How do we judge our confidence? Differential effects of meta-memory feedback on eyewitness accuracy and confidence

According to the cue–belief model, we assess confidence in our memories using self-credibility cues that reflect beliefs about our memory faculties. We tested the influence of meta-memory feedback on self-credibility cues in the context of eyewitness testimony, when feedback was provided prior to “testifying” via a memory questionnaire (Experiment 1) and after an initial memory questionnaire but before participants had to retake it (Experiment 2). Participants received feedback (good score, bad score, or none) on a fictitious scale purported to predict eyewitness memory ability. Those given good score feedback before testifying were more confident (but no more accurate) than those given bad score feedback. Feedback also affected confidence (good increased and bad decreased) and accuracy (good increased) after testifying but only on leading questions. These differential effects of meta-memory feedback on confidence for normal and leading questions are not explained by the cue–belief model. Implications for our confidence judgments are discussed.     

Suicide among foreign residents of Japan

The suicide rate of Koreans living in Japan is twice as high as that of Koreans in South Korea. Reasons for this high suicide rate are discussed, including effects of economic crises and discrimination.     

Anterograde and retrograde amnesia of place discrimination in retrosplenial cortex and hippocampal lesioned rats

Retrograde and anterograde amnesic effects of excitotoxic lesions of the rat retrosplenial cortex (RS) and hippocampus (HPC) were investigated. To test retrograde amnesia, rats were trained with two-arm place discrimination in a radial maze 4 wk and 1 d before surgery with a different arm pair, respectively. In the retention test 1 wk after surgery, both lesion groups showed temporally ungraded retrograde amnesia. To test anterograde amnesia, animals were trained after surgery to discriminate three arm pairs successively within a day, and then after interposition of 1- to 4-wk intervals, one of these pairs, respectively, was tested for retention. RS-lesioned rats could acquire these pairs of place discriminations rapidly but showed a retention interval-dependent impairment in the retention test. Conversely, HPC-lesioned rats took more sessions to acquire these pairs than did the control group, and their retention was approximately 70% of correct performance regardless of retention interval. Results suggest that RS and HPC have different roles in spatial memory and that RS is important for remote memory process.     

The Effect of Intra- and Intergroup Leadership on Group Goal Attainment in a North-South Gaming Simulation

This research investigated the role of leadership functions in a context of intergroup negotiation by using a simulation game of inter-regional conflict and cooperation (SIRC²). As a part of their social psychology course, 151 undergraduate students participated. It was hypothesized that there are four leadership factors in an intergroup context: in-group performance, in-group maintenance, out-group negotiation performance, and out-group relation maintenance. According to a factor analysis, however, the functions of in-group performance and out-group performance merged into the same category and could not be differentiated independently. Moreover, this research provided evidence that opportunities for intergroup communication and the amount of resources available to each group can facilitate these leadership functions. This study also found links between leadership functions and group outcomes. In a group with members who were homogeneous and facing common survival problems, the in-group/out-group performance function facilitated the achievement of the group goal. On the other hand, in a group with members with different roles, and who were self-sufficient for survival, the in-group maintenance function facilitated the achievement of the group goal. Moreover, in the intergroup context, the out-group relationship maintenance function was also important for group goal attainment. These results were interpreted using the path–goal theory and Fiedler's contingency theory.     

Relations between the inflection point on the force-time curve and force-time parameters during static explosive grip

Individual differences in muscle contractile speed during static explosive muscle contraction are reflected in the developmental phase of the force-time curve. The purposes of this study were to clarify the properties and reliability of the inflection point of force-time, statistically dividing speed during static explosive grip into two phases and to assess the relations between that inflection point and others. Static explosive grip data were measured two times with a 5-min. rest (sampling frequency; 100 Hz). 32 healthy, young men (age: 15.5 +/- 0.8 yr., height: 173.9 +/- 7.3 cm, body mass: 71.5 +/- 11.2 kg) participated. 8 static explosive grip parameters were selected: time of reaching, integrated area, and quotient values of the integrated areas up to 0.25, 0.5, and 1.0 sec. divided by maximal grip force. The inflection point was calculated statistically from two regression lines fitted to a developmental phase and the almost steady-state phase of reaching maximal grip force by applying a two-phase regression model. The reliabilities of maximal grip force, time of reaching 90% of maximal grip force, and the integrated area until 0.5 sec. and 1.0 sec. after the onset of grip were good (ICC=.77 to .93). The time of reaching an inflection force value appeared at 0.3 sec. after the onset of grip, corresponding to 80% of maximal grip force, and the reliabilities of the parameters regarding inflection point were good (ICC=.77 to .95). The time determined by boundary data between the former and the latter regression data set and the regression coefficient during the developmental phase correlated significantly with the time of reaching 90% of maximal grip force, the integrated area, and the quotient values of the integrated areas up to 0.25, 0.5, and 1.0 sec. divided by maximal grip force (rs=-.78 to -.96 and -.75 to 0.88, respectively, p<.05). However, these parameters did not correlate with maximal grip force. A force during the developmental phase and maximal grip force can depend on different physiological factors. The time determined by boundary data between the former and the latter regression data set and the regression coefficient during the developmental phase are useful parameters for evaluating static explosive grip.     

