Effects of discrete-trial and free-operant procedures on the acquisition and maintenance of successive discrimination in rats.

Rats were trained on a successive discrete-trial discrimination between two tonal stimuli to examine the effects of availability of a lever during intertrial intervals. In the discrete-trial condition, in which a lever was removed from the chamber during intertrial intervals, 10-s trials were initiated by the presentation of both discriminative stimulus and lever. In the free-operant condition, in which a lever was present during both trials and intertrial intervals, 10-s trials were initiated only by the presentation of a discriminative stimulus. Experiment 1 employed 50-s intertrial intervals and demonstrated that discriminative performances were acquired faster and maintained better in the free-operant conditions than in the discrete-trial conditions. Experiment 2 employed 5-s intertrial intervals and showed that poor discriminative performances in the discrete-trial conditions were improved. These results indicate that the presentation of a lever to start a trial can overshadow or mask the control by a discriminative stimulus and thereby obstruct the acquisition and maintenance of discriminative performances. Furthermore, the overshadowing or masking effects are strengthened as a function of the duration of intertrial intervals.     

Effects of variations in force and stimulus uncertainty on fractionated reaction time.

Previous research has shown that reaction time (RT) and premotor time varied as a function of force even in simple-RT paradigm. The present purpose was to examine whether stimulus uncertainty induced by catch trials would cause programming delay until after the signal to respond. Subjects were required to react and produce a designated peak force as soon as possible after a visual stimulus, with and without catch trials. Five different levels of force were 10, 30, 50, 70, and 90% of the maximum grip strength of subjects. Analysis showed that simple RT and premotor time changed as a function of force, regardless of whether catch trials were removed. These findings suggest that stimulus uncertainty is not a necessary condition for programming delay.     

Comparison of ruminative responses with negative rumination as a vulnerability factor for depression

Several studies have shown that the ruminative responses, which are defined as a coping pattern that focuses on the symptoms of depression and on the possible causes and consequences of these symptoms, are associated with depression. Recently, negative rumination, which is defined as the tendency to continue to think about something bad, harmful, or unhopeful for a long time, has been proposed as a vulnerability factor for depression. The purpose of this study was to compare depression scores associated with negative rumination and ruminative responses. We expected to find depression associated with negative rumination. The sample consisted of 188 Japanese undergraduate students (83 men: M age= 19.0 yr., SD= 1.1; 105 women: M age = 19.1 yr., SD = 1.7) taking a human sciences course at a Japanese university. Subjects participated in an 8-mo. longitudinal study. Logistic analysis indicated that negative rumination was a significant predictor of depression. However, ruminative responses as a whole were not a significant predictor of depression after controlling for negative rumination. These findings suggest that it is important to distinguish whether rumination is focused on negative or nonnegative subject matter.     

Effects of variations in force on fractionated reaction time in simple and choice conditions

The present study examined the effects of force output on fractionated reaction time under simple and choice conditions. 20 subjects were required to react and produce a designated force as soon as possible after a visual stimulus. Five different levels of force were 10, 30, 50, 70, and 90% of the maximum grip strength of the subjects. Analysis showed that reaction time (RT) changed as a function of force in both conditions, with the longest RT occurring at the 70% condition. The same pattern was also evident for premotor time. These findings suggest that the changes in RT with increases in force are mediated predominantly by central rather than peripheral processes.     

Choice and delay of reinforcement: Effects of terminal-link stimulus and response conditions

In two experiments, pigeons were exposed to concurrent-chains schedules in which a single initial-link variable-interval schedule led to access to terminal links composed of fixed-interval or fixed-delay schedules. In Experiment 1, an 8-s (or 16-s) delay to reinforcement was associated with the standard key, while reinforcer delay values associated with the experimental key were varied from 4 to 32 s. The results of Experiment 1 showed undermatching of response ratios to delay ratios with terminal-link fixed-delay schedules, whereas in some pigeons matching or overmatching was evident with the fixed-interval schedules. In Experiment 2, one pair of reinforcer delay values, either 8 versus 16 s or 16 versus 32 s, was used. In the first condition of Experiment 2, different delays were associated with different keylight stimuli (cued condition). In the second condition, different terminal-link delays were associated with the same stimulus, either a blackout (uncued-blackout condition) or a white key (uncued-white condition). To examine the role of responses emitted during delays, the keys were retracted during a delay (key-absent condition) in the third condition and responses were required by a fixed-interval schedule in the fourth condition. Experiment 2 demonstrated that the choice proportions for the shorter delay were more extreme in the cued condition than in the uncued-blackout condition, and that the response requirement imposed by the fixed-interval schedules did not affect choice of the shorter delay, nor did the key-absent and key-present conditions. These results indicate that the keylight-stimulus conditions affected preference for the shorter of two delays and that the findings obtained in Experiment 1 depended mainly on the keylight-stimulus conditions of the terminal links (i.e., the conditioned reinforcing value of the terminal-link stimuli).     

