Facial Approximation Research Articles

The superficial temporal fat pad and its ramifications for temporalis muscle construction in facial approximation

The construction of the facial muscles (particularly those of mastication) is generally thought to enhance the accuracy of facial approximation methods because they increase attention paid to face anatomy. However, the lack of consideration for non-muscular structures of the face when using these “anatomical” methods ironically forces one of the two large masticatory muscles to be exaggerated beyond reality. To demonstrate and resolve this issue the temporal region of nineteen caucasoid human cadavers (10 females, 9 males; mean age = 84 years, s = 9 years, range = 58–97 years) were investigated. Soft tissue depths were measured at regular intervals across the temporal fossa in 10 cadavers, and the thickness of the muscle and fat components quantified in nine other cadavers. The measurements indicated that the temporalis muscle generally accounts for <50% of the total soft tissue depth, and does not fill the entirety of the fossa (as generally known in the anatomical literature, but not as followed in facial approximation practice). In addition, a soft tissue bulge was consistently observed in the anteroinferior portion of the temporal fossa (as also evident in younger individuals), and during dissection, this bulge was found to closely correspond to the superficial temporal fat pad (STFP). Thus, the facial surface does not follow a simple undulating curve of the temporalis muscle as currently undertaken in facial approximation methods. New metric-based facial approximation guidelines are presented to facilitate accurate construction of the STFP and the temporalis muscle for future facial approximation casework. This study warrants further investigations of the temporalis muscle and the STFP in younger age groups and demonstrates that untested facial approximation guidelines, including those propounded to be anatomical, should be cautiously regarded.

The influence of sex, age and body mass index on facial soft tissue depths

Facial soft tissue depth charts are used in the majority of forensic facial approximation methods. In the past, based on the multitude of available soft tissue depth charts, a number of hypotheses were advanced concerning the impact of sex, BMI and age on the depth of tissues. In this study, for the first time, a multivariate analysis was performed on a large-scale study on Caucasian adults to determine the "real" impact of these attributes. The calculation of a robust multiple linear regression of soft tissue thickness versus BMI, age and sex for each landmark separately, allowed us to study the impact from a statistical as well as practical point of view. Former findings were re-evaluated. Additionally, the results confirm the dominant role of BMI in the alterations of facial soft tissue thickness. However, excluding age and sex from the equation should be considered with care and can certainly not be applied to all landmarks. Finally, the regression equation allows increase in the specificity of tissue depths used in real cases by offering practitioners the possibility of calculating individual tissue depths.

Faces of the Teouma Lapita People: Art, Accuracy and Facial Approximation

In 2008 we completed facial approximations of four individuals from the early Lapita Culture, a seafaring people who were the first to settle the islands of the Western Pacific circa 3000 years ago. Typically an approximation is performed as a 3D sculpture or using computer graphics. We chose to sketch what we have been able to determine from the remains because the artistic conventions of drawing work with visual perception in ways that are more complementary to the knowledge, theories and methods that make up the facial approximation of human remains.

Blurring the boundaries: 2D facial approximation of the Teouma Lapita

Blurring the boundaries: 2D facial approximation of the Teouma Lapita

Further Evidence on the Anatomical Placement of the Human Eyeball for Facial Approximation and Craniofacial Superimposition*

Recently a small sampled cadaver study (n = 4) suggested that the human eyeballs are placed closer to the orbital roof and lateral orbital wall as first reported in the anatomical literature many years previously. This contrasts with central positioning of the eyeball within the orbit as advocated by the facial approximation literature. Given the limits of such small samples, this study re-examined globe position in nine new cadavers to help clarify which relationship is accurate. The results essentially confirm prior empirical findings except that the mean lateral divergences from the orbit center were found to be larger--the eyeball was found to be "displaced" 1.4 mm superiorly and 2.4 mm laterally. Medians calculated across all 13 cadavers from this study and the above-mentioned recent report refine these measurements to 1.4 and 2.3 mm respectively. Globe projection values were identical to those observed for living individuals (c. 16 mm).

