Temporal characteristics of visibility in chimpanzees (Pan troglodytes) and humans (Homo sapiens) assessed by a visual-masking paradigm

We used the visual-masking paradigm to compare temporal characteristics of chimpanzee vision with those of humans. Two types of masking experiments were conducted. One type involved masking by noise, in which the visibility of the geometric pattern target was tested with a spatially overlapping noise as the mask stimulus. The other type involved paracontrast and metacontrast masking, in which the mask stimuli flanked but did not spatially overlap the target stimuli. Temporal characteristics regarding the visibility of target stimuli, displayed as functions of temporal asynchrony between target and mask stimuli, differed with the mask type in chimpanzees as in humans. Peak deterioration in visibility occurred at the point of minimum temporal asynchrony both in forward and backward masking by noise, but was not at 0 ms temporal asynchrony when the target and mask stimuli did not spatially overlap. These results suggest that chimpanzees and humans share the underlying mechanisms in two kinds of temporal inhibition caused by spatially overlapping and non-overlapping mask stimuli.     

Stream/bounce perception and the effect of depth cues in chimpanzees (Pan troglodytes)

The stream/bounce display represents an ambiguous motion event in which two identical visual objects move toward one another and the objects overlap completely before they pass each another. In our perception, they can be interpreted as either streaming past one another or bouncing off each other. Previous studies have shown that the streaming percept of the display is generic for humans, suggesting the inertial nature of the motion integration process. In this study, chimpanzees took part in behavioral experiments using an object-tracking task to reveal the characteristics of their stream/bounce perception. Chimpanzees did not show a tendency toward a dominant "stream" perception of the stream/bounce stimulus. However, depth cues, such as X-junctions and local motion coherence, did promote the stream percept in chimpanzees. These results suggest both similarities and differences between chimpanzees and humans with respect to motion integration and object individuation processes.     

The Miyake Island Volcano Disaster in Japan: Loss, Uncertainty, and Relocation as Predictors of PTSD and Depression

This study investigates the relationship between psychological well-being and the impact of loss and psychological uncertainty after the 2000 Miyake Island volcanic eruption. 231 Japanese evacuees (ages 20-93, average 59.52 years old) responded to mailed questionnaires 10 months after the volcanic eruption in 2000. The questionnaire included the Impact of Event Scale-Revised (IES-R) for posttraumatic stress disorder, an 11-item version of the Center for Epidemiological Study-Depression Scale (CES-D), assessment of disaster losses, demographics, and measure of relevant pre- and post-disaster activities (e.g., relocation, worry, doctor visits). Findings indicated that material loss and uncertainty of losses were significantly associated with higher rates of reported PTSD and depression symptoms. Those who relocated multiple times reported significantly higher rates of PTSD symptoms than those who relocated less frequently. Demographic characteristics such as being older, widowed, lower SES, less education, and longer length of residency on the island were also strongly associated with higher reported PTSD symptoms. Depression symptoms were strongly associated with being widowed, lower SES, longer length of residency on the island, and previous experiences of evacuations due to disasters.     

Relationship between masculinity-femininity and concession in an experimental collaborative eyewitness testimony

The present study examined the relationships of masculinity and femininity with concession in an experimental collaborative eyewitness testimony task, using the MORI technique. Participants formed same sex or mixed sex pairs and watched a videotaped event. Their eyewitness memories were assessed three times: immediately after watching, after discussing the event together, and individually 1 week later . The participants' self-confidence in their recalled memories and percentages of concessions were also examined. The Masculinity-Humanity-Femininity Scale was administered to the participants at the end of the experiment. The results showed that masculinity negatively correlated with concession, and that both masculinity and femininity were associated with inaccuracy in collaborative memory recall.