Catching More Offenders with EvoFIT Facial Composites: Lab Research and Police Field Trials

Often the only evidence of an offender s identity comes from the memory of an eyewitness For over 12 years we have been developing software called EvoFIT to help eyewitnesses recover their memories of offenders faces to assist police investigations EvoFIT requires eyewitnesses to repeatedly select from arrays of faces with breeding to evolve a face Recently police forces have been formally evaluating EvoFIT in criminal cases The current paper describes four such police audits It is reported that EvoFIT composites directly led to an arrest in 25 4 of cases overall the arrest rate was 38 5 for forces that used a newer less detailed face-recall interview These results are similar to those found in the laboratory using simulated procedures Here we also evaluate the impact of interviewing techniques and outline further work that has improved system performanc

Testing facial composite construction under witness stress

Facial composite systems may be used by police to help a witness to a crime create a likeness of the perpetrator. Evaluation of new facial composite systems in the laboratory allows a measure of experimental control, but lacks the emotional impact of a real crime. As a step towards a more realistic level of stress for our participant witnesses, we presented target face images while they were engaged in playing an action thriller computer game. The quality of the composites they subsequently produced was compared with that of a second ‘onlooker' participant, who merely observed the game and had the same view of the target face. Heart rate monitoring confirmed that the players were more stressed than the onlookers while the recognition rate of the onlooker composites was twice as good. We conclude that the method holds some promise as a method for composite system evaluation

Witness Interviews: Does recall of relational information improve identifiability of a facial composite?

Facial composites are used by Police to generate lines of enquiry; unfortunately composites made by traditional ‘feature’ systems are not often accurately named. One reason could be that these systems tend to rely on descriptions of the criminal’s facial features, when it has been shown that relationships and distances between facial features—the relational information—is of importance for face recognition. Here, we present two experiments to investigate the usefulness of probing for relational information within witness interviews. Participant-witnesses underwent a typical cognitive interview (CI), an interview in which featural information was probed for before relational information (FR), or an interview in which probing for relational information preceded probing for featural detail (RF). Composites constructed of familiar targets with no delay were recognised better in the former two interviews than the latter, suggesting that relational information interferes with subsequent recall of featural information. However, after a 24 hour delay composites constructed of unfamiliar targets did not differ significantly for naming rates by interview type. This indicates no naming benefit for recalling relational information. However, RF composites were rated as significantly better likenesses to target images after a 24-hour delay, and so future work could explore this further to assess what aspect of the image is improved by recall of relational information

The benefit of context for facial composite construction.

Purpose - The aim of this study was to investigate whether the presence of a whole-face context during facial composite production facilitates construction of facial composite images.Design/Methodology - In Experiment 1, constructors viewed a celebrity face and then developed a facial composite using PRO-fit in one of two conditions: either the full-face was visible while facial features were selected, or only the feature currently being selected was visible. The composites were named by different participants. We then replicated the study using a more forensically-valid procedure: In Experiment 2 non-football fans viewed an image of a premiership footballer and 24 hours later constructed a composite of the face with a trained software operator. The resulting composites were named by football fans.Findings - In both studies we found that presence of the facial context promoted more identifiable facial composite images.Research limitations/implications – Though this study uses current software in an unconventional way, this was necessary to avoid error arising from between-system differences.Practical implications - Results confirm that composite software should have the whole-face context visible to witnesses throughout construction. Though some software systems do this, there remain others that present features in isolation and these findings show that these systems are unlikely to be optimal. Originality/value - This is the first study to demonstrate the importance of a full-face context for the construction of facial composite images. Results are valuable to police forces and developers of composite software

Configural and featural information in facial-composite images

Eyewitnesses are often invited to construct a facial composite, an image created of the person they saw commit a crime that is used by law enforcement to locate criminal suspects. In the current paper, the effectiveness of composite images was investigated from traditional feature systems (E-FIT and PRO-fit), where participants (face constructors) selected individual features to build the face, and a more recent holistic system (EvoFIT), where they ‘evolved' a composite by repeatedly selecting from arrays of complete faces. Further participants attempted to name these composites when seen as an unaltered image, or when blurred, rotated, linearly stretched or converted to a photographic negative. All of the manipulations tested reduced correct naming of the composites overall except (i) for a low level of blur, for which naming improved for holistic composites but reduced for feature composites, and (ii) for 100% linear stretch, for which a substantial naming advantage was observed. Results also indicated that both featural (facial elements) and configural (feature spacing) information was useful for recognition in both types of composite system, but highly-detailed information was more accurate in the feature-based than the holistic method. The naming advantage of linear stretch was replicated using a forensically more-practical procedure with observers viewing an unaltered ¬composite sideways. The work is valuable to police practitioners and designers of facial-composite systems

Familiarity effects in the construction of facial composite images using modern software systems.

