Table 4 exhibits all 98 empirical studies included in the present review. As the media column shows, they cover a wide variety of communication media. Studies mostly refer to integrative negotiation and to a lesser degree to distributive negotiation as well as to group (multi-party) negotiation. Also included are relevant field studies, studies including non-scored negotiation exercises and meta-analyses. The dependent variables column shows the types of dependent variables that the studies report: process measures (e.g. time, behaviors, offer patterns), economic negotiation outcomes (e.g. agreement, individual and joint profit), and socio-emotional outcomes (e.g. satisfaction, trust). Finally, the theories column summarizes which of the above-discussed media-related theories have been used in the articles.
Figures 3, 4 and 5 illustrate the evolution of research interest on communication media in negotiation across the decades. Overall, 25 empirical studies, detected for this review, have been published in the 1960s, 70s, 80s, or 90s. In the subsequent decade, from 2000 to 2009, this number nearly doubled with 49 empirical papers, with 24 following in the 2010s. Regarding the communication media included in the studies (see Fig. 3), FTF seemed to be the standard against which the other media were pitted until the millennium—21 out 25 studies contained a FTF condition. In the 2000s, only 26 out of 49 still contained FTF, while the same amount of studies looked at synchronous CMC, with asynchronous CMC following suit (21 studies). In the 2010s, the latter category drew the most research interest (15 out 24), probably because of a specific concern about email negotiation. Video and audio, in contrast, somehow seemed to have been of less concern to researchers, despite their importance in practice.
Figures 4 and 5, displaying dependent variable categories and dependent variables analyzed in the reviewed studies, show a similar development of changing research interest. In the earlier time interval (1960s to 1990s), a clear emphasis was on economic outcome variables, notably joint profit or a similar dyadic outcome. In the second time interval, negotiation behavior in various conceptualizations became the most often cited dependent variable, possibly because of the greater ease to capture it in written communication, which featured a lot more in the 2000s than before. Figures 4 and 5 also show the lowest interest in socio-emotional outcome variables compared to other outcome variables across all time periods, although relatively speaking analysis of socio-emotional outcomes has increased. This may be due to more recent insights on the importance of socio-emotional outcomes for future relationships between negotiators (e.g. Curhan et al. 2009).
Negotiation Time and Amount of Communication
Various important process characteristics potentially differ between the communication media. To start with, descriptive process characteristics, such as negotiation time and amount of communication, may differ between communication modes. Overall, synchronous media with an audio channel, such as FTF, video, and telephone were found to need less time for finalizing a negotiation than text-based communication such as email or instant messaging (IM) in the majority of studies reporting negotiation time (Galin et al. 2007; Geiger 2014; Mennecke et al. 2000; Purdy et al. 2000; Scheck et al. 2008; Suh 1999; Wang and Doong 2014; Yang 2012). In a similar vein, computer support made text-based negotiation quicker compared to pencil and paper as witnessed by fewer offer rounds in a study by Mahenthiran et al. (1993). Despite the shorter negotiation time in media with an audio channel, the amount of communication was still higher in those media (King and Glidewell 1980; Sheffield 1995). This finding is also mirrored in synchronous versus asynchronous text-based electronic negotiation, where negotiators using an instant messenger (IM) system (synchronous) communicated more than those using email (asynchronous) when one side (the seller) had intricate (vs. simple) arguments (Loewenstein et al. 2005).
Contrary to these majority findings, other studies report no significant time differences between the various media employed (Barkhi et al. 1999; Delaney et al. 1997; King and Glidewell 1980; Smith 1969; Wang and Doong 2014). While in the studies by Smith (1969) and King and Glidewell (1980) sample sizes were too small to reach significance of results, Barkhi et al. (1999) speculate that a greater task-orientation or power application of the most powerful party may be responsible for similar negotiation times between FTF and CMC communication. In Delaney and colleagues’ (1997) study the time taken to use a functional negotiation support system (NSS) in both FTF and CMC may be responsible for equal negotiation times, and Wang and Doong’s (2014) similar finding may be due to the simplicity of their negotiation task (transparent price bargaining). Chinese negotiators in synchronous CMC took more time when they used a native language support tool compared to not using it (Lim and Yang 2008). This may be due to the slower Chinese characters keyboard or eventually because negotiators send more messages and offers in their native (Chinese) compared to a foreign language (English; Lai et al. 2010). When FTF negotiations were supported by a negotiation support system (NSS), they also took longer than without such support (Delaney et al. 1997).
