Social Behavior and Personality , Volume 49, Issue 11, e10825 https://doi.org/10.2224/sbp.10825 www.sbp-journal.com Exploring extremity and negativity biases in online reviews: Evidence from Yelp.com Minjung Roh 1 , Sung-Byung Yang 2 1 College of Business Administration , Pukyong National University, Republic of Korea 2 School of Management, Kyung Hee University, Republic of Korea How to cite: Roh, M., & Yang, S.-B. (2021). Exploring extremity and negativity biases in online reviews: Evidence from Yelp.com. Social Behavior and Personality: An international journal, 49(11), e10825 While some online reviews explicitly praise or criticize a product, others reveal a neutral evaluation. We predicted that extreme reviews would be considered more useful than moderate ones, and that negative reviews would be considered more useful than positive ones. To test these predictions, this study collected a dataset comprising 951,178 reviews of New York restaurants made by 142,286 reviewers on Yelp.com. By combining these two datasets, we incorporated each reviewer’s unique reference point into a model and showed that extremely positive or negative reviews were considered more useful than moderate ones and that negative reviews were considered more useful than positive ones. This dominance of negative over positive reviews was also more pronounced in the conditions of larger variance and lower average ratings for restaurants. Overall, these results support the presence and influence of extremity and negativity biases, particularly in the context of high preference heterogeneity. Keywords extremity bias; negativity bias; online reviews; restaurant reviews; review website; review bias; preference heterogeneity; Yelp.com While advertising and brands have in the past served as the primary means to convey the creative ideas conceived by professional marketers (Keller, 2003; Roy & Banerjee, 2014), the public opinion of lay customers about products and services is exerting increasingly greater effects on marketing (Boerman et al., 2017; Y. Chen & Xie, 2008; Bughin et al., 2010). Individual reviews based on actual experience of product usage have driven the onset and development of the stream of public opinion (Y. Chen & Xie, 2008; H. Zhang & Choi, 2018). The most prominent example is the 5-star review (Vana & Lambrecht, 2021), which has been widely used across various industries, such as restaurants (e.g., OpenTable.com, Yelp.com, Zomato.com), hotels (e.g., Agoda.com, Booking.com, TripAdvisor.com), films (e.g., RottenTomatoes.com), games (e.g., GameSpot.com), and even medical services (e.g., Healthgrades.com). Magnifying this trend, a growing body of marketing and other academic research has informed the topic of review ratings (e.g., Y. Liu & Hu, 2021; Sparks & Browning, 2011; Wei et al., 2013; L. Zhang et al., 2013). The key antecedent factors that merit closer consideration in this context are the distribution and valence of review ratings. Inconsistent results have been obtained regarding whether extreme, compared to moderate, ratings are perceived as more helpful for consumers’ decision making (i.e., extremity bias) and whether negative, compared to positive, ratings are perceived as more useful (i.e., negativity bias). Some empirical studies have provided support for the presence of extremity bias (Choi & Leon, 2020; Filieri et al., 2018; Y. Liu & Hu, 2021; Park & Nicolau, 2015; Purnawirawan et al., 2012), whereas others have found evidence against the existence of such bias (Danescu-Niculescu-Mizil et al., 2009; Mudambi & Schuff, 2010). Similarly, several studies have found evidence of negativity bias (Lee et al., 2008; Papathanassis & Knolle, CORRESPONDENCE Sung-Byung Yang, School of Management, Kyung Hee University, 26 Kyungheedae-ro, Dongdaemun-gu, Seoul 02447, Republic of Korea. Email: sbyang@khu.ac.kr © 2021 Scientific Journal Publishers Limited. All Rights Reserved.