Consequences of Linguistic Distance for Economic Growth. Erkan Gören. Oxford Bulletin of Economics and Statistics, doi:10.1111/obes.12205
Abstract: This paper advances a new country-level measure of ethno-linguistic diversity, making use of Greenberg's definition of diversity by synthesizing information on the share of different ethno-linguistic groups in a country's population and, more importantly, information on intergroup linguistic distances derived from a recently developed lexicostatistical approach. I show that this measure captures ethno-linguistic diversity at lower levels of linguistic aggregation. However, unlike the commonly used phylogenetic language tree approach, I found that these distance-weighted diversity measures continue to have a strong negative statistical association with economic growth that is not sensitive to the underlying resemblance function between ethno-linguistic groups.
Check also Ethnic Diversity and Poverty. By Sefa Awawory Churchill, Russell Smyth
http://www.bipartisanalliance.com/2017/06/ethnic-and-linguistic-fractionalization.html
World Development, Volume 95, July 2017, Pages 285–302
Bipartisan Alliance, a Society for the Study of the US Constitution, and of Human Nature, where Republicans and Democrats meet.
Thursday, October 26, 2017
Musical improvisation skill makes men more attractive as mates. Implications for the origin of music
Musical improvisation skill in a prospective partner is associated with mate value and preferences, consistent with sexual selection and parental investment theory: Implications for the origin of music. Guy Madison, Jakob Holmquist, Mattias Vestin. Evolution and Human Behavior. https://doi.org/10.1016/j.evolhumbehav.2017.10.005
Abstract: Music is a human universal, which suggests a biological adaptation. Several evolutionary explanations have been proposed, covering the entire spectrum of natural, sexual, and group selection. Here we consider the hypothesis that musical behaviour constitutes a reliable or even costly signal of fitness, and thus may have evolved as a human trait through sexual selection. We experimentally tested how musical performance quality (MPQ), in improvisations on the drums, saxophone, and violin, affects mate values and mate preferences perceived by a prospective partner. Swedish student participants (27 of each sex) saw a face of a person of the opposite sex and heard a piece of improvised music being played. The music occurred in three levels of MPQ and the faces in three levels of facial attractiveness (FA). For each parametric combination of MPG and FA, the participants rated four mate value scales (intelligence, health, social status, and parenting skill) and four mate preference scales (date, intercourse, and short- and long term relationship). Consistent with sexual selection theory, mate value ratings were generally increased by MPQ for raters of both sexes. Consistent with more specific hypotheses that follow from combining sexual selection and parental investment theory, women’s but not men’s preference for a long-term, but not short-term, relationship was significantly increased by MPQ, MPQ generally affected women’s ratings more than men’s, FA generally affected men’s ratings more than women’s, and women’s ratings of intelligence were even more influenced by MPQ than by FA.
Keywords: music; evolution; sexual selection; costly signalling; parental investment theory; fitness display; mate value; mate preference; music performance; skill; mating; adaptation; selection pressure
---Posted to a Facebook forum, a comment to this abstract was (https://www.facebook.com/groups/52551573343/permalink/10154984070543344/?comment_id=10154985709673344¬if_id=1509140218997086¬if_t=group_comment):
Z S: did I ever mention evolutionary psychology is dominated by male researchers? :D just saying
I wrote to one of the authors asking for a reply. Stay tuned.
Abstract: Music is a human universal, which suggests a biological adaptation. Several evolutionary explanations have been proposed, covering the entire spectrum of natural, sexual, and group selection. Here we consider the hypothesis that musical behaviour constitutes a reliable or even costly signal of fitness, and thus may have evolved as a human trait through sexual selection. We experimentally tested how musical performance quality (MPQ), in improvisations on the drums, saxophone, and violin, affects mate values and mate preferences perceived by a prospective partner. Swedish student participants (27 of each sex) saw a face of a person of the opposite sex and heard a piece of improvised music being played. The music occurred in three levels of MPQ and the faces in three levels of facial attractiveness (FA). For each parametric combination of MPG and FA, the participants rated four mate value scales (intelligence, health, social status, and parenting skill) and four mate preference scales (date, intercourse, and short- and long term relationship). Consistent with sexual selection theory, mate value ratings were generally increased by MPQ for raters of both sexes. Consistent with more specific hypotheses that follow from combining sexual selection and parental investment theory, women’s but not men’s preference for a long-term, but not short-term, relationship was significantly increased by MPQ, MPQ generally affected women’s ratings more than men’s, FA generally affected men’s ratings more than women’s, and women’s ratings of intelligence were even more influenced by MPQ than by FA.
