Could calendrical savant ability depend on human-specific prefrontal circuitry rather than explicit symbolic calculation?
I’m wondering whether the following hypothesis is plausible, and whether there is any literature that already tests something close to it.
Some autistic savants can calculate the weekday of an arbitrary date extremely quickly, sometimes without being able to clearly explain the algorithm they are using. One possibility is that this is not ordinary explicit symbolic calculation, but an unusual learned computation implemented implicitly in high-level cortical circuitry.
A comparative experiment with apes might help distinguish this from a more evolutionarily ancient pattern-learning account.
You could train symbol-competent apes on a large number of date-like inputs mapped to one of seven outputs according to a hidden Gregorian-calendar-like rule. Importantly, the animals would never be taught the rule explicitly.
Then test the following:
a) memorization of trained examples
interpolation to unseen combinations within the training range
b) extrapolation to dates far outside the training range
c) performance around structurally informative cases such as leap-year and century-like boundaries
Run the same task in ordinary humans and, ideally, people with exceptional calendrical calculation ability.
My hypothesis would be that apes may become very good at memorization or local interpolation but fail at systematic long-range extrapolation, whereas human calendar savants may generalize rapidly despite being unable to verbalize the procedure.
If that happened, would it be reasonable to interpret it as evidence that calendrical savantism depends on a human-specialized frontoparietal/prefrontal computation that can operate implicitly, rather than simply enhanced associative pattern learning?
More specifically, is there a known reason to think anterior prefrontal cortex, hierarchical rule representations, or human-specific frontoparietal connectivity would be necessary for this kind of implicit algorithmic generalization?
And has anything remotely like this been tried in comparative cognition?