Abstract The goal of this study was to investigate the language-based strategies that computermediated communication (CMC) users employ to reduce uncertainty in the absence of nonverbal cues. Specifically, this study investigated the prevalence of three interactive uncertainty reduction strategies (i.e., self-disclosure, question asking, and question/ disclosure intimacy) in reduced-cue settings. Moreover, this study investigated whether these uncertainty reduction strategies increased the verbal statements of affection in CMC. Eighty-one unacquainted cross-sex dyads were randomly assigned to three experimental conditions: face-to-face, visual CMC supported by a webcam, or text-only CMC. Content analysis of the verbal communication revealed that text-only CMC interactants made a greater proportion of affection statements than face-to-face interactants. Proportions of question asking and question/disclosure intimacy were higher in both CMC conditions than in the face-to-face condition, but only question asking mediated the relationship between CMC and verbal statements of affection. No differences in question asking, question/ disclosure intimacy, and verbal statements of affection were observed between the textonly CMC condition and the visual CMC condition. This study provided additional support for social information processing theory by specifying the role of different language-based strategies that may be employed online. Communication Research 39(6) Initial interactions between unacquainted individuals increasingly take place online, for example, on social network sites and online dating sites (Antheunis, Valkenburg, & Peter, 2010; Gibbs, Ellison, & Lai, 2011; . Although these initial conversations often take place in limited-cue settings, they may lead to levels of interpersonal attraction that are similar to those obtained in initial face-to-face interactions (McKenna, Green, & Gleason, 2002; Parks & Floyd, 1996) . Experimental research has repeatedly found that text-based computer-mediated communication (CMC) results in similar or higher levels of interpersonal attraction than face-to-face communication (e.g., Bargh, McKenna, & Fitzsimons, 2002; Nowak, Watt, & Walther, 2005; Ramirez & Zhang, 2007; Walther, 1995) . Interpersonal attraction refers to a positive attitude one holds about another person's social, task, or physical attractiveness (McCroskey & McCain, 1974) . Abstract Although CMC may yield similar results in terms of social outcomes as face-to-face communication, the underlying processes that lead to these outcomes may be different (Walther, Loh, & Granka, 2005) . In initial interactions, partners are driven by a need to reduce uncertainty and form impressions of each other. These impressions, in turn, determine interpersonal attraction (Berger & Calabrese, 1975) . In face-to-face communication, partners rely for a large part on nonverbal cues to form impressions of each other . Because many of these nonverbal cues may not be available online, interaction partners have to rely on different strategies to reduce uncertainty and to form impressions of each other (Ramirez, Walther, Burgoon, & Sunnafrank, 2002) . Abstract Social information processing (SIP) theory poses that in initial text-based CMC conversations, interaction partners are able to adapt to the reduction in nonverbal cues by using other cues to convey social information and thus form impressions of each other (Pena & Hancock, 2006; Walther, 1992) . More specifically, the reduced nonverbal cues of CMC lead conversation partners to use interactive uncertainty reduction strategies, such as selfdisclosure and question asking Tidwell & Walther, 2002) . This enhanced use of interactive uncertainty reduction strategies, in turn, is positively related to interpersonal attraction (Berger & Calabrese, 1975; Cooper & Sportolari, 1997) . Abstract However, most studies investigating impression formation and relationship formation in CMC tend to focus on the outcomes of the interaction processes, such as comparing similarity or attraction across different media conditions . Fewer studies have focused on the interaction processes themselves and investigated the verbal strategies observable in communication partners ' initial conversations (e.g., Joinson, 2001; Pena & Hancock, 2006; Tidwell & Walther, 2002; Walther, 2007) . Tidwell and Walther, for example, investigated how CMC partners use certain language-based strategies to reduce uncertainty. They found that, compared to face-to-face conversations, CMC conversations exhibited a greater proportion of self-disclosure and question asking, resulting in greater attributional confidence and perceived conversation effectiveness. Moreover, they found that CMC conversations were characterized by more intimate self-disclosure than face-to-face conversations. Abstract The goal of this study is to investigate the language-based strategies that users employ to reduce uncertainty in the absence of nonverbal cues. Similar to Tidwell and Walther (2002) asking, and question/disclosure intimacy. We expect that in the absence of nonverbal cues that are used to reduce uncertainty in face-to-face conversations CMC users employ greater proportions of self-disclosure and question asking and will utter more intimate self-disclosures and questions. Abstract Moreover, we pose that these uncertainty reduction strategies may affect displays of verbal affection in text-based CMC. According to uncertainty reduction theory (URT; Berger & Calabrese, 1975) , a reduction in uncertainty in face-to-face communication will lead to an increase in nonverbal affiliative expressiveness, which in turn is positively related to interpersonal attraction (Berger & Calabrese, 1975) . This warrants investigation whether similar processes may occur when investigating text-based CMC. Nonverbal affiliative expressions cannot be displayed in CMC. Therefore, it could be that CMC interactants employ more verbal affiliative expressions in CMC to express affection. Abstract This study extends SIP theory by specifying the uncertainty reduction processes that occur in limited-cue interactions (Hancock, Landrigan, & Silver, 2007; Ramirez et al., 2002; Tidwell & Walther, 2002; Walther et al., 2005) . We aim to identify refined mechanisms that CMC users use to form impressions and to reduce uncertainty in text-based communication. Specifically, we seek to investigate whether verbal statements of affection are indeed more prevalent in channels that limit the use of nonverbal cues that may be communicated. Furthermore, we want to examine whether these verbal statements of affection may occur as a result of interactive uncertainty reduction strategies. To do so, we experimentally compare initial interactions among unacquainted communication partners across three different communication channels: text-based CMC, visual CMC (i.e., text-based CMC supported by a webcam), and face-to-face interaction. Abstract Contemporary CMC environments differ in the extent to which they support the exchange