Keywords: music; evolution; sexual selection; costly signalling; parental investment theory; fitness display; mate value; mate preference; music performance; skill; mating; adaptation; selection pressure
---Posted to a Facebook forum, a comment to this abstract was (https://www.facebook.com/groups/52551573343/permalink/10154984070543344/?comment_id=10154985709673344¬if_id=1509140218997086¬if_t=group_comment):
Z S: did I ever mention evolutionary psychology is dominated by male researchers? :D just saying
I wrote to one of the authors asking for a reply. Stay tuned.
Robust Sex Differences in Jigsaw Puzzle Solving—Are Boys Really Better in Most Visuospatial Tasks?
Robust Sex Differences in Jigsaw Puzzle Solving—Are Boys Really Better in Most Visuospatial Tasks? Vid Kocijan, Marina Horvat and Gregor Majdic. Front. Behav. Neurosci., October 23 2017. https://doi.org/10.3389/fnbeh.2017.00194
Abstract: Sex differences are consistently reported in different visuospatial tasks with men usually performing better in mental rotation tests while women are better on tests for memory of object locations. In the present study, we investigated sex differences in solving jigsaw puzzles in children. In total 22 boys and 24 girls were tested using custom build tablet application representing a jigsaw puzzle consisting of 25 pieces and featuring three different pictures. Girls outperformed boys in solving jigsaw puzzles regardless of the picture. Girls were faster than boys in solving the puzzle, made less incorrect moves with the pieces of the puzzle, and spent less time moving the pieces around the tablet. It appears that the strategy of solving the jigsaw puzzle was the main factor affecting differences in success, as girls tend to solve the puzzle more systematically while boys performed more trial and error attempts, thus having more incorrect moves with the puzzle pieces. Results of this study suggest a very robust sex difference in solving the jigsaw puzzle with girls outperforming boys by a large margin.
Abstract: Sex differences are consistently reported in different visuospatial tasks with men usually performing better in mental rotation tests while women are better on tests for memory of object locations. In the present study, we investigated sex differences in solving jigsaw puzzles in children. In total 22 boys and 24 girls were tested using custom build tablet application representing a jigsaw puzzle consisting of 25 pieces and featuring three different pictures. Girls outperformed boys in solving jigsaw puzzles regardless of the picture. Girls were faster than boys in solving the puzzle, made less incorrect moves with the pieces of the puzzle, and spent less time moving the pieces around the tablet. It appears that the strategy of solving the jigsaw puzzle was the main factor affecting differences in success, as girls tend to solve the puzzle more systematically while boys performed more trial and error attempts, thus having more incorrect moves with the puzzle pieces. Results of this study suggest a very robust sex difference in solving the jigsaw puzzle with girls outperforming boys by a large margin.
‘Big push’ policies can fail, it is important the reliability and gradual increases in technological complexity
Contagious disruptions and complexity traps in economic development. Charles Brummitt et al. Nature Human Behaviour 1, 665–672 (2017), September 2017. DOI:10.1038/s41562-017-0190-6
Abstract: Poor economies not only produce less; they typically produce things that involve fewer inputs and fewer intermediate steps. Yet the supply chains of poor countries face more frequent disruptions — delivery failures, faulty parts, delays, power outages, theft and government failures — that systematically thwart the production process. To understand how these disruptions affect economic development, we modelled an evolving input–output network in which disruptions spread contagiously among optimizing agents. The key finding was that a poverty trap can emerge: agents adapt to frequent disruptions by producing simpler, less valuable goods, yet disruptions persist. Growing out of poverty requires that agents invest in buffers to disruptions. These buffers rise and then fall as the economy produces more complex goods, a prediction consistent with global patterns of input inventories. Large jumps in economic complexity can backfire. This result suggests why ‘big push’ policies can fail and it underscores the importance of reliability and gradual increases in technological complexity.