Facial soft tissue thicknesses for the Portuguese adult population

In recent years there has been an important increment of studies on the determination of facial soft tissue thicknesses for craniofacial identification purposes. In spite of this, there is no information on the particularities of the facial soft tissue depths for the Portuguese adult population. In order to address this lack, the soft tissue thicknesses of a Portuguese cadaver sample of 151 individuals, 103 males and 48 females with ages between 20 and 99 years old, autopsied at the South Branch of the National Institute of Legal Medicine, were measured using published needle puncture methods at 20 anatomical points. The stature and weight of all cadavers were determined and their body mass index (BMI) calculated. In order to prevent post-mortem distortion, soft tissue depths were assessed prior to the individual's autopsy in cadavers whose time of death did not exceed 24 h. From these data, descriptive statistics were calculated and the average soft tissue depths were reported considering the BMI and the sex of the cadavers. In general, males were found to have greater soft tissue depths than females but some landmarks showed the opposite while others presented the same values for both sexes. In spite of this, almost all the differences among the sexes were found to be not statistically significant. The Post Hoc Gabriel test performed between the different BMI categories for mixed sexes and for each sex suggested BMI-related differences on the soft tissue thicknesses, although these vary considerably within and between the sexes with no linear correspondence between the anatomical landmarks. These results, point not only to the necessity to present data in accordance with the sexual dimorphism, but also to consider the BMI as an important variable for better results in the achievement of the likeness of the deceased individuals in both two-dimensional and three-dimensional facial approximations or superimpositions. Additionally, evidence of interpopulation differences in the average soft tissue thicknesses were observed by the comparison of this data set with similar studies from Caucasian groups with different geographic origin.

Anatomy of the nasal profile

There is a lack in the understanding of the variation within the thickness of the soft tissue structures (muscle, skin and fat) overlying the cartilaginous skeleton of the nose and their relationship to the dorsum shape. We examined such relationships by dissecting noses of six adult female and six adult male cadavers, comparing the internal anatomical structures to the external nasal profile. We found that the soft tissue structures differ in thickness along the dorsum and that these differences are individualized. Specifically, continuous presence of subcutaneous fat from root to tip was found in half the sample, one nose had fat only on the tip, another one only on the root, the four others at both positions. The nasalis muscle was identifiable in nine of the 12 noses, transversing the nose in half the sample, and in the remaining three, only the lateral section of the muscle was identified. The superior border of the septal cartilage does not form a linear extension of the profile contour of the nasal bones but angles downwards. The actual profile contour of the dorsum does not follow the profile of the nasal bones or the septal cartilage. These results may influence the current use of nasal guidelines in forensic facial approximation.

The Placement of the Human Eyeball and Canthi in Craniofacial Identification

An accurate understanding of the spatial relationships between the deep and superficial structures of the head is essential for anthropological methods concerned with the comparison of faces to skulls (superimposition) or the prediction of faces from them (facial approximation). However, differences of opinion exist concerning: (i) the position of the eyeball in planes other than the anteroposterior plane and (ii) the canthi positions relative to the bony orbital margins. This study attempts to clarify the above relationships by dissection of a small sample of adult human cadavers (N = 4, mean age = 83 years, s = 12 years). The most notable finding was that the eyeballs were not centrally positioned within the orbits as the more recent craniofacial identification literature expounds. Rather, the eyeballs were consistently positioned closer to the orbital roof and lateral orbital wall (by 1-2 mm on average); a finding consistent with the earlier anatomical literature. While these estimation errors are small ipsilaterally, several factors make them meaningful: (i) the orbital region is heavily used for facial recognition; (ii) the width error is doubled because the eyes are bilateral structures; (iii) the eyes are sometimes used to predict/assess other soft tissue facial structures; and (iv) the net error in facial approximation rapidly accumulates with the subsequent prediction of each independent facial feature. While the small sample size of this study limits conclusive generalizations, the new data presented here nonetheless have immediate application to craniofacial identification practice because the results are evidence based. In contrast, metric data have never been published to support the use of the central positioning guideline. Clearly, this study warrants further quantification of the eyeball position in larger samples and preferably of younger individuals.

