p011fig01.07 The choice of signal function f determines how an initial activity pattern will be transformed and stored in short-term memory (STM). Among [same, slower, faster]-than-linear signal functions, only the last one can suppress noise. It does so as it chooses the population that receives the largest input for storage, while suppressing the activities of all other population, thereby giving rise to a winner-take-all choice.<BR>||  initial pattern (xi(0) vs i): <BR><TABLE border="1"><TR><TD><B>f</b></td><TD><B>Xi(∞)= xi(∞)/sum[j: xj(∞)]</b></td><TD><B>x(∞)</b></td></tr><TR><TD><B>linear</b></td><TD>perfect storage of any pattern</td><TD>amplifies noise (or no storage)</td></tr><TR><TD><B>slower-than-linear</b></td><TD>saturates</td><TD>amplifies noise</tr><TR><TD><B>faster-than-linear</b></td><TD>chooses max [winner-take-all, Bayesian], categorical perception</td><TD>suppresses noise, [normalizes, quantizes] total activity, finite state machine</td></tr></table>