Effectiveness of color in picture recognition memory

Investigations were conducted into the effectiveness of color in picture recognition memory. In the study phase, half of the pictures were presented in color and the other half in black and white. In the test phase, half were presented in the same color mode as the study pictures and the other half in the other mode. In immediate and 1-week-delayed tests, the recognition performance was highest when color pictures were used in both the study and test phases. The recall for the color mode of the study pictures, however, was not as good, even with the color pictures. This suggests that the effectiveness of color in picture recognition is not necessarily due to the memory for colors in the pictures themselves, but is probably due to the distinctiveness of features highlighted by the colors. We also found that in the recall performance for the color mode it was more difficult to detect the deletion of colors than to detect their addition.     

Intrasexual interactions among female golden hamsters (Mesocricetus auratus) over the estrous cycle

Social interactions of cycling female golden hamsters paired with ovariectomized animals in large enclosures were primarily agonistic over the 4-day estrous cycle. These aggressive interactions were intense as indicated by frequent occurrences of chase and flight behavior. Dominant and subordinate social ranks were established in the majority of pairs (96%) tested, and even females in sexual heat were capable of attacking and dominating their rivals. Furthermore, cycling females exhibited significantly more aggressive acts than ovariectomized opponents 1 day prior to sexual receptivity. No differences in fighting patterns were found between animals on the other 3 days of the estrous cycle. Additional analyses revealed clear differences in agonistic elements, including flank marking, between dominant and subordinate females regardless of whether they were gonadectomized or intact. These analyses also showed that dominant individuals frequently chased and bit opponents during encounters within their nesting area. The data are examined for implications on the adaptive organization of female hamster agonistic behavior and the neuroendocrine regulation of species-typical behavior over the estrous cycle.     

The central amygdala nucleus via corticotropin-releasing factor is necessary for time-limited consolidation processing but not storage of contextual fear memory

The central nucleus of the amygdala (CeA) is traditionally portrayed in fear conditioning as the key neural output that relays conditioned information established in the basolateral amygdala complex to extra-amygdalar brain structures that generate emotional responses. However, several recent studies have questioned this serial processing view of the amygdalar fear conditioning circuit by showing an influence of the CeA on memory consolidation. We previously reported that inhibition of endogenous CeA secretion of corticotropin-releasing factor (CRF) at the time of contextual training effectively impaired fear memory consolidation. However, the time-dependent range of CeA CRF secretion in facilitating consolidation processing has not been examined. Therefore, to address this issue, we performed CeA site-specific microinjections of CRF antisense oligonucleotides (CRF ASO) at several post-training time intervals. Rats microinjected with CRF ASO at post-training intervals up to 24-h subsequently exhibited significant impairments in contextual freezing retention in contrast to animals treated 96-h after training. To further establish the validity of the results, CeA fiber-sparing lesions were made at two distinct post-training periods (24-h and 96-h), corresponding respectively to the temporal intervals when CeA CRF ASO administration disrupted or had no significant effects on memory consolidation. Similar to the CeA CRF ASO results, CeA lesions made 24-h, but not 96-h, after training induced significant freezing deficits in the retention test. In conclusion, the current results demonstrate: (1) an extended involvement of CeA CRF in contextual memory consolidation and (2) that contextual fear memory storage is not dependent on a functional CeA.     

Spatiotemporal balance in competing apparent motion is not predicted from the strength of the single-motion percept

Apparent motion is useful for investigating how spatiotemporal cues are integrated to determine the identity of a moving object. To examine its spatiotemporal properties, a competing-motion paradigm has advantages in strict psychophysical evaluation, despite difficulty in object-identity determination, over a non-competing subjective-grading paradigm. The latter has been often used, whereas the former has not been fully investigated. Here, we compared these two paradigms. In the competing-motion experiment, a sample spot was followed by a far and a near test spot with onset asynchrony. We found that the onset asynchrony between the near and far test spots was directly related to the distance ratio between them. This spatial size-invariant relation was not predicted from the strength of the single-apparent-motion percept, estimated from the non-competing subjective-grading experiment in which a sample spot was followed by only one test spot. Moreover, the spatiotemporal balance in competing apparent motion was found not to be valid under negative interstimulus-interval conditions, although a single apparent motion is perceived in those conditions. These clear discrepancies suggest that competing and single apparent motions are processed in a different way according to the difficulty in object identification.     

