Location via proxy:   [ UP ]  
[Report a bug]   [Manage cookies]                
Skip to main content

    Marian Bartlett

    Current pain assessment methods in youth are suboptimal and vulnerable to bias and underrecognition of clinical pain. Facial expressions are a sensitive, specific biomarker of the presence and severity of pain, and computer vision (CV)... more
    Current pain assessment methods in youth are suboptimal and vulnerable to bias and underrecognition of clinical pain. Facial expressions are a sensitive, specific biomarker of the presence and severity of pain, and computer vision (CV) and machine-learning (ML) techniques enable reliable, valid measurement of pain-related facial expressions from video. We developed and evaluated a CVML approach to measure pain-related facial expressions for automated pain assessment in youth. A CVML-based model for assessment of pediatric postoperative pain was developed from videos of 50 neurotypical youth 5 to 18 years old in both endogenous/ongoing and exogenous/transient pain conditions after laparoscopic appendectomy. Model accuracy was assessed for self-reported pain ratings in children and time since surgery, and compared with by-proxy parent and nurse estimates of observed pain in youth. Model detection of pain versus no-pain demonstrated good-to-excellent accuracy (Area under the receiver o...
    ABSTRACT We propose a method to automatically detect emotions in unconstrained settings as part of the 2013 Emotion Recognition in the Wild Challenge [16], organized in conjunction with the ACM International Conference on Multimodal... more
    ABSTRACT We propose a method to automatically detect emotions in unconstrained settings as part of the 2013 Emotion Recognition in the Wild Challenge [16], organized in conjunction with the ACM International Conference on Multimodal Interaction (ICMI 2013). Our method combines multiple visual descriptors with paralinguistic audio features for multimodal classification of video clips. Extracted features are combined using Multiple Kernel Learning and the clips are classified using an SVM into one of the seven emotion categories: Anger, Disgust, Fear, Happiness, Neutral, Sadness and Surprise. The proposed method achieves competitive results, with an accuracy gain of approximately 10% above the challenge baseline.
    We present ongoing work on a project for automatic recognition of spontaneous facial actions. Spontaneous facial expressions differ substantially from posed expressions, similar to how continuous, spontaneous speech differs from isolated... more
    We present ongoing work on a project for automatic recognition of spontaneous facial actions. Spontaneous facial expressions differ substantially from posed expressions, similar to how continuous, spontaneous speech differs from isolated words produced on command. Previous methods for automatic facial expression recognition assumed images were collected in controlled environments in which the subjects deliberately faced the camera. Since people often nod or turn their heads, automatic recognition of spontaneous facial behavior requires methods for handling out-of-image-plane head rotations. Here we explore an approach based on 3-D warping of images into canonical views. We evaluated the performance of the approach as a front-end for a spontaneous expression recognition system using support vector machines and hidden Markov models. This system employed general purpose learning mechanisms that can be applied to recognition of any facial movement. The system was tested for recognition ...
    this paper we show preliminary results for I. Recognition of posed facial actions in controlled conditions, and II. Recognition of spontaneous facial actions in freely behaving subjects
    Research Interests:
    ... Gwen C. Littlewort, Marian S. Bartlett Institute for Neural Computation University of California, San Diego San Diego, CA, USA gwen@mplab.ucsd.edu ... 2. A spatial problem solving task, “rush hour”, in which sliding puzzle pieces in a... more
    ... Gwen C. Littlewort, Marian S. Bartlett Institute for Neural Computation University of California, San Diego San Diego, CA, USA gwen@mplab.ucsd.edu ... 2. A spatial problem solving task, “rush hour”, in which sliding puzzle pieces in a certain sequence will free the desired piece, 3 ...