Number of Offers
Some articles report the number of offers made in negotiations with different media. From the empirical evidence, no clear picture emerges. Neither Schulz and Pruitt (1978) nor Fry (1985) find main effects for media (FTF, paper & pencil) on the number of offers or number of different offers, but only interaction effects: Team oriented FTF negotiators (Schulz and Pruitt 1978) and FTF negotiators in high-low Machiavellianism dyads (Fry 1985) make less offers than the other respective negotiators. In the study by Delaney et al. (1997), most offers are made by FTF negotiators who use a NSS, while the number of offers in synchronous CMC plus a NSS is no different from pure FTF negotiators. Lai et al. (2010) report more offers for e-negotiators who negotiate in their native compared to a foreign language. In sum, those studies only find media differences on the number of offers under various boundary conditions, but no main effect. An interesting notion is added by Damian and colleagues, who compare video only to video negotiations with preliminary asynchronous CMC: their results show that in previously unstructured software requirements negotiations, there are less questions per issue, more extra information per uncertainty, and less clarifications per issue in video only compared to video plus preliminary asynchronous CMC.
Economic Reference Points
Some studies report important economic reference points such as negotiator aspirations, first offers, and concessions. Geiger (2014) finds lower aspirations in text-based electronically mediated negotiations than in the FTF mode. A different finding comes out of Paese and colleagues’ (2003) work, who report higher first offers in email and telephone compared to FTF, when there was no honest disclosure of the opponent’s reservation price. Mahenthiran et al. (1993) report higher first offer spreads for CMC compared to pencil and paper negotiations, and Kurtzberg et al. (2010) find more first offers within the bargaining zone in email communication, when the negotiation was preceded by the exchange of a humorous comic strip. Higher first offers were reported for Hong Kong email versus FTF negotiators, but not for US email negotiators (Rosette et al. 2012). These findings suggest that the communication medium may interact with other variables to produce different offer process parameters in different media. Concerning subsequent concession making, Johnson and Cooper (2009b) report lower levels of concessions in IM compared to telephone negotiations. While Schulz and Pruitt (1978) and Fry (1985) report having measured systematic concession making as a predecessor to integrative outcomes, they provide no figures of the variable in their different communication conditions.
With regard to negotiation behavior or tactics, the literature offers partly diverging findings as pertaining to the different communication media. Early works find more cooperative behavior (Carnevale et al. 1981), more trial-and-error processes to find win–win agreements and more insight (Carnevale and Isen 1986) when negotiators are separated by a visual barrier compared to sitting FTF. This finding is contrary to Barkhi et al. (1999, 2004), who report more truthful information exchange in FTF versus synchronous CMC negotiation, both conditions supported by a NSS. Yuan et al. (2003) find that text only CMC is rated worse to gain mutual understanding than text plus audio or video. Pesendorfer and Koeszegi (2006) report more task-related information exchange in asynchronous versus synchronous e-negotiations, mostly in early and late phases of the negotiation (Koeszegi et al. 2011). In partial contrast, Galin et al. (2007) report more soft tactics in FTF negotiation than in e-negotiation. Graf et al. (2010) find differences on creating value and integrative information exchange in synchronous CMC negotiations compared with synchronous CMC with NSS support, however, they do not report in which direction the differences play out. A number of papers report no differences regarding various integrative behaviors between the different media conditions (collaborative climate: Delaney et al. 1997; problem-solving approach: Yang (2012); positive conflict management: Zornoza et al. 2002; perception of partner’s strategy: Griffith and Northcraft 1994).
