Can You Distinguish Truthful from Fake Reviews? User Analysis and Assistance Tool for Fake Review Detection
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Can You Distinguish Truthful from Fake Reviews? User Analysis and Assistance Tool for Fake Review Detection Jeonghwan Kim∗ Junmo Kang∗ Suwon Shin∗ Sung-Hyon Myaeng School of Computing, KAIST Daejeon, Republic of Korea {jeonghwankim123, junmo.kang, ssw0093, myaeng}@kaist.ac.kr Abstract Customer reviews are useful in providing an indirect, secondhand experience of a product. People often use reviews written by other cus- tomers as a guideline prior to purchasing a product/service or as a basis for acquiring in- formation directly or through question answer- ing. Such behavior signifies the authenticity of reviews in e-commerce platforms. However, fake reviews are increasingly becoming a has- sle for both consumers and product owners. To address this issue, we propose You Only Need Figure 1: YONG - a prototype interface. Given the Gold (YONG), an assistance tool for detecting review input by user, YONG shows 1) whether it is gold fake reviews and augmenting user discretion. or fake with 2) the probability (%), and 3) evidence Our experimental results show the poor human that shows how much each word contributes to model’s performance on fake review detection, substan- final decision. The highlighted evidences show the top tially improved user capability given our tool, p% proportion of the contributors, where the proportion and the ultimate need for user reliance on the can be adjusted using the horizontal slider bar. tool. 1 Introduction (Devlin et al., 2018), fast and scalable anomaly The increasing prominence of e-commerce plat- detection algorithms like DenseAlert (Shin et al., forms gave rise to numerous customer-written 2017) have made effective and promising contribu- reviews. The reviews, given their authentic- tions in detection of fraudulent reviews. Despite ity, provide important secondhand experience to such contributions, these approaches only focus on other potential customers or to information-seeking better modeling to improve the accuracy in fake re- functions such as search and question answering. view detection, instead of its practical applications Meanwhile, fake reviews are increasingly becom- such as assisting users to distinguish fake reviews ing a social problem in e-commerce platforms (i.e., an assistance tool) or filtering out deceptive (Chakraborty et al., 2016; Rout et al., 2018; Ellson, texts for review-based question answering (QA) 2018). Such deceptive reviews are either incen- (Gupta et al., 2019). tivized by the beneficiaries (i.e., sellers, marketers) In the line of Human-Computer interaction or motivated by those with malicious intention to (HCI), there have been a variety of studies on cus- damage the reputation of the target product. tomer reviews (Wu et al., 2010; Alper et al., 2011; To date, there have been many studies (Kim et al., Yatani et al., 2011; Zhang et al., 2020). While there 2015; Wang et al., 2017; Aghakhani et al., 2018; are gold reviews, which are authentic, real-user You et al., 2018; Kennedy et al., 2019) that ad- written reviews, there are fake, deceptive reviews dress fake review detection in the field of natu- as well. All of the previous works on review vi- ral language processing (NLP). The use of high- sualization and interaction implicitly assume the performance deep neural networks such as BERT authenticity of collected reviews. Furthermore, the ∗ Equal contribution. previous works mentioned above confine the scope 53 Proceedings of the First Workshop on Bridging Human–Computer Interaction and Natural Language Processing, pages 53–59 April 20, 2021. ©2021 Association for Computational Linguistics
of research on reviews to interaction and visualiza- their work, a fine-tuned BERT performs the best on tion. crowd sourced Deceptive Opinion Spam (Ott et al., We claim that user capabilities of distinguishing 2013, 2011) data set and automatically obtained fake reviews are seriously unreliable as suggested Yelp (Rayana and Akoglu, 2015) data set. Another in (Lee et al., 2016), and this motivates our work as work proposes a generative framework for fake re- practical research for helping humans discern fake view generation (Adelani et al., 2020). It proposes a reviews. While the two lines of research in NLP pipeline of GPT-2 (Radford et al., 2019) and BERT and HCI have focused on improving the fake review to generate fake reviews. Due to the remarkable detection models and developing effective visual- fluency of these reviews, its participants failed to ization of reviews, respectively, the actual victims identify fake reviews, and surprisingly, gave higher (the users) of fake reviews are being neglected. The fluency score to the generated reviews than to the challenges of carefully curated deceptive reviews gold reviews. Similar result is evidenced in (Don- on the Web necessitate the