  Free recall of random lists of words is a standard paradigm used to probe
human memory. We proposed an associative search process that can be reduced to
a deterministic walk on random graphs defined by the structure of memory
representations. This model makes a parameter-free prediction for the average
number of memory items recalled ($RC$) out of $M$ items in memory: $R =
\sqrt{3\pi M/2}$. This prediction was verified in a large-scale crowd-sourced
free recall and recognition experiment. We uncovered a novel law of memory
recall, indicating that recall operates according to a stereotyped search
process common to all people.
