Abstract Pure surround-type responses elicited from the receptive field surround region by bright or dark annuli could rapidly be reversed into pure centre-type responses by local darkening of the centre. The transition from surround- into centre-type responses was gradual if centre luminance was reduced stepwise. Pure centre-type responses could only be elicited if the whole centre was black. Selective examination of the inner and outer compartments of the surround region showed that the reversal could be achieved throughout the surround region of the receptive field.