need for an assistance ahue et al., 2020), where humans have difficulty tool that helps users avoid fraudulent information. identifying machine-generated sentences. Other In this work, we propose You Only Need Gold related works (Lee et al., 2016) use probabilistic (YONG) (Figure 1), a simple assistance tool that methods such as Latent Dirichlet Analysis (LDA) augments user discretion in fake review detection. to discover word choice patterns and linguistic char- YONG is built upon the body of previous studies by acteristics of fake reviews. fine-tuning BERT and providing a self-explanatory gold indicator to assist users in exploring customer 2.2 Review Interaction and Visualization reviews. Through a series of user evaluations, we The growth of customer reviews sparked research reveal the over-confident nature of people despite on its interaction and visualization. Visualization their poor performance in distinguishing fake re- tools like OpinionBlocks (Alper et al., 2011) pro- views from real ones and the need to implement vide an interactive visualization for better organiza- an explainable, human-understandable features to tion of the reviews in bi-polar sentiments. Similar guide user decisions in fake review detection. We works like OpinionSeer (Wu et al., 2010) and Re- also demonstrate that the application of YONG view Spotlight (Yatani et al., 2011) are also focused effectively augments user performance. on providing an accessible and interactive visual- Our contributions is two-fold, the tool and an ization of reviews. The major drawback of these extensive user understanding, as follows: works is that they naively assume the authenticity of the reviews. From the previous lines of work, • An easy-to-use tool for fake review detection we argue the threat of fake reviews and their im- with the intuitive gold indicator, which con- minence with the rise of generative models (e.g., sists of the following three features: (i) Model GPT-2) necessitate the use of our tool. Decision, (ii) Percentage Indicator (%), and (iii) Evidence. 3 Method • User analysis on fake review detection. Our We build a tool that provides straightforward, intu- work sheds a light on how susceptible human itive features to guide user decision in fake review judgment is to deceptive text. Understanding detection. The tool is built upon a state-of-the-art human decisions and behaviors in discerning NLP model fine-tuned on the OpSpam data set. fake reviews provides an insight into the de- sign considerations of a system or tool for fake 3.1 You Only Need Gold (YONG) reviews. The tool we propose is a prototype for receiving 2 Related Work a review text as an input and returns whether it is “Gold” or “Fake”. YONG is an easy-to-use tool 2.1 Fake Review Detection Using Deep with three features collectively referred to as the Neural Networks gold indicator - namely, (i) Model Decision, (ii) Fake review detection is an extensively researched Probability (%) and (iii) Evidence. Model Deci- topic among deep learning researchers. (Kennedy sion is the model output on the top right corner of et al., 2019) provide a list of analytic compari- Figure 1 as either Gold or Fake. The Probability son of non-neural and neural network models. In (%) is the softmax output, which is also the model 54
Models Accuracy SVM 0.864 FFN 0.888 CNN 0.669 LSTM 0.876 BERT (Kennedy et al., 2019) 0.891 BERT (Ours) 0.896 Figure 2: Experiment Test Bed for YONG - Experi- Table 1: Accuracy performance comparison of conven- ment #2 tional classification models against BERT on OpSpam. carefully chosen based on the criteria of determin- confidence for its decision. The word highlights, ing deception as an effort to ensure truthfulness in which we also define as the Evidence, is a visual- (Ott et al., 2011). The data set is divided into a ization of the attention weights from the last layer training and test set ratio of 8:2 in this work. of BERT to provide an interpretable medium to model’s decision for its users. 4 Experiment and Result 3.2 Fake Review Detection Model 4.1 Research Question To validate the claim made by a previous work To validate the usefulness of our tool and further (Kennedy et al., 2019) that BERT outperforms the understanding of users in the application of our other baselines in fake review detection and to em- tool, we define the following research questions ploy the most effective existing approach to fake (RQ): review detection in our tool, we compare the perfor- RQ1. “How do humans fare against machines mance of BERT against other classification models on fake review detection?” on the OpSpam (Ott et al., 2011, 2013) data set. RQ2. “Does YONG augment human perfor- In Table 1, we report the results of non-neural and mance on the task?” neural network models under the 5-fold cross val- RQ3. “Can we increase the level of human trust idation setting from (Kennedy et al., 2019). Our on YONG by injecting prior knowledge about hu- implementation