Control of lateral weight-transfer initiation during sitting

Whereas many researchers have examined the transition from quiet posture to dynamic state, study of the initiation of lateral weight-transfer during sitting has only begun recently. This action is included in many tasks performed in our daily living, i.e., reaching, dressing, looking backwards, lying down, and shuffling the buttocks. The present study was designed to describe lateral weight-transfer movements of healthy adults, kinematically and kinetically, and to clarify the strategies and speed dependency of lateral weight-transfer initiation during sitting. Seven healthy Japanese male students without orthopaedic or neurological disorders participated. Their lateral weight-transfer movements were measured during sitting, using two force platforms and a 3-dimensional analysis system. Analysis showed that there appear to be two strategies for the initiation of the task: one is the lateral bending of trunk toward the weight-transfer side, and the other is a coordinated reciprocal leg action of both legs. A combination of these strategies is used in a trade-off fashion during natural motions. These results are clinically important for the assessment and therapy of patients with sitting problems.     

Sociotropy-autonomy and situation-specific anxiety

Sociotropy and autonomy are conceptualized as two personality dimensions that relate to individuals' vulnerability to anxiety and depression. Sociotropy is characterized as an excessive investment in interpersonal relationships, and autonomy is characterized as an excessive concern with independence as well as a lack of concern for others. The present study investigated the relationships between sociotropy-autonomy and trait anxiety associated with four types of situations, i.e., Social Evaluation, Physical Danger, Ambiguous Situation, and Daily Routine. 255 undergraduate students completed the Sociotropy-Autonomy Scale, the Endler Multidimensional Anxiety Scale, and the Beck Depression Inventory. Analyses indicated that scores on Sociotropy were positively correlated with rated trait anxiety in situations of Social Evaluation, Physical Danger, and Ambiguous Situations, whereas scores on Autonomy were positively correlated with rated trait anxiety in Daily Routines. These findings are discussed in the context of the diathesis-stress model of anxiety and depression.     

Sociotropy and autonomy: the nature of vulnerability

Sociotropy and autonomy are 2 personality dimensions related to an individual's vulnerability to depression (A. T. Beck, 1983). The Sociotropy-Autonomy Scale (D. A. Clark, R. A. Steer, A. T. Beck, & L. Ross, 1995) and the Personal Style Inventory (C. J. Robins et al., 1994) were developed to assess these personality dimensions independent of each other. The present study is an examination of the relationship between the 2 scales and an attempt to specify the various factors that emerge when the items of the 2 scales are integrated. Participants (N = 514) responded to the Personal Style Inventory, the Sociotropy-Autonomy Scale, and the Beck Depression Inventory (A. T. Beck & R. A. Steer, 1987). A principal component analysis on all of the items of the 2 scales revealed a four-factor structure (2 sociotropy and 2 autonomy). The author examined the relationships between depression, the 4 factors, and the 2 original scales and discussed the results in the context of vulnerability to depression.     

Asymmetries for the categorization of kanji nouns, adjectives, and verbs presented to the left and right

Kanji is one form of written Japanese in which the symbolic/analytic characteristics of language are dissociated from systematic phonetic characteristics; as such, it makes possible a more careful test of which aspect of language is responsible for the frequently observed superior left-hemisphere performance. In this study, subjects were asked to categorize tachistoscopically presented kanji as nouns, adjectives, or verbs. The previously reported (Hatta 1977, Neuropsychologia, 15, 685–688) left-visual-field advantage for kanji was found only in the case of nouns. Adjectives and verbs were processed more rapidly and correctly in the right visual field.     

Autokinetic illusion as affected by suggestions of experimenter and observer.

Two experiments were done to examine whether an experimenter's suggestion and self-suggestion could affect the autokinetic illusion and to specify that effect. Exp. I compared the effect of a facilitative suggestion with a suppressive one, by measuring the moving latency, duration, frequency, and by analyzing the movement trace. Time and frequency did not detect any effects of marked individual differences. Trace analysis, on the other hand, showed that suggestions were effective in the expected direction for some subjects. Exp. II gave the suggestion for and against subjects' dominant direction of the movement and was designed to specify the effect. While effects indicated by time and frequency measures were not consistent, the movement trace showed the effect in suggested directions, which was more distinct for subjects whose nonsuggested illusion was not so markedly directed. These findings indicate that suggestion could affect the spatiotemporal aspect of the illusion, so the trace analysis may be useful for studies in this field.     

Self-awakening, sleep inertia, and P3 amplitude in elderly people

It is well known that sleepiness is sometimes experienced in the afternoon. A short afternoon nap is thought to be effective in reducing sleepiness. However, sleep inertia occurs even after a short nap, and this could be a major risk factor for injuries from falling by the elderly. In the present study, the effect of self-awakening on sleep inertia after a 20-min. nap was examined. Nine participants (M=74.1 yr., SD=5.0 yr.) took part in the three experimental conditions: the self-awakened nap, the forced-awakened nap, and the control (no-nap) conditon. Analysis showed sleepiness and performance after the nap significantly improved compared with the control condition. P3 amplitude tended to be larger after self-awakening than after forced-awakening. The present study indicates a 20-min. nap reduces afternoon sleepiness, and the application of self-awakening may contribute to higher arousal after a nap taken by this elderly group.