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PhD Defense of Vjeran Keric

Vjeran Keric
Thursday, September 7, 2023, 3:00 pm – 6:00 pm

You are cordially invited to the Defense of PhD thesis




Vjeran Keric

Primary supervisor: Natalie Sebanz
Secondary supervisor: Günther Knoblich

Thesis submitted to:
Central European University, Department of Cognitive Science


When it comes to effort, whether mental or physical, people and non-human animals tend to rationalize its expenditure. This is the case both when they act individually and when it comes to humans, cooperatively. The aim of this thesis was to investigate how effort expenditure reflects on collective action, action prediction and joint decision-making. Chapter 2 investigated how energy expenditure influences perceptual estimates of the environment. It showed that perception and effort might be linked but that the nature of this connection is social. More precisely, whether potential effort influences perception is tied to construal of a situation more than it is to energetic costs of an action. The third chapter studied whether distribution of mental effort is rational from a joint perspective, showing that mental effort distribution strategies are mostly focused on minimization of one’s own effort rather than the total amount of effort expended by all participants of an interaction. These results demonstrate that compared to sharing of physical costs, collaborating in tasks involving mental effort are less likely to involve jointly rational strategies of effort distribution. The final empirical Chapter (Study 3) tested whether people expect jointly rational distribution of effort and if this informs prediction of ongoing actions. These experiments revealed that while explicit expectations were in line with joint rationality, online prediction of actions was more informed by immediate individual efficiency considerations. However, these considerations were equally pronounced for the acting agent and their partner, suggesting that prediction was informed, in equal measure, by the efficiency of an acting agent and their partner. Taken together, the findings of this thesis show that considerations of other’s effort (motor or cognitive) guide both action prediction and decision-making but that in both cases neither decisions nor predictions are completely in line with joint rationality.