Symbol Search

Background

The Symbol Search Task is a popular psychological assessment measure of cognitive processing speed requiring visual scanning, attention and pattern matching abilities under time pressure. The Symbol Search task was added to the Wechsler Intelligence Scales after David Wechsler's death in 1991 but the task, being part of his batteries, is nonetheless still attributed to him. To this day, the Symbol Search Task is part of the Wechsler Adult Intelligence Scale (WAIS) and the Wechsler Intelligence Scale for Children (WISC).

The Symbol Search task, as part of the Wechsler Intelligence batteries, is administered as a pencil and paper test. It presents rows of five symbols each that may or may not contain any one of two target symbols to look out for. Participants have to scan each row for these target shapes and mark them if found. If none is found, participants have to select a 'No' button instead. Participants usually have 2 minutes to finish as many rows as they can.

Millisecond's computerized Symbol Search Task follows a similar set up and can be run with mouse or touch input.

Task Procedure

Participants work on 3 practice problems before the actual 2 minute testing period starts. The practice problems are not timed and error responses have to be corrected.

During the test period, each 'page' presents 10 rows with 5 symbols as well as a 'No' button in addition to the two target symbols. The two target symbols are always presented to very left of each row on a different colored background. The Millisecond implementation does not allow row skipping: participants have to finish each row before the next row is activated. Previous responses cannot be corrected. Each selected choice is marked with a blue circle. The default test duration is set to 2 minutes. The maximum number of pages provided is 10.

What it Measures

The Symbol Search Task is predominantly a measure of processing speed

Psychological domains

• Processing Speed: Speed with which the brain can make simple matching operations
• Visual Scanning: Ability to move eyes efficiently to locate specific information
• Selective Attention: Ability to focus on one specific task

Main Performance Metrics

• Correct Count: Number of correct matches made in the given timeframe

Psychiatric Conditions

Symbol Search Task performance tends to be impacted in the following patient groups:

• Attention Deficit Hyperactivity Disorder (ADHD)
• Autism Spectrum Disorder (ASD)
• Dyslexia
• Traumatic Brain Injury (TBI)
• Schizophrenia
• Major Depressive Disorder (MDD)
• Dementia

References

Search Google Scholar for peer-reviewed, published research using the Inquisit Symbol Search.

---

Carone, Patton, Bums, Starrat, Natale, Simpson, . . . Puranik. (2000). Pediatric closed head injury: Using symbol search as a substitute on the WISC-III. Archives of Clinical Neuropsychology, 15(8), 795.

Sweet, L., Paskavitz, J., Oconnor, M., Browndyke, J., Wellen, J., & Cohen, R. (2005). FMRI correlates of the WAISIII Symbol Search subtest. Journal of the International Neuropsychological Society, 11(4), 471-476.

Liebel, S., Clark, U., Xu, X., Riskin-Jones, H., Hawkshead, B., Schwarz, N., . . . Sweet, L. (2015). An FMRI-Compatible Symbol Search Task. 21(3), 231-238.

Ebaid, Deena, Crewther, Sheila G., MacCalman, Kirsty, Brown, Alyse, & Crewther, Daniel P. (2017). Cognitive Processing Speed across the Lifespan: Beyond the Influence of Motor Speed. Frontiers in Aging Neuroscience, 9.