where Zsep(a) and Zsep(b) are the Zsep values and na and nb are the n
values of the 2 learning conditions or the 2 age groups, respectively.
More specifically, to compare learning conditions, the difference
(Zdiff) between easy and difficult conditions was computed separately
for young and older adults, and to compare age groups, the
difference (Zdiff) between young and older adults in the difficult
condition was computed. Because Zdiff is normally distributed with
mean 0 and variance of 1, it can be interpreted as a regular z-value