicating about action-evoking content rather than from the affordance-compatibility of the presented objects. (PsycInfo Database Record (c) 2020 APA, all rights reserved).