Abstract: Poor economies not only produce less; they typically produce things that involve fewer inputs and fewer intermediate steps. Yet the supply chains of poor countries face more frequent disruptions — delivery failures, faulty parts, delays, power outages, theft and government failures — that systematically thwart the production process. To understand how these disruptions affect economic development, we modelled an evolving input–output network in which disruptions spread contagiously among optimizing agents. The key finding was that a poverty trap can emerge: agents adapt to frequent disruptions by producing simpler, less valuable goods, yet disruptions persist. Growing out of poverty requires that agents invest in buffers to disruptions. These buffers rise and then fall as the economy produces more complex goods, a prediction consistent with global patterns of input inventories. Large jumps in economic complexity can backfire. This result suggests why ‘big push’ policies can fail and it underscores the importance of reliability and gradual increases in technological complexity.
Solitude has a deactivation effect on people’s affective experiences, decreasing positive & negative high-arousal affects
Solitude as an Approach to Affective Self-Regulation. Thuy-vy T. Nguyen, Richard M. Ryan, Edward L. Deci. Personality and Social Psychology Bulletin, https://doi.org/10.1177/0146167217733073
Abstract: In this research, we showed that solitude generally has a deactivation effect on people’s affective experiences, decreasing both positive and negative high-arousal affects. In Study 1, we found that the deactivation effect occurred when people were alone, but not when they were with another person. Study 2 showed that this deactivation effect did not depend on whether or not the person was engaged in an activity such as reading when alone. In Study 3, high-arousal positive affect did not drop in a solitude condition in which participants specifically engaged in positive thinking or when they actively chose what to think about. Finally, in Study 4, we found that solitude could lead to relaxation and reduced stress when individuals actively chose to be alone. This research thus shed light on solitude effects in the past literature, and on people’s experiences when alone and the different factors that moderate these effects.
My commentary: What about other species, like primates?
Abstract: In this research, we showed that solitude generally has a deactivation effect on people’s affective experiences, decreasing both positive and negative high-arousal affects. In Study 1, we found that the deactivation effect occurred when people were alone, but not when they were with another person. Study 2 showed that this deactivation effect did not depend on whether or not the person was engaged in an activity such as reading when alone. In Study 3, high-arousal positive affect did not drop in a solitude condition in which participants specifically engaged in positive thinking or when they actively chose what to think about. Finally, in Study 4, we found that solitude could lead to relaxation and reduced stress when individuals actively chose to be alone. This research thus shed light on solitude effects in the past literature, and on people’s experiences when alone and the different factors that moderate these effects.
My commentary: What about other species, like primates?
Significant hump-shaped relation between genetic variation and financial market size
Financial Markets and Genetic Variation. Eric Cardella, Ivalina Kalcheva & Danjue Shang. Journal of International Financial Markets, Institutions and Money, http://www.sciencedirect.com/science/article/pii/S1042443117300392
Highlights
• We examine the relation between genetic variation and financial market activity.
• We use country-level data on predicted genetic variation and financial market size.
• Significant hump-shaped relation between genetic variation and financial market size.
• Results are restricted specifically to equity market size (vs. debt market size).
• Better country-level governance moderates the effect of genetic variation.
Abstract: We investigate the extent to which a country’s degree of genetic variation contributes to the observed variation in financial market activity across countries. We postulate that genetic variation can affect financial markets through its impact on aggregate investment behavior, innovation in the financial sector, and productivity. Our country-level, cross-sectional analysis reveals a significant hump-shaped relation between a country’s predicted genetic variation and the size of its financial markets. This result is consistent with the conjecture that at relatively intermediate degrees of genetic variation, the associated intermediate levels of trust and risk-taking within the country result in the largest investment flows into public financial markets. Our results are robust to different measres of financial market size, several regression specifications, and the inclusion of a broad range of controls such as legal origin, institutional characteristics, culture, natural endowment, and trade openness. Our main findings appear to be restricted specifically to equity markets (vs. debt markets) where there is relatively more uncertainty and, thus, trust and risk-taking are relatively more important. Additional analysis suggests that better overall country-level governance can moderate the role that genetic variation plays in shaping equity market size.