Choice and amount of reinforcement in rats

Rats were exposed to concurrent-chains schedules in which the terminal links were equal, fixed-interval (FI) schedules terminating in one or a varying number of food pellets. In most rats, choice proportions for the larger reinforcer increased with increases in reinforcer amount (e.g., from one to five food pellets). When log response ratios were plotted against log reinforcer amount ratios, the results indicated that the effects of reinforcer amount depended on the length of fixed-interval terminal links, by showing that rats undermatched their response ratios to reinforcer amount ratios with the shorter terminal links (FI 5 s, Experiment 1), whereas they overmatched with the longer terminal links (FI 20 s, Experiment 2). These results demonstrated that the manipulation of FI terminal-link schedules affected the sensitivity of choice to reinforcer amount, and are consistent with the previous findings that choice proportions for the larger of two reinforcers (one vs three food pellets) increased with increases in the length of FI terminal-link schedules.     

Cross‐cultural validation of the factor structure for the Korean version of the Classroom Climate Inventory

The purpose of the present study was to validate the Classroom Climate Inventory (CCI) in Korean middle schools. Specifically, we investigated whether the original eight‐factor structure of the Japanese version of the CCI (Involvement, Affiliation, Friction, Satisfaction, Self‐disclosure, Task Orientation, Order, and Equity) is appropriate for Korean middle schools. The results indicated that the Korean version of the CCI showed a different factor structure from the Japanese CCI. In the cross‐culturally validated CCI, the Friction factor included in the Japanese version was divided into two factors (i.e., Harmony and Conflict), and Equity was excluded. The final model of the Korean CCI displayed acceptable goodness‐of‐fit indices, which indicated that it is a valid instrument by which to measure the classroom climate of Korean middle schools. Lastly, implications for future research and limitations are discussed.     

Extended energy-loss fine structure analysis of 3d transition metals using L ionization edges

The extended energy-loss fine structure (EXELFS) in electron-energy-loss spectroscopy has been compared experimentally with the extended X-ray absorption fine structure (EXAFS), for determining local structure around 3d transition metals. Since the EXELFS spectrum is acquired in an analytical transmission electron microscope, the probing beam can be focused to offer a lateral spatial resolution in the nanometre range, which is several orders of magnitude better than that of X-rays. Also, the microscope allows the area of interest to be imaged and analysed by other methods. However, difficulties in the analysis of EXELFS of 3d transition metals arise from the overlap of the edges in the accessible L series. EXELFS of L ionization edges of crystalline Ni and Cu were examined as test specimens. The overlapped L₁,L₂ and L₃ edges were separated and compared with the K-edge EXAFS of the same samples. The first- and second-nearest-neighbour distances from EXELFS are in agreement with those measured from EXAFS and X-ray diffraction. As a structural probe, however, the accuracy of quantitative analysis of EXAFS is still superior since the L-edge EXELFS decays more rapidly than K-edge EXAFS.     

Death anxiety,altruism, self‐efficacy,and organ donation intention among Japanese college students: A moderated mediation analysis

The shortage of organs for transplantation in Japan has alerted health professionals to the low organ donation rate among Japanese people. The unique cultural view of death and altruism has been suggested leading to their low intent to donate cadaveric organs. A cross‐sectional survey was conducted in Japan to investigate the interplay of death anxiety, altruism, and self‐efficacy in influencing Japanese college students' intention to sign donor cards, in order to mobilise this large potential source of organ donors in the future. Six hundred and seven Japanese non‐donor card signers voluntarily completed a self‐administered questionnaire. The results of mediation and moderated mediation analyses with bootstrap approach suggest that death anxiety indirectly hinders Japanese people's intention to become a donor card signer through lowering of self‐efficacy, while altruism intensifies the positive impact of self‐efficacy on signing intention. These findings provide useful insights for organ procurement organisations seeking behavioural change not only in Japan but also in multi‐ethnic societies with a substantial Japanese population.