Abstract: Apparatus useful in pattern recognition comprising a two-dimensional lattice array of nodal points, said points being occupied by summing amplifiers having positive and negative input terminals, and output terminals, a corresponding input array of points carrying voltage levels, said points being representative of a two-dimensional array of pixels the pattern of which is to be analyzed, said pattern being a member of a set of patterns characterized by an archetypal pattern, electrical connections from the input array of voltage points via resistors to the inputs of the summing amplifiers, the connections being made in a predetermined pattern and the conductance values of the resistors being set by computational procedures such that a prescribed set of input patterns of pixels is formed into output patterns at the output of the amplifiers that are analysable as to correlation between output array patterns and the archetypal pattern for the prescribed set, and correlation means and discrimination means for anal