Digging Past Implausibility

A friend who visited me a week ago swears by zodiac signs, claiming my personality was “such an Aquarius; so goal-driven, stubborn and opinionated.” Even when discussing another friend, this person asked if she was a Scorpio because “Scorpios tend to have really deep-rooted emotional issues — you should watch out.”

Zodiac signs refer to astrological star formations that are supposed to classify people’s personality based on their birthdays While some take them seriously, many people dismiss zodiac signs. How can the stars that shined on a person’s birthday possibly influence something as complicated as that person’s future character?

Yet scientific history contains many similar, implausible explanations for psychological phenomena. Take the fad of phrenology, for instance. Phrenology refers to a process of determining a people’s cognitive faculties by measuring their skulls. The idea was that certain areas of the brain were responsible for cognitive traits such as intelligence or aggressiveness. Having a bump on your skull near an area responsible for aggressiveness could mean that you may be more combative than a normal person, or so the ancient thinking went.

Despite phrenology’s past popularity, no study of which I am aware has found any kind of statistical association between skull shape and behavior. Yet the theory was highly influential in the 19th century, and it was accepted by nearly all European scientists. One must then wonder why those scientists dedicated themselves to a theory that now seems quite preposterous.

Initially, the premises behind phrenology were not so outlandish. We know the brain is by no means homogenous, and certain brain regions are specialized for particular functions. Early scientists once thought people would be better at performing certain tasks if parts of their brains linked to the accomplishment of those tasks were larger. They linked size with increased effectiveness and performance.

In the 19th century, scientists had a general sense of what brain areas were responsible for by analyzing the cognitive symptoms of patients who had injured various brain areas. If patients who have strokes in one section of their brain — cutting off blood flow — experience difficulty speaking, maybe people who have an abnormally large section in the same region would prove more talkative.

Before the era of brain imaging, the sizes of specific brain areas were thought to be best approximated by looking at the skull. However, even if these approximations were close to accurate, the neural basis behind behavior is much too complicated to be explained by size. Cognitive neuroscientists have moved on to correlate behavioral traits with variables such as white matter integrity or blood flow to brain regions, and even these measures are thought to be much too simple to clarify neural mechanisms.

Such pseudoscience has long been discarded, yet even when it is disproved, there are those who still cling to its claims. To return to the original example, why do people cling to simplistic, pseudoscientific theories such as horoscopes? It is universally acknowledged that the brain is one of the most complex creations that nature has ever fashioned. Why do we think that something as simple and implausible as star signs or skull size explain our unique personalities?

Perhaps it is because we love simple explanations. Rather than confronting the complex factors that underlie problems, such as an economic downturn, people seem to prefer answers that are easy to comprehend on a surface level. This is not the same as saying scientists do not respect simplicity; physicists endlessly search for evidence that link fundamental forces and biologists hail natural selection because the simple theory explains so much.

However, simple yet accurate theories are very rare. And while we love simplicity, we should prefer accuracy. Horoscopes are fun, but if you are serious about finding a compatible romantic partner, you might want to consider more than just date of birth.


Ayan Mandal is a junior in the College. Brain History appears every other Tuesday.

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