Sway: A Novel Approach for Simple Reaction Time Measurement

PURPOSE: To examine the reliability and validity of a mobile device application for measuring simple reaction time (SRT).

RATIONALE: Measurement of SRT can help occupational therapists identify individuals with subtly impaired cognitive functioning. SRT assesses the ability to process information quickly, a common problem in individuals with neurological conditions (Barker-Collo, 2006). SRT is typically assessed with specialized equipment or computerized tests that may not be accessible in clinical settings (Schatz, Ybarra,, & Leitner, 2015). Mobile devices may support clinicians in settings without access to dedicated assessment methods.

DESIGN: Cross-sectional design evaluating test–retest reliability and criterion validity of a mobile device application (app) for use in reaction time testing.

PARTICIPANTS: Twenty adults (mean age = 30.7 yr, standard deviation = 11.5; range = 21–59), without known orthopedic, musculoskeletal, or neurological conditions, participated in the study.

METHOD: Participants completed a series of SRT tests using a mobile device (Apple iPod Touch 5th generation; Apple Inc.). Sway (Sway Medical, LLC), a Food and Drug Administration–approved application designed to access the built-in sensors for movement detection, was used for testing. participants completed four sequences of SRT tests, each with 5 trials followed by a minute’s rest. Participants were instructed to hold the device and give a quick shake in response to visual cues on the screen. The time required to respond to each stimulus was recorded by the device.

After completing the Sway SRT tests, participants completed a series of tests using a computerized test of information processing, a gold-standard computerized measure of SRT. Participants completed a total of 20 trials of responding to a stimulus presented on the screen by pressing the spacebar, with response times for each trial recorded.

ANALYSES: Test–retest reliability was assessed using an intraclass correlation coefficient (ICC) between each Sway sequence. Pearson correlations were used to assess criterion validity between Sway and computerized test means.

RESULTS: Test–retest reliability between Sway tests was statistically significant. The lowest agreement occurred between Tests 1 and 2 (ICC = .84, p < .001), and the highest agreement occurred between Tests 3 and 4 (ICC = .90, p < .001). A paired-samples t test revealed a significant difference between Tests 1 and 2, t(19) = 2.53, p = .02. No other comparisons yielded significant differences. Pearson correlation between Sway and computerized test means yielded a significant correlation (r = .67, p < .001).

DISCUSSION: High agreement between individual tests suggests that Sway is a reliable method to assess SRT. A significant difference between the average scores from Tests 1 and 2 may indicate a learning effect and need for practice. Clinicians should allow clients to complete multiple tests to control for the effect. No significant differences were noted between other tests, indicating that a fatigue effect was not observed after four tests.

The strong correlation between Sway and computerized tests indicates that Sway may be suitable for rapidly administering SRT testing in healthy individuals. Future research must be conducted across health conditions and contexts to further evaluate the effectiveness of this approach for clinical use.

IMPACT STATEMENT: Mobile applications, including Sway, may provide clinicians with accessible and accurate objective tests of SRT, allowing for improved care for the people we serve.

References

Barker-Collo, S. L. (2006). Quality of life in multiple sclerosis: Does information-processing speed have an independent effect? Archives of Clinical Neuropsychology, 21, 167–174. http://dx.doi.org/10.1016/j.acn.2005.08.008

Schatz, P., Ybarra, V., & Leitner, D. (2015). Validating the accuracy of reaction time assessments on computer-based tablet devices. Assessment, 22, 405–410. http://dx.doi.org/10.1177/1073191114566622