Clock Drawing Test

The Clock Drawing Test (CDT) is a brief, widely used cognitive screening task in which a patient draws the face of a clock, places the numbers, and sets the hands to a specified time, most commonly ten past eleven. Despite its simplicity, the task draws on a wide network of cognitive abilities including visuospatial construction, executive planning, abstraction, and semantic memory, so that a poorly executed clock can be an efficient signal of cognitive impairment. In a frequently cited 2000 review, Kenneth Shulman asked whether clock drawing might be the ideal cognitive screening test, surveying its many scoring systems and its strengths and weaknesses. The drawing is rated with a scoring rubric that attends to the clock contour, the numbers, the placement and accuracy of the hands, and spatial or executive errors, and a low score flags the need for fuller assessment. Because it takes only a minute or two, requires only paper and pencil, and is relatively insensitive to language and education, the CDT is popular for screening older adults for dementia in clinics, hospitals, and community settings. It is typically used alongside, not instead of, broader instruments such as the Mini-Mental State Examination or the Montreal Cognitive Assessment.