A visual barrier also seems to inhibit competitive behavior (Carnevale and Isen 1986), a finding mirrored in a study by Geiger (2014) who reports lower levels of various competitive behaviors in IM versus FTF negotiations. Pesendorfer and Koeszegi (2006) find less competitive and unfriendly behavior in asynchronous versus synchronous e-negotiation, mostly toward the beginning and the end of negotiations (Koeszegi et al. 2011). The overall empirical evidence, however, draws a slightly different picture: A meta-analysis finds that FTF negotiations are less hostile than virtual negotiations (Stuhlmacher and Citera 2005), especially for women (Stuhlmacher et al. 2007; see also Matheson 1991 for gender effects in synchronous CMC negotiation) and for strangers (McGinn and Keros 2002). This finding also resonates in later papers such that more hard tactics are reported in e-negotiation than in FTF (Galin et al. 2007) and more forcing behavior in IM than FTF negotiation (Giordano et al. 2007). Loewenstein et al. (2005) report more deception in synchronous (IM) e-negotiation compared to asynchronous (email) e-negotiation when sellers were provided with intricate arguments. However, several authors also report no differences in distributive behaviors or reflections thereof in various communication media (negative conflict management: Zornoza et al. 2002; team conflict: Staples and Zhao 2006; negative climate: Delaney et al. 1997) or do not report in which direction differences exist (Graf et al. 2010). Regarding persuasion or the ability to influence the other party, Yuan et al. (2003) report perceived advantages to influence other negotiators in video or audio plus text compared to text only negotiators. Vinciarelli et al. (2014) find that in phone negotiations, the receiver of the call is more persuasive than the caller. While there is no unambiguous picture about the relative occurrence of cooperative and competitive behavior in different communication media, van Es et al. (2004) report that a behavioral strategy change is easier accomplished in asynchronous (email) than synchronous (FTF) media.
Perceptual and Affective Process Variables
Negotiation behavior or tactics is often conceptualized as a dyad-level variable; other papers focus more on individual-level process characteristics. With regard to communicated affect, the literature offers diverging results: While Johnson and Cooper (2009a, 2009b) find less communicated affect in IM than telephone negotiations, Geiger (2014) reports more positive relational messages in asynchronous IM than FTF negotiations. Similarly, Pesendorfer and Koeszegi (2006) find more negative and less positive affect communicated in synchronous versus asynchronous e-negotiation. In a slightly different vein, Duthler (2006) finds that email requests are more polite than voicemail requests.
Pre-negotiation trust, in contrast, seems to be lower for online than FTF negotiators (Naquin and Paulson 2003). This finding is mirrored also in lower self and partner credibility in IM versus FTF integrative negotiation (Citera et al. 2005) as well as higher seller trust in a buyer (benevolence, credibility) in FTF compared to email and reverse auctions (Huang et al. 2008). When procurement complexity was high, seller trust was higher in FTF and email than in reverse auctions (Gattiker et al. 2007).
Rapport during negotiation, i.e. “a state of shared positive affect and mutual interest in the dyad” (Moore et al. 1999, p. 24), seems to be higher in FTF than in email because of more personal information exchange. However, personal information exchange in email negotiation could be fostered by a pre-negotiation phone call (Morris et al. 2002).
Cognitive effort, i.e. “the psychological cost that individuals perceive while processing information” (Wang and Doong 2014, p. 741), during negotiation was found to be higher in a synchronous CMC with NSS support compared to FTF or video with NSS support in a salary negotiation (less analyzable), but lower in a better analyzable price negotiation (Wang and Doong 2014).
