Lengths
The pymetrics (Harver) Lengths game is a probabilistic reward task. A cartoon face flashes with a subtly short or long mouth, while one correct response is covertly rewarded more often to measure both discrimination and reward responsiveness.
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Updated
How to play
A cartoon face flashes briefly. Press Left Arrow if its mouth was SHORT or Right Arrow if its mouth was LONG.
On touch devices, use the left SHORT and right LONG tap zones after the face disappears.
Some correct answers show only a +$0.20 reward cue. All unrewarded answers—including correct and incorrect choices—advance silently and identically.
There is no ✓, ✕, red/green correctness flash, or answer reveal during play. Complete all 90 trials.
In the real assessment
The exact trial count, reward ratio, mouth difference, and flash duration are not public. This reconstruction uses the recommended 90 trials, about 10% length difference, 100 ms flash, and 3:1 rich-to-lean reward ratio—and deliberately preserves the covert feedback schedule.
Skills assessed
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Score improvement across practice attempts
Across our matched practice data, the median candidate improves their score by +14% between their first and fifth practice attempt on a game — with no employer ever seeing practice data.
Read the full methodologyMedian pymetrics score lift by practice attempt
Median paired change vs. first attempt on scored pymetrics practice games. Observed practice association — not a hiring-outcome guarantee.
Lengths practice guide
Read the rules, scoring context and practice strategies for this game.
Read the Lengths guideGameAssessmentPrep is an independent practice platform. We are not affiliated with pymetrics, Harver, or any employer. Our simulations are reconstructions for practice purposes.