Question

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 Association , 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 breastfeeding experiments.

Answer 1

a.) For studies to be Experiments they should fulfil the below criterion:

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.

b.)

The Most common Confounding variables are:

-> Mother's education

-> Mother's age

-> HOME cognitive stimulation

-> HOME emotional support

-> Gestation (weeks)

-> Birth weight (g)

-> Birth order

-> Mother smoked in pregnancy

-> Male infant