FORENSICS 111: EYEWITNESS UNRELIABILITY
The subject of this essay was suggested by one of our readers named Fotini, whom I thank.
Systems designed by nature are sometimes less than perfect, and those designed by humans are ocertainly not perfect. An example is our criminal justice system.
A 1995 book describing a 10-year study of evidence and assessments gathered from criminal justice system personnel indicated that approximately 0.5 percent of persons convicted of felonies were probably innocent. If the estimate is accurate, that amounts to some 10,000 innocent persons per year being incarcerated for crimes they did not commit. Understandably, officials complained that the rate estimate was unreasonably high.
Then, along came DNA testing. Based on DNA analysis, a more recent book placed the estimated rate of innocent persons being convicted close to 10 percent. Pretrial tests performed at the FBI and other crime labs on DNA samples from 18,000 prime suspects exonerated 5,000 (more than 25 percent) of the suspects. In the U.S. during the last two decades, the number of persons on death row who were proved innocent amounted to an error rate of more than 12 percent. The State of Illinois had an error rate of more than 50 percent. The Illinois governor imposed a moratorium on the death penalty until problems could be resolved. There are now reportedly more than two million persons in U.S. prisons and jails. Even if the innocent represent only 0.5 percent of that amount, it means that there are some 10,000 persons staring out from the wrong side of concrete and barbed wire.
For those innocents whose cases involve it, DNA can quite literally be a life saver. Think of all the persons in prison whose innocence cannot be proved by DNA, however, all those who were convicted because of improper investigations, incompetent legal representation, confused or biased testimony, etc.
According to a U.S. Department of Justice study, “The most common cause of wrongful convictions in our judicial system is mistaken identification.” Juries place a lot of trust in eyewitness identification. Unfortunately, as overwhelming evidence indicates, eyewitness identification is often highly inaccurate. A 1987 study revealed that some 300 of 500 wrongful convictions were the result of mistaken eyewitness identification.
Who determines the credibility of eyewitness testimony during a jury trial? That responsibility falls almost exclusively on the shoulders of jury members who are often ignorant of the iffyness of observations and memories. Giving untrue evidence can seriously sabotage the integrity of a trial, but eyewitnesses can be confident their testimony is accurate and yet be unaware that it is not. Jurors decide in secret whether or not the testimony given is true or not and need not reveal their reasons. Only rarely will factual questions lead to successful appeals, so most parties in trials get only one opportunity for justice. In view of the foregoing, it should be apparent that the exceptional influence of eyewitness testimony needs to be balanced by at least an awareness by judge and jury that an eyewitness might not have to lie to give inaccurate testimony.
Believe it or not there is more than one theory about possible causes of eyewitness unreliability, and the included comments are based on those that are reasonably mainstream. Memory, of course, plays a large part in eyewitness unreliability. Memory does not simply record pictures, sounds, tastes, tactile sensations and odors as they are sensed. It (actually they) is much more complex. The following is a (very) brief and bony summation of the MEMORIES (plural) believed to be possessed by humans, but it offers a whiff of the complexity of their functions.
There are four major types of memory. The first type is sensory. As one might expect, sensory memory is divided into iconic (visual), echoic (auditory), taste, tactile and olfactory types. The second memory type is short-term. It is also known as primary, working or active memory and keeps a small amount of information, usually between three and nine elements (numbers, letters or words) readily available for somewhere between two and 60 seconds depending on which theory is being quoted. It retains information just pulled from a sensory memory or from long-term memory. It can also pull up information resulting from mental processing; but that usually falls into the domain of working memory, which modern theorists define as including (being generic to) the older concept of short-term memory. Working memory is also divided into a central executive system that controls cognitive processes, a phonological loop system that deals with sound information and a visuospatial sketchpad system that holds information about what one sees.
The third type is long-term memory, which can retain information from a few days to a lifetime. It is divided into implicit and explicit memories. Implicit memory stores previously learned information that remains essentially unconscious, e.g., how to ride a bike or roller skate. Explicit memory stores things that one consciously recalls and can verbalize, and it is subdivided into semantic and autobiographical memories. Semantic memory stores facts, e.g., historic dates, but not details about how one learns them, and information someone related, but not the exact words used to do so. Semantic memory is actually more similar to knowing than to recollecting. Autobiographical memory involves a recollection of events or episodes in one’s life. Often, it enables one to remember what was said in the past quite accurately. It is from the autobiographical memory that eyewitnesses are most often asked to recall and report information. The foregoing should give readers the idea that some memory theories are divided, subdivided, sub-subdivided….
