Individual differences in human gaze behaviour and the visual system

ended

Does visual perception vary between people? This question has fascinated philosophers for millennia, but largely evaded empirical vision science. Recent findings show that eye-movements towards complex, everyday scenes are drawn to important objects, like faces, but the attentional ‘pull’ of different objects reliably varies between people. We do not yet understand the causes and perceptual consequences of these individual salience biases. Understanding their basis in the individual brain has the potential to reveal general mechanisms of attentional selection. Uncovering their distribution in the general population is key to evaluate their potential as a biomarker. We propose three sets of experiments to achieve these goals. First, we will use psychophysics, virtual reality and mobile eye tracking to probe which visual features are driving individual salience biases and how they affect task-driven and real-world behaviour. Second, we aim to understand the neural mechanisms of attentional selection. It is unclear how the brain selects peripheral targets based on semantic attributes, which are thought to be processed by foveal pathways. We will exploit individual differences and the latest developments in brain imaging to juxtapose competing hypotheses and test the relation of salience biases to fine-scale functional neuroanatomy and connectivity. Third, we will evaluate the diagnostic potential of salience biases. We will record the gaze of thousands of individuals in a public setting to establish a norm sample of free viewing in the general population and compare observers with autism spectrum disorder and schizophrenia to this norm. This project will establish how and why natural gaze behaviour and perception vary between people. It will harness individual differences to uncover the general mechanisms that guide our eyes through the visual world. A norm sample of salience biases will lay the foundation to evaluate their use in clinical and applied settings.