The experiments reported in this paper were carried out to determine the effect moving background patterns have on the response characteristics of directionally specific neurons in the pigeon optic tectum. First, care was taken to select the optimal single stimulus for each cell, then large textured patterns were added to the test stimulus and moved either "in-phase" or "anti-phase". Altogether 214 cells were studied in 77 white Carneaux pigeons and it was found that all cells below a depth of 400 microns were inhibited by backgrounds moved "in-phase" with the optimal test stimulus, while few cells above this level were affected in any way by backgrounds. All directions of background motion containing an "in-phase" vector resulted in rather profound inhibition of the directional response while directions with an "anti-phase" vector produced less inhibition and sometimes were even facilitated by direct "anti-phase". The velocity tuning curves obtained with an optimal single test stimulus and by "anti-phase" movement of backgrounds were essentially similar. "In-phase" inhibition can also be produced by a second spot stimulus located some distance from the test stimulus. This latter effect was used to map the outer margins of the inhibitory receptive fields of deep tectal neurons displaying these effects and it was found they were extremely large, often in excess of 100 degrees in diameter. When masks were used to prevent the moving background from stimulating the excitatory receptive field "anti-phase" movement always produced facilitation. This suggests a double opponent-process directionally specific receptive field organization. These neurons seem well suited to respond to local (object) motion and to ignore translation of the visual image arising from body, head and eye movements.

A vibrotactile auditory prosthetic device was shown to help the deaf: (1) identify environmental sounds, (2) improve speech production, (3) identify English words spoken “live voice,” and (4) receive information complementary to that obtained through lipreading. The device consisted of 1613 octave filters, with center frequencies ranging from 200–8000 Hz. The output of each channel was detected and after logarithmic amplification outputs were transmitted to a 16-channel linear solenoid array placed on the subject's ventromedial forearm. One artificially deafened subject learned 150 words in 55 h and was able to generalize this learning to unfamiliar speakers. The vast majority of words were identified correctly over 70% of the time. Most words that were initially difficult to discriminate were identified correctly as training time increased. A profoundly deaf 13-year-old learned to identify 50 environmental sounds in 12 h using the device. Discrimination of phonemes within lipreading mouth movement groups increased from 39% in the lipreading condition to 88% in the tactile condition. Finally, the intelligibility of the subject's speech improved 104% when vocalization were made with vibrotactile feedback.