Calvin P. Stone

The Reliability of Rat Learning Scores from the Multiple-T Maze as Determined by Four Different Methods

1 This is the first of a forthcoming series of articles dealing with the age factor in animal learning. The research was financed by a grant from the Carnegie Corporation.

The Attitudes and Interests of Premenarcheal and Post Menarcheal Girls

* Received in the Editorial Office on March 20, 1938. 1 Financed by a grant from the Committee for Research on Problems of Sex, National Research Council. The junior author, Dr. Barker, is primarily responsible for the statistical analysis of the data of this report. We are greatly indebted to Dr. Virgil E. Dixon, Supt. of Schools at Berkeley, California, for permission to use pupils of two of the Junior High Schools of that city and for his generous assistance in compiling data from intelligence tests previously administered in these schools.

The Retention of Copulatory Activity in Male Rabbits Following Castration

* Received in the Editorial Office, October 30, 1931. 1 This investigation was financed by a grant from the Committee for Research on Sex Problems, National Research Council.

A Multiple Discrimination Box and Its Use in Studying the Learning Ability of Rats I. Reliability of Scores

*Received in the Editorial Office, August 13, 1928. 1Research on the age factor in animal learning, for which this apparatus was devised, was financed by the Carnegie Corporation. I am grateful to Dr. Burton D. Thuma, Research Assistant, for suggestions concerning: the plan of this apparatus and for his interest and skill in constructing the first usable model.

The Reliability of Rat Learning Scores Obtained from a Modified Carr Maze

*Received in the Editorial Office, June 25, 1928. 1The research was financed by a grant from the Carnegie Corporation

Effects of electro-convulsive shocks on daily activity of albino rats in revolving drums.

Conclusion Electro-convulsive shocks in 6 female rats greatly reduced the amount of their voluntary activity for a short period of time. The major change appears within the first 24 hours and disappears within 48 hours after the last convulsive shock is administered. Within a 2-week period following their last convulsion the majority of the animals closely approximated their pre-shock levels of daily activity.

Change of the Age of Puberty in Albino Rats by Selective Mating.

Summary In this paper evidence is given which clearly indicates the possibility that lowering of the mean age of puberty in rat colonies during the past 30 years may have been due, in part, to selective breeding of early pubescent stock.

Reduction of General Activity in Male Albino Rats from Electro-Convulsive Shock

Summary A series of daily electro-convulsive shocks in 13 male rats, for 5-day periods, significantly reduced concurrent activity as compared with (1) preshock activity, (2) 5-day periods of no-shock, interposed between periods of shock, and (3) the post-shock recovery period. There is a cumulative effect of successive periods of shock. The mean level of activity reached during the post-shock period of 30 days was significantly lower than that of the preshock period. Whether this difference was due to natural decline of activity with age or to lingering effects of electro-convulsive shock was not determined.

The Effect of Castration at Various Ages Upon the Learning Ability of Male Albino Rats: II. Relearning After an Interval of One Year

1 This study was financed by a grant from The Committee for Research on Sex Problems, National Research Council, and the Thomas Welton Stanford Funds for Psychological Research. The original experiments and the first relearning tests were conducted by Commins. The present tests were conducted by Stone and Mr. M. I. Tomilin, his Research Assistant.

Consistency in Lengths of Post-Ejaculatory Quiescent Periods in Adult Male Rats.

Summary Correlations between lengths of post-ejaculatory periods of inactivity in adult male rats were found to range between .65 and .83 for adjacent pauses. These correlations are remarkably high for complex psychobiological functions and are not exceeded by those for any other complex functions similarly studied. It seems probable that these post-ejaculatory pauses may be used as a basis for many fundamental studies of individual differences in male rats.