So why is eyewitness information so unreliable? Obvious reasons for visual inaccuracy include conditions during an observation, such as lighting, distance, distraction, movement, orientation and motion of the object observed and duration of the observation. Noises and distance can interfere with auditory accuracy, and the physical and mental states of the observer can influence both visual and auditory accuracy. Regarding perception, we are not like cameras that record every detail. Our consciousness is not privy to raw data that we sense but only to an interpretation of it. Also, much of the raw data is discarded, leaving only an interpretation; and we are left with no awareness of what facts have been deleted or modified. When there are gaps in reception of visual and auditory information, persons tend to fill them using information from memories, biases and expectations and to interpret what they believe they see and hear and what they expect to see and hear. Most of us have caught just a few key words and mentally transformed them into a meaningful sentence and have seen a few lines and mentally turned them into a sketch of a recognizable object or scene. Interpretation proceeds as a memory forms, and distortion of the memory proceeds right along with it.
An example of an erroneous initial perception based at least partially on expectations is well illustrated by what began with a series of common events and ended with a dreadful climax. Two young men had been hunting bear in a wooded area all day. It was beginning to get dark, and the men were tired. They had been hoping to spot a bear and had been thinking and talking about bears as they walked along a path. Rounding a bend, they spotted a large object in the woods about 25 yards ahead. It was moving, and they heard noises coming from it. Thinking the object was a bear, both men fired at it. Unfortunately, the object was a yellow tent . The movements and noises came from a man and woman making love inside. The woman was killed by one of the bullets. The jury before whom the man whose bullet had struck the woman was tried could not understand how anyone could mistake a yellow tent for a growling bear. The man was convicted of negligent homicide, and he later committed suicide.
An interesting phenomenon, known as memory source confusion, comprises a memory incorporating another memory from a source such as a conversation with another witness or with police or even from an imaginary event. The phenomenon is an example of semantic memory butting into biographical memory territory.
An example of a person confusing information sources (and of stone-headed officials acting unbelievably badly) ironically involves an Australian eyewitness expert. He participated in a discussion of eyewitness memory unreliability on live TV and was later arrested for having raped a woman. He was identified by the victim after having been placed in a lineup. The rape had occurred while he was on TV with other members of the discussion group – not to mention having been watched by what must have been at least thousands of viewers. The discussion group also included an assistant commissioner of police. Despite all that, the police charged the expert with rape. Fortunately, the incident was investigated; and it was discovered that the victim had been watching the very TV program upon which the expert had appeared. She had mentally confused the face of the expert she had been watching with that of the actual rapist. The expert was “eventually” cleared.
Picking perpetrators from a lineup, which can be either simultaneous or sequential, represents a great opportunity for misidentification. Choosing a face that is the most similar to the culprit’s face is known as a relative response. Choosing a face by strictly comparing it to a memory of a perpetrator is known as an absolute response. Eyewitnesses tend to pick a person who most resembles their memory of a perpetrator RELATIVE TO OTHER MEMBERS in the lineup. This is bad enough if a real perpetrator is in fact in a lineup. Even if s/he is not, there will still be someone who most resembles the perpetrator, and an eyewitness is still inclined to pick that person. Misidentification is dramatically reduced if eyewitnesses are told that a perpetrator might or might not be in a lineup. Even so, some eyewitnesses still choose based on relative appearances.
In both simultaneous and sequential lineups, innocent look-alikes are more often misidentified when the similarity of those in a lineup is relatively low as compared to when it is relatively high. Position and order in a lineup have an effect on eyewitness identification. The use of foils, or distractors, in lineups reduced both false and true identifications.
Assembling a lineup including a tall suspect and noticeably shorter foils, including a suspect of one race and foils of another, including a bearded suspect and clean-shaven foils, etc. can obviously bias eyewitness identification. Asking an eyewitness to “take another look at number four” can certainly do the same. Asking an eyewitness to “take another look” at a particular mug shot or leaning forward, raising an eyebrow, voicing approval-sounding noises or gesturing when an eyewitness focuses on a particular picture in a photospread can also transmit signals that bias an eyewitness toward selecting that picture. All this indicates that double-blind procedures should be made standard practice.
Kindly keep in mind that the foregoing text barely scratches the surface of what is behind perception, memory and eyewitness unreliability.
EXTRA FACTS:
Contrary to popular belief, studies indicate that airplane pilots and police officers are no more exempt from making misidentifications and giving inaccurate testimony than the rest of us.
Third parties can also influence the reliability of testimony. Even questions that differ in but one word can be used to do so. For example, asking an eyewitness to estimate the speeds of cars that “smashed” into each other tends to yield higher estimates than for cars that merely “hit” each other. Asking whether a driver stopped at a stop sign can encourage an eyewitness to assume there was a stop sign and to say later that there was such a sign even if there was not.
