The Mackworth Clock Test, developed by Norman Mackworth in 1948, was designed to simulate long-term monitoring tasks like those performed by WWII radar operators. Participants watch a pointer on a clock face and must respond when the hand makes an irregular “double jump.” Accuracy naturally declines over time, a phenomenon known as the vigilance decrement.
Historical Significance
Mackworth’s research revealed that sustained attention decreases quickly, which led to shorter shifts for radar operators. Today, the Mackworth Clock Test remains a cornerstone in attention research and is used in fields such as aviation, security, and neuroscience.
How the Task Works
The clock hand moves in small steps every 650 milliseconds, with occasional “double jumps” (rare skips).
Athletes must respond to these double jumps within 650 milliseconds.
Tapping later than 650 ms reduces accuracy.
Failing to respond within 650 ms counts as a lapse.
Vigilance Decrement Explained
Detection accuracy typically drops by 10–15% within the first 30 minutes and continues to decline over a full two-hour session.
In more demanding versions of the test, lapses can appear within the first 15 minutes.
Why Lapses Matter
A lapse occurs when an athlete fails to respond within the allowed time. The Mackworth Clock’s strict timing reveals true vigilance capacity.
Professional athletes typically record reaction times of 450–550 ms, with only about 5% variation and no lapses over a full 10 minutes.
The average person may have 5–20 lapses during the Mackworth Clock Test.
Athletes often feel they performed better than their results show. If this happens, review their reaction time, accuracy, and variation for the Mackworth Clock Test. In most cases, the data will reveal a higher-than-average reaction time, variation above 20%, and multiple lapses.
Remember, even the smallest delay, for example 651 ms, counts as a miss, not a system error.