=Paper= {{Paper |id=Vol-2404/paper22 |storemode=property |title=Application of Lovheim Model for Emotion Detection in English Tweets |pdfUrl=https://ceur-ws.org/Vol-2404/paper22.pdf |volume=Vol-2404 |authors=Paolo Fornacciari,Stefano Cagnoni,Monica Mordonini,Leonardo Tarollo,Michele Tomaiuolo |dblpUrl=https://dblp.org/rec/conf/woa/FornacciariCMTT19 }} ==Application of Lovheim Model for Emotion Detection in English Tweets== https://ceur-ws.org/Vol-2404/paper22.pdf
                                       Workshop "From Objects to Agents" (WOA 2019)


          Application of Lovheim Model for Emotion
                 Detection in English Tweets
       Paolo Fornacciari, Stefano Cagnoni, Monica Mordonini, Leonardo Tarollo, Michele Tomaiuolo
                                       Dipartimento di Ingegneria e Architettura
                                             Università degli Studi di Parma
                                                       Parma, Italy
                    paolo.fornacciari@unipr.it, stefano.cagnoni@unipr.it, monica.mordonini@unipr.it,
                             leonardo.tarollo1@studenti.unipr.it, michele.tomaiuolo@unipr.it



   Abstract—Emotions are central for a wide range of everyday         a fundamental role, such as medicine [3]. Emotions represent
human experiences and understanding emotions is a key problem         and identify the human being and therefore they influence
both in the business world and in the fields of physiology and        a person’s behavior and decisions and also the relationships
neuroscience.
The most well-known theory of emotions proposes a categorical         with others [4]. In evolutionary terms, their main function is
system of emotion classification, where emotions are classified       to make the individual’s reaction more effective. in situations
as discrete entities, while psychologists say that in general man     where an immediate response is needed for survival. Such a
will hardly express a single basic emotion. According to this         reaction does not use cognitive processes and conscious pro-
observation, alternative models have been developed, which define     cessing. An interesting theme in physiology and neuroscience
multiple dimensions corresponding to various parameters and
specify emotions along those dimensions.                              is the question of how emotions interact with and influence
Recently, one of the most used models in affective computing          other domains of cognition, in particular, attention, memory,
is the Lovheim’s cube of emotions, i.e., a theoretical model that     and reasoning [5]. In fact, the question of how emotions are
focuses on the interactions of monoamine neurotransmitters and        represented in nervous system activity is still an unresolved
emotions.                                                             problem in affective neuroscience [6].
This work presents a comparison between a single automatic
classifier able to recognize the basic emotions proposed in the          The most well-known theory of emotions proposes a cat-
Lovheim’s cube and a set of independent binary classifiers,           egorical system of emotion classification, where emotions
each one able to recognize a single dimension of the Lovehim’s        are classified as discrete entities, independent of each other
cube. The application of this model has determined a notable          and easily distinguishable [7]. Thus the main taxonomies of
improvement of results: in fact, in the best case there is an         emotions divide them into positive and negative and more into
increment of the accuracy of 11,8%.
The set of classifiers has been modeled and deployed on the dis-      details in a few basic emotions: surprise, interest, joy, rage,
tributed ActoDeS application architecture. This implementation        fear, disgust, shame, and anguish [8]. In reality, psychologists
improves the computational performance and it eases the system        and social science experts say that in general man will hardly
reconfiguration and its ability to recognize particular situations,   express a single basic emotion [9]. Every facial expression,
consisting of particular combinations of basic emotions.              every text, every gesture is a composition of multiple emotions.
   Index Terms—Machine learning, sentiment analysis, emotion
detection, natural language processing, software actors.              Such expressions change together with the evolution of speech.
                                                                      Similarly to the different shades of color, emotions are not
                                                                      clearly distinguishable and it is difficult to sharply discern
                       I. I NTRODUCTION
                                                                      one emotion from the others. In argumentations about the
   Sentiment Analysis (SA) applies Machine Learning (ML)              human personality, even the objective and neutral information,
techniques to textual content, for extracting the feelings and        typically used to classify simple information about an object
other information, useful for understanding a person’s opinion        or a theme, cannot be expressed in their pure form.
about a given entity (product, person, topic, etc.). Emotions            Recently, one of the most used models in affective com-
are central for a wide range of everyday human experiences            puting is the Lovheim’s cube of emotions ( [10], [11]),
and understanding emotions is a key problem in the business           that is a theoretical model that focuses on the interactions
world, especially in an era where online communities will             of monoamine neurotransmitters and emotions. Although the
define future products and services [1], [2].                         validity and reliability of this model are still to be determined,
   Mainly in market analysis, being able to discriminate be-          some researches demonstrate that a neurocognitive approach
tween positive and negative comments is often sufficient. But,        is important to determine emotional reactions to, for example,
for other applications that refer to Affective Sciences (AS),         visual stimuli [12].
a more detailed analysis of emotions is more appropriate. As             This work presents a comparison between a single automatic
refer to the scientific study of emotion (or affect) and cover a      classifier able to recognize the basic emotions proposed in
wide range of interdisciplinary fields in which emotions play         the Lovheim’s cube and a set of independent binary classi-




