Wikipedia:School and university projects/Psyc3330 w11/Group19 - Eyewitness memory

Eyewitness memory refers to episodic memories that occur most frequently to the witness of crimes and dramatic events. These witness testimonies are highly relied upon in the judicial system. However, their validity is sometimes questioned due to the many influences that may take part in creating and maintaining these memories. Many experts have accumulated evidence suggesting that eyewitness memory is volatile (Loftus, 1980). Variability in eyewitness memories can be influenced by episodic memory systems, photographic memory, age, facial recognition, and various factors including confidence, interference, and mental state. It has long been speculated that mistaken eyewitness identification plays a major role in wrongful conviction of otherwise innocent individuals. A growing body of research now supports this, and some research indicates that mistaken eyewitness identification accounts for more convictions of the innocent than all other factors combined. Other causes can include, but are not limited to, poorly trained interrogators or forensic scientists, human error in forensics, false confessions, unreliable jailhouse informants, inadequate defense, prosecutorial misconduct, and tampering or withholding police evidence.

Memory Confidence
As a witness identifies a perpetrator, the identification can be made with a particular degree of confidence. This may cause significant individual differences between witnesses. There are two types of confidence: confidence in a witness’ own ability to make an identification (prior to viewing a police line up) and confidence in having made a accurate identification or accurate rejection.

Confidence in ability to make an accurate identification
Confidence of the witness in his/her ability to make correct identification should not be used to assess the accuracy of identification. Witnesses should be asked to attempt identifications, even if their confidence declines. A witness’ confidence in his/her ability to retrieve an accurate identification preceding the actual identification task is not important to the accuracy of the subsequent judgment, as post-identification confidence is a better predictor.

Confidence in having made a correct identification
In numerous experiments, after having given a judgement on the line-up test, witnesses are asked to evaluate their confidence in their choice. After analysis of post-judgment confidence accuracy, witnesses who were exceedingly confident in their identifications are only slightly more likely to be correct when compared to witnesses who exhibit little confidence in their decision. A number of psychologists have investigated factors that might account for the confidence accuracy relationship.

Proposed Theories
The optimality hypothesis proposed by Deffenbacher (1980) states that factors which influence the optimality of information processing also influence the reliability of the confidence estimate. During situations in which information processing conditions are less than optimal (ex. the perpetrator is disguised as the exposure duration is brief) the witness is less precise on the identification test and demonstrates less dependable confidence estimate. The confidence accuracy correlation is thus estimated to be stronger in conditions that help optimal information processing, such as longer exposure time, and weaker under conditions that disable information processing.

Leippe (1980) suggested that certain factors impact identification accuracy without influencing confidence, where as other factors influence confidence without having an effect on identification accuracy. For example, reconstructive processes in memory (i.e. the influence of post-event information on stored memories) can influence identification accuracy while not necessarily impacting confidence. Social influence processes (i.e. committing to a decision) might have an effect on confidence judgements while having little to no effect on the accuracy of the identification.

Although it was thought that confidence of a witness in identifying suspects was very important in the accuracy of identification, it is not. Accuracy in identification is situational and depends on the circumstances surrounding testimony, such as what is neighboring the crime and the identification procedures used. Nonetheless, the confidence of a witness during identification is generally a weak predictor of identification accuracy, as are the quality of descriptions and consistency between descriptions. These factors should not be taken into account when choosing whether or not to conduct a police line-up. When evaluating identification evidence, greater attention should be paid to the circumstances surrounding the identification, as the confidence of the eyewitness less pertinent.

Interference
The testimony of a witness can lose validity due to many external stimuli that may affect what was witnessed during the crime, and therefore obstruct memory. For example, if an individual witnesses a car accident on a very public street, there may be too many cues distracting the witness from the main focus. So many interfering stimulus inputs may have suppressed the importance of the stimulus of focus, the accident. This can cause memory traces for the event to degrade and the representations for those memories may diminish. This is known as the cue-overload principle. Another phenomena that may interfere with an eyewitness’ memory, is retroactive interference. This occurs when new information is processed and can therefore obstruct old information. A common interference that may occur after the event of a crime is the reporting of the crime. Police investigations include questioning, and make suggestions. The processing of new information may disrupt or entirely replace old information, thus losing it.

