<p>Top row shows a sample image made up of white noise uniformly distributed on [0, 1], the template, and the product of the two. The second row shows the effect of averaging across many such representations. Clearly, the signal-to-noise ratio is rapidly improving as the size of the pool being averaged increases, but even the output from a single sample (top row) looks somewhat like the filter. The response to the noise input has revealed some cells with selectivity for the template image. Similarly, neuronal activity seen between stimulus presentations may be the result of noisy inputs to matched filter cells.</p
