Rapid image-segmentation and perceptual transparency share a process which utilises X-junctions generated by temporal integration in the visual system

Perceptual transparency requires local same-polarity X-junctions, which can also be generated by temporal integration under natural dynamic conditions. In this study, segmentation performance and target appearance were measured for a uniform gray target embedded in a random-dot frame presented with a temporally adjacent mask. Although static cues for both segmentation and transparency were unavailable, transparency was observed only when collinear same-polarity edges reduced backward masking, in both the fovea and the perifovea. These results suggest that the visual system has a common underlying mechanism for rapid segmentation and transparency, which utilises same-polarity X-junctions generated by temporal integration.     

Estimation of height for persons in pictures

We report three experiments in which subjects estimated the height of persons seen in pictures. In Experiment 1, 50 realistic photographs were used as targets. The correlation between mean estimated height and actual height was .92, and target’s sex and the ratios of head to trunk, which included horizontal ratio (i.e., a ratio of head width to shoulder width) and vertical ratio (i.e., a ratio of head height to stature), were found to be effective on height estimates, although target’s sex was more effective than ratios of head to trunk. In Experiments 2 and 3, the recognizability of target persons was reduced, respectively, by inverting the person photographs and by degrading the various features of the photographs. The main results were that (1) the correlation between mean estimated height and actual height was .88 for the inverted photographs and was .80, on average, for the degraded drawings; (2) target’s sex was consistently influential in both experiments; (3) vertical ratio was effective for the inverted photographs and the mildly degraded drawings but not for the extremely degraded drawings in which only outlines of target persons were depicted; and (4) the estimation for the outlined pictures was likely to be influenced by fit of clothes to targets’ bodies. From these findings, person stimuli were considered to provide a stable metric stick of visual space under naturalistic circumstances.     

Visual behaviors of soccer players while kicking with the inside of the foot

This study analyzed the visual behaviors of soccer players while they kicked with the inside of the foot, which involved near and far aiming skills. Participants (N = 8) were required to step forward and kick a ball to hit a target. The top three scorers were defined as the High-score group, and the three low scorers were defined as the Low-score group. Analysis indicated that the High-score group was characterized by longer quiet eye durations, which were defined as the final fixation durations on the target prior to the initiation of a kicking movement, than the Low-score group in the preparation phase. The High-score group also set their visual pivot on the frontal space between the target and the ball in the kicking phase. These two visual behaviors of the High-score group are important for soccer players to kick a ball successfully with the inside of the foot.     

An experimental consideration of fixation properties.

While varying the size and complexity of a stimulus object, we measured eye movements during fixation. Although subjects' eyes are fixated at the center of the object, the experimental results indicate that "fluctuation during fixation (FDF)" which is larger movements than "miniature eye movements" occurred. In addition, FDF varies according to the peripherals of fixation points characterized by the size and complexity of the stimulus object.     

Left-side dominance for song discrimination in Bengalese finches (Lonchura striata var. domestica)

Male Bengalese finches are left-side dominant for the motor control of song in the sensorimotor nucleus (the high vocal center, or HVc) of the telencephalon. We examined whether perceptual discrimination of songs might also be lateralized in this species. Twelve male Bengalese finches were trained by operant conditioning to discriminate between a Bengalese finch song and a zebra finch song. Before training, the left HVc was lesioned in four birds and the right HVc was lesioned in four other birds. The remaining four birds were used as controls without surgery. Birds with a left HVc lesion required significantly more time to learn to discriminate between the two songs than did birds with a right HVc lesion or intact control birds. These results suggest that the left HVc is not only dominant for the motor control of song, but also for the perceptual discrimination of song. Accepted after revision: 11 September 2001 Electronic Publication     

Factors shaping vividness of memory episodes: visitors' long-term memories of the 1970 Japan World Exposition

