Study: Analyzing the stand-up speed of proned-out suspects

A proned-out suspect still presents significant potential danger and officers should remain vigilant


Article reprinted from Force Science News #357

Some surprising findings are surfacing in the preliminary analysis of a new study conducted by the Force Science Institute.

The study concerned the speed with which a suspect can scramble up from a proned-out position to a flight-or-fight stance.

Statistically, the suspects were able to rise up fastest from the position with hands tucked under their chests. The slowest was with feet bent back toward seat. (AP Photo/Richard Vogel)
Statistically, the suspects were able to rise up fastest from the position with hands tucked under their chests. The slowest was with feet bent back toward seat. (AP Photo/Richard Vogel)

Results are showing that the time involved is far shorter than you may think, despite positioning tweaks that police officers commonly believe will impede sudden threatening movement.

How much time does the prone position buy?

Proning out a suspect is widely accepted by officers as a tactic that will buy them a reactionary edge in case the subject decides to launch an assault or attempt to flee. But how much of an edge does it really buy?

At an academy in the Midwest, a research team headed by Dr. John O’Neill, a behavioral scientist on the FSI staff, assembled a group of recruit volunteers to find out.

The participants on average fit the physical characteristics of suspects who typically attack LEOs – male, mid-20s in age, just under 6 ft. tall and weighing about 175 lbs. – as determined by an earlier study led by Dr. Anthony Pinizzotto, a former Force Science instructor.

4 positions, 1 command

One at a time, 89 recruits acting as suspects were videotaped starting in two prone positions frequently seen on the street:

  1. Flat on their belly, hands tucked under their chest (a position that offenders may assume in direct defiance of officers’ positioning orders);
  2. Arms out to the side in a T position, palms up.

    Then 66 of the same volunteers were tested starting in two additional prone positions:
  3. Arms out and legs crossed at the ankles;
  4. Arms out, ankles crossed, legs bent so the feet were angled back toward the butt.

As cameras rolled, each “suspect” was given the same simple command: “Stand up as fast as you can.”

'Very surprising' results

“We were expecting to find a lot of variance” among the positions, O’Neill told Force Science News. But when the video footage was time-coded and analyzed frame by frame with the help of computer software that allows for measurements in milliseconds, “very surprising data” became clear.

“From all four positions flat on the ground,” O’Neill says, “the subjects rose up to standing in one second or less. They got up in different ways, but in no more than a second – faster than we expected – they were up with their hands off the ground and their body weight fully supported by their feet in kind of a crouch from which they could launch an aggressive move or start to escape.

“Across the four positions, the most extreme difference between the slowest time to rise and the fastest time was less than only two-tenths of a second. Usually the difference was less than one-tenth of a second.

Statistically, the suspects were able to rise up fastest from the position with hands tucked under their chests. The slowest was with feet bent back toward seat.

“From an analysis standpoint, these miniscule differences have some statistical significance,” O’Neill says, “but from a practical standpoint they appear essentially of no major consequence.”

Take-away

“Our conclusion is that prone positioning, even with supposed hindrances like crossing the legs, is not as safe or as inhibiting to suspects as many officers believe,” O’Neill says. “A proned-out suspect still presents significant potential danger and officers should remain vigilant.”

While the research findings do not lend themselves to recommending a preferred method of prone positioning, O’Neill hopes that future experiments will lead to tactical improvements. “If readers have other variations they’d like to see tested, we’d welcome hearing from them,” he says.

Contact O’Neill at john.oneill@forcescience.org.

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