    Neuropsychological and neuroimaging evidence suggests that the human brain contains facial expression recognition detectors specialized for specific discrete emotions. However, some human behavioral data suggest that humans recognize... more
    Neuropsychological and neuroimaging evidence suggests that the human brain contains facial expression recognition detectors specialized for specific discrete emotions. However, some human behavioral data suggest that humans recognize expressions as similar and not discrete entities. This latter observation has been taken to indicate that internal representations of facial expressions may be best characterized as varying along continuous underlying dimensions. To examine the potential compatibility of these two views, the present study compared human and support vector machine (SVM) facial expression recognition performance. Separate SVMs were trained to develop fully automatic optimal recognition of one of six basic emotional expressions in real-time with no explicit training on expression similarity. Performance revealed high recognition accuracy for expression prototypes. Without explicit training of similarity detection, magnitude of activation across each emotion-specific SVM captured human judgments of expression similarity. This evidence suggests that combinations of expert classifiers from separate internal neural representations result in similarity judgments between expressions, supporting the appearance of a continuous underlying dimensionality. Further, these data suggest similarity in expression meaning is supported by superficial similarities in expression appearance.
    ABSTRACT Engineered features have been heavily employed in computer vision. Recently, feature learning from unlabeled data for improving the performance of a given vision task has received increasing attention in both machine learning and... more
    ABSTRACT Engineered features have been heavily employed in computer vision. Recently, feature learning from unlabeled data for improving the performance of a given vision task has received increasing attention in both machine learning and computer vision. In this paper, we present using unlabeled video data to learn spatiotemporal features for video classification tasks. Specifically, we employ independent component analysis (ICA) to learn spatiotemporal filters from natural videos, and then construct feature representations for the input videos in classification tasks based on the learned filters. We test the performance of proposed feature learning method with application to facial expression recognition. The experimental results on the well-known Cohn-Kanade database show that the learned features perform better than engineered features. The comparison experiments on recognition of low intensity expressions show that our method yields a better performance than spatiotemporal Gabor features.
    Automatic pain recognition from videos is a vital clinical application and, owing to its spontaneous nature, poses interesting challenges to automatic facial expression recognition (AFER) research. Previous pain vs no-pain systems have... more
    Automatic pain recognition from videos is a vital clinical application and, owing to its spontaneous nature, poses interesting challenges to automatic facial expression recognition (AFER) research. Previous pain vs no-pain systems have highlighted two major challenges: (1) ground truth is provided for the sequence, but the presence or absence of the target expression for a given frame is unknown, and (2) the time point and the duration of the pain expression event(s) in each video are unknown. To address these issues we propose a novel framework (referred to as MS-MIL) where each sequence is represented as a bag containing multiple segments, and multiple instance learning (MIL) is employed to handle this weakly labeled data in the form of sequence level ground-truth. These segments are generated via multiple clustering of a sequence or running a multi-scale temporal scanning window, and are represented using a state-of-the-art Bag of Words (BoW) representation. This work extends the idea of detecting facial expressions through 'concept frames' to 'concept segments' and argues through extensive experiments that algorithms such as MIL are needed to reap the benefits of such representation. The key advantages of our approach are: (1) joint detection and localization of painful frames using only sequence-level ground-truth, (2) incorporation of temporal dynamics by representing the data not as individual frames but as segments, and (3) extraction of multiple segments, which is well suited to signals with uncertain temporal location and duration in the video. Extensive experiments on UNBC-McMaster Shoulder Pain dataset highlight the effectiveness of the approach by achieving competitive results on both tasks of pain classification and localization in videos. We also empirically evaluate the contributions of different components of MS-MIL. The paper also includes the visualization of discriminative facial patches, important for pain detection, as discovered by our algorithm and relates them to Action Units that have been associated with pain expression. We conclude the paper by demonstrating that MS-MIL yields a significant improvement on another spontaneous facial expression dataset, the FEEDTUM dataset.
    The goal of this special issue is to provide a state-of-the-art overview of new paradigms, methods, and challenges in Automatic Face and Gesture Recognition. As such we have made a selection of the best evaluated papers in The Eighth... more
    The goal of this special issue is to provide a state-of-the-art overview of new paradigms, methods, and challenges in Automatic Face and Gesture Recognition. As such we have made a selection of the best evaluated papers in The Eighth International Conference on Automatic Face and Gesture Recognition 2008 and we have asked the authors to extend their articles so that they reflect not only the in-depth technical details but also new insights and thorough evaluations of the presented algorithms. Our aim was to highlight the hot ...
    Charles Darwin (1872/1998) was the first to fully recognize that facial expression is one of the most powerful and immediate means for human beings to communicate their emotions, intentions, and opinions to each other. In addition to... more
    Charles Darwin (1872/1998) was the first to fully recognize that facial expression is one of the most powerful and immediate means for human beings to communicate their emotions, intentions, and opinions to each other. In addition to providing information about affective ...