This study investigated how visitors' psychological and behavioural factors, identified in the literature, shaped their vivid long-term memories of their experiences of the Japan World Exposition, Osaka, 1970 (Expo '70) as a context. In this study, 112 memory episodes were identified from the long-term memories of 48 participants; they were rated in terms of their memory vividness and on a set of factors including affect, agenda fulfilment, intentionality, and rehearsal. The influence of these factors on the vividness of episodic and/or autobiographic memories of experiences that occurred 34 years ago was examined in two stages. First, the relationship between memory vividness and individual factors was investigated separately. Second, the relationship between memory vividness and all factors was examined through a multiple regression analysis, and the relative importance of these factors on memory vividness identified. Stage one analysis showed that all factors except intentionality were related to memory vividness in individual analyses, and curvilinear relationships between memory vividness and the factors found. Stage two analysis, in which all factors were included in a multiple regression analysis, found that rehearsal was positively related to memory vividness and all other factors not significant in the presence of rehearsal.     

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.     

Effect of spatial position on visual search for 3-D objects

We examined whether the position of objects in external space affects the visual-search task associated with the tilt of 3-D objects. An array of cube-like objects was stereoscopically displayed at a distance of 4.5 m on a large screen 1.5 m above or below eye height. Subjects were required to detect a downward-tilted target among upward-tilted distractors or an upward-tilted target among downward-tilted distractors. When the stimuli consisted of shaded parallelepipeds whose upper/bottom faces were lighter than their side faces, the upward-tilted target was detected faster. This result was in accordance with the 'top-view assumption' reported in previous research. Displaying stimuli in the upper position degraded overall performance. However, when the shaded objects whose upper/bottom faces were darker than their side faces were displayed, the detection of a downward-tilted target became as efficient as that of an upward-tilted target only at the upper position. These results indicate that it is possible for the spatial position of the stimulus to promote the detection of a downward-tilted target when shading and perspective information are consistent with the viewing direction.     

EFFECTS OF EXPECTATIONS AND BODILY SENSATIONS ON SELF-REPORTS OF PREMENSTRUAL SYMPTOMS

Two experiments examined expectations and bodily sensations in premenstrual symptom reports. Women took a fictitious test that indicated they were either "premenstrual" or "intermenstrual." In Experiment 1, 48 women were studied during their premenstrual phase. In Experiment 2, 82 women were studied during either their premenstrual or intermenstrual phase. Individual differences in retrospective premenstrual distess were assessed prior to the experiments. Both experiments revealed that the higher the woman's retrospective reports of premenstrual distress, the more symptoms she reported in the lab during her premenstrual phase, regardless of what the test indicated. However, women who were told they were premenstrual reported greater symptoms than women who were told they were intermenstrual. In summary, although expectations affect women's symptom reports regardless of their actual phase and history of reported symptoms, premenstrual symptom reports cannot be dismissed as simply expectations, because some women do experience greater symptoms as they approach menstruation.     

Perceived group identity of outgroup members and anticipated rejection: People think that strongly identified group members reject non‐group members

Many studies of intergroup relations have examined the effects of group identity on various types of intergroup cognition and behavior. However, few studies have focused on the perceived group identity of outgroup members. This study examined the effects of perceptions of outgroup identity on anticipated rejection by an outgroup. In Study 1, we administered a questionnaire pertaining to 30 social groups to Japanese undergraduate and vocational students. The collective images and intra‐individual processes relating to perceived outgroup identity were investigated by applying correlation analysis and multilevel structural equation modeling. In Study 2, we conducted an experiment in which we manipulated the participants' perceptions of relative levels of outgroup members' identity. Both studies demonstrated, as predicted, that people anticipated rejection by strongly identified outgroup members more than by weakly identified outgroup members. Furthermore, in Study 2, anticipated same‐group favoritism mediated the relationship between the manipulation of perceived outgroup identity and anticipated rejection. These findings suggest the important role of perceived outgroup identity in intergroup cognition.