19% of my readers self-reported Human Benchmark sequence memory highest scores of level 21+ (after 10 attempts).

3% of my readers self-reported highest scores of 6 or less.

Evidence continues to accumulate showing that on a scale where Americans average IQ 100 (SD = 15), my global readership towers with an average IQ of 129 (SD = 19). Thus assuming a normal curve, the top 19% and bottom 3% should have IQs of 147+ and sub-98 respectively.

Assuming the sequence memory test is sufficiently g loaded, this implies level 21 = IQ 147 and level 6 = IQ 97.

Thus I would predict that a random sample of American youngish adults would average 6.84 (SD = 4.5).

Put simply:

IQ = 77 + (highest level obtained in first 10 tries)(3.33)

However one oddity about the self-reported data is that all of the people scoring 21+ score 24+. Nobody reported a score of 21 to 23. This suggest inaccuracy of self-reported data but it may also suggest that above level 21, the test starts measuring certain cognitive strategies and stops measuring g.