Measuring the Accuracy of Facial Approximations: A Comparative Study of Resemblance Rating and Face Array Methods

The success of facial approximation is thought to depend, at least in part, upon the "accuracy" of the constructed face. However, methods of accuracy assessment are varied and this range in methods may be responsible for the disparate results reported in the literature. The aim of this study was to determine if the accuracy results of one facial approximation were comparable across two different assessment methods (resemblance ratings and simultaneous face array tests using unfamiliar assessors) and if resemblance ratings co-varied with recognition responses. True-positive recognition performance from the facial approximation was poor (21%) while resemblance scores using the same facial approximation were moderately high (3 out of 5 on a five-point scale). These results are not, therefore, consistent and indicate that either different variables are being evaluated by the methods, or the same variable is being examined but with different weight/calibration. Further resemblance ratings tests of the facial approximation to three foil faces from the face array revealed that resemblance scores were similar irrespective of which face was compared, and did not closely correspond with the degree of recognition performance. This was especially the case for isolated comparisons of single faces to the facial approximation. Collectively, these results indicate that resemblance ratings are: (i) insensitive measures of a facial approximation's accuracy; and (ii) inconsistent with results of unfamiliar simultaneous face-array recognition results. These data suggest that familiar and unfamiliar recognition tests should be given increased weight in contrast to current resemblance rating tests.

Beyond the Sphere of the English Facial Approximation Literature: Ramifications of German Papers on Western Method Concepts*

In the English literature, facial approximation methods have been commonly classified into three types: "Russian,""American," or "Combination." These categorizations are based on the protocols used, for example, whether methods use average soft-tissue depths (American methods) or require face muscle construction (Russian methods). However, literature searches outside the usual realm of English publications reveal key papers that demonstrate that the Russian category above has been founded on distorted views. In reality, Russian methods are based on limited face muscle construction, with heavy reliance on modified average soft-tissue depths. A closer inspection of the American method also reveals inconsistencies with the recognized classification scheme. This investigation thus demonstrates that all major methods of facial approximation depend on both face anatomy and average soft-tissue depths, rendering common method classification schemes redundant. The best way forward appears to be for practitioners to describe the methods they use (including the weight each one gives to average soft-tissue depths and deep face tissue construction) without placing them in any categorical classificatory group or giving them an ambiguous name. The state of this situation may need to be reviewed in the future in light of new research results and paradigms.

Assessing facial approximation accuracy: How do resemblance ratings of disparate faces compare to recognition tests?

In the past, the accuracy of facial approximations has been assessed by resemblance ratings (i.e., the comparison of a facial approximation directly to a target individual) and recognition tests (e.g., the comparison of a facial approximation to a photo array of faces including foils and a target individual). Recently, several research studies have indicated that recognition tests hold major strengths in contrast to resemblance ratings. However, resemblance ratings remain popularly employed and/or are given weighting when judging facial approximations, thus indicating that no consensus has been reached. This study aims to further investigate the matter by comparing the results of resemblance ratings and recognition tests for two facial approximations which clearly differed in their morphological appearance. One facial approximation was constructed by an experienced practitioner privy to the appearance of the target individual (practitioner had direct access to an antemortem frontal photograph during face construction), while the other facial approximation was constructed by a novice under blind conditions. Both facial approximations, whilst clearly morphologically different, were given similar resemblance scores even though recognition test results produced vastly different results. One facial approximation was correctly recognized almost without exception while the other was not correctly recognized above chance rates. These results suggest that resemblance ratings are insensitive measures of the accuracy of facial approximations and lend further weight to the use of recognition tests in facial approximation assessment.