Changes in somatosensory evoked potentials and Hoffmann reflexes during fast isometric contraction of foot plantarflexor in humans

In the present study, the extent to which the early component of somatosensory evoked potentials (SEPs) and the Hoffmann (H-) reflex induced by stimulation of the posterior tibial nerve are altered during the ascending and descending phases of fast plantarflexion was investigated. SEPSs and H-reflex of the soleus following tibial nerve stimulation were examined during fast plantarfiexion when performed by nine normal subjects. The analyses focused on differences in amplitude modulation of the P30-P40 component of SEP and the H-reflex between the ascending and descending phases of full-wave rectified and averaged soleus electromyographic (EMG) activity. The H-reflex amplitude was significantly increased and decreased during the ascending and descending phases more than under resting control conditions, respectively. The reduction of SEP amplitude was 49% for the ascending phase and 83% for the descending phases with respect to the resting situation. Modulation of SEP during the ascending and descending phases was robustly retained even during ischemic nerve blockade of large diameter afferent fibers. These findings suggest that the transmission of afferent inputs from muscle spindles to motoneurons and to the somatosensory cortex during fast isometric contraction of the plantar flexor is regulated in a time-dependent fashion by descending commands.     

Dopamine D1 receptors regulate protein synthesis-dependent long-term recognition memory via extracellular signal-regulated kinase 1/2 in the prefrontal cortex

Several lines of evidence suggest that extracellular signal-regulated kinase1/2 (ERK1/2) and dopaminergic system is involved in learning and memory. However, it remains to be determined if the dopaminergic system and ERK1/2 pathway contribute to cognitive function in the prefrontal cortex (PFC). The amount of phosphorylated ERK1/2 was increased in the PFC immediately after exposure to novel objects in the training session of the novel object recognition test. An inhibitor of ERK kinase impaired long-term recognition memory 24 h after the training although short-term memory tested 1 h after the training was not affected by the treatment. The dopamine D1 receptor agonist increased ERK1/2 phosphorylation in the PFC in vivo as well as in cortical neurons in vitro. Microinjection of the dopamine D1 receptor antagonist into the PFC impaired long-term recognition memory whereas the D2 receptor antagonist had no effect. Immunohistochemistry revealed that exposure to novel objects resulted in an increase in c-Fos expression in the PFC. Microinjection of the protein synthesis inhibitor anisomycin into the PFC impaired the long-term recognition memory. These results suggest that the activation of ERK1/2 following the stimulation of dopamine D1 receptors is necessary for the protein synthesis-dependent long-term retention of recognition memory in the PFC.     

Effects of voice and similarity on procedural fairness and trust: A dual process model of public acceptance based on representatives’ participation

In citizen participation, a few representatives of the total citizen population participate in discussions with authorities regarding public decisions and policies. The present study examines a dual process model in which the representatives’ voice and similarity of values facilitate public acceptance through procedural fairness and trust in representatives, respectively. The results of an experiment employing a scenario method, which included participants from Japan (n = 211) and the Netherlands (n = 200), indicate that the representatives’ voice increased procedural fairness and public acceptance when the similarity of representatives was high. The effects of representatives’ voice on public acceptance via procedural fairness was supported in both nations, while other effects of representatives’ similarity on acceptance via trust were indicated only in Japan. These results suggest that the indirect voice of citizens, as conveyed by representatives, plays an important role in increasing perceptions of procedural fairness and public acceptance among citizens.     

Homogeneity perception as a reaction to identity threat: effects of status difference in a simulated society game

The present study examined how members of low status groups would react to a threat to their social identity. Undergraduates participated in a ‘simulated society game,’ and were divided into four groups, each of which was assigned either a high or low status. During a series of game sessions with intergroup competition and cooperation, participants estimated the range of distributions among in‐ group and out‐group members regarding various traits. The central tendency and variability derived from each estimate were analysed. Members of the low status groups deprecated their in‐group with respect to a status‐defining trait, but showed in‐group favouritism regarding alternative, status‐irrelevant traits. Furthermore, the low status members judged their in‐group as more homogeneous than the out‐group regarding the alternative traits, particularly when they were compared to a high status group. The results were interpreted as an indication of a subtle form of maintaining positive in‐group evaluations. Theoretical and methodological implications for the study of status effects are discussed. Copyright © 2004 John Wiley & Sons, Ltd.