As social animals, humans tend to form groups that can range in size from a few individual members to entire nation-states. Historically and through the present day, human groups frequently come into conflict. A noted feature of human intergroup conflict is the proclivity of ingroup members—that is, members recognized as being part of a particular group—to inflict harm upon those considered to be non-members who are part of an outgroup. A new study may help explain the motivation for this hostility. The study found that aggression directed at rival group members increases activity in certain brain regions that are associated with feelings of reward and pleasure. Investigating this potential link further could deepen our understanding of the origins of intergroup aggressiveness and suggest interventions for curbing group-based violence. See also: Aggression; Brain; Motivation; Sociobiology

People consider visual perception to be one of the most trustworthy means of gathering information about the world. However, striking limitations in visual processing occur daily, distorting the precision and completeness of the visual experience and demonstrating that substantial changes in a visual scene often go undetected. In particular, the role of attention in perceptual analysis is paramount for full and accurate comprehension of a visual scene. If certain aspects of visual attention are absent, or at minimum not applied specifically, then change blindness—the inability to discern large changes that occur in clear view of an observer—can occur. Remarkably, the phenomenon of change blindness can be elicited under circumstances in which the changes are made repeatedly and the observer knows that they will occur. See also: Cognition; Neurobiology; Perception; Psychology; Vision; Visual attention

According to new research, young adults who reported higher stress during their childhood and teenage years to adulthood are more likely to suffer high blood pressure, obesity, or other cardiometabolic risk factors than their less-stressed peers. Known cardiometabolic risk factors include age, sex, family history, hypertension, smoking, dysglycemia (abnormality in blood sugar stability), and dyslipidemia (the imbalance of lipids such as cholesterol, triglycerides, LDLs, and HDLs in the body). Now, a group of researchers has found a new risk factor: childhood stress. See also: Cholesterol; Lipoprotein; Triglyceride (triacylglycerol)

Despite the cost-saving advantages of low maintenance and high fuel economy, most battery-powered electric vehicles (EVs) have a limited driving range of about 80 miles (130 kilometers). Not surprisingly, one of the biggest obstacles to consumer acceptance of EVs is range anxiety—the fear of running out of battery power before completing a trip or reaching a charging station. This anxiety can lead EV owners to drive less as a precaution, even though most people would normally drive distances per day that are well within an EV’s fully charged range. See also: Automobile; Electric vehicle

The World Health Organization (WHO) is planning to recognize gaming disorder as a mental health disease in 2018. The 11th revision of the WHO's International Classification of Diseases (ICD), which is a major worldwide reference for epidemiological, clinical, and health-management issues, will include a new listing for a mental health condition termed "gaming disorder," which is related to an individual's overuse of video-game playing. Specifically, this newly classified mental health disorder is characterized by recurrent or persistent gaming behavior in an individual, resulting in the individual's significant impairment in real-life activities and functions, including the deterioration of familial, social, and professional relationships. According to WHO, the condition is manifested particularly by "impaired control over gaming," "increasing priority given to gaming," and "escalation of gaming despite the occurrence of negative consequences." In many ways, gaming disorder will be diagnosed similarly to other addictive disorders. See also: Addiction and addictive disorders; Brain; Computer peripheral devices; Human-computer interaction; Mental disorders; Psychology; Video disk; Video games; Virtual reality

The bacteria that live in the gut (gastrointestinal tract) constitute a large part of an individual's microbiome (also known as microbiota). In general, gut bacteria, also referred to as the microbial flora of the gut, are harbored by normal, healthy humans. Intriguingly, researchers have discovered interactions between the microbiome and the organ systems of the human body. In other words, the gut can be viewed as an ecosystem that may affect the functionality of these various organ systems. In particular, abnormalities within or damage to the bacterial ecosystem of the gut may affect human health and lead to disease states, including those pertaining to the central nervous system and mental health. In fact, the ability of gut bacteria to affect the brain, and thus affect psychological function and behavior, is being studied in a number of investigations. See also: Brain; Central nervous system; Digestive system; Gastrointestinal tract disorders; Human microbiota; Microbial ecology; Microbiome; Psychology