Finally, different types of an accurate assessment of the opponent are reported in the literature. While there are not too many researchers who have dealt with these variables, their findings point in the same direction: For an accurate assessment of the opponent, FTF seems to be the best available medium. In three parties negotiations, Arunachalam and Dilla (1995) find a higher judgment accuracy about the opponent’s specific interests in FTF versus computer-mediated communication (CMC). Griffith and Northcraft (1994) report no difference in integrative judgment accuracy between pencil and paper versus text-based CMC negotiation. Giordano et al. (2007) report a higher deception detection accuracy in FTF versus IM. In a similar vein, Laubert and Parlamis (2019) find consistently low emotion detection accuracy in various text-based electronic negotiations.
Two field studies (Jensen 2009; Townley and Jones 2016) show that both email communication and business letters going back and forth between contractual parties mirror the development of the negotiator relationship during the negotiation and before a deal is closed. “During the three-month period observed, the frequency in use of interpersonal strategies converges as the relationship progresses towards a more contextually stable and more personalized level of communication as trust has been established and power relations have become structured within the legal framework of the contract.” (Jensen 2009, p. 4) Both forms of written communication support the provisional amendment of draft agreements, which serve as the main device for reaching a substantive and legal agreement (Townley and Jones 2016).
Economic Negotiation Outcomes
Economic outcomes in negotiation encompass agreement, individual profits, joint profits, and the dispersion of profits. With regard to agreement, the empirical literature is ambiguous as to which medium fosters or hinders successful completion of a negotiation. Johnson and Cooper (2009a) report a lower probability of agreement in IM versus telephone. In a similar vein, Swaab et al. (2009) find lower exclusion rates for one party in a three party negotiation when parties negotiated FTF (public and private) or only publicly in CMC compared to CMC with private communication only. No differences in agreement rates between different media are reported by McGinn and Keros (2002; FTF, phone, email) and Mahenthiran et al. (1993; pencil and paper, CMC). In contrast, higher rates of agreement in email compared to FTF negotiations of an ethically difficult topic were found by van Es et al. (2004). Similarly, Wolfe and McMurthy (2005) report higher rates of agreement for CMC plus NSS support versus FTF for incongruent expectations in regard to subordinate performance between superior and subordinate in budget negotiations, but no media differences for congruent expectations.
Regarding individual profits in distributive or integrative negotiations, only few studies found an effect of different media. In a distributive labor negotiation, Morley and Stephenson (1969, 1970) report that negotiators using a constrained phone conversation (no interruptions allowed) were most successful in defending their initial power advantage in respective distributive outcomes compared to FTF (constrained/unconstrained) communication. Lim (2000) reports marginally higher individual profits in FTF compared to communication without visual access. Arunachalam and Dilla (1995) report higher individual profits for FTF compared to CMC negotiators in an integrative three parties negotiation. Barkhi et al. (1999, 2004) find higher individual member rewards in the FTF compared to CMC mode in group negotiations with an unequal power structure between leader and group members. This difference is more pronounced when members have a group incentive compared with an individual incentive (Barkhi et al. 2004), in line with Swaab and colleagues’ (2012) communication orientation model and its boundary condition of negotiator orientation. In written only communication, Griffith and Northcraft (1994) find an advantage for pencil and paper over CMC in terms of individual profit. All other reviewed studies that report individual profits, settlement prices in distributive negotiations, or comparable individual outcomes, find no main effect for media on individual profit (Geiger 2014; Giordano et al. 2007; King and Glidewell 1980; Loewenstein et al. 2005; Paese et al. 2003; Rosette et al. 2012; Short 1974; Smith 1969; Suh 1999) or report profit numbers but provide no related significance testing (Kurtzberg et al. 2005a; McGinn and Keros 2002). However, some studies note interaction effects between communication medium and other variables with an impact on individual profit. In a study by Rosette et al. (2012), Hong Kong email sellers reached higher distributive outcomes than Hong Kong FTF and US email and FTF sellers, resembling a culture × medium interaction. In an early study, Short (1974) found that individual profit for consonant negotiators is higher in FTF and video than in audio, where consonance was conceptualized as point values of the negotiation issues that reflected the actual bargainer’s personal beliefs. Greater seller profit in IM than in email were found when the seller used intricate instead of simple arguments (Loewenstein et al. 2005).