Post event information
Elapsed time after a crime alone can greatly affect the probability of a witness correctly identifying a suspect. However, this is not the only influence; events that occurr between the time of the crime and the identification can alter these results. Elizabeth Loftus (1979) suggested that interrogation procedures and related events are possibly sources of distortions to eyewitness memory. A study by Cutler, Penrod, and Martens (1987) analysed the effects of refreshing a witness’ memory by allowing the witness to examine his/her own written description of the perpetrator. Some witnesses were asked to view the description just before a line-up. When paired with other interviewing techniques designed to improve memory, the description analysis improved identification accuracy. However, when review of the description was not paired with other techniques, the effects varied. In situations that made the description of the perpetrator difficult, such as disguise during robbery, the description review resulted in poorer identification accuracy. In conditions that made a correct description less difficult, such as perpetrator not disguised, the description review resulted in an increasingly accurate judgement. As well, the effects of mental rehearsal on detail, recollection, and line-up recollection preceding a staged robbery were studied. In this study the participants witnessed the robbery event, where some participants asked to continually rehearse the event in their mind. It was suggested that rehearsal improved detail recollection. Participants in the rehearsed condition showed improved recognition judgements after a short delay following the event, however when delay was increased (a week) performance was reduced.

Suggestive interrogation procedures
Distortions in a witness’s memory can be induced by suggestive questioning procedures. If such techniques are used by investigators, memory for a perpetrator may be altered and as a result, identification accuracy might decline. Exposing witnesses to other descriptions from other witnesses can change a witness’ memory, especially if the description is deceptive. An example of such misleading information could be suggesting that the perpetrator had a beard, while he did not.

Mug shot searches
Another technique commonly used in identification investigations is the mug shot procedure. Numerous studies have shown such procedures can influence identification accuracy. The presentation of mug shot arrays does not seem to influence identification accuracy. However it can be influential if the police lineups include individuals who were featured in the mug shot array. Individuals appearing in police lineups that also appeared in previous photo arrays may be identified as quickly as identifying the actual target. Therefore, in cases where a suspect is identified from mug shots following a line-up, it is uncertain whether the line-up identification is a result of the recognition of the perpetrator or of the detection of person seen previously in the mugs shots.

View point
Many studies, as well as police procedures, are dependent on photo lineups or police lineups where the eyewitness views the suspects from a distance. This proceedure is done in an attempt to eliminate suspects and identify the perpetrator. These types of line-ups allow only small degrees of visual information for the eyewitness, such as limited viewing angles which would restrict the level of detail, compared to a computerized virtual line-up where witnesses can see the targets from multiple angles and distances. One might anticipate that examination of the suspects from unlimted viewpoints would allow for better recognition cues, then when compared to limited views. However, unlimited visual information may be disadvantageous and counterproductive if the information offered at the time of retrieval was not actually present at the time of memory encoding. For example, if an eyewitness only saw the face of the perpetrator from one angle, seeing the line-up participants from other viewpoints might be distracting. Other studies have demonstrated that unlimited viewpoints do improve accuracy in police lineups. It should also be noted that the eyewitness accuracy improves when the distance between the suspect and witness matches the distance during the initial witnessing of the crime.

Mental state
The mental state of an individual both during a crime and during testimony can affect how well memory retrieval may be. Although stress and arousal in small amounts can aid memory, stress in higher amounts can hinder memory performance. Witnesses of a crime can even suffer from more severe implications, such as Post-Traumatic Stress Disorder (PTSD) or even Psychogenic Amnesia. Studies show that PTSD can negatively affect memory. A study found that there is a negative correlation between individuals with PTSD and explicit memory; the type of memory most commonly used in testimony. This may be due to individuals trying to suppress and forget the traumatic event that they were involved in, which is a common symptom of PTSD. There was however, a stronger positive correlation with PTSD and implicit memory, than when compared to non-PTSD patients. That is, individuals suffering from PTSD had greater implicit memory than individuals not suffering from the disorder. Although explicit memory is more commonly used in eyewitness testimony, implicit memory may still be used. Psychogenic amnesia can severely affect explicit memory. In the event that an individual witnessing of a crime is diagnosed with psychogenic amnesia, also known as dissociative amnesia, the individual will lose all memory of the traumatic event. These cases are most often associated with extremely violent crimes and/or murder. In less severe cases, that is without a psychological diagnosis, memory is also affected. Studies show that moderate levels of stress can help memory. Results show that exposure to stress following recall, assists in activating the emotional memory that was involved during the event by 13.5%. Moreover, in cases such as the witnessing of a crime, the mood-congruency effect (mood congruence) also comes into play. The mood-congruency effect occurs when an individual is retrieving memory while in the same mood-state as when learning occurred. Similar to context-dependent memory, the mood congruency effect  also improves memory, however it is achieved through internal mechanisms, instead of external. Biologically, moderate amounts of stress memory may also be improved by the release of corticosteroids. Conversely, too much stress, and therefore an extreme influx of corticosteroids can affect function of the hippocampus, a part of the brain that mediates memory, and therefore hinder memory. Very high levels of corticosteroid release may even cause amnesia.