Highlights
• We examine the relation between genetic variation and financial market activity.
• We use country-level data on predicted genetic variation and financial market size.
• Significant hump-shaped relation between genetic variation and financial market size.
• Results are restricted specifically to equity market size (vs. debt market size).
• Better country-level governance moderates the effect of genetic variation.
Abstract: We investigate the extent to which a country’s degree of genetic variation contributes to the observed variation in financial market activity across countries. We postulate that genetic variation can affect financial markets through its impact on aggregate investment behavior, innovation in the financial sector, and productivity. Our country-level, cross-sectional analysis reveals a significant hump-shaped relation between a country’s predicted genetic variation and the size of its financial markets. This result is consistent with the conjecture that at relatively intermediate degrees of genetic variation, the associated intermediate levels of trust and risk-taking within the country result in the largest investment flows into public financial markets. Our results are robust to different measres of financial market size, several regression specifications, and the inclusion of a broad range of controls such as legal origin, institutional characteristics, culture, natural endowment, and trade openness. Our main findings appear to be restricted specifically to equity markets (vs. debt markets) where there is relatively more uncertainty and, thus, trust and risk-taking are relatively more important. Additional analysis suggests that better overall country-level governance can moderate the role that genetic variation plays in shaping equity market size.
Biased decision-making in international financial institutions -- mechanical rules overridden to assign a different official rating
Room for discretion? Biased decision-making in international financial institutions. Valentin Lang & Andrea Presbitero. Journal of Development Economics, Volume 130, January 2018, Pages 1-16. https://doi.org/10.1016/j.jdeveco.2017.09.001
Abstract: We exploit the degree of discretion embedded in the World Bank-IMF Debt Sustainability Framework (DSF) to understand the decision-making process of international financial institutions. The unique, internal dataset we use covers the universe of debt sustainability analyses conducted between December 2006 and January 2015 for low-income countries. These data allow us to identify cases where the risk rating implied by the application of the DSF's mechanical rules was overridden to assign a different official rating. Our results show that both political interests and bureaucratic incentives influence the decision to intervene in the mechanical decision-making process. Countries that are politically aligned with the institutions' major shareholders are more likely to receive an improved rating; especially in election years and when the mechanical assessment is not clear-cut. These results suggest that the room for discretion international financial institutions have can be a channel for informal governance and a source of biased decision-making.
Keywords: International organizations; Political economy; IMF; World Bank; Debt sustainability
Abstract: We exploit the degree of discretion embedded in the World Bank-IMF Debt Sustainability Framework (DSF) to understand the decision-making process of international financial institutions. The unique, internal dataset we use covers the universe of debt sustainability analyses conducted between December 2006 and January 2015 for low-income countries. These data allow us to identify cases where the risk rating implied by the application of the DSF's mechanical rules was overridden to assign a different official rating. Our results show that both political interests and bureaucratic incentives influence the decision to intervene in the mechanical decision-making process. Countries that are politically aligned with the institutions' major shareholders are more likely to receive an improved rating; especially in election years and when the mechanical assessment is not clear-cut. These results suggest that the room for discretion international financial institutions have can be a channel for informal governance and a source of biased decision-making.
Keywords: International organizations; Political economy; IMF; World Bank; Debt sustainability
Teaching personal initiative beats traditional training in boosting small business
Teaching personal initiative beats traditional training in boosting small business in West Africa. Francisco Campos et al. Science, Sep 22 2017, Vol. 357, Issue 6357, pp. 1287-1290. DOI: 10.1126/science.aan5329
Abstract: Standard business training programs aim to boost the incomes of the millions of self-employed business owners in developing countries by teaching basic financial and marketing practices, yet the impacts of such programs are mixed. We tested whether a psychology-based personal initiative training approach, which teaches a proactive mindset and focuses on entrepreneurial behaviors, could have more success. A randomized controlled trial in Togo assigned microenterprise owners to a control group (n = 500), a leading business training program (n = 500), or a personal initiative training program (n = 500). Four follow-up surveys tracked outcomes for firms over 2 years and showed that personal initiative training increased firm profits by 30%, compared with a statistically insignificant 11% for traditional training. The training is cost-effective, paying for itself within 1 year.
