Researchers at the US Army Research Laboratory (ARL) are working on a project to explore how imperfect brain signals affect a soldier's ability to shoot a weapon.

Although soldiers improve their trigger control with practice, an involuntary muscle twitch often reduces the ability to smoothly pull the trigger and accurately hit a target.

A twitch is caused when imperfect signals are sent to the finger muscle from the brain via neurons.

During the research, ARL kinesthesiologist Dr. Matt Tenan found that after a long rucksack march in brutal heat, a soldier's ability to smoothly pull the trigger and accurately hit a target declined as signals from the brain weaken due to fatigue.

Army researchers have used an electrical device to optimise how the brain controls muscles and reduce twitches.

"Army researchers have used an electrical device to optimise how the brain controls muscles and reduce twitches."

The device features an artificial trigger containing a force transducer, which measures the strength of a person's trigger pull.

It uses a piezoelectric vibrator connected to the person's wrist, and an acupuncture wire, which is stuck into the person's muscle, without causing pain or bleeding.

The wire is in turn connected to an ultrasound device that detects and displays muscle activity as sine waves on a computer screen.

Smoothly curved waves indicate a smooth trigger squeeze, while chopped or jerky sine waves show an ‘erratic’ trigger pull.

Researchers have found that electrical and noise stimulation have similar effects when tested separately.

Vibration stimuli has been used to smoothen trigger squeezes, as producing vibration using a battery and an oscillator is easier in battlefield conditions.

Image: The US Army Research Laboratory has invented a device to help soldiers to smoothly pull the trigger. Photo: courtesy of David Vergun.