Time-of-Day Effects on Competitive Speedcubing Performance

Competitive speedcubing - the timed solving of Rubik's Cube puzzles under standardised World Cube Association (WCA) rules - uniquely couples rapid visuospatial processing and working memory with high-speed bimanual fine motor execution, making it a tractable paradigm for investigating time-of-day associations in real-world expert cognitive-motor performance. We analysed 6,600 record-setting performances across four puzzle categories (3 × 3 × 3, 4 × 4 × 4, 5 × 5 × 5, 6 × 6 × 6) from WCA competitions held between 2003 and 2025 using an exposure-adjusted framework in which record probability is expressed as records per attempt within 15-minute local-time bins, evaluated against a within-competition permutation null that preserves schedule structure. Raw record counts exhibit a bimodal distribution with morning and evening peaks; however, exposure adjustment demonstrates that this pattern is substantially attributable to the non-uniform scheduling of competition rounds across the day. After schedule correction, the 4 × 4 × 4 event shows a statistically significant suppression of record probability during the 12:30-15:00 window (outside-to-inside ratio: 1.14×; one-tailed permutation p = 0.020), consistent in timing with the post-prandial alertness dip. This effect is not statistically significant for the 3 × 3 × 3, 5 × 5 × 5, or 6 × 6 × 6 events. Sensitivity analyses confirm that the 4 × 4 × 4 finding is broadly distributed across regions and competitive eras and persists within early rounds alone. The late-evening elevation in raw counts is explained by final-round competitor selection. These results demonstrate the methodological importance of exposure adjustment in ecological performance analyses and identify a residual midday suppression in 4 × 4 × 4 record probability that warrants further investigation.