Abstract: Standard business training programs aim to boost the incomes of the millions of self-employed business owners in developing countries by teaching basic financial and marketing practices, yet the impacts of such programs are mixed. We tested whether a psychology-based personal initiative training approach, which teaches a proactive mindset and focuses on entrepreneurial behaviors, could have more success. A randomized controlled trial in Togo assigned microenterprise owners to a control group (n = 500), a leading business training program (n = 500), or a personal initiative training program (n = 500). Four follow-up surveys tracked outcomes for firms over 2 years and showed that personal initiative training increased firm profits by 30%, compared with a statistically insignificant 11% for traditional training. The training is cost-effective, paying for itself within 1 year.
Beyond questionable research methods: The role of omitted relevant research in the credibility of research
Schmidt, Frank L. (2017). Beyond questionable research methods: The role of omitted relevant research in the credibility of research. Archives of Scientific Psychology, 5(1), 32-41. http://dx.doi.org/10.1037/arc0000033
ABSTRACT: Governments often base social intervention programs on studies done by psychologists and other social scientists. Often these studies fail to mention other research suggesting that such interventions may have a limited chance of actually working. The omitted research that is not mentioned often shows that the behaviors and performances targeted for improvement by the environmental intervention programs are mostly caused by genetic differences between people and for that reason may be more difficult to change than implied in these studies. This is particularly true when the goal is to greatly reduce or eliminate differences between people in such domains as school achievement, impulsive behaviors, or intelligence. This problem of omitted research creates two problems. It tends to call into question the credibility of all social science research, even the studies that do not omit relevant research. And from an applied point of view, it leads to the expenditure of taxpayer dollars on programs that are unlikely to produce the desired outcomes.
SCIENTIFIC ABSTRACT: This article explores an important credibility problem in the research literature beyond the issue of questionable data analysis methods: the problem of omission of relevant previous research in published research articles. This article focuses on this problem in 2 areas: (a) studies purporting to demonstrate the effects of people’s experiences on their later life outcomes while failing to discuss or mention the probable causal role of genetic inheritance in producing these effects, despite the strong evidence for this connection from behavior genetics research; and (b) studies of specific aptitudes (specific abilities) such as verbal, spatial, or reasoning that fail to acknowledge or mention that such aptitudes are indicator variables for general mental ability (GMA; or intelligence) and that after proper control for GMA the residuals in these aptitudes make essentially no contribution to prediction of real world academic, occupational, or job performance. It is only the GMA component in such aptitudes that produces the ability to predict. As is well known today, the issue of the credibility of research conclusions is prominent (Ioannidis, 2005). In both the areas examined in this article, these deficiencies create serious and unnecessary credibility problems, and the doubts they inspire about credibility could unfortunately be generalized to other research areas in which these problems do not exist.
KEYWORDS: research credibility, behavior genetics, general mental ability, intelligence, specific abilities
---
The purpose of this article is to draw attention to an important problem in the research literature beyond the issue of questionable statistical data analysis methods in research. That is the problem of the omission of relevant research findings in published research articles. This article has focused on this problem in two areas. The first area consists of studies purporting to demonstrate the effects of people’s experiences on their life outcomes. Many studies drawing causal conclusions about these experiences fail to mention the probable causal role of genetic inheritance in producing these effects, despite the overwhelming evidence for this connection from behavior genetics research. The second area consists of studies of specific aptitudes (specific abilities) such as verbal, quantitative, and spatial, or reasoning. Many such studies fail to acknowledge or even mention that such aptitudes are indicator variables for GMA and that after proper control for GMA the residuals in these aptitudes make essentially no contribution to prediction of real world academic, occupational, or job performance. It is only the GMA component in such aptitudes that produces the ability to predict.