A novel method of automated skull registration for forensic facial approximation

Modern forensic facial reconstruction techniques are based on an understanding of skeletal variation and tissue depths. These techniques rely upon a skilled practitioner interpreting limited data. To (i) increase the amount of data available and (ii) lessen the subjective interpretation, we use medical imaging and statistical techniques. We introduce a software tool, reality enhancement/facial approximation by computational estimation (RE/FACE) for computer-based forensic facial reconstruction. The tool applies innovative computer-based techniques to a database of human head computed tomography (CT) scans in order to derive a statistical approximation of the soft tissue structure of a questioned skull. A core component of this tool is an algorithm for removing the variation in facial structure due to skeletal variation. This method uses models derived from the CT scans and does not require manual measurement or placement of landmarks. It does not require tissue-depth tables, can be tailored to specific racial categories by adding CT scans, and removes much of the subjectivity of manual reconstructions.

Estimating Eyeball Protrusion from Body Height, Interpupillary Distance, and Inter-Orbital Distance in Adults

Eyeball protrusion is one characteristic that must be assessed/predicted in craniofacial identification methods of skull-face superimposition and facial approximation. Previously it has been suggested that average exophthalmometry values, as measured on living individuals, should be used. However, it is unknown if proptosis prediction can be improved beyond the accuracy obtained when using mean values. Some authors have suggested that relationships between exophthalmos, height, interpupillary distance, and interorbital distance exist and it has been reported that these latter variables can be used to estimate eyeball projection. However, crucial tests are yet to be conducted. This study measures these variables and tests the accuracy of exophthalmometry means, a previously proposed prediction equation, and newly derived regression equations to determine which methods provide the best results. Data indicate that variation in exophthalmos is fairly small and as such prediction from other variables, like body height, are weak; thus, exophthalmometry means currently offer the best practical method of prediction. It should be noted that up to 2 mm error from either side of the mean is expected for 68% of cases.

Recognition by forensic facial approximation: Case specific examples and empirical tests

The skeletal remains of one individual found near Adelaide in 1994, although not known at the time, were the first evidence of what was to be a serial killing reported to have resulted in the highest casualty list to date in Australia (12 victims). Since the usual methods of identification could not be used or were unsuccessful on these remains, facial approximations were produced and advertised over the 4-year period following their discovery, in an attempt to help to identify them. However, no identification was made. In 1999, the remains were reported to be identified by radiographic comparison. Approximately 3 months before this identification was made, another facial approximation was produced by the first author (CNS), but this face was never advertised in the media. Although rarely reported in the literature, this paper provides an example where facial approximation methods were not successful in a forensic scenario. The paper also reports on empirical tests of the facial approximation created by the first author to determine if this facial approximation might have been useful had it been advertised. The results provide further evidence that high resemblance of a facial approximation to the target individual does not indicate recognizability, as the facial approximation was poorly recognized even though it bore good resemblance to the target individual. The usefulness of facial approximation techniques is discussed within the context of this case and more broadly. Methods used to assess the accuracy of facial approximations are also discussed and further evaluated.

Parents’ perspectives on the communication skills of their children with severe disabilities

Background The development of communication skills in children with severe disabilities partly depends on the responsivity of partners to all forms of communicative behaviour. This study explored the behaviours that parents interpret as communicative.Method Parents of 10 children aged 4 to 9 years were interviewed about the forms of communication used by their children. All the children had severe intellectual disability and were unable to use spoken language as their primary means of communication.Results Parents described a wide range of behaviours, including the use of facial expressions, body movements, vocalisations, gestures, word approximations and words, formal and made‐up signs, and object and picture symbols, as communicative behaviours.Conclusions Parents interpreted many of these behaviours, including challenging behaviours, as communicative, but may need support to encourage presymbolic communicative behaviours. Where formal alternative and augmentative communication had been introduced by schools, parents were not always supportive of its use at home.

Facial approximation: a review of the current state of play for archaeologists

Facial approximation: a review of the current state of play for archaeologists

Dual X-ray absorptiometry for estimating the volume of the soft tissue in the human skull

The aim of this study was to analyze the relationship between soft and hard tissue measurements of the head so as to identify the range of soft tissues parameters that should be applied in forensic facial approximation. The study was performed on 85 healthy female volunteers with an age range of 35-45 years. Total and regional body composition analysis was undertaken with subjects in a recumbent position using dual X-ray absorptiometry. The head was defined from the inferior part of the mandible to the vertex. We found the range of total head soft tissue weight to be between 3.02 and 4.96 kg. The quantity of soft tissue applicable to Caucasian female subjects in good health was estimated by subtracting the weight of the brain (approximately 1.17 kg in a typical adult female) from these values. Thus, the minimum and maximum values of the soft tissue are 1.85 and 3.79 kg, respectively.

