Materials and procedure

In order to explore the effects of two kinds of social influence with different levels opinions on purchase intention, this research was conducted by dividing the participants into two groups. Group 1 is the scenario that informational social influence with positive opinion and negative opinion from shopping companions. Group 2 is the scenario that normative social influence with positive opinion and negative opinion from shopping companions. The materials for this study was presented in the form of questionnaires, and the simulated scenarios were designed in the form of scripts. We gave all of the participants the story and asked them to imagine that they go shopping with their shopping companions. In the process, their shopping companions would separately provide them positive opinion and negative opinion about the product. After reading the story of simulated scenarios, all participants were required to complete questionnaires to answer the questions that how they would behave in this condition.

The definition of informational social influence from others is a comparative basis of personal knowledge ability to understand the familiarity with commodities;

normative social influence from others is a comparative basis of personal opinions to understand the similarities and differences between your own opinions and those of others. Thus, this research described the product’s function and quality as the statement

of informational social influence, and the description related to the product’s social and psychological risks is the statement of normative social influence. Furthermore, in positive (negative) opinion with informational social influence condition, this research described the product with the advantages (disadvantages) of function and quality as the statement; in positive (negative) opinion with normative social influence condition, this research described the product with the advantages (disadvantages) of social attributes.

In group 1 which is in the informational social influence condition, participants were required to read the following script: Imagine today that you and your shopping companion are shopping in a shopping mall and see a backpack with various colors and styles on display. So, you and your shopping companion decide to go in and have a look. After entering the backpack shop, you are attracted by a kind of good-looking backpack with good color and special design, which makes you a little excited. After you take it up and have a look, you suddenly feel hesitant because you have never heard of this brand or even bought a product of this brand. So, you decide to ask your shopping companion for opinions. Thus, in positive opinion condition, shopping companion said “I heard that pressure-reducing straps and wear-resistant fabrics are the main features of this brand's backpack, and this one is also made of water-proof material. Moreover, there is also a layer of waterproof glue inside, and the use of YKK zippers is also more durable. It's a heavy-duty backpack!” In the contrary, in negative opinion condition, shopping companion said “Although this backpack is made of pressure-reducing shoulder strap and memory cotton filling, the thickened shoulder

there are few layers in the backpack, which makes it difficult to classify items.” The detailed information is provided in Appendix study 1A.

After reading the script, first, participants were required to answer one question for the manipulation checks in order to test whether participants know that this was an experiment of shopping with shopping companions. The question is “Do you know that you are shopping with friends in a simulated shopping scenario instead of shopping alone?” (Dahl, Manchanda, & Argo, 2001). And participants were required to answer this question taking on a seven-point scale (1= “Totally don’t know” to 7= “Totally know”), when the participants choose this item above five, it means that the experimental manipulation of this study is successful.

Second, participants were required to answer four questions taking on a seven-point scale (1= “Totally disagree” to 7= “Totally agree”) to check if they generated

“perceived social value” (Sweeney & Soutar, 2001) with the product from shopping companions’ opinions. Four questions are: 1. “Purchasing this product will make me feel acceptable to others?” 2. “Purchasing this product will improve the way my friends perceive me?” 3. “Purchasing this product will have a good impression on my friends?”

4. “Purchasing this product will obtain a social approval from others?” And then participants were required to answer three questions taking on a seven-point scale (1=

“Very low” to 7= “Very high”) of purchase intention as Dodds et al. (1991) and Zeithaml (1988) were performed. Three questions are: 1. “The likelihood I purchase this product is?” 2. “The probability that I take this product into consideration to purchase is?” 3. “My willingness to recommend this product to my family and friends?”

In group 2 which is in the normative social influence condition, participants were required to read the following script: Imagine today that you and your shopping companion are shopping in a shopping mall and see a backpack with various colors and styles on display. So, you and your shopping companion decide to go in and have a look. After entering the backpack shop, you are attracted by a kind of good-looking backpack with good color and special design, which makes you a little excited. After you take it up and have a look, you suddenly feel hesitant because you have never heard of this brand or even bought a product of this brand. So, you decide to ask your shopping companion for opinions. Thus, in positive opinion condition, shopping companion said “I heard that this backpack is the latest popular style now! You can carry it and have a good look. It's very suitable for you! If you carry it out, many people will envy you. It's the front end of fashion.” In the contrary, in negative opinion condition, shopping companion said “There are too many people carrying this backpack. No matter where you go, you will bump into others' bags. It has been out of fashion for a long time! And I think it’s not suitable for you, not good at all!” The detailed information is provided in Appendix study 1B.

After reading the script, procedures and questions were similar as group 1. First, participants were required to answer one question for the manipulation checks to test whether participants know that this was an experiment of shopping with shopping companions (Dahl et al., 2001) taking on a seven-point scale (1= “Totally don’t know”

to 7= “Totally know”). Second, participants were required to answer four questions

(1= “Totally disagree” to 7= “Totally agree”), and finally answered three questions about purchase intention (Dodds et al., 1991; Zeithaml, 1988) taking on a seven-point scale (1=“Very low” to 7=“Very high”).