Confusing Causation and Correlation: Media Distortions of Research

Bugaboos of media science reporting.
PsyBlog has an interesting post from a few weeks ago — a list of eight ways the media distorts research findings. Perhaps the most compelling in the list is the tendency to confuse causation with correlation. Even among the educated there is a confusion about the difference between proving cause and effect (causation) and examining the relationship between two variables (correlation). Probably the most infamous example of two variables is that of smoking and lung disease.

For instance: Smoking and lung cancer.
Despite widespread common belief to the contrary, a link between the two has never been proven. Rather, over the years a compelling body of evidence strongly suggests that there is a strong connection between smoking and lung disease. This is not the same as proving causation. No one has ever observed smoke entering a lung and metastasizing lung tissue. That smoking causes lung cancer is the hypothesis. The large body of research that supports the hypothesis elevates the idea to a theory. It is possible that at some point some new research will disprove this theory, in which case a new hypothesis about the link between lung cancer and smoking would be developed.

Not being disproved — not the same as being proven.
The theory is robust because lots of evidence supports it. But not being disproved is not the same as being proven. For instance, just because we cannot disprove that aliens founded Western civilization does not necessarily mean that the idea is true. Working hypotheses are not discarded in psychology quite as often as, for instance, in astrophysics, but they are challenged from time to time.

Another hypothesis: Learning, memory and sleep.
Though not a confusion of causation and correlation, here’s an example of a hypothesis being revised, if not rejected: For years it has been commonly thought that learning is consolidated at night. That neuronal connections are strengthened and learning somehow reinforced during sleep. A January 20 article in Nature Neuroscience suggests a different hypothesis. Essentially this hypothesis is that the brain expends so much energy learning during the day that we simply cannot afford to learn at night — the brain shuts down. This theory is supported by molecular and electro-physiological studies in rats to evaluate synaptic potentiation. An exciting aspect of current brain research is the degree to which neuronal processes can be observed.

Kalea Chapman, Psy.D.


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Clinical Psychologist practicing in the Los Feliz neighborhood of Los Angeles, California.

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