Ageing and distraction: The effect of central and peripheral cognitive and sensory systems

Aging involves changes in both sensory and cognitive processes. Both of these are likely to contribute to increased difficulty ignoring distractions with age. However, the influence of sensory processes on overcoming distractions has rarely been controlled for or assessed, with the majority of studies confounding age and sensory loss. Critically, fully understanding distraction in ageing requires separating peripheral, sensory, processes from more central, cognitive change. Moreover, theoretical models have largely focused on distractions from within the same sensory modality, yet in real life, we are faced with distractions from multiple senses. The aim of the PhD project is therefore to extend current theoretical models based on distractions within the same sense to include distractions from other sensory modalities, as well as to isolate the role of cognitive and sensory processes. The project also has the potential for societal impact in terms of maintained daily functioning and independence of older citizens, who might sometimes feel overwhelmed by complex and distracting situations.
In order to investigate distraction in more detail, an approach that can disambiguate these different stages of processing is needed. Interference from distraction can arise from interference between the brain's representations of stimulus inputs or from interference between the responses to those stimuli. In our previous research we used a modified colour-word Stroop task where response choices were paired so that the distraction could either cue a different response to the attended feature ('response/cognitive interference') or the distraction and attended feature differed in sensory input but share the same response ('stimulus/sensory interference'). Our findings suggested that older people maintain the ability to inhibit cross-modal distractors at early, sensory processing, stages and, thus maintain the ability to avoid cross-modal distraction.
A further limitation of previous work is that auditory and visual distractions have not been tested in a symmetric design, where distractions in each modality have been tested in the same experiment and in the same way. The first stage of the PhD project will therefore use a new fully symmetric task design to compare the interactions between sensory and cognitive processes in ignoring unimodal and cross-modal distraction in healthy older and younger adults. Participants are asked to respond to the location of a tone or light while ignoring written or spoken locations (up/down/left/right). This has the advantage that performance in both senses is evaluated using identical measures where the strength of the signal is psychometrically matched.
One possible extension of this work is to assess the impact of sensory quality on cross-modal distraction. This can be done by a) systematically varying the quality of the stimuli shown to people with good sensory abilities and/or by measuring the effects of ameliorating sensory loss via cataract removal and the use of hearing aids.
A second possible avenue of exploration is to extend the lab-based findings to more real-life tasks and situations, based on previous engagement/co-creation work highlighting that older people find (book) shops particularly distracting. This represents a significant step-change of applied cognitive brain research with potential real-world applications.