of nonverbal cues. Although some CMC applications, such as e-mail, are predominantly text based, other environments offer additional cues. For example, social network sites offer self-descriptions, photos, and wall postings that may all be used to passively observe social information, which may help to form impressions (Antheunis et al., 2010) . Moreover, instant messaging conversations frequently include audio or video (Peter, Valkenburg, & Schouten, 2007) . Therefore, it is increasingly relevant to compare impression formation and uncertainty reduction mechanisms across communication channels that differ in the number of nonverbal cues they convey . Abstract Recent theories have argued that CMC users can adapt to the medium by decoding contextual and stylistic cues and using language-based strategies to gain information about the conversation partner's characteristics, attitudes, and emotions, which allows for an increase in intimate relational communication. SIP theory assumes that in many initial communications, people are motivated to reduce uncertainty about each other and, therefore, will try to adapt to the constraints offered by CMC (Walther, 1992; Walther & Parks, 2002) . The theory poses that in absence of the nonverbal cues that may normally be used to convey (6) relational information, CMC users adapt to the remaining communicative cues---language and textual display--to form impressions of each other (Pena & Hancock, 2006; Tidwell & Walther, 2002; Walther, 1992) . Abstract Originally, SIP theory stated that the reduced nonverbal cues in CMC would cause online interpersonal relationships to require more time to develop than traditional face-to-face relationships because CMC users need time to adjust to the constraints of the medium (Walther, 1992) . However, when people are motivated to get to know each other, for example, by the task they conduct or by anticipated future interaction (Walther, 1995) , they may quickly adopt verbal cues to reduce uncertainty and form impressions. This eventually leads to levels of attraction similar to face-to-face communication (Hancock et al., 2007; Tidwell & Walther, 2002; Walther, 1992) . Abstract The hyperpersonal approach specifies the mechanisms of how CMC may sometimes exceed interpersonal levels of face-to-face communication (Walther, 1996) . This approach posits that in the absence of nonverbal cues CMC interactants tend to focus on those cues that are available. Therefore, they will engage in an "overattribution" process, leading to idealized impressions of each other (Hancock & Dunham, 2001) . Although the hyperpersonal approach acknowledges that these overattributions may be either positive or negative depending on the cues that are initially conveyed, these impressions are most likely to be positive. Due to the absence of nonverbal cues in CMC, interactants can engage in selective self-presentation, which leads to positive rather than negative overattributions. Moreover, research has shown that when two strangers meet online with the goal of getting to know each other, the initial communication is often positive, resulting in higher levels of interpersonal attraction (e.g., McKenna et al., 2002; Ramirez & Zhang, 2007; Walther, 1995) . Abstract SIP theory posits that when nonverbal cues are added to a communication channel, the amount of social information that can be communicated increases (Walther, 1992) . Therefore, adding nonverbal cues to an interaction will likely result in a reduced need to use languagebased strategies to form impressions of each other because many other cues are available with which people may reduce uncertainty and form impressions of each other (e.g., gestures, clothing style). Therefore, the use of language-based strategies to reduce uncertainty is likely to be higher in text-based CMC than in face-to-face communication. Abstract No studies have specifically compared visual and text-based CMC to face-to-face communication. Joinson (2001) compared text-based CMC with visual CMC (i.e., video without audio) and found amount of self-disclosure to be greater in text-only CMC than in visual CMC. Because self-disclosure is a language-based uncertainty reduction strategy, these findings may point to a reduced need for the use of these strategies in visual CMC compared to text-based CMC. Compared to text-based CMC, visual CMC allows several cues that may help reduce uncertainty, such as eye contact, head nods, and facial expressions . However, visual CMC still lacks many cues (e.g., audio, haptic) compared to face-to-face communication. Therefore, we expect a higher use of language-based strategies to reduce uncertainty in visual CMC than in face-to-face communication. Moreover, because visual CMC gives off more nonverbal cues than text-based CMC, we expect a higher use of language-based strategies to reduce uncertainty in text-based CMC than in visual CMC. Abstract SIP theory predicts that CMC users adapt to the reduction of nonverbal cues by using language-based strategies to reduce uncertainty and form impressions of each other (Walther, 1992; Walther et al., 2005) . Although originally developed to explain social attraction and relationship development in initial face-to-face interactions, URT provides a useful addition to SIP theory by specifying the mechanisms that reduce uncertainty in initial interactions (Berger & Calabrese, 1975) . URT poses that, when people meet, they are motivated to form impressions of each other in order to reduce the uncertainty they have about the other person. Uncertainty reduction is the gathering of information that allows the information seeker to predict someone's attitudes and behavior. Lower levels of uncertainty, in turn, may increase one's liking and affection for his or her communication partner (e.g., Afifi & Metts, 1998; Berger & Calabrese, 1975; Douglas, 1990 Douglas, , 1994 . Abstract According to URT, people generally can use three types of uncertainty reduction strategies to get to know a target person: passive, active, and interactive strategies (Berger & Calabrese, 1975; Berger, Gardner, Parks, Schulman, & Miller, 1976) . Passive strategies are those in which an informant unobtrusively observes the target person, for instance, by observing the target person's nonverbal behaviors. Active strategies involve proactive efforts to get to know the target person, without confronting the person, for example, by questioning other people about the target person. Interactive strategies require a direct interaction between the communication partners, for example, by asking questions or through reciprocal self-disclosure (e.g., Berger & Calabrese, 1975; Jourard, 1971) . Abstract In initial communication through text-based CMC, people can only rely on the verbal information that is available to form these initial impressions (Hancock & Dunham, 2001; Walther, 1992; Walther et al., 2005) . In these initial online encounters, passive and active uncertainty reduction strategies are more difficult to employ than in similar face-to-face