Recent studies, as summarized, for example, in E. Mortensen et al. (2002). The association between duration of breastfeeding and adult intelligence. Journal of the American Medical o ciation , 287 , 2365–2371, suggest that breast-feeding of infants may increase their subsequent cognitive ((IQ) development. Both experiments and observational studies are cited. (a ) What determines whether some of these studies are experiments? (b) Name at least two potential confounding variables controlled by breast-feeding experiments.
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Also, we do not have access to those studies.
However, for (a) an experiment has:
An independent variable is the potential stimulus or cause, usually directly manipulated by the experimenter, so it could also be called a manipulative variable.
A dependent variable is the response or measure of results.
Extraneous variables — other than the independent variable — potentially can affect the dependent variable, so they must be controlled. If possible, you try to keep them constant between the experimental and control group.
The experimental group receives the independent variable.
The control group is similar to experimental, except it does not receive the independent variable. Extraneous variables are balanced between experimental and control groups.
(a) To determine whether a study is an experiment, we need to look at its research design. Experiments involve the manipulation of an independent variable by the researcher and the random assignment of participants to different groups. This allows for the establishment of cause-and-effect relationships. In the case of breastfeeding studies, experiments would involve the deliberate manipulation of the duration or intensity of breastfeeding in infants, with some infants being breastfed for longer durations or higher intensity, and others receiving formula or no breastfeeding at all.
(b) Potential confounding variables that could be controlled in breastfeeding experiments include:
1. Maternal IQ: The intelligence of the mother could influence both her decision to breastfeed and the cognitive development of her child. By controlling for maternal IQ, researchers can better isolate the impact of breastfeeding on intelligence.
2. Socioeconomic status (SES): Breastfeeding rates tend to be higher among mothers with higher socioeconomic status. SES is also associated with cognitive development, so controlling for this variable allows researchers to determine whether the benefits of breastfeeding on intelligence are independent of socioeconomic factors.
These are just two potential confounding variables, but there could be others depending on the specific study design. By taking measures to control for these variables, researchers can better attribute any observed differences in intelligence to the duration or intensity of breastfeeding.