Stimulus set and example neuron. a, The joint tuning for direction and disparity was studied by presenting stimuli that varied in both direction of stimulus motion and binocular disparity. The resulting firing rates give rise to a joint tuning function, which depends on both direction and disparity. b, A map representation of the joint tuning function. Maps have been aligned such that 0° corresponds to the preferred direction. Calibration indicates firing rate calculated over the 1 sec stimulus interval. This neuron is tuned for orientation and disparity. The neuron is orientation selective because there are two (opposite) directions for which it is strongly activated. c, A neuron that is tuned for direction and disparity. d, A neuron that exhibits a significant interaction between direction and disparity. Note that direction is circular and hence wraps around.