Manual Versus Saccadic Assessment of Inhibition and Switching Deficits: Evidence the Saccadic System Exhibits Resistance to Healthy Aging

Inhibition and switching deficits occur with healthy aging and many clinical conditions, compromising performance of daily tasks and thus quality of life. Saccade tasks have often been used to assess inhibition and switching deficits, but they require access to expensive eye-tracking equipment and trained personnel. Moreover, with respect to switching, the aging literature suggests manual tasks may be more sensitive to deficits than saccade tasks. Here we directly compared the two response modalities for assessing inhibition and switching abilities, and characterised changes with healthy aging. We measured in 60 young adults (18-24 years) and 60 older adults (60-72 years) performance on keypress and saccade tasks identical in all ways except for response modality. Results showed that saccadic and manual responses significantly correlated, suggesting keypress tasks can act as a proxy for saccade tasks. Regarding aging effects, compared to saccadic responses, manual responses showed more robust inhibition and switching deficits, which suggests keypress tasks are more sensitive to age-related decline. Moreover, a lack of switching deficits for saccadic responses suggests the oculomotor system may be more resistant to age-related decline. Future research is needed to test whether these patterns extend to clinical populations with inhibition and switching deficits