A stone tool is, in the most general sense, any tool made of stone. Although stone-tool-dependent cultures exist even today, most stone tools are associated with prehistoric societies that no longer exist.

The study of stone tools is often called lithic analysis by archaeologists. Stone tools may be made of chipped stone or ground stone. A person who makes chipped stone implements is called a flintknapper.

Chipped stone tools are made from cryptocrystalline materials such as chert, radiolarite, chalcedony or obsidian via a process known as lithic reduction. One simple form of reduction is to strike stone flakes from a nucleus (core) of material using a hammerstone or similar hard hammer fabricator. If the goal of the reduction strategy is to produce flakes, the remnant lithic core may be discarded once it has become too small to use. In some strategies, however, a flintknapper reduces the core to a rough unifacial or bifacial preform, which is further reduced using soft hammer flaking techniques or by pressure flaking the edges. More complex forms of reduction include the production of highly standardized blades, which can then be fashioned into a variety of tools such as scrapers, knives, sickles and microliths. In general terms, chipped stone tools are nearly ubiquitous in all pre-metal-using societies because they are easily manufactured, the tool stone is usually plentiful, and they are easy to transport and sharpen.

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UC Davis News: General Interest

Biracial Asian Americans and Mental Health
Mon, 18 Aug 2008 00:00:00 -0700
A new study of Chinese-Caucasian, Filipino-Caucasian, Japanese-Caucasian and Vietnamese-Caucasian individuals concludes that biracial Asian Americans are twice as likely as monoracial Asian Americans to be diagnosed with a psychological disorder. The study by researchers at the Asian American Center on Disparities Research at the University of California, Davis, was reported Sunday at the annual meeting of the American Psychological Association in Boston. "Up to 2.4 percent of the U.S. population self-identifies as mixed race, and most of these individuals describe themselves as biracial," said Nolan Zane, a professor of psychology and Asian American studies at UC Davis. "We cannot underestimate the importance of understanding the social, psychological and experiential differences that may increase the likelihood of psychological disorders among this fast-growing segment of the population." Zane and his co-investigator, UC Davis psychology graduate student Lauren Berger, found that 34 percent of biracial individuals in a national survey had been diagnosed with a psychological disorder, such as anxiety, depression or substance abuse, versus 17 percent of monoracial individuals. The higher rate held up even after the researchers controlled for differences between the groups in age, gender and life stress, among other factors. The study included information from 125 biracial Asian Americans from across the U.S., including 55 Filipino-Caucasians, 33 Chinese-Caucasians, 23 Japanese-Caucasians and 14 Vietnamese-Caucasians. The information was obtained from the 2002-2003 National Latino and Asian American Study, the largest nationally representative survey ever conducted of Asian Americans. Funded by the National Institute of Mental Health, the landmark survey involved in-person interviews with more than 2,000 Asian Americans nationwide. The survey yielded a wealth of raw data for researchers to analyze for insights into Asian American mental health. Zane and Berger did not look at the mental health of non-Asian Americans. Future research should investigate the factors that explain the higher rate of diagnosed psychological disorders among biracial Asian Americans, Zane said. Possibilities include influences of ethnic identification and experiences of ethnic discrimination.
Suicide in Asian Americans
Mon, 18 Aug 2008 00:00:00 -0700
Asian Americans whose families experience a high degree of interpersonal conflict have a three-fold greater risk of attempting suicide when compared with Asian Americans overall, according to a new study by University of California, Davis, researchers. The risk is tripled even among those who have never had a diagnosis of depression. The findings were reported Sunday at the annual meeting of the American Psychological Association in Boston. "Because of the great emphasis on harmony and family integration in many Asian cultures, family conflict is an important factor to consider when studying suicidal behaviors among Asian Americans," said Stanley Sue, a professor of psychology and Asian American studies at UC Davis and one of the study's authors. "Our study suggests that we need to more precisely determine the kinds of family conflicts that are associated with suicide risk among Asian Americans, and find means of preventing these family problems." Sue's study is a new analysis of data from the 2002-2003 National Latino and Asian American Study, the largest nationally representative survey ever conducted of Asian Americans. Funded by the National Institute of Mental Health, the landmark survey involved in-person interviews with more than 2,000 Asian Americans nationwide. Subjects were asked about income, marital status, age at time of immigration or number of generations their families have been in the United States, English language proficiency, family conflict, and suicidal thoughts and suicide attempts, among other questions, yielding a wealth of raw data for researchers to examine for insights into Asian American mental health. In the national survey, 2.7 percent of the Asian Americans interviewed reported having attempted suicide at some point during their lives; 9.1 percent of the total group reported having had suicidal thoughts. Further mining the survey data, Sue and lead investigator Janice Cheng, a psychology graduate student, sorted out the suicide-prone individuals' answers to additional survey questions that asked about past diagnosis of depression and family income. The researchers compared the answers with those of interviewees who had not reported suicidal thoughts or suicide attempts. The researchers found that among Asian Americans in the national survey, family conflict was a significant risk factor for suicidal thoughts and suicide attempts -- independent of depression, low income or gender. "This is the first nationally representative investigation of family conflict and suicidal behaviors among Asian Americans," Sue said. "Our findings suggest that high family conflict has an independent and additive effect in predicting lifetime suicidal thoughts and suicide attempts among Asian Americans." Previous studies by other researchers have shown that certain subgroups of Asian Americans, including college students and Asian American women older than 65, have relatively high rates of suicide or suicide attempts compared with the rest of the nation. However, the UC Davis study was not designed to compare rates of suicide among different groups.
Adults Easily Fooled by Children's False Denials
Mon, 18 Aug 2008 00:00:00 -0700
Adults are easily fooled when a child denies that an actual event took place, but do somewhat better at detecting when a child makes up information about something that never happened, according to new research from the University of California, Davis. The research, which has important implications for forensic child sexual abuse evaluations, was presented Sunday at the annual meeting of the American Psychology Association in Boston. "The large number of children coming into contact with the legal system -- mostly as a result of abuse cases -- has motivated intense scientific effort to understand children's true and false reports," said UC Davis psychology professor and study author Gail S. Goodman. "The seriousness of abuse charges and the frequency with which children's testimony provides central prosecutorial evidence makes children's eyewitness memory abilities important considerations. Arguably even more important, however, are adults' abilities to evaluate children's reports." In an effort to determine if adults can discern children's true reports from false ones, Goodman and her co-investigators asked more than 100 adults to view videotapes of 3- and 5-year-olds being interviewed about "true" and "false" events. For true events, the children either accurately confirmed that the event had occurred or inaccurately denied that it had happened. For "false" events -- ones that the children had not experienced -- they either truthfully denied having experienced them or falsely reported that they had occurred. Afterward, the adults were asked to evaluate each child's veracity. The adults were relatively good at detecting accounts of events that never happened. But the adults were apt to mistakenly believe children's denials of actual events. "The findings suggest that adults are better at detecting false reports than they are at detecting false denials," Goodman said. "While accurately detecting false reports protects innocent people from false allegations, the failure to detect false denials could mean that adults fail to protect children who falsely deny actual victimization." Goodman's co-authors include Donna Shestowsky, acting professor of law at UC Davis, and doctoral students Stephanie Block, Jennifer Schaaf and Daisy Segovia. Goodman was among the first researchers to undertake academic study of children's eyewitness accounts. She is the author of three books and more than 170 scientific articles in the field; some have been cited in U.S. Supreme Court decisions. She is the 2008 recipient of the American Psychological Association's Urie Bronfenbrenner Award for Lifetime Contributions to Developmental Psychology.

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