settings because they require more effort. Therefore, in text-based CMC settings, conversation partners have to rely on the interactive uncertainty reduction strategies to form impressions of each other Tidwell & Walther, 2002) . Abstract Based on the interactive uncertainty reduction strategies that conversation partners can employ in text-based CMC, three strategies can be distinguished by which conversation partners form impressions of each other in text-based CMC (Tidwell & Walther, 2002) . The first two strategies focus on self-disclosure and question asking, respectively. First, conversation partners may ask questions in order to procure answers with which to reduce uncertainty. Second, they may use self-disclosure as an uncertainty reduction strategy because self-disclosure of one's self elicits self-disclosure from the target person, due to the norm of reciprocity (e.g., Jourard, 1971) . In text-based CMC, we expect a greater proportion of the conversation to be devoted to question asking and self-disclosure, compared to visual CMC and face-to-face communication. Abstract The third strategy is question/disclosure intimacy, which relates to the depth of the questions and self-disclosures made in the conversation. Question asking and self-disclosure are quite often employed in initial communication because, in the first phases of acquaintanceship, people disclose nonintimate information about a broad range of topics. In more at Tilburg University on October 30, 2012 crx.sagepub.com Downloaded from Abstract Communication Research 39(6) advanced phases of relationship formation, however, people tend to deepen their communication and disclose more intimate aspects of themselves (Altman & Taylor, 1973; Jourard, 1971) . Similar to Tidwell and Walther (2002), we argue that the latter strategy, which is normally observed in later stages in relationship formation, may be employed in initial communication in text-based CMC because of the paucity of other means to reduce uncertainty. Therefore, question/disclosure intimacy may be higher in reduced cue settings (Walther, 1996) . Abstract In this study, we investigate the use of verbal statements of affection as a consequence of uncertainty reduction in CMC. According to Berger and Calabrese (1975) , a reduction in uncertainty will lead to an increase in nonverbal affilitiative expressiveness in face-to-face interactions. Verbal statements of affection may play a similar role in text-based CMC. Due to the absence of nonverbal cues that may be transmitted in text-based CMC, verbal statements of affection may be more often displayed in text-based CMC to compensate for the lack of nonverbal cues . Similar to nonverbal affiliative statements in face-to-face communication, these verbal statements of affection may predict interpersonal attraction in CMC. Walther et al. (2005) , for example, found that verbal statements of affection were positively related to affinity in CMC settings, whereas in face-to-face settings only nonverbal expressive behavior predicted affinity. We expect that a reduction of nonverbal cues will lead communication partners to employ a greater proportion of verbal statements of affection to compensate for the lack of nonverbal affiliative statements. Therefore, we hypothesize, Hypothesis 1: Text-based CMC yields a greater proportion of verbal statements of affection than visual CMC can, which in turn yields a greater proportion of verbal statements of affection than face-to-face communication. Abstract We posit that the three interactive uncertainty reduction mechanisms will mediate the relationship between communication channel and verbal statements of affection. Similar to nonverbal affiliative expressions, verbal statements of affection are more likely to occur once uncertainty has been reduced. When the amount of nonverbal cues that may be communicated decreases in a communication channel, communication partners are more likely to revert to interactive uncertainty reduction strategies--question asking, selfdisclosure, and question/disclosure intimacy--to reduce uncertainty and form impressions of the other (e.g., Gibbs et al., 2011; Tidwell & Walther, 2002) . The use of these interactive uncertainty reduction strategies, in turn, may positively influence verbal statements of affection. Abstract at Tilburg University on October 30, 2012 crx.sagepub.com Downloaded from Abstract Antheunis et al. Abstract Proportion of self-disclosure. Several studies have demonstrated that CMC interactions result in higher levels of self-disclosure compared to face-to-face interactions (Bargh et al., 2002; Coleman, Paternite, & Sherman, 1999; Joinson, 2001; Tidwell & Walther, 2002) . As nonverbal cues decrease, conversation partners need to rely on interactive uncertainty reduction strategies to reduce uncertainty and to form impressions of each other. Because self-disclosure is an interactive uncertainty reduction strategy, we expect that a larger part of the conversation will be devoted to self-disclosure in the absence of nonverbal cues. Therefore, the proportion of self-disclosure in a conversation will be greater as nonverbal cues decrease in a channel. Abstract Self-disclosure reduces uncertainty in CMC (Antheunis et al., 2010) . According to Berger and Calabrese, a reduction in uncertainty may positively affect nonverbal affiliative expressions in face-to-face interactions (Berger & Calabrese, 1975) . Moreover, self-disclosure stimulates interpersonal attraction (e.g., Bargh et al., 2002; Collins & Miller, 1994) . According to Altman and Taylor's social penetration theory (1973), self-disclosure is viewed as "rewarding because it communicates the discloser's interpersonal attraction and the desire to initiate a more intimate relationship" (Collins & Miller, 1994, p. 458). In addition, disclosing more aspects of one's inner self creates bonds of empathy, which enhances interpersonal attraction between interaction partners (Bargh et al., 2002) . Self-disclosure also encourages interpersonal attraction in reduced-cue CMC settings (Antheunis, Valkenburg, & Peter, 2007; Bargh et al., 2002; Collins & Miller, 1994; McKenna et al., 2002) . Because verbal statements of affection may be used to signify interpersonal attraction in text-based CMC settings, a greater proportion of self-disclosure in a conversation may be positively related to verbal statements of affection. Therefore, our second hypothesis is, Hypothesis 2a: Text-based CMC yields a greater proportion of self-disclosure than visual CMC, which in turn yields a greater proportion of self-disclosure than face-to-face communication. Hypothesis 2b: Proportion of self-disclosure mediates the relationship between the different communication channels and verbal statements of affection. Abstract Proportion of question asking. Two empirical studies have found direct questioning to be higher in text-based CMC than in face-to-face communication (Antheunis et al., 2007; Tidwell & Walther, 2002) . Because question asking is another interactive uncertainty