=Paper= {{Paper |id=Vol-2474/shortpaper9 |storemode=property |title=Facial expression recognition from nao robot within a memory training program for individuals with mild cognitive impairment |pdfUrl=https://ceur-ws.org/Vol-2474/shortpaper9.pdf |volume=Vol-2474 |authors=Berardina Nadja De Carolis,Giuseppe Palestra,Olimpia Pino |dblpUrl=https://dblp.org/rec/conf/smc/CarolisPP19 }} ==Facial expression recognition from nao robot within a memory training program for individuals with mild cognitive impairment== https://ceur-ws.org/Vol-2474/shortpaper9.pdf
       Facial expression recognition from nao robot
     within a memory training program for individuals
              with mild cognitive impairment
               1st Berardina De Carolis                            2nd Giuseppe Palestra                             3rd Olimpia Pino
          Department of Computer Science                          Research Department                         Department of Psychology
            University of Bari “A. Moro”                               HERO srl                                  University of Parma
                      Bari, Italy                                     Apulia, Italy                                 Parma, Italy
            berardina.decarolis@uniba.it                       giuseppepalestra@gmail.com                       olimpia.pino@unipr.it

   Abstract—Mild Cognitive Impairment refers to a borderline state             provide helpful feedback, to analyze patients’ performances
between healthy aging and dementia. Memory-training program                    over the time [4]. The psychologists’ primary objective for MCI
plays a crucial role in the reduction of the possible conversion in
dementia and a robot mediated memory training is useful to                     patients is to keep their cognitive ability when functional
overcome limits of traditional programs. The present study addresses           capabilities and independence are not compromised [2]. The
the effectiveness of a system in automatically recognize facial                worldwide incidence of MCI expects to increase in the next few
expression from video recorded sessions of a robot mediated memory
training lasted 2 months involving 21 patients. The system is able to
                                                                               years [3]; however, space and personnel shortages are already
recognize facial expressions from group sessions handling partially            becoming a problem owing to an unprecedented rise in life
occluded faces. Findings showed that in all participants the system is         expectancy [3]. In very recent years, new tools and
able to recognize facial expressions.                                          technologies based on machine learning and robotics are
   Index Terms—facial expression recognition, social robot, memory
training, Mild Cognitive Impairment
                                                                               successfully applied to the field of psychology and could be
                                                                               used to in memory training program for people with MCI.
                                                                               Humanoid robots are able to improve mood, emotional
                           I.   INTRODUCTION                                   expressiveness and social relationships among patients with
                                                                               dementia [5]– [7] also executing many assistive functionalities
   Mild Cognitive Impairment (MCI) concerns a stage between
                                                                               [8]–[10] and providing life assistance demonstrating that the
normal aging and early dementia marked by cognitive deficit
                                                                               information support provided by the robot also has the
characterized by scores below the norm on psychometric
                                                                               potential to improve the daily life of persons with a mild level
tests, preserved functional abilities and high levels of quality
                                                                               of dementia [5]. Most recent advances in information and
of life [1]. The prevalence of MCI in individuals >65 years of age
                                                                               communication technologies have enabled the development
is between 10 and 20%. MCI is highly likely to convert in
                                                                               of telepresence robots to connect a family member and a
dementia at a rate of about 13% per year and in the rest of the
                                                                               person with dementia as a means of enhancing
patients the impairment persists stable or even return to
                                                                               communication between these two parties [11]. The
normal over time [2]. Dementia was estimated to have been
                                                                               humanoids skills are progressively enhanced: they are able to
detected around the globe at the rate of one new patient
                                                                               recognize faces, call people by their name, shape their
about every 7 seconds. Therefore, MCI has become a relevant
                                                                               behavior considering the mood of people interacting with
research topic because it could play a critical role in
                                                                               them [12], [13]. Some robots can also reproduce emotions
distinguishing developmental changes in lifespan memory
                                                                               [12], [14], making their human mate feel welcomed, and
from those that are real signs of the disorder. Delaying the
                                                                               simulating empathy [15], [16]. Kinetics technology can help
onset of dementia by as little as one year could decrease the
                                                                               them reproduce movements [17], while speech recognition
global burden of Alzheimer’s by 9 million of patients in 2050
                                                                               software allows them to respond to what people say, even in
[3]. In order to maintaining cognitive functions non-
                                                                               many different languages. During human-robot interaction,
pharmacological programs are developed. These programs
                                                                               the mirror-circuit, responsible for social interaction, is verified
involve qualified psychologist and therapists in order to
                                                                               to be active [18] suggesting that humans can consider robots
conduct new tasks and new exercises, to monitor the
                                                                               as real companions with their own intentions. Many studies
performance of the patients, to
                                                                               have employed the robot NAO. If appropriately programmed,
                                                                               it is able to decode human emotions, simulate emotions
  SAT19: 1st Workshop on Socio-Affective Technologies: an interdisciplinary
approach, October 7, 2019, Bari, Italy                                         through the color of his eyes or the position of the body,
                                                                               recognize faces and model physical exercise to a group of



