How sandbag-able are concussion sideline assessments? A close look at eye movements to uncover strategies.
John-Ross Rizzo, Todd E Hudson, John Martone and 7 others
PMID 33529094WHAT IT FOUND
When twenty healthy volunteers were coached to fake poor King-Devick test scores, their eye movements changed.
Longer pauses between eye movements, more eye movements, and more backward eye movements helped detect the faking.
Key findings
01Coached sandbagging made King-Devick times substantially longer than best effort, with a mean increase of 41.5 ± 23.9 seconds, and only four participants produced a sandbag time less than 10 seconds longer than their best effort time.
02During sandbagging, eye movements showed longer median inter-saccadic intervals, more saccades, and more saccades in the wrong direction.
03Eye movement metrics detected sandbagging better than a model using King-Devick times alone.
STILL TO COME
How it was doneWhat they found
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What it does not show
The study included only twenty healthy adult non-athletes, so it does not show how athletes, younger people, or people with concussion would behave. Eye movement data were unusable for one participant, so that participant contributed only age and test times. The small sample makes the eye movement model vulnerable to overfitting. Sleep, medications, caffeine or guarana were not measured, and these could affect sandbagging.
Declared interests
The study had NIH extramural research support. No author received financial compensation or consultant fees from King-Devick Test, Inc., and the authors reported no other pertinent disclosures.
The easy way to misread this
Do not conclude that eye movement testing is ready to use on the sideline to detect sandbagging. This was a pilot in twenty healthy adults without histories of traumatic brain injury, and eye movement data were unusable for one participant.