A psychophysical experiment was conducted to investigate an evaluation method for the combined effects of infrasound and audible noise. In the experiment, subjective rating of 80 mixed noise stimuli were obtained from 15 subjects on 22 semantic-differential-type scales. The stimulus noise conditions were mixtures of one of eight pure tones at 5, 10, 20, and 40 Hz and one of eight 1/3 octave band noises with centre frequencies 63, 125, 250, and 500 Hz. The rating data were subjected to a principal component analysis and yielded two principal components, these were interpreted as the perceptual components of infrasound and audible noise respectively. On the basis of this result, a psychophysical model was proposed to make two-dimensional predictions of subjective ratings from the physical variables of the noise stimuli. Following this model, a best weighting curve, in combination with the A-weighting curve and their regression weights, were estimated. The results showed that the psychological model successfully described the rating data.

Runway performance of rats was studied as a function of reinforcement schedule (100% reward vs. 50% reward) and drug dosage level (10 mg/kg, and 20 mg/kg, i.p. of CDP, and saline). The groups injected with 10 mg/kg of CDP ran faster on initial trials than the other groups, but slightly slower on later trials than the corresponding saline groups. The 50% reward saline group was superior in speeds in early trials but much inferior in later trials to the 100% reward saline group. A similar finding was obtained with 10 mg/kg of CDP. However, the 100% reward group was superior in speeds in final trials than the 50% reward group when both were injected with 20 mg/kg of CDP. As a whole response speeds decreased as the dosage level of CDP increased. The results were discussed in terms of tranquilizing and depressant effects of CDP.

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The cortical potentials (EEG) of the albino rat were studied from birth to maturity. For several days after birth the EEG recordings were mostly flat with occasional appearance of 6 to 12 c/s waves of low voltage. After 5 days a long sequence of highly rhythmic waves of the same frequencies was most characteristic, often synchronous with the respiratory cycle and even after gross bodily movement. Frequency of these rhythms increased to 14 to 18 c/s at 14 days. High-voltage slow waves during behavioral sleep appeared after 7 days from birth and sleep spindles were shown after 20 days. The “activated sleep” pattern was identified and the typical features of the adult EEG were nearly complete from 20 to 30 days of age.