Effects of Cognitive Ageing on Finding and Selecting Reliable Landmarks

Not every object is a useful landmark when learning routes, be it due to repetitive occurrence or visual appearance. Salient objects might be easier to memorize than non-salient objects, but if they appear more than once along a route, they cannot be used as reliable landmarks. As cognitive ageing affects executive functions and control of attention, we hypothesized that it could also impact on the process of selecting navigationally relevant objects as landmarks. Here we investigated how cognitive ageing affects people’s ability to select unique objects as landmarks when learning novel routes. We created two types of routes through a virtual care home each comprising four intersections each with two objects. On simple routes, the unique landmarks were also salient. On complex routes, in contrast, the salient objects occurred twice, while the non-salient objects were unique. The behavioural data showed that younger participants outperformed the older participants in route learning and the eye-movement data revealed some systematic differences between age groups. Specifically, older adults spent less time attending navigationally relevant information, but both groups effectively directed gaze towards the unique and away from the non-unique objects, even if these were more salient. While the findings highlight differences in control of attention between age groups, we believe that these differences cannot account for the pronounced differences in route learning performance. Instead, we show that individual differences in word list learning and Corsi blocks task performance were predictive for route learning performance in the older, but not the younger, participant group