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fiers, each one able to recognize a single dimension of the          In a previous work of ours [14] we used a hierarchical
Lovehim’s cube. A set of classifiers has been modeled on the         approach so that first we looked for the polarity of a text and
actor-based architecture proposed in [13] for data analysis.         then the primary emotion associated with it. This hierarchy
This implementation improves the computational performance           of classifiers has made the system more flexible and slightly
and it eases the system reconfiguration, to recognize particu-       improved the performance respect to a flat classifier trained
lar situations, that is particular combinations of percentages       on the same dataset based on six emotions. In the present
of basic emotions. In fact in the Lovehim cube, the basic            work, we have tried to exploit a more recent and more refined
emotions are classified on a three-dimensional model that            theory of emotions that is able to perform a multidimensional
allows highlighting their reciprocal relations, which difficult      analysis of them. Some work of this kind is present in [28],
to distinguish in a hierarchical model, in which all emotions        even if the authors used a two-dimensional model, while our
are first of all divided into negative, neutral and positive (see    reference model has three dimensions: the different emotions
for example [14].                                                    are inside a cube whose vertices are the eight "pure" emotions.
   A curiosity, and a difficulty in the implementation of this          Also, in this case, the system is more flexible than a flat
model for the recognition of emotions on Twitter, was the lack       classifier able to classify the eight primary emotions as it is
of available data for the “distress / anguish” emotion. That         possible to define a set of points in our multidimensional
class is commonly found in the datasets for facial emotion           model that represent combinations of “pure” emotions to
recognition but not in textual datasets, probably due to the         associate "real" human moods. Furthermore, in this case, the
approach of the human beings towards the written text [15].          comparison of the flat classifier trained on the same dataset
   The paper is structured as follows. Section 2 gives a brief       gave significantly better results. It is not possible to make a
overview of the background in emotion detection. Section 3           direct comparison between the two systems as they refer to
describes the implemented framework and Section 4 describes          different datasets and to different data collection approaches.
the experimental results. Section 5 reports the concluding              The models of Parrot, Plutchik, and Lovheim are shown
remarks.                                                             below. Parrot’s model belongs to the set of categorical emotion
                                                                     models which define a list of discrete categories of emotions.
                     II. R ELATED W ORK                              Parrott proposed an emotion classification model structured
   The techniques of Sentiment Analysis aim at the study and         on three levels, each representing a list of emotions [29]. The
analysis of textual information, with the purpose of detecting       model collects more than 100 emotions and is shown in Figure
evaluations, opinions and emotions related to a specific entity      1.
(product, person, topic, etc.). This type of analysis has impor-
tant applications in the political, economic and social fields,
such as Web Reputation and Social Media Analytics. Social
media and the rise of social networking platforms are one of
the most important social phenomena in the last years [16] and
the studies of SA on platforms like Twitter are very common
in the scientific literature ( [17]–[19]. Datasets based on tweets
are used in different tasks of Semantic Evaluation (SemEval),
such as in [20] and [21].
   SA, with thousands of articles written about its methods and
applications (see for example [22]–[24], is a well-established
field in Natural Language Processing. Emotion Detection can
be viewed as a natural evolution of Sentiment Analysis and its
more fine-grained model [25]. This paper summarizes the emo-
tion models that are mostly used in emotion-based research.
Emotion extraction from different types of social network
components is a research topic which is being investigated
for a long time now. An updated more comprehensive survey
of Emotion Detection from a text can be found in [26].
   Some works in the literature for emotion detection have an
approach based on lexicon or keyword and in this case they
refer to an annotated dictionary or a knowledge base; but many
recent works adopt a machine learning approach [27], in this
work we use a framework that is based on supervised machine
learning algorithms.
   Most of the works in the literature refer to the theory of                             Fig. 1. Parrot’s model.
the six primary emotions: in general, a text is recognized as
belonging to one of these emotions by an automatic classifier.         The other two models belong to the class of dimensional