reduction strategy (Berger et al., 1976) , we also expect that a larger part of the conversation will be devoted to question asking when nonverbal cues are reduced in a channel. Moreover, because question asking procures answers that may reduce the level of uncertainty (Antheunis et al., 2010; Tidwell & Walther, 2002) , question asking may also mediate the relationship between the different communication channels and verbal statements of affection. Therefore, we hypothesize, Abstract Text-based CMC yields a greater proportion of question asking than visual CMC, which in turn yields a greater proportion of question asking than face-to-face communication. Question/disclosure intimacy. CMC does not only stimulate the amount of question asking and self-disclosure, it also stimulates their depth (Tidwell & Walther, 2002) . In order to reduce uncertainty, conversation partners may ask more intimate questions as nonverbal cues are reduced. Moreover, the absence of nonverbal cues in text-based CMC would make CMC users less attentive to the self and the other, easing the arousal associated with using uncertainty reduction strategies such as intimate self-disclosure and asking intimate questions (e.g., Joinson, 2001; Lea, Spears, & De Groot, 2001; Walther, Slovacek, & Tidwell, 2001) . The relative anonymity of reduced-cue settings may also encourage asking for and disclosing intimate information (Kiesler, Siegel, & McGuire, 1984) . Abstract The higher the degree of question/disclosure intimacy in a conversation, the more uncertainty is reduced (Tidwell & Walther, 2002) , which in turn may affect the degree of verbal statements of affection made in a conversation. Empirical research has consistently demonstrated that intimacy fosters attraction (e.g., Berg & Archer, 1983; Laurenceau, Feldman Barret, & Pietromonaco, 1998) . Self-disclosure that involves emotions is believed to generate more intimacy than self-disclosure that is mainly factual because emotional selfdisclosure enables the listener to support and confirm core aspects of the discloser's view of his or her self (Reis & Shaver, 1988) . Accordingly, Collins and Miller (1994) stated, "It is likely that the mechanisms thought to enhance interpersonal attraction are more strongly communicated by the quality of one's disclosure than by the quantity of information revealed" (p. 465). Because verbal statements of affection may be used to signify interpersonal attraction in text-based CMC settings, greater question/disclosure intimacy may be positively related to verbal statements of affection. Therefore, our last hypothesis is, Hypothesis 4a: Text-based CMC results in a higher level of question/disclosure intimacy than visual CMC, which in turn results in a higher level of question/ disclosure intimacy than face-to-face communication. Hypothesis 4b: Question/disclosure intimacy mediates the relationship between the different communication channels and verbal statements of affection. Abstract To investigate the actual language-based strategies that people use to reduce uncertainty, we conducted an experiment between unacquainted students. A total of 162 undergraduate students (81 men and 81 women), between 17 and 31 years of age (M = 21.07, SD = 2.61), participated in cross-sex dyads for the experiment. The majority of the participants (70%) were recruited from a first-year introductory course in communication science in which a total of 350 students took part, divided over 15 separate classes. The remaining 30% of the participants were recruited from a database with first-and second-year students of a large university who had agreed to participate in research projects. To form cross-sex dyads, participants were asked to sign up for a 1-hr time slot. Only one man and one woman could sign up in a particular time slot. Students were specifically asked not to sign up with someone they already knew. Wherever possible, we paired students from different classes, as well as communication science students with students from other disciplines. This reduced the likelihood that communication partners would already know each other. After the experiment, all of the participants stated that they did not previously know their conversation partner. Abstract Because self-disclosure depends on the gender composition of a group, we formed only cross-sex dyads (Dindia & Allen, 1992; Hacker, 1981) . Moreover, adding a gender composition (i.e., male-male, female-female, and male-female groups) to our experimental design could have led to power problems. Because scores of individual participants in a dyad are not independent from each other (e.g., Kenny, 1995 Kenny, , 1996 , we assessed the degree of interdependency between the participants in a dyad using the method for distinguishable dyads as proposed by Alferes and Kenny (2009) . Correlations between interaction partners for the mediating and dependent variables varied from .31 (self-disclosure) to .76 (question/ disclosure intimacy), p < .01. We were interested in the effects of between-dyad predictor variables (i.e., experimental condition) and outcome variables. In such cases, the recommended strategy is to use the dyad as the unit of analysis (Kenny, 1996 (Kenny, , 2008 . Therefore, individual scores of the dyads' participants were collapsed, and we used the dyad rather than the individual participant as the unit of analysis. Hence, the analyses in this article are based on 81 cross-sex dyads. Abstract 1 Abstract The dyads were randomly assigned to one of the three experimental conditions: a face-to-face condition (n = 27), a visual CMC condition (n = 27), and a text-only CMC condition (n = 27). For each dyad, both participants were instructed to report to different rooms in order to ascertain that they did not see each other before the experiment started. The participants received the instructions for the experimental task separately and were led to the lab afterwards. For the experimental task, we used a get-acquainted exercise (Frank & Gilovich, 1989) : Participants were instructed to get to know each other during the conversation, and they were free to talk about anything they wanted. Abstract In the text-only and visual CMC condition, participants interacted via instant messaging software that had been especially designed for the experiment. The instant messaging software used was a Java-based chat application that was integrated in the browser window. The software was similar to instant messaging software in that the participants could see the conversation unfold in the upper part of the screen, while typing was done in a small field below the conversation window. Participants could use text and a range of emoticons to communicate with each other. The software differed from instant messaging applications in that the participants did not see a picture or photo of themselves or the other participant, had no access to the contact list, and could not log out of the chat or start other conversations. Abstract at Tilburg University on October 30, 2012 crx.sagepub.com