Probably the best covered (see also Fig. 5) and most debated dependent variable in negotiations in different communication media is joint profit or a similar dyadic economic outcome variable (e.g., pareto efficiency). Among the research that reports joint profit, many studies on integrative negotiation find no significant difference on this variable between different communication media conditions (Ang et al. 2013; Calefato et al. 2012; Damian et al. 2000, 2003; Delaney et al. 1997 [when both FTF and CMC negotiators had access to a NSS]; Galin et al. 2007; King and Glidewell 1980; Loewenstein et al. 2005; Naquin and Paulson 2003; Potter and Balthazard 2000; Purdy et al. 2000; Rangaswamy and Shell 1997; Scheck et al. 2008; Schulz and Pruitt 1978; Wachter 1999; Yang 2012). No difference either was found in joint outcomes between email negotiators with or without a 5 min up front phone call (Morris et al. 2002) as well as for cooperative versus non-cooperative negotiators in CMC negotiation supported by a NSS (Lai et al. 2006) or native versus non-native language negotiators in asynchronous CMC (Lai et al. 2010). Multi-lingual support in synchronous CMC negotiation also did not impact joint outcomes, but the availability of a NSS did (Lim and Yang 2008).
In contrast to these findings, other studies on integrative negotiation report higher joint profit for negotiators without visual access compared to FTF (Carnevale and Isen 1986; Carnevale et al. 1981; Fry 1985 for high-low Machiavellianism dyads only; Lewis and Fry 1977), and higher profits for email versus FTF negotiators (Citera et al. 2005; Croson 1999). Among heterogeneous groups, better negotiation group performance was reached in CMC than FTF, but not in homogeneous groups (Staples and Zhao 2006).
On the contrary, Arunachalam and Dilla (1992, 1995) report higher joint profit for FTF negotiators compared to CMC negotiators in a three parties negotiation. These results are mirrored by Diermeier et al.’ (2008) results in a three parties coalition negotiation, and they are particularly evident when only private communication was allowed, but not public communication. Hollingshead et al. (1993) report greater joint profit for FTF versus CMC negotiators, and Turnbull et al. (1976) found superior dyadic outcomes for FTF or video compared to audio only. For high-high Machiavellianism dyads, Fry (1985) reports higher joint profits in FTF compared to a negotiation with a visual barrier. Damian et al. (2008) as well as Arthi (2009) show that video conferencing preceded by asynchronous text chat leads to fewer open issues in software requirements negotiation than video conferencing only and thus to better dyadic performance.Footnote 1 Joint profit was also greater in pencil and paper compared to CMC in a study by Mahenthiran et al. (1993).
Sheffield (1995) reports no significant main effects of text versus audio or visual access versus no visual access on joint profit, but an interaction between negotiator orientation (individualistic vs. cooperative) and visual access: The highest joint profit was reached when cooperative negotiators had visual access, independent of whether they used a text based or an audio based medium. These results are deepened by Swaab and colleagues’ (2012) meta-analysis who find superior joint outcomes when a visual, an audio, or a synchronous channel was present compared to when this was not the case, and especially when negotiators were neutrally disposed toward each other. For non-cooperative negotiators, this effect reversed, and for cooperative negotiators, no interaction could be found.
If one looks at the different findings on joint gain across the time intervals covered by this review, it is noticeable that the earliest period (1960s to 1990s) provides the greatest spread of outcomes. Four studies find a benefit for no visual access compared to FTF, while five studies find an advantage of FTF against other communication media, with another five studies reporting no statistically significant difference. In the later periods, only one study each finds a benefit or detriment of FTF, while fifteen report no difference between the covered media any more. Together with the weakening research interest on joint profit (see Fig. 5) this observation may be an indication that negotiators’ communication practices have changed and that they have adapted to a more diverse array of communication media.