Context reinstatement
Contextual reinstatement is a common technique used to help eyewitnesses remember details about a specific environment– reviewing the initial environment in which the original information was encoded. Taking a witness back to the scene where the event occurred, for example, will help facilitate the accuracy in identifying perpetrators. Reinstatement is thought to improve recall as it provides memory retrieval cues. Research has demonstrated that pairing faces of suspects or words with contextual cues at the scene of the crime will enhance performance on recognition tasks. Therefore, it seems practical that these results can be applied to eyewitness identification. Methods commonly used to examine context reinstatement include photographs of the environment/scene, mental contextual reinstatement cues, and guided recollection. Studies show that re-exposing participants to the crime scene does enhance performance in facial recognition. There were also notable effects for context reinstatement where improvement on correct identifications while increasing false alarms. Reports also show that the magnitude of improvement via context reinstatement increased in life-like situations compared to laboratory studies. ==

Experimental Context
An alteration of context was found to be one of the most important predictors of recognition accuracy. Such changes in experiential context have been shown to have effects similar to transformations in appearance, such as disguises. Criminal identifications can be influenced by a change in context. Investigators must account for the fact that encountering an acquaintance that we usually see in one context, such as work place, alters memory generalizability when compared to encountering the same acquaintance in another environment that acts like an unassociated context. such as a grocery store. The changes in environment make it difficult to identify this acquaintance. Initially, the individual might seem familiar but because this person is not in the normal context, it might be difficult to place the face and recall the name. Researchers have begun to implement procedures for reinstating the context surrounding a specific event in an attempt to improve identification accuracy. Reinstating the crime scene is often not possible sometimes, however it is possible to have eyewitnesses imagine and thus mentally reinstate the surroundings with imagery instructions and other mnemonic devices. In some instances, objects from the crime scene such as guns or clothing can be used additionally to help reinstate the context. Such methods have successfully shown to improve reliability and accuracy of eyewitness recall.

Misinformation effect
Witnesses can be be subject of memory distortions that can alter their account of events. It is of particular interest that the memory of an eyewitness can become compromised by other information, such that an individual's memory becomes biased. This can increase Eyewitnesses' sensitivity to the misinformation effect. Individuals report what they believe to have witnessed at the time the crime occurred, even though this may be the result of a fabricated false memory. These effects can be a result of post event information. It is very important to provide witnesses with helpful response options on memory tests and to be warned of misleading influences that might affect how the memory of the event is recalled at a later time. Many employees, police force workers, and others are trained in post-warning, in order to reduce influences on the misinformation effect, which can be predicted before crime. In their studies, many researchers use eyewitnesses to study retrieval-blocking effects, which interfere with a witness’ ability to recall information. Misleading information prior to the event can also influence misinformation effects. However, retrieval-blocking methods can counteract misleading information in most cases. In addition, when eyewitnesses are given warning to avoid misinformation, more significant and accurate testimonies could be produced. Other studies also address how misinformation effect seems to amplify over increasing recall. Discussing events and being questioned multiple times may cause various versions of the testimonies. However, the earliest records prove to be most accurate due to a minimized misinformation effect.

