Motion Induced Blindness – The visual phenomena that kills – By Dan Flowers

Dan’s Bio, and contact info appear at the end of the article

Most of us remember being taught in driver’s education class to keep up a continuous check in our mirrors and to keep our eyes moving and our head on a swivel.  Jet fighter pilots are taught in much the same manner, to keep the eyes constantly moving from the instruments, to the horizon, to the sky around them.  Great advice to promote situational awareness, but what many do not realize is its value in negating another potential killer:  Motion Induced Blindness.

What is Motion Induced Blindness?  MIB can best be described as the brain’s inability to process what the eyes see when the input becomes too complicated. So, it simply does not process some of the input, and things “disappear”.   A commonly heard comment from drivers who have been in crashes, particularly ones in which the other vehicle approached from the side, is:  “I never saw it coming!”  And they really didn’t.  I know what you are thinking…Given our peripheral vision, how does this happen?

This most often happens when we allow our eyes and attention to fixate on a point or object, and the brain is trying to process both the fixed point and multiple moving objects in the peripheral vision at the same time.   The human peripheral vision is amazingly adept at picking up movement, and providing the brain a 3D moving picture of what is around us.   We unknowingly short-circuit this ability by becoming visually fixated on a point for more than 2-3 seconds at a time, after which we are taking some of the brain’s processing offline, and it begins to miss moving objects and detail in the periphery. 

As a professional sniper instructor, I train snipers to detect targets by using a “neutral focus scan”.  This technique leverages on the brain and peripheral vision’s ability to detect movement (which is the best indicator) as well as other target indicators such as shapes, shine, shadows, color, contrast, textures, and object spacing which appear anomalous, or out of place with their environment.  The technique of neutral focus requires that you not focus on any individual item at first, but instead let your eyes relax at a middle distance while moving the eyes in overlapping “steps” from side to side.  They move through the scan not stopping at any one area more than 3-4 seconds.  The irregularities (target indicators) appear magically as your brain automatically finds them.  Then each can be given closer scrutiny.  An interesting thing happens as soon as you focus on a single object however.  The other irregularities visible during your initial scan fade as you look at the point, but reappear as soon as your eyes start moving again.  This physiological effect could literally be called “tunnel vision”, not to be confused with the metaphorical term that most security practitioners associate with for a loss of situational awareness.

With the understanding of this “tunnel vision” effect in mind, let’s complicate matters even more by placing the entire world in motion… While driving, the brain and peripheral vision is working overtime.  We have our scan going, not letting our eyes fixate for any length of time.  While we are doing this, we can even recognize and process multiple moving objects on different paths.  When the eyes fixate on a point however, the ability to see all of the objects in motion is degraded.  Based on this premise I developed a thesis that would help explain in layman’s terms why MIB happens.

My thesis is as follows:  When the eyes are fixated on a point, the brain can still process a lot of movement.  However, it cannot process all of it and must do “triage”.  It therefore “sees” the objects which constitute the majority that are all moving in the same direction.  It sees these as an integrated whole and concentrates its remaining processing power there.  That means that it “sees” all of the surroundings of the vehicle which are moving on a single axis opposite your direction of travel.  This is a very effective way for the brain to keep you from striking objects in that particular direction of travel.  The problem arises when the brain runs out of bandwidth and no longer has the ability to process “minority” objects that are moving differently.   The danger occurs when the brain is attempting to process all of the points of input in the following equation:

Fixed point (FP)   +   Majority Visuals on Axis 1 (MV1) + minority visuals on axis 2 (mv2)

FP + MV1 + mv2 = Overload.

The brains’ answer?  FP + MV1 – mv2 = FP + MV1

Apparently mv2, after being dropped from the equation by your brain, feels disenfranchised, develops a serious attitude, becomes invisible and crashes into your car!

