but they all result from scientists’ attempts to organize observations of people at all ages. Developmental scientists conduct research to gather information and answer questions about how people grow and change over their lives. They devise theories to organize what they learn from research and to suggest new hypotheses to test in research studies. In turn, research findings are used to modify theories. By conducting multiple studies over time, developmental scientists refine their theories about lifespan human development and determine new questions to ask.
The Scientific Method
Researchers employ the scientific method, a process of posing and answering questions by making careful and systematic observations and gathering information. The scientific method provides an organized way of formulating questions, finding answers, and communicating research discoveries. Its basic steps are as follows:
1 Identify the research question or problem to be studied and formulate the hypothesis, or proposed explanation, to be tested.
2 Gather information to address the research question.
3 Summarize the information gathered and determine whether the hypothesis is refuted, or shown to be false.
4 Interpret the summarized information, consider the findings in light of prior research studies, and share findings with the scientific community and world at large.
In practice, the scientific method usually does not proceed in such a straightforward, linear fashion. Frequently, research studies raise as many questions as they answer—and sometimes more. Unexpected findings can prompt new studies. For example, researchers may repeat an experiment (called a replication) to see whether the results are the same as previous ones. Sometimes analyses reveal flaws in data collection methods or research design, prompting a revised study. Experts may also disagree on the interpretation of a study. Researchers may then conduct new studies to test new hypotheses and shed more light on a given topic. For all of these reasons, scientists often say the scientific method is “messy.”
Methods of Data Collection
The basic challenge that scientists face in conducting research is determining what information is important and how to gather it. Scientists use the term data to refer to the information they collect. How can we gather data about children, adolescents, and adults? Should we simply talk with our participants? Watch them as they progress through their days? Hook them up to machines that measure physiological activity such as heart rate or brain waves? Developmental scientists use a variety of different methods, or measures, to collect information.
Observational Measures
Observational measures are methods that scientists use to collect and organize information based on watching and monitoring people’s behavior. Developmental scientists employ two types of observational measures: naturalistic observation and structured observation.
Scientists who use naturalistic observation observe and record behavior in natural, real-world settings. For example, Coplan, Ooi, and Nocita (2015) studied peer interaction patterns in children by observing 9- to-12-year-old children in the schoolyard during recess and lunch. They recorded the children’s activity and interaction with peers and found that children who were consistently unengaged with peers tended to show high levels of problems, such as anxiety, depression, and loneliness, as reported by both the children and their mothers.
This researcher is using a video camera to observe and record the facial expressions a newborn baby makes while it sleeps.
Thierry Berrod, Mona Lisa Production / Science Source
Sometimes the presence of an observer causes those being observed to behave in unnatural ways or ways that are not typical for them. This is known as participant reactivity, and it poses a challenge to gathering by naturalistic observation. One way of reducing the effect of observation is to conduct multiple observations so that the children get used to the observer and return to their normal behavior. Another promising method of minimizing participant reactivity is to use an electronically activated voice recorder (EAR) (Mehl, 2017). Participants carry the EAR as they go about their daily lives. The EAR captures segments of information over time: hours, days, or even weeks. It yields a log of people’s activities as they naturally unfold. The EAR minimizes participant reactivity because the participant is unaware of exactly when the EAR is recording. For example, researchers who study child trauma use EAR to sample conversations between parents and children to understand how parent–child interactions influence children’s adjustment and how the family environment can aid children’s recovery from trauma (Alisic, Krishna, Robbins, & Mehl, 2016).
Naturalistic observation permits researchers to observe patterns of behavior in everyday settings, such as whether a particular event or behavior typically precedes another. Such observations can help researchers determine which behaviors are important to study in the first place. For example, a scientist who studies bullying by observing children’s play may notice that some victims act aggressively before a bullying encounter (Kamper-DeMarco & Ostrov, 2017). The scientist may then decide to examine aggression in victims not only after a bullying incident but also beforehand. Naturalistic observation is a useful way of studying events and behaviors that are common. Some behaviors and events, however, are uncommon or are difficult to observe, such as physical aggression among adults, requiring a researcher to observe for very long periods of time to obtain data on the behavior of interest. For this reason, many researchers make structured observations.
Structured observation entails observing and recording behaviors displayed in a controlled environment, a situation constructed by the experimenter. For example, children might be observed in a laboratory setting as they play with another child or complete a puzzle-solving task. The challenges of identifying and categorizing which behaviors to record are similar to those involved in naturalistic observation. However, the laboratory environment permits researchers to exert more control over the situation than is possible in natural settings. In addition to cataloguing observable behaviors, some researchers use technology to measure biological functions such as heart rate, brain waves, and blood pressure. One challenge to conducting structured observations is that people do not always behave in laboratory settings as they do in real life.
Self-Report Measures
Interviews and questionnaires are known as self-report measures because the person under study answers questions about his or her experiences, attitudes, opinions, beliefs, and behavior. Interviews can take place in person, over the phone, or over the Internet.
The interviewer is asking this young boy about his own experiences, opinions, and behavior. Interviews and questionnaires are known as self-report measures.
Per-Anders Petterson/Corbis News/ Getty Images
One type of interview is the open-ended interview, in which a trained interviewer uses a conversational style that encourages the participant, or the person under study, to expand his or her responses. Interviewers may vary the order of questions, probe, and ask additional questions based on responses. The scientist begins with a question
