I found an interesting research study that shows what happens inside the brains of scientists as they view statistical graphs of the type commonly used in peer-reviewed research. I don’t have the citation in front of me, but it was published in a very prominent research journal. Here’s a brief summary of the research.
A research team took ten scientists and placed them inside an fMRI. The fMRI shows which parts of your brain are active as your brain processes different types of information. The scientists were shown a variety of graphs taken from actual peer-reviewed publications.
As you might expect, the part of your brain that activates first when you are presented an image of a graph is your visual cortex. For most graphs, this was quickly followed by an activation of the parietal lobe, the part of your brain responsible for numerical computations.
But some graphs showed a different pattern. If the graph included a p-value, activation of the visual cortex is followed by activation of an area of your amygdala that is as yet poorly understood. The research team called this portion of the amygdala the p-value receptor.
If your p-value receptor is activated and the p-value is larger than 0.05, the p-value receptor sends strong signals to the pain centers of the brain. This is clearly an adaptive behavior. Scientists who routinely produce p-values larger than 0.05 will not survive and reproduce.
If the p-value receptor is activated and the p-value is 0.05 or smaller, the p-value receptor sends strong signals to the pleasure centers of the brain. Again this is an adaptive behavior. But the interesting finding is that there is a dose response effect. The p-value receptor produces about the same level of pleasure stimulation for p-values of 0.05, 0.04, 0.03, and 0.02. But p-values of 0.01 show an increase in stimulation that becomes even strong for p-values of 0.0099 and smaller. Perhaps there is some pattern associated with p-values that have two zeros to the right of the decimal place that is stronger then a p-value with just a single zero.
The scientists also examined the effect of p-values reported in scientific notation. There was an increase in latency when the p-value receptor is fed a p-value in scientific notation. This probably represents an attempt to decode the scientific notation. But p-values in scientific notation with exponents of -4 or smaller showed an eventual spike in activation of the pleasure centers of the brain that are comparable to those achieved during orgasm.
The research also noted a second important effect of the p-value receptor. Once the p-value receptor is stimulated, the entire cereberal cortex, the portion of your brain associated with logic and complex thinking, is immediately shut down. This insures that a scientist’s brain will focus only on the pleasure or pain associated with the p-value and will ignore the power of the study, the magnitude of the treatment effect, and other unimportant issues.
The researchers suggest that statisticians who want to earn more consulting income and insure repeated business should do their best to produce only p-values that stimulate the pleasure centers of the brain.
You can find an earlier version of this page on my blog.