The scientific method illuminates and illustrates human development as nothing else does. Facts, hypotheses, and possibilities have all emerged that would not be known without science—and people of all ages are healthier, happier, and more capable than people of previous generations because of it.
For example, infectious diseases in children, illiteracy in adults, depression in late adulthood, and racism and sexism at every age are much less prevalent today than a century ago. Science deserves credit for all these advances. Even violent death is less likely, with scientific discoveries and universal education considered likely reasons (Pinker, 2011).
Developmental scientists have also discovered unexpected sources of harm. Video games, cigarettes, television, shift work, and asbestos are all less benign than people first thought. Even life-sustaining medical measures, such as restarting a stopped heart, and mechanical respirators, may sometimes impede optimal development in late adulthood.
Although the benefits of science are many, so are the pitfalls. We now discuss three potential hazards: misinterpreting correlation, depending too heavily on numbers, and ignoring ethics.
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correlation A number that indicates the degree of relationship between two variables, expressed in terms of the likelihood that one variable will (or will not) occur when the other variable does (or does not). A correlation indicates only that two variables are related, not that one variable causes the other to occur.
Probably the most common mistake in interpreting research is confusing correlation with causation. A correlation exists between two variables if one variable is more—or less—likely to occur when the other does. A correlation is positive if both variables tend to increase together or decrease together, negative if one variable tends to increase while the other decreases, and zero if no connection is evident.
To illustrate: From birth to age 9, there is a positive correlation between age and height (children grow taller as they grow older), a negative correlation between age and napping (children nap less often as they grow older), and zero correlation between age and number of toes (children do not grow new toes with age). (Now try the quiz on correlation in Table 1.5.)
| Two Variables | Positive, Negative, or Zero Correlation? | Why? (Third Variable) |
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_____________ | _____________ |
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_____________ | _____________ |
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_____________ | _____________ |
| For each of these three pairs of variables, indicate whether the correlation between them is positive, negative, or nonexistent. Then try to think of a third variable that would determine the direction of the correlation. | ||
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Answers:
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Many correlations are unexpected. For instance, first-born children are more likely to develop asthma than are later-born children, teenage girls have higher rates of mental health problems than do teenage boys, and newborns of immigrants weigh more than do newborns of nonimmigrants. All these surprising correlations are discussed later.
However, correlation is not causation. Just because two variables are correlated does not mean that one causes the other—even if it seems logical that it does. Correlation proves only that the variables are connected somehow. Many mistaken and even dangerous conclusions are drawn because people misunderstand correlation.
The most important caution for all scientists, especially for those studying humans, is to uphold ethical standards in their research. Each academic discipline and every professional society involved in the study of human development has a code of ethics (a set of moral principles) and specific practices within a scientific culture to protect the integrity of research.
Especially for Future Researchers and Science Writers Do any ethical guidelines apply when an author writes about the experiences of family members, friends, or research participants?
Response for Future Researchers and Science Writers: Yes. Anyone you write about must give consent and be fully informed about your intentions. They can be identified by name but only if they give permission. For example, family members gave permission before anecdotes about them were included in this text. My nephew David read the first draft of his story (see pages 20–21) and is proud to have his experiences used to teach others.
Ethical standards and codes are increasingly stringent. In the United States, most educational and medical institutions have an Institutional Review Board (IRB), a group that permits only research that follows certain guidelines. Although IRBs often slow down scientific study, some research conducted more than 50 years ago, before IRBs were established, was clearly unethical, especially when the participants were children, members of minority groups, prisoners, or animals (Blum, 2002; Washington, 2006). Scientists—and everyone else—are horrified to learn about the Tuskeegee study that did not treat people who had syphilis, or the Little Albert research that taught an infant to fear white furry things.
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Ethical principles underlying all research in human development include that researchers must ensure that participation is voluntary, confidential, and will not harm the participants. This entails the informed consent of the participants—that is, they must understand and agree to the research procedures, knowing what risks are involved. If children are involved, consent must be obtained from the parents as well as the children, and the children must be allowed to end their participation at any time.
Although protection of participants may conflict with the goals of science, scientists now believe that protection of participants is paramount. The Canadian Psychological Association suggests four guiding principles, which are expressed in similar ways in other disciplines and other nations:
All four principles should be followed, if possible, but they are ranked in order of importance: Respect for individuals trumps social responsibility.
Once a study has been completed, additional issues usually arise. Scientists are obligated to “promote accuracy, honesty, and truthfulness” (American Psychological Association, 2010).
Deliberate falsification is unusual. When it does occur, it leads to ostracism from the scientific community, dismissal from a teaching or research position, and, sometimes, criminal prosecution.
Another obvious breach of ethics is to “cook” the data, or distort one’s findings, in order to make a particular conclusion seem to be the only reasonable one. This is not as rare as it should be. Tenure, promotion, and funding all encourage scientists to publish, and publishers seek remarkable findings. Awareness of this danger is leading to increased calls for replication (Carpenter, 2012).
Scientists are rewarded for publishing surprising results. When a hypothesis is not confirmed, that may lead to the “file drawer problem”; that is, a study is filed away and never published because the results are not exciting.
Ethical standards cannot be taken for granted. As stressed in the beginning of this chapter, researchers, like all other humans, have strong opinions that they expect research to confirm. Therefore, sometimes without even realizing it, they might try to achieve the results they want. As one team explains:
Our job as scientists is to discover truths about the world. We generate hypotheses, collect data, and examine whether or not the data are consistent with those hypotheses…[but we] often lose sight of this goal, yielding to pressure to do whatever is justifiable to compile a set of studies we can publish. This is not driven by a willingness to deceive but by the self-serving interpretation of ambiguity…
[Simmons et al., 2011, pp. 1359, 1365]
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Obviously, collaboration, replication, and transparency are essential ethical safeguards for all scientists.
Finally one crucial ethical concern should begin the process of scientific study for all developmentalists: to study issues that will help “all kinds of people, everywhere, of every age” live satisfying and productive lives. Consider these questions, for instance:
The answer to all these questions is a resounding NO. The reasons are many, but a major one is that these topics are controversial. Some researchers avoid them, fearing unwelcome and uninformed publicity (Kempner et al., 2005). Few funders are eager to support scientific studies of drug abuse, poverty, nonstandard families, or death, partly because people have strong opinions on these issues that may conflict with scientific findings and conclusions. Religion, politics, and ethics shape scientific research, sometimes stopping investigation before it begins. For instance, federal legislation passed in 1997 virtually prohibits federal funding for research on gun use.
The next cohort of developmental scientists will build on what is known, mindful of what needs to be explored. Remember that the goal is to help all 7 billion people on Earth fulfill their potential. Much more needs to be learned. The next 24 chapters are only a beginning.
Although science has improved human development in many ways, caution is needed in interpreting results and in designing research. Sometimes people think that correlation indicates cause. It does not.
Research on human development must subscribe to high ethical standards. Participants must be respected and must give informed consent. Political and publishing concerns can interfere with objective research. Scientists must study and report data on issues that affect the development of all people.
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