People face a vast range of different cognitive tasks in their lives. Classic problem-solving theories do not fully capture the impact of the task structure on sequential decision-making. Here, we argue that it is important to consider task features that determine the search space structure of a task as it presents itself to the problem solver because the search space determines which algorithms are appropriate to solve the problem optimally. Knowledge of these optimal algorithms provides a base for cognitive modelling (...) of sequential decision-making. We propose a new task taxonomy by identifying ten features in four categories related to search space properties. We describe how these constrain the space of optimal algorithms. Furthermore, we categorise and compare several sequential decision-making tasks used in studies on human behaviour with our taxonomy and illustrate how the proposed task features can inform the creation of new tasks and computational modelling of behaviour. (shrink)

The efficient coding hypothesis posits that sensory systems are tuned to the regularities of their natural input. The statistics of natural image databases have been the topic of many studies, which have revealed biases in the distribution of orientations that are related to neural representations as well as behavior in psychophysical tasks. However, commonly used natural image databases contain images taken with a camera with a planar image sensor and limited field of view. Thus, these images do not incorporate the (...) physical properties of the visual system and its active use reflecting body and eye movements. Here, we investigate quantitatively, whether the active use of the visual system influences image statistics across the visual field by simulating visual behaviors in an avatar in a naturalistic virtual environment. Images with a field of view of 120° were generated during exploration of a virtual forest environment both for a human and cat avatar. The physical properties of the visual system were taken into account by projecting the images onto idealized retinas according to models of the eyes' geometrical optics. Crucially, different active gaze behaviors were simulated to obtain image ensembles that allow investigating the consequences of active visual behaviors on the statistics of the input to the visual system. In the central visual field, the statistics of the virtual images matched photographic images regarding their power spectra and a bias in edge orientations toward cardinal directions. At larger eccentricities, the cardinal bias was superimposed with a gradually increasing radial bias. The strength of this effect depends on the active visual behavior and the physical properties of the eye. There were also significant differences between the upper and lower visual field, which became stronger depending on how the environment was actively sampled. Taken together, the results show that quantitatively relating natural image statistics to neural representations and psychophysical behavior requires not only to take the structure of the environment into account, but also the physical properties of the visual system, and its active use in behavior. (shrink)