Downloaded from Abstract 766 Abstract The visual CMC condition was similar to the text-only condition, but participants saw each other's face in a window at the right-hand corner of the computer screen, directly beside the conversation window. The webcam screen was a high-quality 320 x 240 pixel full-color screen running at 30 frames per second. The video screen was integrated in the browser window. Therefore, participants could not close the video window or stop the video stream. To check whether the participants were attentive to the video stream during the interaction, we coded the transcripts of the visual CMC conversations for specific references to the video stream. In 23 of the 27 groups (85%) specific references were made to the webcam stream. For example, one participant typed, "Ah, I see you are also having tea," and another said that his partner looked like "a model on the cover of a woman's glossy." The visual CMC condition offered no audio and only video. In both CMC conditions, the interaction automatically stopped after 24 min. Abstract The face-to-face condition took place in an observation room that resembled a living room and was equipped with two couches at a 90 degree angle to one another. Both of the participants were seated on a different couch. After 12 min, the experimenter reentered the room and the interaction stopped. In all three conditions, participants could not stop the conversation before the time limit. However, after the experiment, none of the participants indicated that they had wanted to leave the conversation before the time limit was reached. Abstract Different time periods were allocated to the face-to-face condition and the CMC conditions because CMC is relatively slow in comparison with face-to-face communication (Tidwell & Walther, 2002; Walther, 1996; Walther et al., 2001) . Therefore, in both CMC conditions, participants interacted for 24 min. In the face-to-face condition, participants interacted for 12 min. The CMC conversations were logged and the face-to-face conversations were recorded (audio only) and subsequently transcribed. We asked the participants for their permission to use their conversations for our content analysis. None of the participants refused. Finally, the participants were paid a fee (15 Euros) for their participation. The participants were debriefed orally right after the experiment and with more detail via e-mail 1 week after the experimental period. Abstract Content Analysis 758 Communication Research 39(6) Initial interactions between unacquainted individuals increasingly take place online, for example, on social network sites and online dating sites (Antheunis, Valkenburg, & Peter, 2010; Gibbs, Ellison, & Lai, 2011; . Although these initial conversations often take place in limited-cue settings, they may lead to levels of interpersonal attraction that are similar to those obtained in initial face-to-face interactions (McKenna, Green, & Gleason, 2002; Parks & Floyd, 1996) . Experimental research has repeatedly found that text-based computer-mediated communication (CMC) results in similar or higher levels of interpersonal attraction than face-to-face communication (e.g., Bargh, McKenna, & Fitzsimons, 2002; Nowak, Watt, & Walther, 2005; Ramirez & Zhang, 2007; Walther, 1995) . Interpersonal attraction refers to a positive attitude one holds about another person's social, task, or physical attractiveness (McCroskey & McCain, 1974) . 758 Although CMC may yield similar results in terms of social outcomes as face-to-face communication, the underlying processes that lead to these outcomes may be different (Walther, Loh, & Granka, 2005) . In initial interactions, partners are driven by a need to reduce uncertainty and form impressions of each other. These impressions, in turn, determine interpersonal attraction (Berger & Calabrese, 1975) . In face-to-face communication, partners rely for a large part on nonverbal cues to form impressions of each other . Because many of these nonverbal cues may not be available online, interaction partners have to rely on different strategies to reduce uncertainty and to form impressions of each other (Ramirez, Walther, Burgoon, & Sunnafrank, 2002) . 758 Social information processing (SIP) theory poses that in initial text-based CMC conversations, interaction partners are able to adapt to the reduction in nonverbal cues by using other cues to convey social information and thus form impressions of each other (Pena & Hancock, 2006; Walther, 1992) . More specifically, the reduced nonverbal cues of CMC lead conversation partners to use interactive uncertainty reduction strategies, such as selfdisclosure and question asking Tidwell & Walther, 2002) . This enhanced use of interactive uncertainty reduction strategies, in turn, is positively related to interpersonal attraction (Berger & Calabrese, 1975; Cooper & Sportolari, 1997) . 758 However, most studies investigating impression formation and relationship formation in CMC tend to focus on the outcomes of the interaction processes, such as comparing similarity or attraction across different media conditions . Fewer studies have focused on the interaction processes themselves and investigated the verbal strategies observable in communication partners' initial conversations (e.g., Joinson, 2001; Pena & Hancock, 2006; Tidwell & Walther, 2002; Walther, 2007) . Tidwell and Walther, for example, investigated how CMC partners use certain language-based strategies to reduce uncertainty. They found that, compared to face-to-face conversations, CMC conversations exhibited a greater proportion of self-disclosure and question asking, resulting in greater attributional confidence and perceived conversation effectiveness. Moreover, they found that CMC conversations were characterized by more intimate self-disclosure than face-to-face conversations. 758 The goal of this study is to investigate the language-based strategies that users employ to reduce uncertainty in the absence of nonverbal cues. Similar to Tidwell and Walther (2002) , this study investigates three different uncertainty reduction strategies: self-disclosure, question asking, and question/disclosure intimacy. We expect that in the absence of nonverbal cues that are used to reduce uncertainty in face-to-face conversations CMC users employ greater proportions of self-disclosure and question asking and will utter more intimate self-disclosures and questions. 758 Moreover, we pose that these uncertainty reduction strategies may affect displays of verbal affection in text-based CMC. According to uncertainty reduction theory (URT; Berger & Calabrese, 1975) , a reduction in uncertainty in face-to-face communication will lead to an increase in nonverbal affiliative expressiveness, which in turn is positively related to interpersonal attraction (Berger & Calabrese, 1975) . This warrants investigation whether similar processes may occur when investigating text-based CMC. Nonverbal affiliative expressions cannot be displayed in CMC. Therefore, it could be that CMC interactants employ more verbal affiliative expressions in CMC to express affection. 