## 2 Literature Review  
### Effect of Voice Review on Trust and Purchase Intention  
Voice shopping is a service that enables online shopping with voice through intelligent voice agent, and is known as \"voice commerce,\" \"voice shopping,\" or \"v-commerce\" [20]. According to Cappemini [21], consumers prefer voice shopping compared to web shopping because of its convenience (52%), ability to multi-task and do things hands free (48%), and its help for automating routine shopping (41%). In voice shopping, voice assistant delivers information about a product that a consumer wants to explore or purchase, but it is not able to offer information about many products at once because voice interface cannot convey multiple information (e.g., reviews from many people about the product) in a short period of time. Unlike the existing online shopping environment where consumers can actively explore various products, voice shopping is likely to provide a passive product search process focusing on limited information on recommending products delivered by voice agents. Therefore, for voice shopping consumers, it is a very important to receive trustful review in a format that reduces the cost of searching for information as much as possible. For a long time, trust has long been considered one of the top elements in online transactions [5; 6; 7; 22], and lack of trust was the reason behind e-commerce's struggle with low usage rate in the past [23]. Not only does online trust enhance online shopping intention, but a low level of trust is known to prevent users from purchasing online, especially among female [24; 25]. In addition, [PERSON] and [PERSON] [26] refer that E-commerce which fails to gain customer's trust is \"doomed\". Various studies also find that reviews can greatly affect the level of trust among users. For example, review has a positive impact on the level of trust in e-commerce [27]. Electronic word of mouth (eWOM) and perceived web quality has effect on user's trust [28], and while dependent on user's gender, eWOM still had effect on level of trust, and should be designed more carefully [24]. Following the evidence, we hypothesize that providing reviews in voice shopping would lead to higher level of trust than the current voice shopping format which is not giving any review information (e.g., Amazon Alexa. Nugu from 11 st Street). Additionally, different types of review also affect users differently. For example, reviews that are centered around product's benefits have a higher recall rate than reviews that are centered around product's attributes [29], and review content that is focused on product's quality-related statements increases review helpfulness [30]. Following this, types of review provided in voice shopping might also influence users in different ways. In this study review by rating (i.e., suggest product's overall rating of reviews) and review by feature (i.e., suggest list of product's features and its average score) were investigated because they are both a type of review popularly used in large e-commerce such as Amazon and Coupang. While review by rating and review by feature is both a summary of product reviews, rating review only offers numerical information and does not specify which aspects were positive or negative [31], and feature review gives information about several product features with a detailed summary [12]. Additionally, review by rating could have a greater an impact on the users than review by feature as it is known to have impact on initial trust perceptions [32]. Therefore, in this study, two different types of review (i.e., review by rating and review by feature) are each compared with no review condition. The hypotheses are as follows. **Hypotheses H1**. : _A voice agent which provides reviews by rating leads higher level of trust in voice shopping and trust in vendor than a voice agent with no review._  
**Hypotheses H2**.