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emotion models, which define a few dimensions with some pa-
rameters and specify emotions according to those dimensions.
Plutchik argued that there are only eight basic emotions (joy,
trust, fear, surprise, sadness, anticipation, anger, and disgust),
but these emotions can be combined. He suggested the wheel
model (2D) in 1980 to describe how emotions are related
[30]. The model proposed by Plutchik is summarized in Figure
2. It is possible to observe that this model describes a wide
spectrum of emotions, each of them representing a different
combination of primary emotions.




                                                                                Fig. 3. Emotions’ Mapping on Lovheim’s Cube




                      Fig. 2. Plutchik’s wheel.

   Finally, Lovheim proposed a three-dimensional model based                 Fig. 4. Role of neurotransmitters in the Lovheim model
on the relationship between neurotransmitters and emotions
[10]. In the model, the three neurotransmitters serotonin,
dopamine and noradrenaline form the axes of a coordinate             a phenomenon that occurs when the energy of a cell rapidly
system, while the eight basic emotions (shame, anxiety, fear,        grows/decreases , starts the release of these neurotransmitters
anger, disgust, surprise, joy, and interest) are placed in the       from the presynaptic terminal nerve through a process of
eight vertices. Each vertex of the cube corresponds to one of        exocytosis: a cellular process by which a cell expels molecules.
the eight possible combinations of the three neurotransmitters,      Neurotransmitters are packed into vesicles in the presynaptic
as shown in Figure 3. The relationship between emotions and          neuron. Once released, they enter the synapse by attaching to
neurotransmitters is shown in Figure 4.                              receptors in the post-synaptic neuron. In biology, the neuro-
   Neurotransmitters represent a certain type of hormones            transmitters considered by Lovehim in relation to emotions
that affect the amino acids located in the brain and transmit        have the following functions:
information from one neuron to another. To gain a better               1) Serotonin, also known as the happiness hormone, deals
understanding of how neurotransmitters have an effect on our              with numerous functions such as regulation of circadian
emotions, a brief explanation of their functioning is needed.             rhythms (sleep), appetite control, blood pressure control,
An electrical signal (or nerve impulse) travels along the neural          control of sexual behavior. It has a positive effect on
pathways until it reaches their end. Once the end of the                  memory, has inhibitory effects on the perception of
path is reached, the electrical signal is transformed into a              pain, and intervenes in social relations. Low levels of
chemical signal (neurotransmitter) inside the synapses (space             serotonin lead to a decline in mood, depression, states of
between neurons). This signal, crossing the synapses, will be             anxiety, and aggression. High levels of serotonin instead
transformed back into an electrical signal. The action potential,         determine a state of well-being, serenity, tranquillity, and




