Hospitalised patients will be asked to undertake a number of tests at their bedside. These tests will be administered to patients once only. Patients will be visited by two different researchers on the same day, with a gap of approximately 15-60 min between assessment visits assuming that consent is provided in the first visit. The first visit will involve assessment of capacity and (in those thought likely to be capable of giving consent) obtaining informed consent, as well as assessment of delirium (reference tests) and cognition. The second visit will involve the DelApp assessment (index test). Thus, the index test and reference tests are administered by independent raters. Where the patient is unable to provide consent for themselves, proxy consent will be sought, and if granted, the same visits as above will occur.