A reviewer suggested that research areas beyond the two examined in this article should be addressed. However, the first area examined here is very broad and includes research in many areas and specialties of psychology and the social sciences. These include the research areas of academic achievement, aggressive behavior, abusive behavior within families, failure in intimate relationships, authoritative versus authoritarian parenting, effects of parental reading on children, later effects of self-control displayed in childhood, and effects of personality traits on behaviors and perceptions. These multiple areas of research are all observational or correlational. Areas of experimental research are not included because (in theory) randomization of subject assignment controls for hidden or unrecognized causal variables (lurking variables; Joiner, 1981). However, experimental psychology research as typically found in the literature, although not subject to the problems examined in this article, has other serious problems; for example, see Schmidt and Oh (2016). In addition, Jussim, Crawford, Anglin, Stevens, and Duarte (2016) discussed the tendency in experimental social psychology for researchers to fail to consider alternative and plausible interpretations of their findings and pointed out that this omission reduces the credibility of their research conclusions.
The issue of the credibility of research conclusions is prominent today (Ioannidis, 2005). In both the areas examined in this article, these deficiencies create serious and unnecessary credibility problems, and the doubts they inspire about research credibility could unfortunately be generalized inappropriately to other research areas in which these problems do not exist. So it is important that this problem be addressed and corrected.
However, it is also important not to leave the impression that all studies have these problems. Studies can be found that are exemplary. One example is the study by Dinescu et al. (2016). This study examined the hypothesis that when people marry, their level of alcohol consumption decreases. They acknowledged that marriage per se might not be the causal variable and that people who marry might be genetically different from those who do not. So they controlled for genetic effects using a sample of 1,703 monozygotic and 722 dizygotic twins. Their results showed the even after controlling for genetic effects, people drank less after marriage than they had before marriage. Another exemplary study is Gotlib et al. (2015). This study found that apparently healthy women whose mothers suffered from depression had shorter telomeres and greater cortisol reactivity to stress than did women whose mothers had never been depressed. They acknowledged that this effect could be genetic or environmental or both, and they called for research to determine the relative contributions of genetic and environmental causes. There is another particularly important example. For over 25 years, Terrie Moffitt and Avshalom Caspi have conducted longitudinal research studies that have taken into account both genetic and environmental contributions to human behaviors. And in 2016 they received the Distinguished Scientific Contributions Award for this work from the American Psychological Association (Award for Distinguished Scientific Contributions, 2016). These and other examples in the literature show that it is possible to conduct research of the type called for in this article.
The hope is that the information presented in this article will lead to recognition in the literature of the role of behavior genetics findings in studies interpreting relationships between experiences and later life outcomes; and to recognition of the central role of GMA in studies examining specific aptitudes and abilities. At present the literatures in these two areas contain many studies that are scientifically incomplete. These changes are important for establishment of the credibility of research conclusions in these areas and may help to deter credibility losses across other areas of research.
ABSTRACT: Governments often base social intervention programs on studies done by psychologists and other social scientists. Often these studies fail to mention other research suggesting that such interventions may have a limited chance of actually working. The omitted research that is not mentioned often shows that the behaviors and performances targeted for improvement by the environmental intervention programs are mostly caused by genetic differences between people and for that reason may be more difficult to change than implied in these studies. This is particularly true when the goal is to greatly reduce or eliminate differences between people in such domains as school achievement, impulsive behaviors, or intelligence. This problem of omitted research creates two problems. It tends to call into question the credibility of all social science research, even the studies that do not omit relevant research. And from an applied point of view, it leads to the expenditure of taxpayer dollars on programs that are unlikely to produce the desired outcomes.
SCIENTIFIC ABSTRACT: This article explores an important credibility problem in the research literature beyond the issue of questionable data analysis methods: the problem of omission of relevant previous research in published research articles. This article focuses on this problem in 2 areas: (a) studies purporting to demonstrate the effects of people’s experiences on their later life outcomes while failing to discuss or mention the probable causal role of genetic inheritance in producing these effects, despite the strong evidence for this connection from behavior genetics research; and (b) studies of specific aptitudes (specific abilities) such as verbal, spatial, or reasoning that fail to acknowledge or mention that such aptitudes are indicator variables for general mental ability (GMA; or intelligence) and that after proper control for GMA the residuals in these aptitudes make essentially no contribution to prediction of real world academic, occupational, or job performance. It is only the GMA component in such aptitudes that produces the ability to predict. As is well known today, the issue of the credibility of research conclusions is prominent (Ioannidis, 2005). In both the areas examined in this article, these deficiencies create serious and unnecessary credibility problems, and the doubts they inspire about credibility could unfortunately be generalized to other research areas in which these problems do not exist.
