PRELIMINARIES I begin my detailed application of rational analysis with human memory for a number of reasons. Human memory is the field of cognitive psychology with which I have had the longest association, going back over 20 years. It is also the area of cognition where I got my first glimmers of how a rational
analysis could apply. However, my main reason for starting with human memory is my belief that it is the field in cognitive psychology that is most in need of rational analysis. It has seen an amazing succession of mechanistic models, including a number of mine. It is almost taken as an axiom in the field that there is no rhyme or reason as to why human memory works the way it does. The task of the mechanistic theorist is to search an astronomical space of bizarre combinations of mechanisms to find something that fits the data.