The ease with which we recognize a face, understand spoken words, read handwritten
characters, identify our car keys in our pocket by feel, and decide whether
an apple is ripe by its smell belies the astoundingly complex processes that underlie
these acts ofpattern recognition. Pattern recognition — the act oftaking in raw
data and taking an action based on the “category” ofthe pattern — has been crucial
for our survival, and over the past tens of millions of years we have evolved highly
sophisticated neural and cognitive system
s for such tasks.