1. A neural device which comprises a plurality of neural elements each of which has a memory having a plurality of storage locations at each of which locations a number representing a probability is stored, means for addressing the storage locations, and means for causing to appear at an output of the neural element, when the storage locations are addressed, an element output signal, the probability of the element output signal having a given one of first and second values being determined by the number stored at the addressed location, the neural elements having their outputs connected in common to means for accumulating the element output signals thereof and for decaying the result of the accumulation; and thresholding means for receiving at its input the decayed result and generating an output signal at its output when the said decayed result exceeds a predetermined level.