UK Biobank cognitive assessment questionnaire
The UK Biobank cognitive test battery was designed to be administered unsupervised, and, although there were staff members present in the UK Biobank clinic during test administration, participants were expected to work through the cognitive assessment independently without a tester observing. Because no tester was there to help participants understand the test instructions, the onscreen instructions for each test must be clear. To assess this, after completing the UK Biobank cognitive assessment participants were asked, "Did you generally find that the instructions for all the tasks were clear?". Participants answered either yes or no. Next, participants were shown screenshots of each UK Biobank cognitive test and were asked "Were the instructions for this test clear?". Participants answered either yes or no.
The UKB Numeric Memory task was designed to assess backward digit span, which involves participants remembering a sequence of digits and then mentally reversing them in their mind. However, for this task, all the numbers in the to-be-remembered sequence were presented on the screen at once. This meant that some individuals were able to get the correct answer by reading the number sequence from right-to-left and not reversing the digits in their mind. These individuals are actually performing a forward digit span, which is an easier task. To identify the number of participants who completed this task forwards or backwards, participants were asked how they completed this task. The possible options were: read from left-to-right and reversed the digits in your mind; read from right-to-left and did not need to reverse digits in your mind; a mixture of both; something different.
