1. A method of assessing a sensory nervous system of a subject, including: simultaneously presenting two or more parts of the sensory system with respective sequences of stimuli, varying each sequence over time between a null stimulus and one or more less frequent non-null stimuli, controlling the variation of each sequence so that neighbouring parts of the sensory system are less likely to receive simultaneous non-null stimuli, measuring one or more simultaneous responses by the subject to the sequences of stimuli, and determining weight functions from the responses for assessment of the sensory system.