of BERT outperforms all the other man and model performance?” baseline models, reaching a 90% accuracy. Based on the model performances on OpSpam data set RQ4. “How much influence does each feature in Table 1 and the renowned language understand- of the gold indicator have on human trust?” ing capability of BERT (Devlin et al., 2018), we Here, we define the term “trust” as the level of decide to employ BERT in our tool. We also fine- human reliance on the tool’s decision. To be spe- tune our BERT with the HuggingFace (Wolf et al., cific, as we evaluate in Section 4.5, the level of trust 2020) version of bert-base-uncased, where is calculated on the participant-machine agreement the [CLS] embedding is used for binary sequence (regardless of the ground-truth label). Through the classification. experiments that correspond to the RQs, we build a concrete understanding of user behaviors in the 3.3 Training & Dataset presence of customer-generated reviews and the To fine-tune BERT and to choose carefully curated gold indicator through human performance evalua- data on fake review detection, we use the Deceptive tion on fake review detection. Opinion Spam corpus, also known as the OpSpam 4.2 Experimental Design data set (Ott et al., 2011, 2013). This data set con- sists of a total of 1,600 review instances, which is We provided 10 reviews from the data set to a total divided into truthful (i.e., gold) and deceptive re- of 24 participants. The 10 reviews were randomly views. The gold reviews are extracted from the 20 sampled, resulting in correct-to-wrong ratio of the most popular hotels in Chicago (800 gold reviews) model prediction to 7:3 (i.e., 7 correct and 3 wrong and the set of fake reviews are built using Amazon model predictions; score = 0.70), and the Gold- Mechanical Turk (AMT) (800 fake reviews). The to-Fake ratio to 5:5. From Experiment 1 to 4 we gold reviews are not artificially generated, but are assess the following criteria: human discretion, tool 55
Trust 4.4 Helpfulness Assessment Experiment Condition Score (low / high group) Exp. 1 w/o tool 0.41 - To evaluate the helpfulness of our tool in augment- Exp. 2 w/ tool 0.54 0.81 / 0.79 ing user performance on fake review detection, we w/ tool Exp. 3 & score 0.56 0.83 / 0.71 provide the gold indicator as in Figure 2. For a fair comparison, the participants were given the - Model 0.70 - same reviews as in Experiment 1. In Table 2, the Table 2: Average scores (i.e., the number of correct de- accuracy increases substantially from 0.41 to 0.54 cision w.r.t. the ground truth) of participants and the by simply providing the gold indicator with the model, and the level of trust (i.e., participant-model review text. Before proceeding to Experiment 3 - agreement). Here, low and high groups are those with trust level assessment, we provide the participants below and above average scores in Exp. 1, respectively. their own scores on Experiment 1 and the model score to see if the injection of prior bias (i.e., being helpfulness, trust level on the tool, and feature-level aware of the performance gap) could influence the influence on decisions made: participants to more align their answers with those Experiment 1. Users are required to classify of the model. fake reviews given 10 reviews without our tool. 4.5 Trust Level Assessment Experiment 2. Users conduct the same task provided our tool (i.e. gold indicator). As previously stated, the participant is shown both Experiment 3. Users are shown their score and scores prior to entering the experiment. The result the model score for Experiment 1, and conduct the shows an increase in the average score in Experi- same task as in Experiment 2. ment 3 compared to that in Experiment 1. With the Experiment 4. Users are asked to score how user awareness of their and model scores shown to each of the three features in our tool influences improve the average participant score on the task, their decision. we decide calculate the change in the level of user We designed and built a separate Experiment trust on our tool. The trust level is calculated based test bed (Figure 2) using React 1 and FastAPI 2 to on the proportion of overlapping answers (Table 2). conduct an extensive quantitative and qualitative The analysis on the trust level reveals two disparate experiments on the participants of our study. To groups: (i) Those who earned lower score than av- alleviate the learning effect, the participants are erage in Experiment 1 and (ii) those who earned made unaware of the ground-truth answers and higher score than average in the same experiment. stay oblivious to both their and model scores (until While the latter shows a drop in trust level from Experiment 3). Experiment 2 to 3 (0.79 → 0.71), the former shows an increase in the trust level (0.81 → 0.83). 4.3 Human Discretion Assessment From Experiment 1, 2 to 3, we see the increase in In Experiment 1, we assess the human performance average accuracy from 0.41 to 0.54, and to 0.56, re- on fake review detection. The participants are not spectively. To evaluate the statistical significance of given any hint - only the raw text. At the end of the changes, we apply one-way repeated ANOVA Experiment 1, we ask the participants enter their with a post-hoc test to see that there are signifi- expected score. Here, the “score” corresponds to cant differences between Experiments 1 and 2 (p the number of correct decisions with respect to the
