Background. Savant calendar calculators can supply with
speed the day of the week of a given date.
Although memory is suggested to be an important component of this unusual
ability, memory
function has never been systematically investigated in these skilled yet
learning impaired individuals.
Methods. Eight savant calendrical calculators, most of whom
had autism, were compared with eight
verbal IQ, age and diagnosis matched controls on digit and word span tests
and measures of long-term
memory for words and calendrical information (individual years). In an
analogue to the
‘generation effect’, the savants' memory for dates was
also compared following calculation and
study/read tasks.
Results. The savants did not differ from controls on measures
of general short- and long-term
memory. They did, however, show a clear recall superiority for the long-term
retention of
calendrical material. They also remembered calculated dates better than
those that were only
studied.
Conclusions. A general mnemonic advantage cannot explain savant
date calculation skills. Rather,
through exposure to date information, the savants are suggested to develop
a structured calendar-related
knowledge base with the process of calculation utilizing the interrelations
within this
knowledge store. The cognitive processing style characteristic of autism
may also play a role in the
acquisition of this savant ability.