KEYWORDS: research credibility, behavior genetics, general mental ability, intelligence, specific abilities
---
The purpose of this article is to draw attention to an important problem in the research literature beyond the issue of questionable statistical data analysis methods in research. That is the problem of the omission of relevant research findings in published research articles. This article has focused on this problem in two areas. The first area consists of studies purporting to demonstrate the effects of people’s experiences on their life outcomes. Many studies drawing causal conclusions about these experiences fail to mention the probable causal role of genetic inheritance in producing these effects, despite the overwhelming evidence for this connection from behavior genetics research. The second area consists of studies of specific aptitudes (specific abilities) such as verbal, quantitative, and spatial, or reasoning. Many such studies fail to acknowledge or even mention that such aptitudes are indicator variables for GMA and that after proper control for GMA the residuals in these aptitudes make essentially no contribution to prediction of real world academic, occupational, or job performance. It is only the GMA component in such aptitudes that produces the ability to predict.
A reviewer suggested that research areas beyond the two examined in this article should be addressed. However, the first area examined here is very broad and includes research in many areas and specialties of psychology and the social sciences. These include the research areas of academic achievement, aggressive behavior, abusive behavior within families, failure in intimate relationships, authoritative versus authoritarian parenting, effects of parental reading on children, later effects of self-control displayed in childhood, and effects of personality traits on behaviors and perceptions. These multiple areas of research are all observational or correlational. Areas of experimental research are not included because (in theory) randomization of subject assignment controls for hidden or unrecognized causal variables (lurking variables; Joiner, 1981). However, experimental psychology research as typically found in the literature, although not subject to the problems examined in this article, has other serious problems; for example, see Schmidt and Oh (2016). In addition, Jussim, Crawford, Anglin, Stevens, and Duarte (2016) discussed the tendency in experimental social psychology for researchers to fail to consider alternative and plausible interpretations of their findings and pointed out that this omission reduces the credibility of their research conclusions.
The issue of the credibility of research conclusions is prominent today (Ioannidis, 2005). In both the areas examined in this article, these deficiencies create serious and unnecessary credibility problems, and the doubts they inspire about research credibility could unfortunately be generalized inappropriately to other research areas in which these problems do not exist. So it is important that this problem be addressed and corrected.
However, it is also important not to leave the impression that all studies have these problems. Studies can be found that are exemplary. One example is the study by Dinescu et al. (2016). This study examined the hypothesis that when people marry, their level of alcohol consumption decreases. They acknowledged that marriage per se might not be the causal variable and that people who marry might be genetically different from those who do not. So they controlled for genetic effects using a sample of 1,703 monozygotic and 722 dizygotic twins. Their results showed the even after controlling for genetic effects, people drank less after marriage than they had before marriage. Another exemplary study is Gotlib et al. (2015). This study found that apparently healthy women whose mothers suffered from depression had shorter telomeres and greater cortisol reactivity to stress than did women whose mothers had never been depressed. They acknowledged that this effect could be genetic or environmental or both, and they called for research to determine the relative contributions of genetic and environmental causes. There is another particularly important example. For over 25 years, Terrie Moffitt and Avshalom Caspi have conducted longitudinal research studies that have taken into account both genetic and environmental contributions to human behaviors. And in 2016 they received the Distinguished Scientific Contributions Award for this work from the American Psychological Association (Award for Distinguished Scientific Contributions, 2016). These and other examples in the literature show that it is possible to conduct research of the type called for in this article.
The hope is that the information presented in this article will lead to recognition in the literature of the role of behavior genetics findings in studies interpreting relationships between experiences and later life outcomes; and to recognition of the central role of GMA in studies examining specific aptitudes and abilities. At present the literatures in these two areas contain many studies that are scientifically incomplete. These changes are important for establishment of the credibility of research conclusions in these areas and may help to deter credibility losses across other areas of research.