Anthropological facial 'reconstruction--recognizing the fallacies, 'unembracing' the errors, and realizing method limits.

Despite being practiced for over the last 200 years, facial approximation methods remain in their infancy as the soft tissue prediction methods employed have not been tested and justified. Scientific testing is the only way forward and much of it is needed. The lack of systematic scientific tests in the past has enabled many misleading notions to become established. Many of these notions appear to have arisen and been sustained as a result of practitioner biases--this is clearly evident even in the name commonly used to describe the method of building faces from skulls, for "facial reconstruction" implies everything the method is not, e.g., technical/scientific, exact, and credible. Although facial approximation methods are useful for forensic investigation (even if they do not generate identifications through true positive recognitions of the faces), the public should beware of the marketing and political ploys employed within the profession. These ploys give rise to some impressive, but unjustifiable claims--but do not just take my word for it; evaluate the evidence for yourself with disregard to the indoctrination waged by the facial "reconstruction" field in general, including that promoted by what I have had to say here. Use your own reason and intellect and see which conclusions you reach.

Predicting Mouth Width from Inter-Canine Width—A 75% Rule

It has been suggested that inter-canine width plus 57% of the cumulative distance between the lateral aspect of the canines and the pupil centers can be used to estimate mouth width. Evidence also suggests that the distance between the medial irises approximates actual mouth width fairly well. However, these soft tissue prediction guidelines are limited because they rely on accurate medio-lateral positioning of the pupils within the orbits, for which no systematic empirical evidence appears to exist at this stage. It would, therefore, be more appropriate to use only known hard tissue landmarks in mouth width prediction. This study reports the results of using inter-canine width as a percentage of mouth width for its prediction. This method seems favorable in comparison to the other guidelines because it is as accurate, uses known hard tissue landmarks, and does not rely on assumptions concerning pupil location. Estimating mouth width by using the canines alone, therefore, seems the best guideline to use in facial approximation techniques, at least given knowledge existing at this stage.

Facial approximation: an evaluation of mouth-width determination.

Facial approximation techniques rely on the prediction of soft tissues from the skull, yet few prediction methods have been scientifically evaluated, despite being frequently used in the past. This study tests several published and commonly used methods for determining mouth width from the skull. The methods tested are: 1) that mouth width is equal to the distance between the pupils; 2) that mouth width is equal to the distance between the medial borders of the iris; and 3) that mouth width is equal to the distance between the most lateral junctions of the canines and the first premolars. The study primarily examines living Australian European and Central/South East Asian participants (of both sexes) using photogrammetric methods. The results of this study indicate that methods 1 and 3 are highly inaccurate. Method 1 overestimated mouth width, on average, by approximately 11 mm (SD, 4 mm), while method 3 underestimated mouth width by approximately 13 mm (SD, 3 mm). Method 2 was the most accurate of the methods evaluated, but on average underrepresented mouth width by approximately 2 mm (SD, 4 mm). All three methods produced mouth-width predictions that, in general, were statistically different from actual mouth widths (P < 0.05). A new guideline, describing mouth width as canine width plus 57% of the cumulative distance between the lateral canine borders and the pupil centers on each side was found not to differ at statistically significant levels from actual mouth widths (P > 0.05). On average, this guideline did not under/overestimate actual mouth width, with the difference between them being 0 mm (SD, 3 mm). The increased accuracy of this new guideline in comparison to others suggests that it is the most appropriate for facial approximation. However, it should be further tested using independent samples. The finding that commonly used mouth-width prediction guidelines are not accurate suggests that many facial approximations previously made have incorrect mouth widths. This could reduce the recognition of these facial approximations and may, especially if other guidelines are inaccurate, render the facial approximations unrecognizable as their respective target individual (individual to whom the skull belongs).