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     happiness.                                                                                 TABLE I
  2) Dopamine deals with the following functions: move-                                    M APPED E MOTIONS
     ment, memory, sleep, mood, learning, attention, and                           Lovheim Emotion         Emotion
     reward. An excess or deficiency of dopamine is the                            Joy               happiness;fun;relief
     cause of numerous diseases such as Parkinson’s, drug                          Excitement        love;enthusiasm
                                                                                   Surprise          surprise
     addiction and schizophrenia.                                                  Anger             hate
  3) Noradrenaline is released by the brain in response to                         Disgust           boredom
     strong physical or psychological stress. It accelerates                       Fear              worry
     the heart rate, increases the release of glucose from                         Shame             sadness
                                                                                   Anguish           -
     energy reserves, and increases blood flow. Noradrenaline
     also intervenes in the preparation of the body in the
     so-called attack or flight reaction. Noradrenaline is the
                                                                     B. Architectures of the classification systems
     neurotransmitter of excitement: low levels are related
     to depression, poor memory, lower than average alert               One of the main targets of this study is to compare results
     levels. Too high levels are linked to increased anxiety         obtained by a FLAT classifier, trained using the training set
     and fear.                                                       directly, with results obtained by a classifier trained using a
                                                                     Lovheim architecture and a corresponding training set. The
                III. C LASSIFICATION SYSTEM                          file modeled according to Lovheim’s theory is split into 3
                                                                     binary training sets, according to high/low levels of the three
   This chapter describes the structure of the realized classi-      characteristic neurotransmitters: serotonine, dopamine, nora-
fication system, including the preparation of the dataset, the       drenaline. Then, three binary classifiers are trained and their
learning techniques, and the actor-based architecture.               results are combined and compared with those obtained from
                                                                     the simple FLAT classifier. Moreover, since in all publicly
                                                                     available dataset there are only 7 out of the 8 emotions of
A. Actor-based System
                                                                     Lovheim’s Cube, an assumption has been adopted to avoid
   For realizing this kind of multilevel classification system,      the problem.
we have used ActoDES, which is a software framework which               The dataset contains a collection of tweets (22900), which
adopts the actor model for simplifying the development of            address different topics. Each tweet is labeled with one of the
complex distributed systems [13], [31]. In fact, it eases the        following emotions: sadness, worry, hate, boredom, surprise,
creation of complex intelligent systems, supporting the exe-         happiness, fun, relief, love, enthusiasm.
cution of multiple autonomous classifiers which communicate             Since the annotated classes do not correspond to Lovheim’s
by means of asynchronous messages. This way, a composite             basic emotions, another step is needed before training files
classifier can be deployed as a set of loosely coupled cooper-       can be created: mapping the dataset emotions onto Lovheim’s
ating actors. Each simple classifier and each processing step        cube (3). So the emotion classifications proposed by Parrott
can instantiated as an actor, allowing the whole architecture        and Plutchik have been used. The list of mapped emotions is
to be defined at a high level of abstraction, where single           shown in table I.
actors can be replaced and reconfigured to evaluate alternative
approaches. According to the received messages, an actor                                 IV. T RAINING S ETS
can update its state and change its behaviors, terminate its
own execution, send messages to other actors, create new               After the mapping has been completed, 4 training files have
actors, etc. Particular interaction patterns allow communities of    been created:
actors to self organize in dynamic scenarios, involving online         • 1 FLAT Training set: this file has 22900 tweets, where
learning. A subscription service is available in ActoDES, to             each one is labelled with one of the following emotions:
facilitate the development of collaborative applications with            Shame, Fear, Anger, Disgust, Surprise, Joy, Excitement.
actors, as shown in [32]. It is very useful for the integration of     • 3 BINARY Training sets: these files have 22900 tweets,
multiple actors participating in a structured classification task.       where each one is labeled with 1/0 which indicates the
Other services, developed for this project, provide additional           high/low level of the neurotransmitter for the correspond-
functionalities to actors, for the continuous analysis of various        ing Lovheim emotion.
social streams.                                                          E.g., let us consider the following tweet: "wants to hang
   Leveraging ActoDES and the additional mentioned services,             out with friends soon!"
we have built a software system which can be used to track               This tweet is labeled with the interest/excitement emotion
and study a news feed from social media, with an architecture            in the FLAT training set. According to Lovheim’s theory,
that can be extended to different cases and also to more                 this emotion has the following coordinates in the cube
complex problems. In particular, it can be configured for online         (1,1,1), which correspond to high levels of serotonine,
operation, handling streams of messages and continuously                 dopamine and noradrenaline. So, this tweet has been
learning from a growing dataset.                                         labeled in each binary training sets with a 1.