    Copyright © 2019 for this paper by its authors. Use permitted under Creative Commons License Attribution 4.0 International (CC BY 4.0).
seniors [19], and equipped to measure of health and                           interfere with study participation, such Parkinson’s disease,
environmental parameters [20]. Robotics could partially fill in               HIV/AIDS, or other contraindications. Informed consent was
some of the identified gaps in current health care and home                   obtained from all the patients or from their legal
care/self-care provisions for promising applications in these                 representatives when appropriate. 21 individuals (10 females
fields that we expect to play relevant roles in the near future.              and 11 males) participated in the experiment with a mean age
With emerging research suggesting that mobile robot systems                   of 73.45 years (SD = 7.71). The mean education level was of
can improve elderly care [6], [7], [10], also through the                     9.90 years (SD = 4.58) with a minimum value of 5 years
development of a coding system aimed at measuring                             corresponding to the conclusion of the elementary school and
engagement-related behavior across activities in people with                  a maximum value of 18 years which corresponds to a bachelor
dementia [21], [22]. With the growing incidence of pathologies                degree.
and cognitive impairment associated with aging, there will be
                                                                              B. Robot Mediated Memory Training Program
an increasing demand for maintaining care systems and
services for elderly with the imperative of economic cost-                       The memory training exercises were implemented on NAO
effectiveness of care provision. In our previous work [23], NAO               on the basis of exercises described in literature [24] and aimed
has been evaluated as mediator in a memorytraining program                    to train: i) focused attention; ii) divided and alternate
for people with MCI in a center for cognitive disorders therapy.              attention; and iii) categorization and association as learning
   The focus of the present paper was evaluate the feasibility                strategies. Five tasks were implemented in NAO, considering
and usefulness of NAO platform in cognitive stimulation. In                   the characteristics of the robot:
human interaction emotional and social signals expressing                         1) Reading stories;
additional information are essential. For this aim, particular                    2) Questions about the story;
attention was paid to quantifying the effectiveness of robot on                   3) Associated/not associated words;
well being of the training recipients and this was realized                       4) Associated/not associated word recall;
measuring facial expressions at the same time gaze when                           5) Song-singer match;
human participants interact with the synthetic agent. This
study aims to exploit video clips recorded during the 2-month                 C. Video corpus
experiment of the previous study analyzing facial expressions                   In this study, we used a corpus of 48 memory program
of the participants in the experiment. The system presented is                session video clips of one hour from 24 therapeutic sessions.
able: i) to recognize group facial expression thanks a multiface              Each video clips recorded three or four participants. These
detector; ii) to recognize facial expression in partially occluded            videos were recorder during two months by two cameras
faces. This paper is organized as follows. Section 2 presents                 placed in the therapeutic room and they have been used to
Materials and Methods used. Section 3 reports experimental                    record all participants. Overall, at the end of the experiment
results. Finally, conclusions are drawn.                                      for each participant a total of eight hours of video have been
                                                                              collected.
                    II. MATERIALS AND METHODS
A. Participants                                                               D. Group Facial Expression Recognition System
   The participants were selected from the population of                         The group facial expression recognition system detect faces
outpatients attending the Center for Cognitive Disorders and                  in the corpus and then recognize 6 basic emotions (anger,
Dementia of AUSL Parma (Italy). All the participants were                     disgust, fear, happiness, sadness and surprise) plus neutral
firstly evaluated by memory-disorders specialists. The                        expression. The video analysis system is based on a previous
diagnosis of MCI was based on a detailed medical history,                     study that aimed to recognize six basic emotions through facial
relevant physical and neurological examinations, negative                     expression [25] but the system has been improved in order: i)
laboratory findings, and neuroimaging studies. Subjects are                   to work in groups using a multi-face detector; ii) handle partial
enrolled according to the following inclusion criteria: a)                    occlusions of the face. In group facial expression recognition
diagnosis of MCI obtained through Petersen guidelines, and                    handle occlusions is very important in order to ensure a high
full marks in the two tests measuring daily living activities (ADL            accuracy rate. Indeed, sometimes the face of the participants
and IADL); b) both genders; c) chronological age comprised                    is occluded by a hand as well as by an arm of the other
between 45 and 85 years; and d) without pharmacological                       participants as shown in Figure 1.
treatment. Exclusion criteria were a diagnosis of major
neurocognitive disorder (defined using DSM 5 criteria), history
of symptomatic stroke (although silent brain infarction was not
an exclusion), history of other central nervous system
diseases, serious medical or psychiatric illness that would




