Final answer:
Experimental methods infer causation due to random assignment of participants which controls for lurking variables, allowing researchers to isolate the effect of the independent variable on the outcome.
Step-by-step explanation:
Experimental methods allow us to infer causation primarily because of random assignment. When researchers conduct a controlled experiment, participants are randomly selected and assigned to different groups, which limits the influence of lurking variables.
Such a design ensures that the only significant difference between the groups is the independent variable being tested. For example, participants taking aspirin versus a placebo in a study allows researchers to observe the direct effects of aspirin on heart attack risk. Random assignment ensures that any other potential variables that could affect the outcome are distributed evenly across both groups, making it more likely that any observed effects are due to the experimental treatment rather than other factors.
Experiments allow for the manipulation of the independent variable while controlling for extraneous variables, enabling researchers to make causal statements about the relationship between variables in the developmental process.