Dispersion of Profits
The dispersion of individual profits or the equality of outcomes also feature as a dependent economic variable in some studies. Arunachalam and Dilla (1992, 1995) find higher dispersion of individual profit in CMC than in FTF in a three parties negotiation. Among strangers, but not among friends, McGinn and Keros (2002) also find greater dispersion of profits in email compared to FTF. On the contrary, Croson (1999) finds a lower dispersion of individual outcomes in email compared to FTF negotiation. Again other studies report no differences in the dispersion of individual profits according to different media (Delaney et al. 1997 when FTF and CMC both used a NSS; Lim 2000; Wachter 1999). However, using either a NSS (Delaney et al. 1997; Lim 2000; Lim and Yang 2008)) or a multilingual support tool (Lim and Yang 2008) seems to promote more equal outcomes, independent of the communication channel.
Boundary Conditions of Economic Outcomes in Text-Based Electronic Negotiation
In the last two decades, special attention has been cast on text-based electronically mediated negotiations, mostly by email, IM or an internet based chat system. Overall, some boundary conditions helped, and others hindered success in such negotiations. Moore et al. (1999) found that negotiations were more likely to fail when neither a personal relationship nor common in-group status existed between negotiators. In a similar vein, Pesendorfer et al. (2007) and Pesendorfer and Koeszegi (2007) report that personal knowledge of each other and/or social embeddedness help handle high intensity conflicts better and increase agreement probability. In a distributive property negotiation conducted via email, where agents represented the principals, disproportionately higher agreement rates were found among agents that were similar and familiar compared to those who were lower in similarity and/or familiarity (Kurtzberg et al. 2005a). Volkema et al. (2010) report a positive correlation between agreement and perceived honesty of the other party in email negotiation. Hine et al. (2009) found that successful e-negotiations contained more positive emotion and agreeable language than failed ones, although they were actually shorter in time. Geiger and Parlamis (2014) show that email comfort, a person’s affective attitude towards email, is positively related to joint gain, individual gain and social value in integrative email negotiation. In addition, reactive medium management, i.e. trying to reactively fix shortcomings of the medium, was negatively related to joint profit and social value in email negotiation (Parlamis and Geiger 2015). In electronic text-based communication, some more interaction effects can be witnessed: In a study by Lai et al. (2010), in a native language group the buyer’s utility was higher than the seller’s, but not in a non-native language group in asynchronous CMC negotiation. In synchronous CMC, negotiators who had access to a NSS reached higher individual outcomes than those without (Lim and Yang 2008), however, no such effect could be found for using a multi-lingual support tool. Kurtzberg and Naquin (2010) write that email negotiators who received emails with a disclaimer statement in an email footer had lower individual and joint outcomes than those receiving email with a confidentiality statement or no statement at all. Ultimately, Kurtzberg et al. (2010) report higher joint profit in email negotiation when they were started with a humorous event compared to when not.
Socio-emotional Negotiation Outcomes
Beyond economic negotiation outcomes, some papers also report a variety of socio-emotional outcomes in negotiations conducted in different communication media. As one of the first studies, Carnevale et al. (1981) observe a more positive negotiation atmosphere for negotiators without visual access compared to FTF. Regarding negotiator satisfaction with the negotiation outcome, disparate results are stated: Some papers report highest satisfaction in FTF communication with other media at a disadvantage (Barkhi et al. 1999; Hollingshead et al. 1993; Naquin and Paulson 2003; Wachter 1999 for process but not for outcome satisfaction; Wolfe and Murthy 2005), or higher levels of satisfaction when audio or video channels were present compared to text only (Scheck et al. 2008). Others report greater satisfaction in text-based CMC compared with FTF (Delaney et al. 1997; Geiger 2014; Giordano et al. 2007). Similarly, Pesendorfer and Koeszegi (2006) found higher satisfaction with the outcome in asynchronous versus synchronous computer mediated negotiation. Moreover, a number of papers report no difference in outcome and/or process satisfaction (Ang et al. 2013; Jain and Solomon 2000; Lim and Yang 2008; Purdy et al. 2000; Wang and Doong 2014; Yang 2012) for various media and/or support systems (NSS, multi-lingual). The work by Wang and Doong (2014) suggests that the type of negotiation (easily analyzable, difficult to analyze) may interact with the medium to influence process satisfaction: While it is highest in text-based CMC with NSS support for an easily analyzable task, it is lowest for a more difficult one, compared with FTF and video supported by a NSS. Kurtzberg et al. (2010) found that in email negotiation sending a funny cartoon upfront led to greater satisfaction. In NSS supported text-based CMC, perceived control, fairness and collaborative atmosphere of the system enhance negotiator satisfaction (Wang et al. 2010).
