Evaluating the contributions of age-related changes in sensory acuity and cognitive control on the speed and accuracy of visual search

The ability to identify and locate task-relevant objects in the scene is a key component of functional vision. In psychology and human neuroscience, this ability has been investigated using visual search tasks, which measure the speed and accuracy of detection for a target among non-target (distractor) stimuli. Ageing is associated with changes in sensory and cognitive processes, which are likely to impact the efficiency of search. Despite this, evidence to support age-related changes in the efficiency of visual search is mixed. Contradictory findings reflect heterogenous samples and different measures used to investigate age-related changes in sensory and cognitive components of search. Studies investigating age-related changes in sensory acuity rarely test cognitive mechanisms associated with the evaluation of visual input, short-term memory or the planning and execution of saccades. Studies testing cognitive components of search, rarely control for the effects of age-related differences in visual acuity. To address these limitations, the present project will quantify age-related changes in sensory acuity by employing different psychophysical techniques to measure contrast and chromatic sensitivity for stimuli across the visual field. In addition, the study will combine simultaneous eye tracking and electroencephalogram (EEG) recording to obtain accurate measures of the neural responses that modulate target representation, guidance, selection and identification during search. EEG measures will include fixation-based potentials and power analyses at specific frequency bands. The combination of eye movement and EEG data will provide unique insights into age-related changes in the cognitive and neural mechanisms that support the selection and evaluation of information during visual search.