Changes in visual processing strategy: effects of context, task, and training

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I investigate how our brains use visual information so that we may perceive the outside world. To do so, I perform psychophysical experiments where human participants make judgements about stimuli. I design these experiments to allow performance to be compared against predictions from models of visual processing. I can then investigate the strategies that the brain uses to solve these tasks. In my upcoming research, I will explore how these processing strategies change under various conditions. Under Signal Detection Theory, the visual system is performing a continuous statistical inference on noisy and unstable input signals. This frames the "problem" of vision in terms of uncertainty. The noisy input is used to resolve this uncertainty into a perceptual experience. It is proposed that the processing incorporates the principles of efficient coding. This would predict there should be an adaptive strategy, tailoring its processing based on the task posed to it. There is previous evidence that the visual system adapts in this way both from my own work and from other laboratories. For example, I will investigate a possible homeostatic balance in the integration of noisy signals. Greater integration reduces noise, but comes at the cost of a loss of precision. By measuring behaviour, inferences can be made about the underlying processing. It is possible however to design many tasks that all target a single underlying function. One example is the mechanism by which visual contours are joined-up into a continuous percept. Recently, I have developed a new method to probe this. The conclusions drawn from the new task differ from those found previously. This may be due to the system adjusting its contour processing on the basis of the task. Alternatively, differences in stimulus design may alter processing in a system which is task-agnostic. I will use different tasks to constrain an understanding of contour integration, and its relationship to other functions performed on similar stimuli. I am interested in the time scale over which these changes in strategy occur. Does it shift pre-emptively in response to the expected demands? Or must it be entrained during task experience? There is also the question of how effects would transfer between different tasks. Recent studies have shown that training can have a fundamental impact on how visual information is processed. I will explore this. Psychophysics allows us to investigate visual processing directly through is effects on behaviour. My research into how humans perform visual tasks will improve techniques to measure that performance. Understanding how the brain tackles the shifting challenges involved in vision may also help us see how it performs other functions. This is of interest to computer vision researchers, to reveal cases where fixed solutions are insufficient. Finally, knowing the strengths and weaknesses of our abilities allows them to be considered when designing systems for human interaction.