Some more papers report constructs related to satisfaction. Wachter (1999) found decreasing outcome affect from FTF through video and audio to CMC. In Jain and Solomon’s (2002) paper, FTF provides greater effectiveness of communication and a more positive perception of group processes than CMC. Wolfe and Murthy (2005) report greater task conflict and relational conflict in synchronous CMC with a NSS compared with FTF. Results regarding desire for future interaction partly mirror the results for satisfaction: Naquin and Paulson (2003) find a higher desire for future interaction in FTF than email negotiations. In contrast, no influence of media richness (FTF, video, audio, email) on desire for future interaction when controlling for collaboration and satisfaction was observed by Purdy et al. (2000). Media richness does also not impact the likelihood of renegotiations in practice (Schoop et al. 2008). State anger in FTF versus CMC negotiations seems to be moderated by the type of conflict: in functional conflict it is lower in FTF while in dysfunctional conflict it is higher in FTF compared with CMC (Chen and Tseng 2016).
Trust formation during negotiation seems to be influenced by the medium: Generally, some papers find higher negotiation trust and/or credibility in the opponent in FTF than in email negotiations (Citera et al. 2005; Lu et al. 2017; Naquin and Paulson 2003; Wachter 1999). These findings are mirrored in purchasing processes where trust formation (benevolence, credibility) during FTF negotiations is greater than in email negotiations when procurement complexity is low. However, there are no significant differences between face-to-face and email when procurement complexity is high. (Huang et al. 2008). Similarly, trust was higher in audio plus text or video plus text than in text-only CMC negotiations (Scheck et al. 2008; Yuan et al. 2003). Interestingly, avatar mediated communication witnessed a greater positive change in trustworthiness compared to video (Ang et al. 2013). For email negotiations, emails with a disclaimer message lead to lower trustworthiness than those without or with a confidentiality footer only (Kurtzberg and Naquin 2010) and to higher trust when a funny cartoon is sent compared to when it is not (Kurtzberg et al. 2010).
Socio-emotional Evaluation of the Opponent and the Self
Some socio-emotional evaluations also have to do with the opponent. Positive feelings towards the opponent were greater in dyads that had a 5 min phone conversation and then negotiated via email than those who only negotiated by email (Morris et al. 2002). In a different study, negotiators experienced greater friendliness in asynchronous versus synchronous computer mediated negotiation (Pesendorfer and Koeszegi 2006). Avatar mediated communication witnessed a greater change in opponent likeability compared to video (Ang et al. 2013). Interpersonal awareness did not vary between FTF and electronically multi-media supported negotiations (video, text, document sharing; Damian 2002). In email negotiation, correctly perceiving the opponent’s emotion seems very difficult (Laubert and Parlamis 2019). Also in email negotiation, loyalty of an agent to the other agent in agent-agent property negotiations is highest when agents are similar and familiar and seems to go hand in hand with the highest agreement rates (Kurtzberg et al. 2005a). Moreover, negotiators seem to rate their peers worse when the peer appraisal after negotiation is provided by email as compared to pencil and paper (Kurtzberg et al. 2005b).