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                                                                              expression and an average accuracy of 94,24% on 6 basic facial
                                                                              expression plus neutral.
                                                                                 Overall, the system extracts 32 geometric features that have
                                                                              been used in total or in part (to handle occlusions) in order to
                                                                              train a model. To recognize facial expression, the system uses
                                                                              a classification module that, through a Random Forest
                                                                              classifier, analyzes the geometric characteristic vectors to
                                                                              determine the facial expression.
                                                                                                               III. RESULTS
             Fig. 1. Examples of occlusion in the video corpus.                   In order to test the system, the video clips of the corpus have
                                                                              been down sampled at 1 frame per second. For each
  After identifying a face, the system extracts, for each face,               participant 28,800 frames have been analyzed (1
facial landmarks locating 77 key points. Once the 77 points are               frame/second x 8 hours of recording). To evaluate the facial
identified, the software tracks linear, polygonal, elliptical and             expression recognition during the memory training program
                                                                              mediated by the robot: i) the number of detected face (nFD);
                                                                              ii) and the number of each facial expression recognized (nFE)
                                                                              for each frame for each participants in the video corpus have
                                                                              been used as metrics. Overall, the system was able to analyze
                                                                              all the




         Fig. 2. Facial expression analyzing software flow diagram.


                                                                                  Fig. 3. Facial expression recognized in the video corpus in percentage.
angular characteristics, i.e. the distance between two points to
find the following: three lines describing the left eyebrow; two
defining the left eye; one for the cheeks; one for nose; eight                video corpus and all the 21 faces of the participants have been
for the mouth. The system then determines polygonal                           detected. With respect to nFD, it has been observed that, in
features, calculating the area delimited by irregular polygons                percentage, a face has been detected in total of the corpus
created using three or more key reference points, specifically:               with a success rate of 56%. Moreover, respect to the nFE, it has
one for the left eye; one forming a triangle between the                      been observed that in each frame where a face had been
corners of the left eye and the left corner of the mouth; one                 detected (also if partially occluded) the system was able to
for the mouth. Thus, the system traces the elliptic                           recognize a facial expression. In percentage, the three most
characteristics, calculated by the ratio between the major axis               common facial expressions are neutral that has been founded
and the minor axis of the ellipse, in particular seven ellipses               in the 41% of the frames, happiness in the 17% and sadness in
are chosen between the reference points: one for the left                     the 15% as shown in Figure 3.
eyebrow; three for the eye, left upper and lower eyelid; three                   In Table I are reported the number of frames where a face
for the mouth, lower and upper lips. The pipeline of the system               had been detected and Table II reports the number of facial
is depicted in Figure 2. The system has been tested on the                    expression recognized for each participant divided into facial
Extended Cohn-Kanade (CK+) data set, a well known facial                      expressions.
expression image database of 123 individuals of different
gender, ethnicity and age. The system reach an average facial                                                   TABLE I
expression recognition accuracy of 95,46% on six basic facial                             NUMBER OF FACE DETECTED (NFD) FOR EACH PARTICIPANT (#).




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                        Participant (#)     nFD                               track of the mood of the individuals involved during the
                                1          23,567                             training sessions. In future work, other analysis on the video
                                2          22,678                             corpus will be done to understand the engagement, how the
                                3          16,709                             participants have been involved during the memory training
                                4          18,541
                                                                              program and how to better involve the individuals with MCI in
                                5          20,341
                                                                              new memory training program mediated by a social robot.
                                6          16,354
                                7          15,980
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