1. A method of assessing a sensory nervous system of a subject, including: simultaneously presenting, using a stimulator, to two or more parts of the sensory nervous system respective sequences of spatially sparse stimuli, the stimuli being presented as a tessellation or contiguous array of adjacent neighbouring stimulus regions defined on dimensions of the sensory nervous system, the tessellation or contiguous array having borders and corners defining said stimulus regions, varying using a processor each sequence of stimuli of each region over time between a null stimulus and one or more less frequent non-null stimuli with the probability of a single non-null stimulus occurring of P, controlling using said processor the variation of each sequence of stimuli presented to neighbouring parts of the sensory nervous system so that the adjacent neighbouring stimulus regions either share a border or a corner having a probability 0 of presenting a simultaneous non-null stimulus, rendering the stimuli spatially sparse, measuring using a monitor each of one or more simultaneous responses by the subject to the sequences of spatially sparse stimuli, and determining using said processor weight functions from the simultaneous responses for assessment of the sensory nervous system.