758 This study extends SIP theory by specifying the uncertainty reduction processes that occur in limited-cue interactions (Hancock, Landrigan, & Silver, 2007; Ramirez et al., 2002; Tidwell & Walther, 2002; Walther et al., 2005) . We aim to identify refined mechanisms that CMC users use to form impressions and to reduce uncertainty in text-based communication. Specifically, we seek to investigate whether verbal statements of affection are indeed more prevalent in channels that limit the use of nonverbal cues that may be communicated. Furthermore, we want to examine whether these verbal statements of affection may occur as a result of interactive uncertainty reduction strategies. To do so, we experimentally compare initial interactions among unacquainted communication partners across three different communication channels: text-based CMC, visual CMC (i.e., text-based CMC supported by a webcam), and face-to-face interaction. CMC Theories and the Role of Reduced Nonverbal Cues Contemporary CMC environments differ in the extent to which they support the exchange of nonverbal cues. Although some CMC applications, such as e-mail, are predominantly text based, other environments offer additional cues. For example, social network sites offer self-descriptions, photos, and wall postings that may all be used to passively observe social information, which may help to form impressions (Antheunis et al., 2010) . Moreover, instant messaging conversations frequently include audio or video (Peter, Valkenburg, & Schouten, 2007) . Therefore, it is increasingly relevant to compare impression formation and uncertainty reduction mechanisms across communication channels that differ in the number of nonverbal cues they convey . CMC Theories and the Role of Reduced Nonverbal Cues Recent theories have argued that CMC users can adapt to the medium by decoding contextual and stylistic cues and using language-based strategies to gain information about the conversation partner's characteristics, attitudes, and emotions, which allows for an increase in intimate relational communication. SIP theory assumes that in many initial communications, people are motivated to reduce uncertainty about each other and, therefore, will try to adapt to the constraints offered by CMC (Walther, 1992; Walther & Parks, 2002) . The theory poses that in absence of the nonverbal cues that may normally be used to convey 760 Communication Research 39(6) relational information, CMC users adapt to the remaining communicative cues---language and textual display--to form impressions of each other (Pena & Hancock, 2006; Tidwell & Walther, 2002; Walther, 1992) . 760 Originally, SIP theory stated that the reduced nonverbal cues in CMC would cause online interpersonal relationships to require more time to develop than traditional face-to-face relationships because CMC users need time to adjust to the constraints of the medium (Walther, 1992) . However, when people are motivated to get to know each other, for example, by the task they conduct or by anticipated future interaction (Walther, 1995) , they may quickly adopt verbal cues to reduce uncertainty and form impressions. This eventually leads to levels of attraction similar to face-to-face communication (Hancock et al., 2007; Tidwell & Walther, 2002; Walther, 1992) . 760 The hyperpersonal approach specifies the mechanisms of how CMC may sometimes exceed interpersonal levels of face-to-face communication (Walther, 1996) . This approach posits that in the absence of nonverbal cues CMC interactants tend to focus on those cues that are available. Therefore, they will engage in an "overattribution" process, leading to idealized impressions of each other (Hancock & Dunham, 2001) . Although the hyperpersonal approach acknowledges that these overattributions may be either positive or negative depending on the cues that are initially conveyed, these impressions are most likely to be positive. Due to the absence of nonverbal cues in CMC, interactants can engage in selective self-presentation, which leads to positive rather than negative overattributions. Moreover, research has shown that when two strangers meet online with the goal of getting to know each other, the initial communication is often positive, resulting in higher levels of interpersonal attraction (e.g., McKenna et al., 2002; Ramirez & Zhang, 2007; Walther, 1995) . 760 SIP theory posits that when nonverbal cues are added to a communication channel, the amount of social information that can be communicated increases (Walther, 1992) . Therefore, adding nonverbal cues to an interaction will likely result in a reduced need to use languagebased strategies to form impressions of each other because many other cues are available with which people may reduce uncertainty and form impressions of each other (e.g., gestures, clothing style). Therefore, the use of language-based strategies to reduce uncertainty is likely to be higher in text-based CMC than in face-to-face communication. 760 No studies have specifically compared visual and text-based CMC to face-to-face communication. Joinson (2001) compared text-based CMC with visual CMC (i.e., video without audio) and found amount of self-disclosure to be greater in text-only CMC than in visual CMC. Because self-disclosure is a language-based uncertainty reduction strategy, these findings may point to a reduced need for the use of these strategies in visual CMC compared to text-based CMC. Compared to text-based CMC, visual CMC allows several cues that may help reduce uncertainty, such as eye contact, head nods, and facial expressions . However, visual CMC still lacks many cues (e.g., audio, haptic) compared to face-to-face communication. Therefore, we expect a higher use of language-based strategies to reduce uncertainty in visual CMC than in face-to-face communication. Moreover, because visual CMC gives off more nonverbal cues than text-based CMC, we expect a higher use of language-based strategies to reduce uncertainty in text-based CMC than in visual CMC. Uncertainty Reduction Processes SIP theory predicts that CMC users adapt to the reduction of nonverbal cues by using language-based strategies to reduce uncertainty and form impressions of each other (Walther, 1992; Walther et al., 2005) . Although originally developed to explain social attraction and relationship development in initial face-to-face interactions, URT provides a useful addition to SIP theory by specifying the mechanisms that reduce uncertainty in initial interactions (Berger & Calabrese, 1975) . URT poses that, when people meet, they are motivated to form impressions of each other in order to reduce the uncertainty they have about the other person. Uncertainty reduction is the gathering of information that allows the information seeker to predict someone's attitudes and behavior. Lower levels of uncertainty, in turn, may increase one's liking and affection for his or her communication partner (e.g., Afifi & Metts, 