The mesostriatal dopamine system is prominently implicated in model-free reinforcement learning, with fMRI BOLD signals in ventral striatum notably covarying with model-free prediction errors. However, latent learning and devaluation studies show that behavior also shows hallmarks of model-based planning, and the interaction between model-based and model-free values, prediction errors, and preferences is underexplored. We designed a multistep decision task in which model-based and model-free influences on human choice behavior could be distinguished. By showing that choices reflected both influences we could (...) then test the purity of the ventral striatal BOLD signal as a model-free report. Contrary to expectations, the signal reflected both model-free and model-based predictions in proportions matching those that best explained choice behavior. These results challenge the notion of a separate model-free learner and suggest a more integrated computational architecture for high-level human decision-making. (shrink)

Although seemingly irrational choice abounds, the rules governing these mis-steps that might provide hints about the factors limiting normative behavior are unclear. We consider three experimental tasks, which probe different aspects of non-normative choice under uncertainty. We argue for systematic statistical, algorithmic, and implementational sources of irrationality, including incomplete evaluation of long-run future utilities, Pavlovian actions, and habits, together with computational and statistical noise and uncertainty. We suggest structural and functional adaptations that minimize their maladaptive effects.

One character in Cortázar's novel truly believes in cosmic rhythm. This belief is characteristic of a magical view of the universe central to 1960s counterculture. The other characters in Los Premios, like the implied narrator, reject Persio's essentialism; they dismiss the notion that there is really any rhythm common to art, humanity, and the universe. However, there are key points in the narrative, inspired by falling in love and by works of art, at which their world does appear patterned by (...) just such a rhythm, a ‘swing cósmico’. The novel itself turns out to depend on the intermittent conviction of this rhythm, not objectively embedded in anything, but always seen, living, and dying in time; the price of art is the acceptance of this rhythmed mortality. (shrink)

Mallarmé's reputation as a seminal thinker has steadily grown, yet his literary theory has received little attention and the great theoretical articles of his later years have never been properly studied. This book represents the first attempt to examine the later Mallarmé's extraordinary and systematic literary idealism through a careful scrutiny of his work. Dayan makes selective use of the textual approaches of certain post-structuralist theorists, especially Derrida, pointing out the many similarities between their positions and Mallarmé's, but also noting (...) the vital differences. These differences, Dayan argues help to explain not only Mallarmé's continuing elusiveness, but also the failure of modern literary theory to face the question that Mallarmé always considered central: What is good poetry? (shrink)

Bayesian decision theory provides a simple formal elucidation of some of the ways that representation and representational abstraction are involved with, and exploit, both prediction and its rather distant cousin, predictive coding. Both model-free and model-based methods are involved.

We use neural reinforcement learning concepts including Pavlovian versus instrumental control, liking versus wanting, model-based versus model-free control, online versus offline learning and planning, and internal versus external actions and control to reflect on putative conflicts between short-term temptations and long-term goals.