Well, that seems plausible, although what is going on there is being divisible by 2, not being prime. If your general hypothesis is correct, then if we used a base 9 system numbers divisible by 3 might seem off. However, I’m not aware of any bias against numbers divisible by 5. And there’s some evidence that suggests that parity is ingrained human thinking (children can’t much more easily grasp the notion of whether a number is even or odd, and can do basic arithmetic with even/oddness much faster than with higher moduli).
Well, that seems plausible, although what is going on there is being divisible by 2, not being prime. If your general hypothesis is correct, then if we used a base 9 system numbers divisible by 3 might seem off. However, I’m not aware of any bias against numbers divisible by 5. And there’s some evidence that suggests that parity is ingrained human thinking (children can’t much more easily grasp the notion of whether a number is even or odd, and can do basic arithmetic with even/oddness much faster than with higher moduli).