The present study examined numerical discrimination learning of sequentially presented objects in rats. Rats were trained to respond to a third object among six same ones arranged in a row. The objects were put on one of ten goal wells filled with sand in a rectangular open field. A food reward was given at the bottom of the correct well (under the third object). Since the assignment of objects to the wells was changed from trial to trial, rats could not identify the correct stimulus based on either location of specific goal box or distance from start point. Inaccessible food rewards put in wire mesh tea strainers were set in the incorrect wells to control possible odor cues. After rats learned the numerical discrimination task reliably, partitions with openings were inserted between the goal wells and thus rats could encounter the object stimuli only sequentially. Although rats’ performances deteriorated initially, they recovered rapidly and reached reliable levels. However, when novel test objects were introduced to the training, rats’ performance deteriorated to chance level. To eliminate possible trial-and-error learning to the test stimuli, food rewards were presented not only for the third but also second and fourth test stimuli. Because performance deteriorated on the training trials as well as the test trials, it was suggested that rats learned to respond to the second or fourth stimulus through the nondifferential reinforcement for the second, third, and fourth test stimuli. Although these results suggest that rats can discriminate numerical aspects of sequentially encountered objects, it also suggests that another method for testing transfer of the numerical discrimination to novel test stimuli is needed.

This study examined how university students’ self-control and attitude toward delay relate to their smartphone usage time. The study focuses on both subjective and objective smartphone usage time. Participants were 74 university students who use iPhones. First, we conducted a correlation analysis by measuring subjective and objective usage time for online use such as SNS, online video viewing, and games. Next, participants’ personal characteristics, such as self-control and attitude toward delay, were measured using a 6-item method and a 5-item method, respectively. Consequently, the study found a positive correlation between subjective and objective usage time for "SNS" and "games" during 24 hours. However, no correlation was found between "videos and the Internet" or "total time ". Additionally, a positive correlation was found with external control and a negative correlation with reformative self-control scores in subjective time spent on "video and Internet". Conversely, the score of reformative self-control negatively correlated with subjective time for "video and Internet", but no correlation was found with objective time for "video and internet." The findings suggest that self-control and smartphone use differ regarding subjective and objective measures, including the purpose of use.

In the general life-course, people have engaged in occupational processes over extensive time periods. In the context of cognitive aging and health, there are more and more studies showing that mental activities on the job have been associated with cognitive functioning (in later life). To assess the mental activities of the occupational experiences (occupational complexity), some researchers have used DOT, originally developed in the U.S., while others have recently employed O*NET which replaced DOT. Although the Japanese version of DOT and O*NET (O-NET) was developed as well, the procedure and contents were different from those in the U.S. Therefore, it is unclear which database better accounts the occupational complexity in Japan. In this study, we obtained complexity scores from both databases for the same person’s occupational information and examined their associations with cognitive performance. The results indicated that complexity scores based on O-NET could better explain more variance in cognitive performance across the cognitive domains compared to DOT. Furthermore, this association was more pronounced for the older age group. Even though the Japanese version of DOT and O-NET did not correspond, it is suggested that the data from O-NET may reflect the various skills required to perform the complex job.