Fundamentals of the clock drawing test and its digital evolution

June 30 2023

The clock drawing test has been a go-to method for evaluating patients for cognitive impairment since the early 1900s. But it has only been since the 1970s and 1980s that administration of the clock drawing test became standardized. Dr. Edith Kaplan, one of the most renowned neuropsychologists of the 20th century, took a new approach to administering the test, incorporating elements from the Boston Process Approach. This approach holds that assessing the process and strategy used by patients to complete cognitive tasks — and the errors that emerge, not just the final results — makes for richer, more accurate insights into their cognitive health.

Dr. David Libon and Dr. Rod Swenson both trained with Dr. Kaplan, and have been active clinicians and researchers in the field of neuropsychology for their entire careers. As such, they’re well-versed in both the clock drawing test and the Boston Process Approach. We had the opportunity to talk to them about the fundamentals of the test, as well as how the incorporation of process-based insights took the analysis of patients’ clock drawings to a new level.

The roots of process-based assessments

Dr. Kaplan's mentor, Dr. Heinz Werner, was one of the creators of Gestalt psychology, a field of psychology that started in early 20th century Europe. In his thesis, Werner emphasized that psychological testing should look at patients’ behaviors as they solved various cognitive tasks. This approach would allow those administering a test to go beyond summary scores by studying the types of errors people make when solving a task and how any self-corrections occurred.

Dr. Kaplan applied Werner’s ideas to the patients she studied at the Boston VA Medical Center and systematically developed the Boston Process Approach. Over decades, Kaplan developed numerous neuropsychological tests to give providers insight into the means by which a cognitive test score is derived, and ultimately empower them with a better understanding of a patient’s cognitive status.

The draw of the clock drawing test

Why is the clock drawing test still so popular today? Swenson and Libon attribute part of its draw to its universality and familiarity for both patients and providers.

“The clock drawing test assesses a wide number of underlying cognitive abilities. And it's also an engaging test [ . . . ] people like clocks, people have a knowledge of time and time representation. So the clock drawing test is very well tolerated across a wide number of patient populations.” - Dr. David Libon

Swenson expounded on this by explaining the basic elements of the clock drawing test.

When clinicians administer the test, they ask their patients for two versions of a clock drawing. The first is the “command” test condition, when a patient is asked to “draw the face of a clock, put the numbers in, and set the hands at 10 after 11.” The second condition involves having the patient copy a clock that has the clock hands set at 10 after 11.

The beauty of having these two conditions is that they measure overlapping but different cognitive functions. With the command test, the patient has to remember what the clinician asked and execute it. With the copy test, however, the patient simply has to copy the clock in front of them. Having the two together reveals additional insights. For example, sometimes for patients with cognitive impairment, errors and related behavior that emerged during the command test condition remain strong in their minds when asked to do the copy clock; they’re simply not able to appreciate that the parameters of the test have changed, thus resulting in significant impairment. Together, the two tests allow clinicians to investigate several underlying cognitive constructs, including memory, executive functioning, visuospatial reasoning, scanning, motor output and language processing.

Setting a specific time

The setting of time on the clock drawing test used to be somewhat arbitrary. Dr. Kaplan brought a clinical angle to this aspect of the test by standardizing the time requested to be for “10 after 11.”

“That is the kind of command that pulls for frontal system impairment. So many patients, for example, when asked to draw the clock hands at “10 after 11” will draw one to the 10 and one to the 11 because of the stimulus-found nature of the instruction, so it was a way to pull for dysexecutive impairment.” - Dr. Rod Swenson

Certain areas of the brain related to language are adjacent to those related to the capacity for learning. This means that people might draw the clock circle well, but experience difficulty on two key fronts:

  • Understanding that they’re not being asked to draw the clock hands to the numbers 10 and 11
  • Disambiguating the syntax of the command to set the hands to 10 after 11

Because of these two considerations, providers can use the clock drawing test to test for frontal system impairment.

“This is part of the genius that Dr. Kaplan brought to bear on this test. But it also illustrates again the multidimensionality, the multiple underlying cognitive abilities that clock drawing can help assess.” - Dr. David Libon

Deeper insights with a digital clock drawing test

The Boston Process Approach revolutionized the clock drawing test. Now, AI is taking both the approach and cognitive assessment to the next level.

A digital clock drawing test with process-based analytics can detect subtle signs of cognitive issues that the eyes of the most experienced neuropsychologists can’t catch. While a provider might notice some hesitation when a patient draws the face of the clock, for instance, this test will indicate precisely how long the hesitation lasted.

Process-based cognitive tests can capture a vast array of other metrics as well, including both the speed at which the patient executes each pen stroke and how much time elapses before they execute the next stroke. These latencies in response time and other process metrics recorded provide rich insights into the patient’s cognitive health far beyond a mere completed drawing of the clock.

And with the digital clock test from Linus Health, providers can play back a recording of the patient’s drawing of their completed clock drawing. This function enables a clinician to observe where patients struggled and develop more insights into their cognitive functioning – ultimately enabling them to both identify the presence of an issue and act earlier to bring better understanding to their patients’ cognitive health.

“What the original neurologists in Europe were doing when they had patients and they didn't have MRI scans was giving patients things to do and then watching them. They watched them closely and were great observers. And Edith took that to another level. If she were alive today and looking at what was happening through digital advancements, she'd have a big grin on her face. Because this is really exciting stuff.” - Dr. Rod Swenson

For more on the evolution of the clock drawing test, click here.