How does the attention change the way in which our brain processes visual information? What processes mediate human learning in perceptual tasks? How does our brain decide where to direct our eyes when we search for an object in a visual scene? Do the neural mechanisms mediating eye movements and perceptual decisions process visual information in similar manners? I typically study these questions by comparing human performance to that of the optimal Bayesian observer (typically implemented on a computer). I also study the visual, cognitive and decision processes by which doctors detect and classify abnormalities in medical images and use computer models to improve the way in which we display medical images so that doctors can do fewer errors in clinical diagnosis.