Finally, some socio-emotional outcomes have to do with the self. Mahenthiran et al. (1993) show that negotiators’ perceived autonomy in budget negotiations is greater under pencil and paper versus CMC. Lai et al. (2010) find a higher language self-efficacy and negotiation self-efficacy for native versus non-native e-negotiators.
Critical Assessment of Empirical Findings
The diversity of empirical findings underscores that this research field within group decision and negotiation is still far from consensus as to the effects of different media on most negotiation processes and outcomes. Therefore, the original assumption that FTF is the most suitable communication medium for negotiation, voiced in many theoretical writings and empirically substantiated in some, especially earlier ones, needs to be taken with many grains of salt. As the review of empirical studies shows, only two types of process variables seem to mostly benefit from FTF communication: the formation of trust, including its components of benevolence and credibility, and the accurate assessment of the opponent. For all other process and outcome variables, this review revealed diverging findings. In some instances, FTF produces more cooperative and less competitive behavior, in others it is the other way around. In turn, sometimes differences in outcomes in one or the other direction can be observed; in many instances, no such variations were found.
Social information processing theory and the communication orientation model in negotiation provide some theoretical suggestions as to how some of the diverging findings can be reconciled, e.g. by regarding negotiator orientations (Swaab et al. 2012). Specifically, the communication orientation model suggests that more channels (i.e. audio, visual, synchronicity) benefit initially neutral negotiators, harm non-cooperative negotiators, and do not influence cooperative negotiators in reaching good dyadic outcomes. In addition, several other boundary conditions may be valuable to understand differences in negotiation processes and outcomes in various communication media. In media with fewer channels, notably CMC, the review suggests that a personal relationship or similar constructs (social embeddedness, similarity, familiarity) can make up for some of the missing richness in those media (e.g. Pesendorfer et al. 2007). A positive communication style (honesty, agreeable language, humor, positive emotion transmission) and a person’s familiarity and comfort with a communication medium may do the same (e.g. Geiger and Parlamis 2014). Other boundary conditions, assessed in past research, include person- or role-specific aspects (culture, Rosette et al. 2012, Machiavellianism, Fry 1985, in-group homogeneity, Staples and Zhao 2006), expectations and incentives (Barkhi et al. 1999, 2004; Mahenthiran et al. 1993), partner similarity and familiarity (Kurtzberg et al. 2005a, b) as well as characteristics of the negotiation task (analyzability, Wang and Doong 2014, type of conflict, Chen and Tseng 2016, complexity, Gattiker et al. 2007).
Beyond various boundary conditions assessed in some empirical papers, several other reasons may be responsible for why the different empirical studies do not fully converge in their results regarding the various dependent variables. First, the timeframe from which this review draws empirical papers is six decades. In these six decades, both the availability and the use of different communication media have dramatically increased. Thus, it is at least questionable whether the same study with a similar sample of test persons would have come to the same results, say, in 1995 and 2015.
Second, while some studies offer differentiated results by explicitly looking at interaction effects between communication medium and other variables, their concrete data collection procedures may implicitly introduce more boundary conditions, not controlled for in this review or earlier meta-analyses (Stuhlmacher and Citera 2005). For example, it may indeed make a difference in results whether a FTF versus IM negotiation study is conducted among tech-savvy engineering students (Damian et al. 2000) or among communication students (Mennecke et al. 2000). Another obvious boundary condition, practically not regarded so far in negotiation studies, is people’s attitude towards or preference for a certain communication medium (e.g. Kelly and Keaten 2007).
Third, as the review of empirical findings shows, for many important process and outcome variables, null findings are reported, i.e. no statistically significant differences between media conditions. Interestingly and in contrast to the original studies, all pertinent meta-analyses—although necessarily less fine-grained in differentiating various media—find significant differences in outcomes between various media categories or characteristics. Thus, missing statistical power due to small sample sizes also represents a potential explanation for many of the null findings.