An excellent interactive example can be accessed online here:  http://www.msf-usa.org/motion.html

In the realm of law enforcement or protective security, the potential implications go beyond avoiding vehicular accidents, and into the recognition of any threat or assailant who might be approaching your moving vehicle.  I thought that the phenomenon deserved more attention and study to see if the MIB effect was a serious consideration when dealing with potential assailants and ambushes.  To test this premise I had a friend assist me in a test.  As a graduate of VDI’s Protective and Evasive Driving Course I had some solid ideas of how to simulate a test scenario.

Using the huge parking lot of a recently closed local manufacturing facility, we conducted the first test by placing a row of traffic cones perpendicular to the path of travel, with a small gap for the car to pass through.  Beyond this gap some distance I placed a cone of a different color as a Fixed Point on which to focus.  My “assailant” stood to the side, and as I was about to pass, would run forward and throw a large water-soaked rag at the windshield of the vehicle as it passed.  I drove at speeds of 30-50 mph toward the gap in the cones, while focusing on the far colored cone.  Even in the empty parking lot, out of many repetitions, I had but the slightest impression of the attacker 30% of the time, all at the lower speeds.  It was quite shocking the first few times when the “thwack!” of the rag arrived, seemingly from nowhere!

The test was repeated on a 2 lane rural road with heavily wooded roadsides and the results even more pronounced, probably due to the greater visual distraction of the trees.   When focus was fixed ahead, the attacker was never detected, despite closing within easy pistol or Molotov cocktail range.  When side-to-side scanning, or neutral focus was used, the attacker was detected 100% of the time. 

 Key Observations:

  • Ability to detect minority visual (mv2) threats decreased as the intensity of the fixed point focus increased.
  • Ability to detect threats decreased as focus time on the fixed point increased.
  • Ability to detect threats degraded as speed increased.
  • Ability to detect threats decreased with an increasing volume of MV1 visual distracters.
  • Tendency towards fixed-point focus increases with fatigue, on open highways, and areas of lower perceived threat.
  • Motion Induced Blindness was almost completely eliminated by active scanning and avoidance of point visual fixation.

Security drivers and LEO’s need to consider this, especially in a world where many criminals and terrorists are well acquainted with the concept of the L-shaped ambush.  Fight the natural inclination to lock onto a potential threat, or stare down the road beyond the intersection.  Keep your eyes moving.  What you don’t see can kill you!

Dan’s contact info

Email:  dkflowers@skybest.com   -  info@theballisticedge.com

Dan’s company The Ballistic Edge :   www.theballisticedge.com

Dan’s Bio

Dan is a graduate of VDI’s Protective and Evasive Driving Course, he served in the US Army as an infantryman and sniper, before beginning work in the private defense and security industry in 1992. Since then he has been continuously employed in various positions as a professional firearms trainer and security specialist providing contract instruction and / or security services for various client companies in the US and over 20 countries abroad. He has also instructed law-enforcement special operations and leadership development courses at state colleges and private universities

Dan has been particularly involved in study of human factors and methods to develop conditioned response through training.  He has been very active in the development of simulations training for small arms and tactics, and was capability designer of 2 sniper simulation trainers for the SOF community.

Dan’s company, The Ballistic Edge, provides sniper training, subcontract R&D, T&E, ballistic algorithms, and assists integration of new equipment or simulation for client commands and agencies.  During his career, Dan had the privilege to both instruct, and learn from, thousands of personnel from every branch of the US Armed Forces, federal, state, and local law-enforcement agencies, as well as private security contractors

Comments

  1. Very solid intel in this write up, people might look at you crazy for constant scanning be it in the car, in a conversation ect, but you will know what is going on when others witll not and it will keep you in a nice state or readiness in the area between the Yellow and Orange.

  2. Steve Haley says:

    This is a great article based on scientific principles. Thanks Dan for going through the effort.

    Along the same lines, this is why SWAT teams have gone away from and the military is going away from dynamic clearing of structures.

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