1998; Berger & Calabrese, 1975; Douglas, 1990 Douglas, , 1994 . Uncertainty Reduction Processes According to URT, people generally can use three types of uncertainty reduction strategies to get to know a target person: passive, active, and interactive strategies (Berger & Calabrese, 1975; Berger, Gardner, Parks, Schulman, & Miller, 1976) . Passive strategies are those in which an informant unobtrusively observes the target person, for instance, by observing the target person's nonverbal behaviors. Active strategies involve proactive efforts to get to know the target person, without confronting the person, for example, by questioning other people about the target person. Interactive strategies require a direct interaction between the communication partners, for example, by asking questions or through reciprocal self-disclosure (e.g., Berger & Calabrese, 1975; Jourard, 1971) . Uncertainty Reduction Processes In initial communication through text-based CMC, people can only rely on the verbal information that is available to form these initial impressions (Hancock & Dunham, 2001; Walther, 1992; Walther et al., 2005) . In these initial online encounters, passive and active uncertainty reduction strategies are more difficult to employ than in similar face-to-face settings because they require more effort. Therefore, in text-based CMC settings, conversation partners have to rely on the interactive uncertainty reduction strategies to form impressions of each other Tidwell & Walther, 2002) . Uncertainty Reduction Processes Based on the interactive uncertainty reduction strategies that conversation partners can employ in text-based CMC, three strategies can be distinguished by which conversation partners form impressions of each other in text-based CMC (Tidwell & Walther, 2002) . The first two strategies focus on self-disclosure and question asking, respectively. First, conversation partners may ask questions in order to procure answers with which to reduce uncertainty. Second, they may use self-disclosure as an uncertainty reduction strategy because self-disclosure of one's self elicits self-disclosure from the target person, due to the norm of reciprocity (e.g., Jourard, 1971) . In text-based CMC, we expect a greater proportion of the conversation to be devoted to question asking and self-disclosure, compared to visual CMC and face-to-face communication. Uncertainty Reduction Processes The third strategy is question/disclosure intimacy, which relates to the depth of the questions and self-disclosures made in the conversation. Question asking and self-disclosure are quite often employed in initial communication because, in the first phases of acquaintanceship, people disclose nonintimate information about a broad range of topics. In more 762 Communication Research 39(6) advanced phases of relationship formation, however, people tend to deepen their communication and disclose more intimate aspects of themselves (Altman & Taylor, 1973; Jourard, 1971) . Similar to Tidwell and Walther (2002) , we argue that the latter strategy, which is normally observed in later stages in relationship formation, may be employed in initial communication in text-based CMC because of the paucity of other means to reduce uncertainty. Therefore, question/disclosure intimacy may be higher in reduced cue settings (Walther, 1996) . Verbal Statements of Affection in Text-Based CMC In this study, we investigate the use of verbal statements of affection as a consequence of uncertainty reduction in CMC. According to Berger and Calabrese (1975) , a reduction in uncertainty will lead to an increase in nonverbal affilitiative expressiveness in face-to-face interactions. Verbal statements of affection may play a similar role in text-based CMC. Due to the absence of nonverbal cues that may be transmitted in text-based CMC, verbal statements of affection may be more often displayed in text-based CMC to compensate for the lack of nonverbal cues . Similar to nonverbal affiliative statements in face-to-face communication, these verbal statements of affection may predict interpersonal attraction in CMC. Walther et al. (2005) , for example, found that verbal statements of affection were positively related to affinity in CMC settings, whereas in face-to-face settings only nonverbal expressive behavior predicted affinity. We expect that a reduction of nonverbal cues will lead communication partners to employ a greater proportion of verbal statements of affection to compensate for the lack of nonverbal affiliative statements. Therefore, we hypothesize, Hypothesis 1: Text-based CMC yields a greater proportion of verbal statements of affection than visual CMC can, which in turn yields a greater proportion of verbal statements of affection than face-to-face communication. The Mediating Role of Three Uncertainty Reduction Mechanisms We posit that the three interactive uncertainty reduction mechanisms will mediate the relationship between communication channel and verbal statements of affection. Similar to nonverbal affiliative expressions, verbal statements of affection are more likely to occur once uncertainty has been reduced. When the amount of nonverbal cues that may be communicated decreases in a communication channel, communication partners are more likely to revert to interactive uncertainty reduction strategies--question asking, selfdisclosure, and question/disclosure intimacy--to reduce uncertainty and form impressions of the other (e.g., Gibbs et al., 2011; Tidwell & Walther, 2002) . The use of these interactive uncertainty reduction strategies, in turn, may positively influence verbal statements of affection. Proportion of self-disclosure. Several studies have demonstrated that CMC interactions result in higher levels of self-disclosure compared to face-to-face interactions (Bargh et al., 2002; Coleman, Paternite, & Sherman, 1999; Joinson, 2001; Tidwell & Walther, 2002) . As nonverbal cues decrease, conversation partners need to rely on interactive uncertainty reduction strategies to reduce uncertainty and to form impressions of each other. Because self-disclosure is an interactive uncertainty reduction strategy, we expect that a larger part of the conversation will be devoted to self-disclosure in the absence of nonverbal cues. Therefore, the proportion of self-disclosure in a conversation will be greater as nonverbal cues decrease in a channel. Proportion of self-disclosure. Self-disclosure reduces uncertainty in CMC (Antheunis et al., 2010) . According to Berger and Calabrese, a reduction in uncertainty may positively affect nonverbal affiliative expressions in face-to-face interactions (Berger & Calabrese, 1975) . Moreover, self-disclosure stimulates interpersonal attraction (e.g., Bargh et al., 2002; Collins & Miller, 1994) . According to Altman and Taylor's social penetration theory (1973), self-disclosure is viewed as "rewarding because it communicates the discloser's interpersonal attraction and the desire to initiate a more intimate relationship" (Collins & Miller, 1994, p. 