A comparative study of sexual drive in adult male rats as measured by direct copulatory tests and by the Columbia obstruction apparatus.

Abstract

The primary aim of this investigation was to determine the reliability of the above measures of sexual vigor and the correlation between them. 33 adult male rats were used. The scores for the direct tests of sexual vigor were based upon observation of copulatory and ejaculatory frequency. The reliability coefficients for these observations ranged from .68 to .91. Reliability coefficients for the tests with the Columbia obstruction apparatus ranged from .64 to .89. Product-moment correlations for direct observations vs. obstruction tests ranged from .32 to .39. The authors claim, therefore, that "there is a low, but true, relation between copulatory vigor and willingness to undergo punishment to reach the female in the obstruction apparatus as herein used." When corrected for the unreliability of the two tests, the correlation becomes .44. The present findings are compared with those of previous investigators. Bibliography.

The pattern and measurement of sexual behavior in the male guinea pig.

“…This observation is reminiscent of Stone's (17) statement that the amount of sexual excitement aroused in the young male rat, and apparently in the adult as well, depends to a marked degree on the excitability of the receptive female, and of the statement by Beach (7,8) that different stimulus objects vary in their excitatory value. DISCUSSION Summarization of the data bearing on the pattern of sexual behavior in the male guinea pig leads to a comparison of this species with the rat, which has been used so widely in studies of reproductive behavior (1,6,8,10,11,17,19,20,21,22). An impressive list of similarities is obtained: the manner of the male's approach to the female at the beginning of the test, the sequence in which the measures of behavior are displayed by higher-drive and lower-drive individuals, the variation in the number of intromissions that seem necessary for the stimulation of ejaculation, the prolongation of the intromission that terminates in ejaculation, the existence of differences between individuals, the occurrence of a refractory period following ejaculation, and the modification of the pattern that is associated with the receptivity of the female.…”

“…(20). In the rat, each ejaculation is preceded by a variable number of intromissions, as few as 3 and as many as 44 (9,10,19,20). In the guinea pig, ejaculation occurred more frequently at the time of the first intromission than following any larger number, although the median was between 3 and 4 intromissions.…”

Effects of ejaculation on sexual behavior in the male rat.

“…mating is resumed and several more intromissions result in a second ejaculation. A number of workers have observed that the second ejaculation is preceded by fewer intromissions or copulations than is the first (Beach & Jordan, 1956;Larsson: 19S6, 1958;Stone & Ferguson, 1940;Stone, Tomilin, & Barker, 1935). It is also known that the copulations preceding the second ejaculation are more closely spaced in time than are those preceding the first (Beach Si Jordan, 1956).…”

Consistency of tests of copulatory frequency in the male albino rat.

“…3 Fluctuations in mean scores from experiment to experiment may also be expected. Stone, Tomilin, and Barker report mean scores on a group of 33 animals of 15.61 for the first test, 13.24 for a second test given 20 minutes later, 14.09 for a third test given one week after the first 2 tests, and 11.91 for the fourth test which followed the third one by 20 minutes (2). The factors mentioned above, plus differences in test spacing, for the two groups and in the age of the rats, are probably adequate to account for the differences between the means obtained by Stone et al and the present investigator.…”