General lighting can overcome accidental viewing.

When seeing an object in a scene, the presumption of seeing that object from a general viewpoint (as opposed to an accidental viewpoint) is a useful heuristic to decide which of many interpretations of this object is correct. Similar heuristic assumptions on illumination quality might also be used for scene interpretation. Here we tested that assumption and asked if illumination information helps determine object properties when seen from an accidental viewpoint. Test objects were placed on a flat surface and illumination was varied while keeping the objects' images constant. Observers judged the shape or rigidity of static or moving simple objects presented in accidental view. They also chose which of two seemingly very similar faces was familiar. We found: (1) Objects might appear flat without shadow information but were perceived to be volumetric objects or non-planar in the presence of cast shadows. (2) Apparently non-rigid objects became rigid with shadow information. (3) Shading and shadows helped to infer which of two face was the familiar one. Previous results had shown that cast shadows help determine spatial layout of objects. Our study shows that other properties of objects like rigidity or 3D-shape can be disambiguated by shadow information.

Virtual reality: A new track in psychological research.

One major challenge of social interaction research is to achieve high experimental control over social interactions to allow for rigorous scientific reasoning. Virtual reality (VR) promises this level of control. Pan and Hamilton guide us with a detailed review on existing and future possibilities and challenges of using VR for social interaction research. Here, we extend the discussion to methodological and practical implications when using VR.

Three-Dimensional Normal Facial Growth from Birth to the Age of 7 Years.

BACKGROUND: With the advent of computer-assisted three-dimensional surface imaging and rapid data processing, oral and maxillofacial surgeons and orthodontists are enabled to analyze facial growth three dimensionally. Normative data, however, are still rare and inconsistent. The aim of the present study was to establish a valid reference system and to give normative data for facial growth. METHODS: Three-dimensional facial surface images were obtained from 344 healthy Caucasian children (aged 0 to 7 years). The images were put in correspondence by means of six landmarks close to the skull base (exocanthion, endocanthion, otobasion inferius). Growth curves for 21 landmarks were estimated in the three dimensions. RESULTS: Facial regions close to the skull base (orbit and ear) showed a biphasic growth pattern, with accelerated growth during the first year of life that subsided to a decreased and linear velocity thereafter. Landmarks on the nose, lips, and chin demonstrated either a curvilinear or a linear growth pattern. CONCLUSIONS: The rapid increase of the orbit and ear region in infancy is a secondary phenomenon to the rapid growth of the neurocranium during the first year of life. Thereafter, maxillary and mandibular growth prevails. The present study gives three-dimensional normative data for an expanded growth span between birth and childhood.

Quantifying human sensitivity to spatio-temporal information in dynamic faces.

A great deal of perceptual and social information is conveyed by facial motion. Here, we investigated observers' sensitivity to the complex spatio-temporal information in facial expressions and what cues they use to judge the similarity of these movements. We motion-captured four facial expressions and decomposed them into time courses of semantically meaningful local facial actions (e.g., eyebrow raise). We then generated approximations of the time courses which differed in the amount of information about the natural facial motion they contained, and used these and the original time courses to animate an avatar head. Observers chose which of two animations based on approximations was more similar to the animation based on the original time course. We found that observers preferred animations containing more information about the natural facial motion dynamics. To explain observers' similarity judgments, we developed and used several measures of objective stimulus similarity. The time course of facial actions (e.g., onset and peak of eyebrow raise) explained observers' behavioral choices better than image-based measures (e.g., optic flow). Our results thus revealed observers' sensitivity to changes of natural facial dynamics. Importantly, our method allows a quantitative explanation of the perceived similarity of dynamic facial expressions, which suggests that sparse but meaningful spatio-temporal cues are used to process facial motion.

Three-dimensional assessment of facial development in children with unilateral cleft lip with and without alveolar cleft.

Children with cleft lip or cleft lip and alveolus represent a minor group in the cleft population. The aim of this study was to analyze the faces of these children. In a prospective, cross-sectional study, 344 healthy children and 30 children with cleft lip or cleft lip and alveolus were scanned three-dimensionally at the age of 0 to 6 years. Twenty-one standard anthropometric landmarks were identified, and the images were superimposed. Growth curves for normal facial development were calculated. The facial morphology of cleft children was compared with that of unaffected children.Facial morphology and growth in the transverse direction of the examined patients appeared broadened in all levels. Especially the nasal landmarks indicated a widening of the nose. The landmarks ac l, sbal l, sbal r, c l, sn l, and ls l differed significantly from unaffected children. In the sagittal and vertical dimensions, there was no significant difference compared with unaffected children.Our study demonstrates that surgical and orthodontic treatment can restore the vertical and sagittal dimensions of the face in children with cleft lip with and without alveolar clefts; however, the transverse dimension-especially the nose-remains too broad.

Enhancing medical communication training using motion capture, perspective taking and virtual reality.

The aim of this work is to increase the effectiveness of real world medical training simulations by helping trainees gain a better understanding of the importance of communication and teamwork. Therefore we develop an online application which can be used together with real world simulations to improve training. To produce the online application we reconstructed two real world scenarios (one with students and one with practitioners) in an immersive virtual environment. Our application enables the trainees to view the scenario from different perspectives or to freely explore the environment. We aim to integrate it into the medical student curriculum at the University of Tübingen.

Three-dimensional assessment of facial development in children with Pierre Robin sequence.

Newborns with Pierre Robin sequence (PRS) have mandibular hypoplasia, glossoptosis, and possibly cleft palate. Their facial appearance is characteristic. The further facial development is controversial. The aim of this study was to analyze the facial development of children with PRS.In a prospective, cross-sectional study, 344 healthy children and 37 children with PRS and cleft palate younger than 8 years were scanned three-dimensionally. Twenty-one standard anthropometric landmarks were identified, and the images were superimposed. Growth curves for normal facial development were calculated. The facial morphology of children with PRS was compared with that of healthy children.The facial growth of children with PRS in the transversal and vertical direction was normal. In the sagittal direction, the mandibular deficit was confirmed. Except for the orbital landmarks and nasion, all landmarks of the midface demonstrated a significant sagittal deficit. This difference to healthy children remained constant for all ages.Our study cannot support the theory of mandibular catch-up growth. The sagittal deficit of the midface could be observed in all ages. This indicates that children with PRS have a very early, severe, and persistent underdevelopment of this part of the face. We conclude that this disturbance must be addressed in early childhood with orthodontic and speech therapy.