Computerized measures of finger tapping: Reliability, malingering and traumatic brain injury

Abstract

We analyzed computerized finger tapping metrics in four experiments. Experiment 1 showed tapping-rate differences associated with hand dominance, digits, sex, and fatigue that replicated those seen in a previous, large-scale community sample. Experiment 2 revealed test–retest correlations (r = .91) that exceeded those reported in previous tapping studies. Experiment 3 investigated subjects simulating symptoms of traumatic brain injury (TBI); 62% of malingering subjects produced abnormally slow tapping rates. A tapping-rate malingering index, based on rate-independent tapping patterns, provided confirmatory evidence of malingering in 48% of the subjects with abnormal tapping rates. Experiment 4 compared tapping in 24 patients with mild TBI (mTBI) and a matched control group; mTBI patients showed slowed tapping without evidence of malingering. Computerized finger tapping measures are reliable measures of motor speed, useful in detecting subjects performing with suboptimal effort, and are sensitive to motor abnormalities following mTBI.

Keywords:

• Finger oscillation
• Symptom validity
• Traumatic brain injury
• Tapping rate
• Motor speed
• Tap failure
• Index finger
• Effort
• Test–retest

Notes

¹The CCAB includes the following computerized tests and questionnaires: finger tapping, simple reaction time, Stroop, digit span forward and backward, phonemic and semantic verbal fluency, verbal list learning, spatial span, trail making, vocabulary, design fluency, the Wechsler Test of Adult Reading (WTAR), visual feature conjunction, risk and loss avoidance, delay discounting, the Paced Auditory Serial Addition Task (PASAT), the Cognitive Failures Questionnaire (CFQ), the Posttraumatic Stress Disorder Checklist (PCL), and a traumatic brain injury (TBI) questionnaire.

²Presentation® software provides measures of timing precision for each event that averaged less than 0.5 ms for button depressions and releases. As in our previous study, we noted occasional ITIs that were less than 40 ms (0.1% of all measured taps). Because these extremely quick taps were much faster than fastest sustained observed tapping speed (∼130 ms), all taps faster than 40 ms were removed from the data, and the time accounted for by these taps was allotted to the subsequent tap.

Figure 1.  Top: Tapping measures assessed by the computer. Measurements include down time (DT), the time that the mouse button was depressed, and movement initiation time (MIT), the interval between button release and the next button press. The sum of DT and MIT defined the intertap interval (ITI) for each button press. Bottom: Example profile for a single subject tapping (only 15 s of the 30-s time period is shown). Dominant hand index finger performance is illustrated by ITI, MIT, and DT. Three tap failures are illustrated. To view a color version of this figure, please see the online issue of the Journal.