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                                            Fig. 5. Distributed ActoDeS application architecture.



                             TABLE II                                                              TABLE III
                 R ESULTS FOR FLAT TRAINING SET.                            C OMBINED RESULTS FOR N EUROTRANSMITTERS TRAINING SETS .

                                   FLAT Results (%)                                                       Neurotransm. Results (%)
              Lovheim Emotions     P     R       F1                                   Lovheim Emotion      P      R          F1
              Joy                 48.1 47.9     48.0                                  Joy                 56.8   65.9    61.0
              Excitement          53.0 22.9     32.0                                  Excitement          64.5   36.5    46.6
              Surprise            42.1 5.5      9.7                                   Surprise            87.3   8.7     15.9
              Anger               48.4 23.2     31.3                                  Anger               52.2   33.9    41.1
              Disgust             29.2 4.5      7.7                                   Disgust             4.0    7.0     5.1
              Fear                41.1 73.9     52.9                                  Fear                52.4   79.2    63.0
              Shame               46.7 24.7     32.3                                  Shame               69.5   42.6    52.8
              Weighted Average    45.6 44.1     40.6                                  Weighted Average    59.9   55.7    53.5
              Accuracy                  44.1                                          Accuracy                      55.7



A. Pre-Processing                                                       C. Assumption
    For each training file, a quite classical set of preprocessing         Since a dataset which contains at least an emotion that
filters is applied. The configuration is obtained after an itera-       could be labeled as distress/anguish has not been found, an
tive optimization process. In particular, sentences are vector-         escamotage has been adopted to remove predictions that could
ized according to the bag of words approach, after applying the         have been classified as this class, because it wasn’t present in
Iterated Lovins stemmer, stopwords removal, and tokenization            the training file.
for unigrams and bigrams. Finally, the most relevant and useful            This problem arises because the results are obtained from
features are selected for the resulting data, according to the          the 8 combinations of serotonine, dopamine and noradrenaline
InfoGain algorithm, with a zero threshold.                              levels: it could happen that the following combination (0,0,1)
                                                                        is predicted, which corresponds to the distress/anguish emo-
                V. E XPERIMENTAL R ESULTS                               tion in Lovheim’s cube.
   This chapter presents the results retrieved applying the dif-           The following assumption is adopted: considering the pre-
ferent compared classification systems, supervised approach             dictions and the confidence levels associated with each tweet,
using the 10-folds-cross validation methodology on the differ-          classify the text with the closest emotion. Table IV shows
ent training sets.                                                      the neurotransmitters results, after applying the assumption.
                                                                        In table VII, the related confusion matrix is shown.
A. FLAT training set
  The results for the FLAT training set are shown in table II,                                      VI. C ONCLUSIONS
while its confusion matrix is shown in table V.                            Recently, one of the most used models in affective comput-
                                                                        ing is the Lovheim’s cube of emotions: a theoretical model that
B. Binary training sets                                                 focuses on the interactions of monoamine neurotransmitters
   The results obtained from each binary training file would            and emotions. This research work has compared a single
be irrelevant if taken individually: it is necessary to consider        automatic classifier, able to recognize the basic emotions pro-
the combination of the predictions on these 3 datasets. The             posed in the Lovheim’s cube, with a set of independent binary
combined results are shown in table III.                                classifiers, each one able to recognize a single dimension of
   The corresponding confusion matrix is shown in table VI.             the Lovehim’s cube.




