Can Pupil Size Predict IQ?

Could IQ–a famous standard of intelligence that has long eluded quantification–be as easy to measure as pupil size? Could the reason why establish a link between norepinephrine and fluid intelligence (and therefore, Mental Mojo consumption–See last paragraph)? Georgia psychologists Jason Tsukahara and colleagues hypothesize affirmatively in a paper they published two months ago.

First a little background. Pupils have long been known to vary in size due to changes in emotional state and cognitive effort (i.e., brain strain). As Tsukahara writes:

Starting in the 1960s it became apparent to psychologists that the size of the pupil is related to more than just the amount of light entering the eyes. Pupil size also reflects internal mental processes. For instance, in a simple memory span task, pupil size precisely tracks changes in memory load, dilating with each new item held in memory and constricting as each item is subsequently recalled.

In other words, it is old news one’s pupils get big when one’s brain is working hard.

However, it wasn’t until the past couple of months that an actual correlation between resting pupil diameter and fluid intelligence (a major component of IQ) was shown. The revelation came as a result of Tsukahara’s study of 331 individuals across various ethnic groups. The researchers tested it for confounding variables such as age, gender or nicotine/caffeine consumption, and the correlation held up.

So what does this mean? Tsukahara doesn’t have the answer yet, but he has a theory. Specifically, he thinks that the larger pupil size reflects a higher baseline of norepinephrine, a member of the catecholamine family (you may be more familiar with norepinephrine’s siblings, adrenaline and dopamine) that boosts the brain’s processing speed and connectivity.

So how does this relate to Mental Mojo? The key is something that Team Mojo knew when they formulated Mental Mojo: our bodies derive catecholamines from L-Tyrosine, one of Mental Mojo’s active ingredients. It therefore follows that if Tsukahara is right, then a link between fluid intelligence and Mental Mojo consumption will be established in the near future. Yet another reason why Mental Mojo is Rocket Fuel for Your Brain.

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