Psychologists have long argued that eyewitness testimony should be taken with a grain of salt since it relies on something inherently unreliable: human memory. When there are , his or her brain will often work to fill them in. This can be nudged by leading questions from other people or by our own preconceived notions of what makes sense. And, the way we remember an incident can be influenced by the level of stress we were under while experiencing it.
The flawed nature of memory unsurprisingly affects the accuracy of facial composites, the sketches of suspects produced based on eyewitness accounts. A 2007 psych study done by Iowa State University found that facial composites did not end up looking like the intended faces, even when those faces were familiar to the witnesses. In addition, the producing of sketches often inhibited recognition ability later on, when witnesses were asked to identify suspects in lineups.
But hope is on the horizon for this messy aspect of criminal justice. One day, law enforcement officials may be able to produce more accurate facial sketches by examining the DNA left behind at a crime scene. Scientists have identified five genes associated with different facial features. The characteristics they code for are quite specific–three examples being the length of the nose, the distance between the cheekbones and the distance from the eyes to the bridge of the nose.
As more and more such genes involved with “facial morphology” are identified, the researchers say, they could become quite valuable in forensics work. Traits like eye color and hair color can already be tested for using DNA samples, so testing in conjunction for facial features could theoretically lead to the composite of a face, to a fair degree of accuracy. Criminals beware.