Task co-representation has been proposed to rely on the motor brain areas' capacity to represent others' action plans similarly to one's own. The joint memory (JM) effect suggests that working in parallel with others influences the depth of incidental encoding: Other-relevant items are better encoded than non-task-relevant items. Using this paradigm, we investigated whether task co-representation could also emerge for non-motor tasks. In Experiment 1, we found enhanced recall performance to stimuli relevant to the co-actor also when the participants' task required non-motor responses (counting the target words) instead of key-presses. This suggests that the JM effect did not depend on simulating the co-actor's motor responses. In Experiment 2, direct visual access to the co-actor and his actions was found to be unnecessary to evoke the JM effect in case of the non-motor, but not in case of the motor task. Prior knowledge of the co-actor's target category is sufficient to evoke deeper incidental encoding. Overall, these findings indicate that the capacity of task co-representation extends beyond the realm of motor tasks: Simulating the other's motor actions is not necessary in this process.

Previous research has shown that human infants and young children are sensitive to the boundaries of certain social groups, which supports the idea that the capacity to represent social categories constitutes a fundamental characteristic of the human cognitive system. However, the function this capacity serves is still debated. We propose that during social categorization the human mind aims at mapping out social groups defined by a certain set of shared knowledge. An eye-tracking paradigm was designed to test whether two-year-old children differentially associate conventional versus non-conventional tool use with language-use, reflecting an organization of information that is induced by cues of shared knowledge. Children first watched videos depicting a male model perform goal-directed actions either in a conventional or in a non-conventional way. In the test phase children were presented with photographs taken of the model and of a similarly aged unfamiliar person while listening to a foreign (Experiment 1) or a native language (Experiment 2) text. Upon hearing the foreign utterance children looked at the model first if he had been seen to act in an unconventional way during familiarization. In contrast, children looked at the other person if the model had performed conventional tool use actions. No such differences were found in case of the native language. The results suggest that children take the conventionality of behavior into account in forming representations about a person, and they generalize to other qualities of the person based on this information.

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What makes agents fundamentally different from each other from the viewpoint of a 10‐month‐old infant? While infants at this age can already individuate human‐like objects from non‐humanlike ones and self‐propelled agents from inert objects, little is known of when and how they start individuating within the domain of agents. What is clear from previous studies is that differences in surface and dynamic features are not sufficient. We hypothesized that mental properties—in this case the agents' preferences—can serve as an individuating property. In our study, we familiarized infants with two animated agents who had different preferences. The agents sequentially and repeatedly emerged from behind an occluder, and then each agent approached one of two target objects before returning behind the occluder. After familiarization, the occluder was lifted, revealing either one agent or two agents. While infants successfully individuated the agents in the preference‐demonstration condition, they failed to do so in the exposure‐only condition in which perceptually similar surface and dynamic features of the agents were presented but without indicating preferences. Our study thus provides evidence that mental properties can help individuate agents, grounding the claim that infants understand agents as mental entities at their core.