Mackworth Clock Vigilance Test

Background

The Mackworth Clock Test (MCT) is a classic neuropsychological measure of sustained attention in the context of monotonous stimulation with rare signal events. N. H. Mackworth developed the test for the British Air Force to evaluate vigilance of radar technicians during World War II. The original Mackworth Clock instrument provided a monotonous clock-like setup with a discretely moving hand that moved from one position to the next at constant speed but occasionally skipped a position ('signals'). Participants had to watch this monotonous clock setup for long periods while being prepared to press a Morse key immediately upon detection of such signal jumps.

In contrast to the similar Continuous Performance Test (CPT), that was originally developed by Haldor Rosvold only slightly later in 1956, the Mackworth Clock, despite its early promise, lacked public interest, likely because no instrument nor standardized task procedure was easily accessible. With the emergence of computer testing, the interest in the MCT was revived, and in 2011, Kenneth L. Lichstein and colleagues published and validated a computerized design and procedure of the Mackworth Clock test that closely mirrored the original MCT setup.

Task Procedure

Participants are shown a circle of 100 white dots. A single red dot moves from dot to dot at constant speed (changing positions every 1s). Occasionally, the red dot skips several positions, and participants must the spacebar as soon as they notice such a skip event.

The test consists of two runs (though not announced to participants). Each round takes 30 minutes and runs 12 skip events. A short practice session of 1 minute (with 2 skip events) is optional to run to familiarize participants with the procedure.

What it Measures

The MCT is a measure of sustained attention.

Psychological Domains

• Sustained Attention: Ability to maintain focus on a continuous repetitive task over a long time.
• Inhibitory Control: Ability to withhold a response to non-target stimuli

Main Performance Metrics

• Reaction Time: Speed of responses (processing speed, alertness)
• Omission Errors: Rate of missed targets (inattention)
• Commission Errors: Rate of false alarms, or responses to non-targets (response inhibition)
• d': Measure of discriminability/sensitivity to targets

Psychiatric Conditions

Performance on the MCT tends to be impaired in patients with the following psychiatric conditions:

• Attention Deficit Hyperactivity Disorder (ADHD)
• Traumatic Brain Injury (TBI)
• Dementia

Test Variations

References

Search Google Scholar for peer-reviewed, published research using the Inquisit Mackworth Clock Vigilance Test.

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Mackworth, N. H. (1948). The breakdown of vigilance during prolonged visual search. Quarterly Journal of Experimental Psychology, 1, 6-21.

Giambra. L. M.. & Quilter, R. E. (1988). Sustained attention in adulthood: A unique, large-sample, longitudinal and multicohort analysis using the Mackworth Clock Test. Psychology and Aging, 3, 75-83.

Lichstein, K.L., Riedel, B.W., & Richman, S.L. (2000). The Mackworth Clock Test: A Computerized Version. The Journal of Psychology, 134, 153-161.

Williamson, A.M., Feyer, A.M., Mattick, R.P., Friswell, R., & Finlay-Brown, S. (2001). Developing measures of fatigue using an alcohol comparison to validate the effects of fatigue on performance. Accident Analysis and Prevention, 33, 313-326.

Wichniak, A., Waliniowska, E., Musinska, I., Czasak, K., Jakubczyk, T., Wierzbicka A., Wolkow, L., & Jernajczyk, W. (2011). P.3.c.016 EEG slowing, vigilance and daytime sleepiness during treatment with sedative and non-sedative antipsychotics. European Neuropsychopharmacology, 21, S477.

Blatter, K., Graw, P., Münch, M., Knoblauch, V., Wirz-Justice, A., & Cajochen C. (2006). Gender and age differences in psychomotor vigilance performance under differential sleep pressure conditions. Behavioural Brain Research, 168, 312-317.