TheSquealer

The original studies on short term memory i believe date back to the 50s with the first being a famous one called something like '7 plus or minus 2" which said that our short term memory can hold 7 pieces of information on average. This became the basis for telephone numbers being 7 digits.

One who took this further is K Anders Ericsson (leading expert on the development of Expertise) - where he began to do studies with a gentleman - reading out a series of numbers at 1-second intervals (so it can't be transferred to long term memory). He could initially do 7 easily. After some practice could reliably recite 8 digits back. After much more, he could do 9. The progress continued until he stopped i think of somewhere around 80 digits read to him at 1-second intervals.

Others continued his work, passing 200.

The world record now is i believe well beyond 400. That's listening to someone call out numbers at 1 second intervals for almost 7 minutes and then reciting them back. All learned. Not an innate gift.

The point is that even something such as this which seems like a miraculous gift is nothing more than a learned skill that comes with intense practice. In particular, its simply about developing memory retrieval structures to organize and group the information in a meaningful manner so that it might be recited back correctly. The original guy used running scenarios - such as "on this date, at this time, xxxx people ran an xxx race and the best time was xx.xx.xx.xxx". Those tactics have to change as the strings of digits increase in length and the individual has to figure out new methods to organize, group and successfully retrieve the information.