We investigate the effect of target familiarity on the construction of facial composites, as used by law-enforcement to locate criminal suspects. Two popular software construction methods were investigated. Participants were shown a target face that was either familiar or unfamiliar to them and constructed a composite of it from memory using a typical ‘feature’ system, involving selection of individual facial-features, or one of the newer ‘holistic’ types, involving repeated selection and breeding from arrays of whole faces. The study found that composites constructed of a familiar face were named more successfully than composites of an unfamiliar face; also, naming of composites of internal and external features were equivalent for unfamiliar targets, but internal features were better named than external features for familiar targets. These findings applied to both systems, although benefit emerged for the holistic type due to more accurate construction of internal features and evidence for a whole-face advantage

The impact of external facial features on the construction of facial composites

Witnesses may construct a composite face of a perpetrator using a computerised interface. Police practitioners guide witnesses through this unusual process, the goal being to produce an identifiable image. However, any changes a perpetrator makes to their external facial-features may interfere with this process. In Experiment 1, participants constructed a composite using a holistic interface one day after target encoding. Target faces were unaltered, or had altered external-features: (i) changed hair, (ii) external-features removed or (iii) naturally-concealed external-features (hair, ears, face-shape occluded by a hooded top). These manipulations produced composites with more error-prone internal-features: participants’ familiar with a target’s unaltered appearance less often provided a correct name. Experiment 2 applied external-feature alterations to composites of unaltered targets; although whole-face composites contained less error-prone internal-features, identification was impaired. Experiment 3 replicated negative effects of changing target hair on construction and tested a practical solution: selectively concealing hair and eyes improved identification

Recovering faces from memory: the distracting influence of external facial features.

Recognition memory for unfamiliar faces is facilitated when contextual cues (e.g. head pose, background environment, hair and clothing) are consistent between study and test. By contrast, inconsistencies in external features, especially hair, promote errors in unfamiliar face-matching tasks. For the construction of facial composites, as carried out by witnesses and victims of crime, the role of external features (hair, ears and neck) is less clear, although research does suggest their involvement. Here, over three experiments, we investigate the impact of external features for recovering facial memories using a modern, recognition-based composite system, EvoFIT. Participant-constructors inspected an unfamiliar target face and, one day later, repeatedly selected items from arrays of whole faces, with ‘breeding’, to ‘evolve’ a composite with EvoFIT; further participants (evaluators) named the resulting composites. In Experiment 1, the important internal-features (eyes, brows, nose and mouth) were constructed more identifiably when the visual presence of external features was decreased by Gaussian blur during construction: higher blur yielded more identifiable internal-features. In Experiment 2, increasing the visible extent of external features (to match the target’s) in the presented face-arrays also improved internal-features quality, although less so than when external features were masked throughout construction. Experiment 3 demonstrated that masking external-features promoted substantially more identifiable images than using the previous method of blurring external-features. Overall, the research indicates that external features are a distractive rather than a beneficial cue for face construction; the results also provide a much better method to construct composites, one that should dramatically increase identification of offenders

Constructing identifiable composite faces: The importance of cognitive alignment of interview and construction procedure.

We investigated the impact of congruency between the witness interview and method used to construct a composite face. Experiment 1, using a typical feature-by-feature composite method, revealed that aligning cognitive processes during interview and face construction enhanced the effectiveness of composites compared with composites produced following unaligned (incongruent) procedures. Experiment 2 revealed that incorporating character judgements in the witness interview substantially enhanced identification of feature-based composites when constructing the central (internal) features first, suggesting that such judgements focus attention on this region of the face. Experiment 3 explored alignment of processes using an approach based on an evolutionary algorithm, a method requiring witnesses to create a composite by selecting from arrays based on the eye-region. A combination of character judgements, first for the whole face and then for the eye region, led to best-identified composites. Overall, results indicate that more effective composites are produced when both interview and construction procedures are aligned cognitively. Results are discussed with relevance to the theory of transfer-appropriate processing (Morris, Bransford, & Franks, 1977)

EvoFIT: A holistic, evolutionary facial imaging technique for creating composites

EvoFIT, a computerized facial composite system is being developed as an alternative to current systems. EvoFIT faces are initially presented to a witness with random characteristics, but through a process of selection and breeding, a composite is “evolved.” Comparing composites constructed with E-FIT, a current system, a naming rate of 10% was found for EvoFIT and 17% for E-FIT. Analysis revealed that target age was limiting factor for EvoFIT and a second study with age-appropriate targets visible during composite construction produced a naming rate similar to E-FIT. Two more-realistic studies were conducted that involved young target faces and two current systems (E-FIT and PROfit). Composites from both of these experiments were poorly named but a significant benefit emerged for EvoFIT