15 retarded children and 15 normal children were presented with a series of sonic stimulus of three intensities and three frequencies (4000, 1000, and 250 cps.) The Alpha rhythm was recorded by an eight-channel OFFNER TYPE T EEG. The electrodes were mounted on the frontal, parietal, and occipital lobe with bipolar technique.

The results showed that: 1) no evidence was found to support a negative relationship between intelligence and orienting reflex, 2) there was no significant interaction between intelligence and stimulus intensity, and 3) habituation rates did not differ between intelligence groups, but related to the trails of repeated stimulation. These results could not wholly support Luria´s assumption of poor orienting reflex in mentally retarded children.