Do you recognize this face? Most people probably do, but try describing it from memory.
Kind of like a taller head. Does he have brown eyes? They’re not exactly deep-set. Green
eyes? Bland features. I don’t remember like any dimples or moles. Ben Affleck’s nose...
Not flat but not super pointy either. So this is the challenge faced by police sketch
artists. They interview victims and witnesses about a criminal’s
face and their drawings go out to the public with the goal of soliciting tips.
Take a good look at that sketch. If that man looks familiar... If you have any information you're asked to call metro crimestoppers.
we wanted to find out how accurate these sketches are, and if there might be a better way to
put those memories onto paper.
There really isn’t any good data on how often a sketch helps police catch a criminal
on the loose. but by the looks of it, more often than not,
they don’t achieve a very strong likeness. There are certainly some notable exceptions,
like this sketch made of Oklahoma City bomber Timothy McVeigh.
or cases where the suspect has a really distinctive look.
but mostly they’re kind of a shot in the dark. In academic experiments, sketches were identified
only around 8% of the time Now that’s arguably better than nothing, but
there are also risks to putting out a bad sketch.
This man served 12 years in prison for a crime he didn’t commit after someone said he looked
like the sketch of a rapist and then the victim wrongly chose him from a lineup.
Here’s why this is so hard. Psychologists have long known that we process human faces
holistically, rather than on the level of individual features.
Here’s an example: take a look at this photo.
Now which of these is the mouth you saw? Generally
people are worse at getting this right than if the mouths are shown in the original facial context.
Or try this - are the top halves of these
faces the same? How about these? We’re generally quicker to answer when the halves are misaligned
than when they're aligned. That suggests that it’s difficult for us to focus on just one part of a face.
The rest of the face tends to interfere. So our brains aren’t well suited to describe
individual facial features but that’s typically what victims and witnesses are asked to do.
And that’s been the fatal flaw for the many attempts to improve upon the hand-drawn sketch,
dating back to the 1960s when police tried using these mechanical kits of interchangeable features.
Picture puzzles to put mugs in the jug.
Then came computer programs that were slightly
more customizable but still relied on feature-by-feature reconstruction.
In laboratory tests, these systems performed pretty badly.
But the latest generation of computer programs seems more promising. This system was developed
by psychologists at the University of Winchester in the UK. It makes use of the fact that we’re
good and recognizing faces but bad at recalling their parts.
After the victim or witness specifies the gender, age and race, it presents randomly
generated faces instead of individual features. and all the person has to do is choose a few
faces that most resemble the suspect. Using what’s called a genetic algorithm, those
faces then get bred together and a new set of faces appears. They can also adjust holistic
variables, like attractiveness. When they tested this program in the lab,
participants were able to generate these celebrity faces from memory.
And when they tried it in 5 real police departments, it led to arrests around 40% of the time on
average and up to 60% in the most recent trial. For example, this composite helped police
catch a man who raped two women in Manchester. Someone called in after they recognized the
image as a local fast food worker. Nearly half of violent crimes go unsolved
in the US. that includes around 60% of forcible rapes. Sketches are easy to poke fun at but
they’ve been one of the only tools detectives have in the absence of other evidence. So
it’s good news that in the future, they might be slightly less of an art and more of a science.