Serial Sevens/Threes Task

Background

Serial Subtraction tasks (Serial-7, Serial-3), are cognitive measures of executive functioning and processing speed. The general task is the same for both: given a random starting number, subtract 7 (3) as often as possible within a certain timespan. Both tasks involve working memory (hold the current number in short term memory, manipulate it and update it), and require numerical ability as well as focus over an extended period. They differ in their level of difficulty. While the Serial-3 task is relatively easy for most adults and can be seen as a test of how fast people can process simple information, the Serial-7 task is more demanding, requires more cognitive resources and is thus considered a more sensitive measure of executive impairments.

The Serial Subtraction paradigm is credited to Emil Kraepelin (1899) who proposed serial subtraction (specifically subtracting 7 from 100) as a way to measure disturbances in attention. Variants of the Serial Subtraction tasks are standard components of several contemporary cognitive diagnostic instruments such as the Mini-Mental State Examination (MMSE), the Montreal Cognitive Assessment (MoCA), and the Cognitive Demand Battery (CDB).

Task Procedure

The general task to perform is the same for both tests: given a starting number (e.g. randomly chosen from 800-999), participants are asked to mentally subtract 3 (7) from this number as often as possible within a certain time frame (here: 2 minutes). Participants enter their solution to each new subtraction step via a response dial. Each response is evaluated only relative to the previously entered number.

What it Measures

Serial Subtraction tasks are measures of executive functioning and processing speed.

Psychological domains

• Executive Functioning: Monitoring working memory and updating working memory by replacing old, no longer relevant information with new, relevant one
• Working Memory: Storage and manipulation of information in short term memory
• Processing Speed: Speed of information processing
• Sustained Attention: Ability to maintain focus on a continuous repetitive task over a long time.

Main Performance Metrics

• Accuracy: number of correct subtractions made within the time limit as a measure of Working Memory
• Errors/ErrorRate: number of incorrect subtractions as a measure of attention lapses or increase of fatigue
• Total Responses: number of total submissions made as a measure of information processing speed

Psychiatric Conditions

The following patient groups show impaired performance on Serial Subtraction tasks

• Dementia
• Mild Cognitive Impairment (MCI)
• Traumatic Brain Injury (TBI)
• Stroke
• Depression
• Schizophrenia

Test Variations

References

Search Google Scholar for peer-reviewed, published research using the Inquisit Serial Sevens/Threes Task.

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Kennedy, D.O. & · Andrew B. Scholey, A.B. (2000). Glucose administration, heart rate and cognitive performance: effects of increasing mental effort. Psychopharmacology (2000) 149:63–71.

Srygley, Mirelman, Herman, Giladi, & Hausdorff. (2009). When does walking alter thinking? Age and task associated findings. Brain Research, 1253, 92-99.

Margaret Anne Defeyter, & Riccardo Russo. (2013). The effect of breakfast cereal consumption on adolescents’ cognitive performance and mood. Frontiers in Human Neuroscience, 7(NA), NA.

Kannape, O., Barré, A., Aminian, K., & Blanke, O. (2014). Cognitive Loading Affects Motor Awareness and Movement Kinematics but Not Locomotor Trajectories during Goal-Directed Walking in a Virtual Reality Environment. PLoS One, 9(1), E85560.

Kim, Needle, Thomas, Higginson, Kaminski, & Swanik. (2016). A sex comparison of reactive knee stiffness regulation strategies under cognitive loads. Clinical Biomechanics, 35, 86-92.