Feature Decision Probability Evidence (Jain and Wallace, 2019; Kobayashi et al., 2020). Influence 3.69 3.91 1.87 (Jain and Wallace, 2019) show that the much touted attention weights’ transparency for model decision Table 3: Influence score for each feature of the gold is unaccounted for and do not provide meaning- indicator. ful explanations. (Kobayashi et al., 2020), further- more, shows that focusing only on the parallels between the attention weights and linguistic phe- 1-to-5 scale for how much influence did each fea- nomena within the model is insufficient and thus ture have on their decision. Here, the scale at 1 requires a norm-based analysis. Based on such ob- represents “No Influence”, while scale at 5 means servation, a possible addition to our tool can be “Major Influence”. In Table 3, we show the average generating textual explanations (Liu et al., 2018) or rating per gold indicator feature. This result shows providing not only the token-level highlights as in that the Probability (%) plays the primary role in Figure 2, but also more high-level (e.g., sentence-, convincing users that model prediction is correct. paragraph-level information) highlights that show In other words, the higher the probability score, the a comprehensible process to model decision. more “trustworthy” the model decision becomes. 6 Conclusion 5 Discussion Our work proposed You Only Need Gold (YONG), There are three major findings in this work. In a an assistant tool for fake review detection. From fake review detection setting, (i) human capabil- a series of experiments, we deepened our under- ity is unreliable and needs machine assistance, (ii) standing of human capability in fake review detec- the interpretable hidden weights are hardly expli- tion. We observed that people were generally over- cable, and (ii) for DNN-powered assistive tools confident with their ability to discern fake reviews like YONG, it is essential to provide faith-gaining from real ones, and we discovered that the model features for its users. far outperforms its human counterparts, suggesting A notable finding is the difference between in- the need for effective design to convince users to terpretability and explainability. In this work, we trust the model decision. Furthermore, our work re- distinguish the two terms to ease their equivocal veals the need to develop more “explainable” tools use. Interpretability refers to the property of be- and promotes collaboration of users and the ma- ing able to describe the cause and effect of the chine for fake review detection. For future work, model through observation, whereas explainability expanding the scope of our tool to other fields such refers to the human-understandable qualities that as products and restaurants would likely contribute can be accepted on the terms of human logic and to its generalizability. intuition. Although numerous existing works (Lee et al., 2017; Vig, 2019; Kumar et al., 2020) have Acknowledgments repeatedly provided an interpretable look into the This work was supported by Institute for Informa- model’s decision making process through layer- tion & communications Technology Planning & wise hidden vector or attention weight visualiza- Evaluation(IITP) grant funded by the Korea govern- tion, most stop at showing the colored vectors ment(MSIT) (No. 2013-2-00131, Development of and matrices. In Figure 2, we can see how the Knowledge Evolutionary WiseQA Platform Tech- model places much attention on proper and com- nology for Human Knowledge Augmented Ser- mon nouns like “Chicago,” and “morning,” that fail vices). to disambiguate and explain the reasoning process of our model for a human to understand. We can also observe in Table 3, where the evidence (i.e., References highlighted words based on the attention weights) David Ifeoluwa Adelani, Haotian Mai, Fuming Fang, shows the lowest influence score on the users of Huy H Nguyen, Junichi Yamagishi, and Isao our tool. This result implies that users found the Echizen. 2020. Generating sentiment-preserving feature either obsolete or inexplicable, leading to fake online reviews using neural language models and their human-and machine-based detection. In the low reference to the respective feature. These International Conference on Advanced Information findings are also supported by a number of pre- Networking and Applications, pages 1341–1354. vious works on attention weights’ explainability Springer. 57
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