Biomedical subjects
Publications and source records attributed to C E RICE.
Measurements were made of the ability of four blind subjects to use echoes to discriminate between objects of different sizes placed in front of them. Threshold estimates indicate that objects with area ratios as low as 1.07/1 could be discriminated.
Two captive sea lions (Zalophus californianus) presented with a series of size-discrimination tasks showed preferences for the smaller of two targets and gave virtually errorless performances despite changes in the form and relative size of the targets. Further tests revealed that they were capable of discriminating a size-difference ratio as small as 1.06:1.
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Electrophoretic examinations were made on sera collected monthly for a period of eleven months from ten cattle naturally or experimentally infected with Johne's bacilli and from ten contact sheep. With one exception, the percentage estimates for the four major classes of serum proteins, albumin, alpha(1)-, alpha(2)-, beta- and gamma-globulins did not differ significantly in sera from infected and non-infected, presumably healthy cattle. One cow with a persistently high complement-fixing titre with Johne's bacillus antigen, showed an exceptionally high proportion of gamma-globulin in its serum. The percentage of gamma-globulin tended to be higher in sera of contact sheep than in that of normal sheep sera but the monthly variation in the relative proportion of these and other globulins showed no evident relationship to the fluctuations observed in the specific complement-fixing and anti-complementary properties of these sera.
A captive 8-year-old dolphin, well adapted to contact with human beings, was tested by the discrimination method for underwater perception of visual forms or patterns. The animal successfully discriminated 21 of the 25 pairs of stimuli presented. After having learned a particular combination, the dolphin was immediately able to respond to different but related pairs which had been modified in various ways. The memory of the animal for discriminations previously made was excellent.
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An experiment was performed to determine the effect on imprinting strength of forcing the following response during the critical period in chicks. Results of the procedures used indicate that although imprinting occurred with forced following, it was not as strong as it is when the following is voluntary.
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