Study title

While adults can readily report another agent’s false belief, theories of belief processing typically assume that this process requires the inhibition of one’s own salient current knowledge: belief processing involves overcoming an initial “egocentric bias” towards one’s own knowledge. However, evidence for the presence of egocentric bias during tasks in which adults explicitly report another agent’s false belief is surprisingly limited, with some studies providing conflicting results (e.g., Wang & Leslie, 2016; Rubio-Fernandez, 2017), failures to replicate (e.g., Ryskin & Brown-Schmidt, 2014; Samuel et al., 2018) or data that do not clearly support the presence of an egocentric bias (e.g., Back & Apperly, 2010). In three lab-based psychology experiments we used computer mouse tracking to attempt to measure, in adults, egocentric bias during an unexpected transfer false belief task. Mouse tracking allows researchers to measure the online competition between different response options when one makes a decision, and thus has the potential to reveal attraction to response options that reflect participants’ own knowledge during a false belief task. In all three experiments, participants viewed video scenarios in which an agent had either a true belief (“TB-scenarios”) or a false belief (“FB-scenarios”) as to the location of a set of keys. In each video, the agent first watched the keys hidden in one of two cups. The keys were then moved to the other cup either in the agent's presence (TB-scenarios) or absence (FB-scenarios). At the end of each video participants used a mouse to answer questions presented on the screen by moving the mouse from the bottom centre of the screen to click on one of two response boxes located in the top left and right of the screen. Key experimental questions required participants to either answer "where are the keys currently hidden?" (“reality” questions) or "where does she think the keys are?" (“belief” questions). Participants...