458) . In addition, disclosing more aspects of one's inner self creates bonds of empathy, which enhances interpersonal attraction between interaction partners (Bargh et al., 2002) . Self-disclosure also encourages interpersonal attraction in reduced-cue CMC settings (Antheunis, Valkenburg, & Peter, 2007; Bargh et al., 2002; Collins & Miller, 1994; McKenna et al., 2002) . Because verbal statements of affection may be used to signify interpersonal attraction in text-based CMC settings, a greater proportion of self-disclosure in a conversation may be positively related to verbal statements of affection. Therefore, our second hypothesis is, Hypothesis 2a: Text-based CMC yields a greater proportion of self-disclosure than visual CMC, which in turn yields a greater proportion of self-disclosure than face-to-face communication. Hypothesis 2b: Proportion of self-disclosure mediates the relationship between the different communication channels and verbal statements of affection. Proportion of self-disclosure. Proportion of question asking. Two empirical studies have found direct questioning to be higher in text-based CMC than in face-to-face communication (Antheunis et al., 2007; Tidwell & Walther, 2002) . Because question asking is another interactive uncertainty reduction strategy (Berger et al., 1976) , we also expect that a larger part of the conversation will be devoted to question asking when nonverbal cues are reduced in a channel. Moreover, because question asking procures answers that may reduce the level of uncertainty (Antheunis et al., 2010; Tidwell & Walther, 2002) , question asking may also mediate the relationship between the different communication channels and verbal statements of affection. Therefore, we hypothesize, Hypothesis 3a: Text-based CMC yields a greater proportion of question asking than visual CMC, which in turn yields a greater proportion of question asking than face-to-face communication. 764 Communication Research 39(6) Hypothesis 3b: Proportion of question asking mediates the relationship between the different communication channels and verbal statements of affection. Communication Research 39(6) Question/disclosure intimacy. CMC does not only stimulate the amount of question asking and self-disclosure, it also stimulates their depth (Tidwell & Walther, 2002) . In order to reduce uncertainty, conversation partners may ask more intimate questions as nonverbal cues are reduced. Moreover, the absence of nonverbal cues in text-based CMC would make CMC users less attentive to the self and the other, easing the arousal associated with using uncertainty reduction strategies such as intimate self-disclosure and asking intimate questions (e.g., Joinson, 2001; Lea, Spears, & De Groot, 2001; Walther, Slovacek, & Tidwell, 2001) . The relative anonymity of reduced-cue settings may also encourage asking for and disclosing intimate information (Kiesler, Siegel, & McGuire, 1984) . Communication Research 39(6) The higher the degree of question/disclosure intimacy in a conversation, the more uncertainty is reduced (Tidwell & Walther, 2002) , which in turn may affect the degree of verbal statements of affection made in a conversation. Empirical research has consistently demonstrated that intimacy fosters attraction (e.g., Berg & Archer, 1983; Laurenceau, Feldman Barret, & Pietromonaco, 1998) . Self-disclosure that involves emotions is believed to generate more intimacy than self-disclosure that is mainly factual because emotional selfdisclosure enables the listener to support and confirm core aspects of the discloser's view of his or her self (Reis & Shaver, 1988) . Accordingly, Collins and Miller (1994) stated, "It is likely that the mechanisms thought to enhance interpersonal attraction are more strongly communicated by the quality of one's disclosure than by the quantity of information revealed" (p. 465). Because verbal statements of affection may be used to signify interpersonal attraction in text-based CMC settings, greater question/disclosure intimacy may be positively related to verbal statements of affection. Therefore, our last hypothesis is, Hypothesis 4a: Text-based CMC results in a higher level of question/disclosure intimacy than visual CMC, which in turn results in a higher level of question/ disclosure intimacy than face-to-face communication. Hypothesis 4b: Question/disclosure intimacy mediates the relationship between the different communication channels and verbal statements of affection. Method Sample To investigate the actual language-based strategies that people use to reduce uncertainty, we conducted an experiment between unacquainted students. A total of 162 undergraduate students (81 men and 81 women), between 17 and 31 years of age (M = 21.07, SD = 2.61), participated in cross-sex dyads for the experiment. The majority of the participants (70%) were recruited from a first-year introductory course in communication science in which a total of 350 students took part, divided over 15 separate classes. The remaining 30% of the participants were recruited from a database with first-and second-year students of a large university who had agreed to participate in research projects. To form cross-sex dyads, participants were asked to sign up for a 1-hr time slot. Only one man and one woman could sign up in a particular time slot. Students were specifically asked not to sign up with someone they already knew. Wherever possible, we paired students from different classes, as well as communication science students with students from other disciplines. This reduced the likelihood that communication partners would already know each other. After the experiment, all of the participants stated that they did not previously know their conversation partner. Because self-disclosure depends on the gender composition of a group, we formed only cross-sex dyads (Dindia & Allen, 1992; Hacker, 1981) . Moreover, adding a gender composition (i.e., male-male, female-female, and male-female groups) to our experimental design could have led to power problems. Because scores of individual participants in a dyad are not independent from each other (e.g., Kenny, 1995 Kenny, , 1996 , we assessed the degree of interdependency between the participants in a dyad using the method for distinguishable dyads as proposed by Alferes and Kenny (2009) . Correlations between interaction partners for the mediating and dependent variables varied from .31 (self-disclosure) to .76 (question/ disclosure intimacy), p < .01. We were interested in the effects of between-dyad predictor variables (i.e., experimental condition) and outcome variables. In such cases, the recommended strategy is to use the dyad as the unit of analysis (Kenny, 1996 (Kenny, , 2008 . Therefore, individual scores of the dyads' participants were collapsed, and we used the dyad rather than the individual participant as the unit of analysis. Hence, the analyses in this article are based on 81 cross-sex dyads. 1 Procedure The dyads were randomly assigned
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