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                           TABLE IV
 C OMBINED RESULTS FOR N EUROTRANSMITTERS TRAINING SETS USING                   [11] J. Vallverdú, M. Talanov, S. Distefano, M. Mazzara, A. Tchitchigin,
                          ASSUMPTION .
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                Joy                   56.8    65.9   61.0                            tourism emotion research,” Current Issues in Tourism, pp. 1–7, 2017.
                Excitement            64.5    36.4   46.6                       [13] G. Lombardo, P. Fornacciari, M. Mordonini, M. Tomaiuolo, and
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     341–348, 2012.                                                                  and Computer Science, vol. 1, 2015, pp. 1–5.




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          Workshop "From Objects to Agents" (WOA 2019)



                                   TABLE V
                   C ONFUSION M ATRIX FOR FLAT TRAINING SET.

                                        FLAT Confusion Matrix
                Joy    Excitement       Surprise Anger Disgust         Fear    Shame
  Joy          2441       230             34       17         5        2193      175
  Excitement   857        593             13       12         4        966       145
  Surprise     320         47             88       16         1        1043      98
  Anger         80         13              8      275         2        678       131
  Disgust       12          1              1        6         7        106       24
  Fear         865        122             43      118         2        5492      791
  Shame        502        112             22      124         3        2871     1194




                                 TABLE VI
          C ONFUSION M ATRIX FOR N EUROTRANSMITTERS TRAINING SET.

                               Neurotransmitters Confusion Matrix
                Joy    Excitement   Surprise Anger Disgust             Fear    Shame
  Joy          3358       199          0          4         14         1460      60
  Excitement   887        944          3         158        4          553       37
  Surprise     338        157         131         71       105         448       248
  Anger         49         37          1         396        1          652       33
  Disgust       23          0          1          0         11          78       44
  Fear         913         83          0          66        9          5881      478
  Shame        347         43          14         63       132         2160     2047




                                 TABLE VII
   C ONFUSION M ATRIX FOR N EUROTRANSMITTERS ( ASSUMPTION ) TRAINING SET.

                         Neurotransmitters Confusion Matrix (assumption)
                Joy    Excitement   Surprise Anger Disgust         Fear        Shame
  Joy          3358       199           0          4        14     1460          60
  Excitement   887        944           6        158        4       553          38
  Surprise     338        157          160       117       105      448          288
  Anger         49         37           15       397        1       652          36
  Disgust       23          0           1          0        11       78          44
  fear         913         83           3         66        9      5881          478
  Shame        347         43           29        68       132     2160         2049




                                     TABLE VIII
                                R ESULTS COMPARISON

                                                                       Neurotransmitter
                           FLAT (%)           Neurotransmitter (%)
                                                                      (assumption) (%)
                     P        R        F1      P      R      F1       P       R      F1
Joy                 48.1     47.9     48.0    56.8   65.9   61.0     56.8   65.9    61.0
Excitement          53.0     22.9     32.0    64.5   36.5   46.6     64.5   36.4    46.6
Surprise            42.1     5.5      9.7     87.3   8.7    15.9     74.8   9.9     46.6
Anger               48.4     23.2     31.3    52.2   33.9   41.1     49.0   33.4    39.8
Disgust             29.2     4.5      7.7     4.0    7.0    5.1      4.0    7.0     5.1
Fear/Terror         41.1     73.9     52.9    52.4   79.2   63.0     52.4   79.1    63.0
Shame               46.7     24.7     32.3    69.5   42.6   52.8     68.5   42.4    52.4
Weighted Average    45.6     44.1     40.6    59.9   55.7   53.5     59.2   55.9    53.7
Accuracy                     44.1                    55.7                   55.9




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