No abstract

According to the free energy principle biological agents resist a tendency to disorder in their interactions with a dynamically changing environment by keeping themselves in sensory and physiological states that are expected given their embodiment and the niche they inhabit (Friston in Nat Rev Neurosci 11(2):127-138, 2010. doi:10.1038/nrn2787). Why would a biological agent that aims at minimising uncertainty in its encounters with the world ever be motivated to seek out novelty? Novelty for such an agent would arrive in the form of sensory and physiological states that are unexpected. Such an agent ought therefore to avoid novel and surprising interactions with the world one might think. Yet humans and many other animals find play and other forms of novelty-seeking and exploration hugely rewarding. How can this be understood in frameworks for studying the mind that emphasise prediction error minMany thanks to Andy Clark for excellent feedback and suggestions on earlier drafts of this paper, and to Jelle Bruineberg for helping us to understand the recent literature in cognitive neuroscience on epistemic value. We are extremely grateful for detailed reviews we received from two anonymous reviewers that helped us to significantly improve and sharpen our arguments. Erik Rietveld would like to acknowledge the research funding awarded by the Netherlands Organisation for Scientific Research (NWO) 123Synthese imisation? This problem has been taken up in recent research concerned with epistemic action-actions an agent engages in to reduce uncertainty. However that work leaves two questions unanswered, which it is the aim of our paper to address. First, no account has been given yet of why it should feel good to the agent to engage the world playfully and with curiosity. Second an appeal is made to precision-estimation to explain epistemic action, yet it remains unclear how precision-weighting works in action more generally, or active inference. We argue that an answer to both questions may lie in the bodily states of an agent that track the rate at which free energy is being reduced. The recent literature on the predictive brain has connected the valence of emotional experiences to the rate of change in the reduction of prediction error (Joffily and Coricelli in PLoS Comput Biol 9(6):e1003094, 2013. doi:10.1371/journal.pcbi.1003094; Van de Cruys, in Metzinger and Wiese (eds) Philosophy and predictive processing, vol 24, MIND Group, Frankfurt am Main, 2017. doi:10.15502/9783958573253). In this literature valenced emotional experiences are hypothesised to be identical with changes in the rate at which prediction error is reduced. Experiences are negatively valenced when overall prediction error increases and are positively valenced when the sum of prediction errors decrease. We offer an ecological-enactive interpretation of the concept of valence and its connection to rate of change of prediction error. We show how rate of change should be understood in terms of embodied states of affordance-related action read...

The incidence of complicated parapneumonic effusions in children with community-acquired pneumonia increased from 1996 to 1999 and then declined concomitant with the introduction of the pneumococcal conjugate vaccine. Although cases caused by S. pneumoniae have decreased, community onset methicillin-resistant Staphylococcus aureus has emerged as a cause of pneumonia with complicated effusions in children.