8 male and 8 female Es each tested 8 male and 8 female Ss in a simple sorting task. During an initial 1.5 min. each S's base rate of response was ascertained; following this, the E delivered a supportive statement every 30 sec. for the next 5.5 min. Performance did not increase as a function of the introduction of the supportive statements. Significant differences in base rate and in performance after the base rate period were found as a function of sex of E and of the interaction between sex of E and sex of S. Highly reliable differences appeared in the performance of Ss tested by different Es. The rankorder correlations of men and women tested by men and by women were significant, indicating a similar hierarchy in level of performance of male and female Ss tested by the male Es and a similar hierarchy for Ss tested by female Es.In recent studies (i.e., Stevenson, 1961) of the effectiveness of adults as reinforcers of children's performance, social reinforcement delivered by women has been found to have a greater effect on the performance of boys than of girls and social reinforcement delivered by men has been found to have a greater effect on the performance of girls than of boys. In addition, significant differences have been found among adults of each sex in the degree to which they are effective in modifying children's performance. It is the purpose of this study to determine whether a significant interaction between sex of experimenter and sex of subject is found when adults are the subjects, and to determine whether there are reliable differences among adults in their effectiveness in modifying the performance of other adults. METHOD SubjectsThe subjects were 128 men and 128 women recruited as volunteers from summer school classes at the University of Minnesota. The mean CA of

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The International Tree-Ring Data Bank (ITRDB) provides public access to over 3000 tree-ring data sets collected over the past century, yet 809 of these sites have end dates between AD 1950 and 1980. These data cannot be calibrated with at least the past 30-40 years of instrumental data when used in climate reconstructions. We developed new tree-ring data sets at five sites in Maine, USA, to update earlier collections. Four of the five collections were successfully updated, with environmental changes at the fifth site limiting our success. Our results highlight the limits to tree longevity in a dynamic world and the need to increase and formalize efforts toward updating chronologies. We initiate a discussion to set forth explicit guidelines that help create consistent efforts to updating chronologies and provide a guide to beginning dendrochronologists who are particularly well suited to contribute to this area of work. The research was carried out through an introductory dendrochronology course taught at the University of Wisconsin-Platteville and offers a model to help direct the increasing availability of human resources to the rapidly growing field of dendrochronology.