    We investigate the problem of computer recognition of "Duchenne" vs. non-Duchenne smiles. Duchenne smiles include the contraction of the orbicularis oculi, the sphincter muscles that circle the eyes. Genuine, happy smiles can be... more
    We investigate the problem of computer recognition of "Duchenne" vs. non-Duchenne smiles. Duchenne smiles include the contraction of the orbicularis oculi, the sphincter muscles that circle the eyes. Genuine, happy smiles can be di#erentiated from posed, or social ...
    We present ongoing work on a project for automatic recognition of spon- taneous facial actions. Spontaneous facial expressions differ substan- tially from posed expressions, similar to how continuous, spontaneous speech differs from... more
    We present ongoing work on a project for automatic recognition of spon- taneous facial actions. Spontaneous facial expressions differ substan- tially from posed expressions, similar to how continuous, spontaneous speech differs from isolated words produced on command. Previous methods for automatic facial expression recognition assumed images were collected in controlled environments in which the subjects delib- erately faced the camera.
    ABSTRACT We present a systematic comparison of machine learning methods applied to the problem of fully automatic recognition of facial expressions. We explored recognition of facial actions from the Facial Action Coding System (FACS), as... more
    ABSTRACT We present a systematic comparison of machine learning methods applied to the problem of fully automatic recognition of facial expressions. We explored recognition of facial actions from the Facial Action Coding System (FACS), as well as recognition of full facial expressions. Each video-frame is first scanned in real-time to detect approximately upright-frontal faces. The faces found are scaled into image patches of equal size, convolved with a bank of Gabor energy filters, and then passed to a recognition engine that codes facial expressions into 7 dimensions in real time: neutral, anger, disgust, fear, joy, sadness, surprise. We report results on a series of experiments comparing recognition engines, including AdaBoost, support vector machines, linear discriminant analysis, as well as feature selection techniques. Best results were obtained by selecting a subset of Gabor filters using AdaBoost and then training Support Vector Machines on the outputs of the filters selected by AdaBoost. The generalization performance to new subjects for recognition of full facial expressions in a 7-way forced choice was 93% correct, the best performance reported so far on the Cohn-Kanade FACS-coded expression dataset. We also applied the system to fully automated facial action coding. The present system classifies 18 action units, whether they occur singly or in combination with other actions, with a mean agreement rate of 94.5% with human FACS codes in the Cohn-Kanade dataset. The outputs of the classifiers change smoothly as a function of time and thus can be used to measure facial expression dynamics.
    Computer animated agents and robots bring a social dimension to human computer interaction and force us to think in new ways about how computers could be used in daily life. Face to face communication is a real-time process operating at a... more
    Computer animated agents and robots bring a social dimension to human computer interaction and force us to think in new ways about how computers could be used in daily life. Face to face communication is a real-time process operating at a time scale of less than a second. In this paper we present progress on a perceptual primitive to automatically detect frontal faces in the video stream and code them with respect to 7 dimensions in real time: neutral, anger, disgust, fear, joy, sadness, surprise. The face finder employs a cascade of ...
    ABSTRACT Non-verbal behavior is a mode of human interaction that is critical to communication, especially in situations where speech is sparse. In this study, we developed novel visualizations (called behavioral recurrence plots) to... more
    ABSTRACT Non-verbal behavior is a mode of human interaction that is critical to communication, especially in situations where speech is sparse. In this study, we developed novel visualizations (called behavioral recurrence plots) to reveal the non-verbal behavior patterns of a tutor instructing a thirteen year old student in a mathematical problem, and the time-locked responses of the student solving a series of problems. In the first phase of analysis, video recordings were manually annotated to document the participants' speech, behavior, gesturing, fidgeting, and eye gaze over time, and automatic detection of movement was used to extract gross human motion. In a second phase of analysis, recurrence plots were used to visualize the interaction dynamics between the tutor's behaviors and between the tutor and student. The recurrence plots reveal the global structure of the tutoring session, points of interest and transitions, as well as interactions between the many modes of non-verbal communication.