The Science of Perception and Film Continuity


Carefully examine this x-ray.  See the gorilla?
In a test, most trained radiologists missed it.

One of the most important jobs in movie and television production is Continuity, making sure that the actors and sets appear exactly the same from scene to scene.  This job requires someone who is detail oriented in the extreme, very meticulous in approach, with a good visual memory.

And yet some amazingly distracting continuity flubs slip through.  Harry Potter's T-shirt abruptly changing from a crew neck to a Henley shirt in 'The Order of the Phoenix,' or how in 'Pretty Woman,' Julia Roberts' croissant morphs into a pancake.  Did you catch these continuity errors?  Probably not – until they were pointed out to you.

An example that nearly ruined a classic movie for me occurs in the classic flick Casablanca.  I must have watched the movie twenty times before I caught it, and once I did, I haven’t been able to watch the movie without thinking, “it’s coming up.  Wait for it.  It’s almost here.  There.  There’s the blunder.  How could anyone miss that?” 

Did anyone on the Warner Brothers production team catch it?  Apparently not, or if they did, they didn’t feel it was worth re-shooting the scene to correct it.  Or maybe they understood that people simply don’t see things they’re not looking for.

You could call it the Gorilla in the Room effect.  You may be aware of effect, especially if you work in production continuity, and there is research to back this up.  The effect is this:  Study participants, all radiologists very skilled at reading x-ray images, were assigned a task on a computer, and while focused on the task, participants failed to notice the image of a gorilla embedded in the x-ray.  How could they miss it?  They weren’t looking for it so they didn’t see it.

What researchers did is ask 24 radiologists to perform a standard lung nodule detection task. They examined five scans; each scan contained an average of 10 nodules. A gorilla, 48 times larger than the average nodule, was inserted in the last scan. The researchers found that 83 percent of radiologists did not report seeing the gorilla.

Script Supervising
and Film Continuity

by Pat P. Miller

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"When engaged in a demanding task, attention can act like a set of blinders, making it possible for stimuli to pass, undetected, right in front of our eyes," explained Trafton Drew, PhD, a post-doctoral researcher at Brigham and Women's Hospital (BWH) in Boston[i].  Known as “inattentional blindness,” researchers think that not noticing things in the background has an evolutionary basis that as one researchers says, “Keeps us sane.”

"The radiologists missed the gorillas not because they could not see them, but because the way their brains had framed what they were doing. They were looking for cancer nodules, not gorillas," explained Jeremy Wolfe, senior psychologist and director of the Visual Attention Laboratory at BWH.

This phenomena is basic to the way our brains function, and is why people are hired to pay attention to the small, and even the large continuity issues.  Maybe only 17% of the audience will catch the flub, but they will tell their friends and soon most people are aware of it and will start noticing it.

Why we miss subtle visual changes, and why it keeps us sane
Don't worry if you missed those continuity bloopers. Vision scientists have discovered an upside to the brain mechanism that can blind us to subtle changes in movies and in the real world, a "continuity field" in which we visually merge together similar objects seen within a 15-second time frame.

"The continuity field smooths what would otherwise be a jittery perception of object features over time," said David Whitney, associate professor of psychology at UC Berkeley.  "Essentially, it pulls together physically but not radically different objects to appear more similar to each other," Whitney added. "This is surprising because it means the visual system sacrifices accuracy for the sake of the continuous, stable perception of objects.[ii]"

“Conversely, without a continuity field, we may be hypersensitive to every visual fluctuation triggered by shadows, movement and myriad other factors. For example, faces and objects would appear to morph from moment to moment in an effect similar to being on hallucinogenic drugs.”

Using the Gorilla in the Room Effect
Since publication of Poe’s The Purloined Letter in 1844, authors and later screenwriters have used the Gorilla in the Room Effect as a plot devise.  The entire Peter Faulk series, Columbo, was based on the missing clue in plain sight that no one else noticed.  It might have been an object out of place, or an unobserved step in a logical progression that Columbo picked up that eventually catches the killer.  We knew from the first scene who the killer was.  The show almost teased us with the unobserved yet obvious object or event.  “Did you see it?  Did you catch it?”

Look at it as a game between the writer and the reader or viewer.  Can you come up with something obvious but unnoticed that is the lynch pin of your plot and story?  Something that will make your audience think along with your protagonist, involving them more deeply in your story? 

You can test the Gorilla in the Room.  Wear a button on your shirt or jacket that you surreptitiously change for another button of a radically different color and message in the same position and watch if anyone notices.  You could do the same thing with a scarf, or change your hair style right in the middle of a party.  Think of how much fun you can have taking advantage of the fact we’re all programmed to not notice these subtle changes.

For those who love Casablanca, I apologize for dooming you to look for the continuity flaw.  Rather than watching for enjoyment, you will now watch the film looking for the very minor but disconcerting mistake.  “It’s coming up.  Wait for it.  It’s almost here.  There.  There’s the blunder.  

How could anyone miss that?” 

Related stories:

[i]   T. Drew, M. L.- H. Vo, J. M. Wolfe. The Invisible Gorilla Strikes Again: Sustained Inattentional Blindness in Expert Observers. Psychological Science, 2013
[ii]   University of California - Berkeley. "Why we miss subtle visual changes, and why it keeps us sane." ScienceDaily, 30 March 2014.


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