Fear & Loading: Triggers And Fingers

by
posted on June 2, 2015
** When you buy products through the links on our site, we may earn a commission that supports NRA's mission to protect, preserve and defend the Second Amendment. **
trigger.jpg
Sometimes I research a little too much on subjects, but I ran across something last week I think you’ll find interesting. The paper, titled “Quantifying the Independence of Human Finger Movements: Comparisons of Digits, Hands, and Movement Frequencies,” appeared in The Journal of Neuroscience on Nov. 15, 2000. Charlotte Hager-Ross and Marc H. Schieber conducted the research and composed the article.

Their experiments attempted to determine how well humans could move one digit on their hand without moving the others. It didn’t focus on shooting, but when we move the trigger, our thumb—accustomed to years of working in tweezer-like concert with the index finger—often inadvertently applies point-of-impact-altering pressure to the pistol grip or rifle stock.

The scientists determined the ability to avoid the problem varies considerably and, “To some extent such intersubject variability may reflect differences in the long-term motor experiences of each subject,” they wrote. Those “long-term motor experiences” are what we call practice, range time, tickling the trigger.

As for the wisdom of slowing down and really squeezing, “Negative correlations—lower individuation indexes at higher movement frequencies—were found for all digits except the thumb.” So the faster you pull the trigger, the greater the accuracy-robbing pressure applied by the rest of your hand (with the exception of the thumb).

For the average test subject, the thumb was not immune to movement, however. “We found that even when asked specifically to move one digit without moving any other digits, normal human subjects produced low-amplitude motion in noninstructed digits simultaneous with the large-amplitude motion of the instructed digit.”

Why does it happen? Adjoining and shared muscles, tendons and tissue are part of the explanation, but there’s more at play according to the pair. “…[T]he motoneuron pools innervating different finger muscles receive considerable shared central input.”

None of this is earth-shattering news, and it should come as no surprise they found, “…the thumb and index finger showed the highest degrees of individuation and stationarity, i.e., the greatest independence.” It is, however, nice when science verifies the sage advice to practice and slow down your shots.

And, if you haven’t been practicing with your off-hand regularly, you’re officially out of excuses. “In strongly right-handed subjects, however, we found no evidence of a systematic difference in finger movement independence between the right and left hands in terms of either individuation or stationarity,” the researchers wrote. In fact, there may be a slight advantage in using the weak side for long-distance shooting. “Performing a separate paired comparison of the individuation indexes for each digit of the right versus left hand revealed a significant difference only for the thumb, where the individuation index was higher for the left, nondominant thumb than for the right.”

Latest

Mossberg 940 Pro New Models 01
Mossberg 940 Pro New Models 01

Mossberg Introduces SPX & Professional Models To 940 Pro Tactical Line

Mossberg has expanded its popular 940 Pro Tactical shotgun line with SPX and Professional models, with each adding a slate of upgraded components and accessories designed to enhance the shotgun's capabilities.

Preview: Streamlight Sidewinder X

This high-output, multi-fuel, military-style light with a tilting head is perfect for hunters and home defenders looking for more than just a handheld light...

The Armed Citizen® July 4, 2025

Read today's "The Armed Citizen" entry for real stories of law-abiding citizens, past and present, who used their firearms to save lives.

A Guide To Double-Stack 1911s

The 2011 brings double-stack capacity and modular upgrades to the 1911 platform, but not every wide-body 1911 out there earns that name.

Legislators Enjoy Afternoon Of Clays With Benelli USA, Among Others

A bipartisan group of Maryland state legislators met with firearm industry manufacturers and representatives for a day of clays shooting while also attending discussions on the positive economic impacts of the shooting sports.

2025 Ammunition Product Of The Year: Winchester .21 Sharp

For continuing to innovate, particularly in a corner of the ammo world that has seen very little recently, we named the Winchester .21 Sharp as our Ammunition Product Of The Year.

Interests



Get the best of American Rifleman delivered to your inbox.