Children and Testimony
Children’s Testimony refers to when children are required to testify in court after witnessing or being involved in a crime. A child may be the main or only witness for a crime committed; and as a result, it is common to find a child in the middle of a criminal case serving as an eyewitness. Cases may last for years, potentially causing children to be involved in the interviewing process for prolonged periods of time. Many long delays between the time of the criminal event and their interviews may effect the memory for the event. Therefore, long-term memory is often studied in children’s testimony. Both procedural memory and declarative memory are used in testimonies. In situations where a child is the main witness of a crime, the result of the hearing is dependant on his or her memory of the event. Factors that would influence the testimony include how well a child can identify the individuals involved, the setting of the crime, and the accuracy of their explanation. Children can also be involved in testimony not only when they are witnesses, but also when they are victims. Due to the sensitivity of these cases, strategic interviewing is implemented for children, which may result in the validity of the memory to suffer. Strategic interviewing must be assessed with sensitivity on an individual bases and without leading questions, as they may influence the child’s answer. Additional influences may include individuals surrounding the child prior to, and during the hearing. If children hear new information from such individuals, studies show that children will more than likely agree with what the others said – regardless of the child’s initial opinion. Studies on children show that the average child is at greater risk for memory loss, due to the brain’s immaturity and plasticity, when compared to an average adult. It has been shown that, information encoded and stored in memory is dependent on the extent of knowledge regarding the event. That is, if a child is exposed to an event that he or she knows little about, their memory of the event will not be as accurate when compared to a child who is more knowledgeable on event-related topics. Furthermore, studies show that multiple interviews can ensure a more accurate testimony, as they can improve the accuracy of one’s memory. However, when leading and misguidance become involved, children who are interviewed and questioned multiple times may begin to believe what was discussed in previous interviews actually occurred.

Facial Recognition
Court systems heavily rely on an eyewitness’ memory for faces. The usefulness of eyewitnesses’ memory for facial recognition may not be valid and it has been shown that in experimental tasks, participant performance was closer to chance than actually being able to recognize faces previously presented. These face-specific cognitive and neural processes show contributions to holistic processing and recognition in the episodic memories of eyewitnesses. Unreliability may be a result of mismatching between how faces are holistically and composite systems retrieve features in faces during an event. It can be suggested that race bias may also influence recognition for faces, which can significantly affect the memory of a witness. Individuals who identify most closely with a particular race or their own race, show less reliability in identifying other unfamiliar races. This suggests that memory is an individual process and that conceptualization of race causes racial ambiguity in facial recognition. Monoracial eyewitnesses may depend on categorization more than multiracial eyewitnesses, who develop a more fluid concept of race. Perception may affect the immediate encoding of these unreliable notions due to prejudices, which can influence the speed of processing and classification of racially ambiguous targets. The ambiguity in eyewitness memory facial recognition can be attributed to the divergent strategies that are used when under the influence of racial bias.

Photographic Memory (Eidetic Memory)
Perception and knowledge of the world stem and expand from the selection and integration of stimuli hitting our sensory receptors. As a result, the most precise visual memories possible could only be the images that created the initial visual integration and not the stimulus array itself. Individuals who are said to posses “eidetic memories”(eidetic memory), may be of particular use in courtrooms when acting as an eyewitness, as they have the ability to hold to an image in mind for longer and with more accuracy than the average individual. This would be particularly useful at the time of a crime to retain images such as the perpetrator’s face, clothes, license plate, etc. These mental photographs may be comparable to presenting a real tangible photograph of the event witnessed. However, the memories of those who claim to have superior photographic memories are just as flawed as the memories of individuals who have normal mnemonic abilities. This would affect the validity of testimonies from witnesses with photographic memories. Witnesses who believe that they are able to retrieve an accurate mental photograph will be much more confident in their account of the event and may influence the trial outcome. Accuracy recall of such visual scenes is a controversial issue. In the past, eidetikers were believed to have extremely accurate recall for visual displays, but modern research findings might reveal a different story. Some research demonstrates that eidetic children have greater recall accuracy for visual details compared to non-eidetic children. Other researchers have failed to any advantage between the two groups. It is also hypothesized that eidetic imagery is not exactly related to memory and improve recall for visual details. If this is true, photographic memory is not particularly in the courtroom, which could explain the general failure to detect its existence in adults. Eidetikers cannot produce images of each and every sensory experience on demand. Alternatively, images are created only if the stimulus contains interesting material and a coherent structure. This characteristic critically reduces possible application to criminal justice. Even though there are various thoughts and ideas regarding photographic memory, some people do have exceptional memories, which will help improve the accuracy of eyewitness identification. The frequency of eidetic imagery is low in adults and shows greatest frequency in early child development. However it is almost non-existent past the age of 7. When procedures are used to classify eidetic memory separate from the characteristic of afterimage and memory image, a small number of children are classified as true eidetikers.