Preliminary Study of the Effects of Methyl Alcohol Fumes on Brightness Discrimination in the White Rat

In an effort to determine by objective methods the effects of the fumes of methyl alcohol on the brightness discrimination of white rats when the alcohol in no way came in contact with the animal's skin, three sets of animals, eighteen in all, about one month old, were used as subjects. The apparatus consisted of the Yerkes discrimination box and brightness apparatus with movable stimulus adapter, the sources of light being two standard 25-watt mazda lamps placed 16½ inches from the stimulus plates. The amperage was regulated by a resistance coil and a Weston ammeter. Training was first given in the learning to discriminate the positive stimulus of light (0.30 amperes) from darkness. When the animal had learned well enough so that in three successive days his trials averaged 90 per cent correct, the amperage of the light was reduced, and training continued, until the animal reached an intensity of light which forbade further discrimination, and after further testing, the last lowest discrimination intensity was regarded as the animal's lower discrimination limen. After the limen had been reached and determined, the animal was placed in a cage through which alcohol fumes were passed, and remained there from a minimum of 11 days to a maximum of 24 days (for different animals). All rats kept continuously in the cage became sick, but, except for a few cases, none of the animals refused to attempt discrimination and all were able to maintain the limen they had reached before the application of alcohol fumes. The authors believe that continued practice in the alcohol fume cage over and above the practice the rats had received before the application of alcohol did not lead to the result that the rats' brightness sensitivity was in no wise decreased. From Psych Bulletin 20:05:00458.