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Directions for Professional Social Matching Systems

By Thomas Olsson, Jukka Huhtamäki, Hannu Kärkkäinen

Communications of the ACM, Vol. 63 No. 2, Pages 60-69

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Supporting human collaboration has been a central driver of the development of information and communication technology. A relatively recent approach to this end is social matching, referring to computational ways of identifying and facilitating new social connections between people.36 Social matching is most often connected with partnering for leisurely and romantic relationshipsin fact, the most well-known social matching systems revolve around dating scenarios (for example, Tindera) or triggering opportunistic interactions with strangers (for example, Happnb).

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Key Insights


This article focuses on Professional Social Matching (PSM), which we define as the matching of individuals or groups for vocational collaboration and co-creation of value. This covers organizational activities, including recruitment, headhunting, community building, and team formation within or across organizations as well as individually driven activities like mentoring, seeking advisory relationships, and general networking.

From a technological perspective, computer-supported PSM is based on computational approaches to profiling actors (organizations and individuals), modeling their qualities, analyzing their mutual social suitability and relevance, and presenting the recommendations to the users. For example, prescriptive data analytics9 can utilize social network analysis (SNA) for explicating the social ties between actors and machine learning-based approaches to analyze their competences and interests and to identify suitable pairs of actors. The resulting computational system can manifest as proactive people recommender systemsor social recommender systems15or other kinds of data-driven decision-support systems31 for social matching. Conventional examples include recommendations of other professionals to follow in various social media services as well as more specific expert search systems.40

This fusion of various analytical and algorithmic approaches for a broad and multifaceted application area forms an intriguing, interdisciplinary space for research and development of novel algorithms and information systems. This article reviews relevant literature in three key scientific domains that present important understanding necessary to reach the potential of future computational systems (as illustrated in Figure 1).

Figure 1. Overview of relevant scientific domains, concepts, and research areas to develop next-generation computer-supported PSM.

Our synthesis is based on two central yet paradoxical ideas. One the one hand, computational support for choosing collaborators seems beneficial because purely human-driven matching is prone to limitations and biases in human decision-making and the boundedly rational understanding of the breadth of alternatives. On the other hand, algorithmic matching involves risks of strengthening the human biases, for example, through biased training data,29,39 providing socially unacceptable or seemingly illogical recommendations or introducing unanticipated detrimental mechanisms to professional collaboration and social structures.

To address the problem of role differentiation between human and computational reasoning in PSM decisions, this article builds on recent abundant discussions on the ethics of information technology (for example, O'Neill29 and Shilton33). We review and problematize some premises in current paradigms of system design that might also seem intuitively appropriate when developing PSM systems. While the academic community has already acknowledged that simplistic aims and metrics, such as prediction accuracy in recommender systems, might misguide a research field at large,26,37 we follow a similar critical line of thinking on a broader scale. We underline the importance of area-specific application and systemic consideration when defining design goals and computational approaches.

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Motivating the Computational Approach

Why is computational support necessary in PSM? Traditionally, the identification and choice of professional partners take place manually by individuals (for example, matching an employer with a suitable employee, or choosing with which peers to collaborate). Long known in the science of cognition and reasoning, much of human decision-making is limited by the capacity of information processing (that is, bounded rationality34), is inclined to be based on intuition, heuristics, and cognitive shortcuts,19 and strives for minimizing cognitive effort.

In choosing collaborators, human decision-making can result in tendencies like homophily, the preference of interacting with like-minded others,21 and leaning on existing social networks and a geographically limited pool of candidates. In social networking, people tend to strengthen existing social clusters (that is, triadic closure14) rather than reach for unknown communities and individuals. Similarly, formation of working groups within organizations is often based on arbitrary choices even though the combination of people can significantly influence group productivity and satisfaction.35

In other words, human biases can result in suboptimal collaboration and untapped co-creative potential, particularly in knowledge work and creative industries that demand cross-pollination of ideas and perspectives. It has been argued that fruitful collaboration and high innovation capability result from complementary viewpoints among a diverse group of actors.27 Substantial research in management science and information systems hint that, in particular, activities that require divergent thinking in groups benefit from diversity2 (for example, startups pursuing innovations or corporation boards aiming at holistically optimal strategic decisions). Heterogeneity in terms of knowledge has also been found important to managerial performance and in particular to innovation performance.32

While the jury is still out on the optimal balance of collaborators on the similarity-diversity continuum (for example, Aral et al.4), we argue that current computational solutions strengthen similarity-seeking behavior. Furthermore, it is noteworthy that diversity is not only about differences in identity-related qualities like gender, ethnicity, and personality types; it is also about cognitive diversity in terms of skills, competences, knowledge, and interests, and it is about social diversity in terms of social behavior and networks.

The need to identify optimal collaborators and fruitful skill combinations will increase in the future as dynamism in work life is expected to increase and co-creation chains turn into networks with increasingly complex structure. Examples of relevant trends and phenomena include increasing emphasis on ad hoc freelancer groups in creative industry, micro entrepreneurship, and piecework3 as well as strongly interdependent actors in business and innovation ecosystems. The more interdependency and collaborative value creation there is on a systemic scale, the more important and impactful the decision-making on social matching becomes.

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Opportunities for Computational PSM

The question of how computational systems could support PSM matching in particular remains relatively unexplored when considering the breadth of collaborative professional activities. Prior research and development work have addressed expert search (for example, Wang et al.40), recommendations for inspiring individuals or organizations to follow in social media, and machine learning solutions for identifying suitable candidates in recruitment and headhunting (for example, Faliangka11). Recommending new collaborators has been explored in a few algorithmic experiments and user studies (for example, Tsai et al.37).

However, this vein of research remains on the fringes of recommender systems research and is limited to the context of conferences (for example, Chen et al.8) or analyzing publication data in academia (for example, Pham et al.30). As for supporting teamwork, computational solutions have been explored in, for example, optimizing the organizing and managerial practices of a team.42 However, the question of the ideal team composition remains underexplored. At the same time, the new technical enablers and current trends in work-life allow for novel PSM solutions. The amount of data on people and organizations is increasing, which has paved the way for the rapid evolution of machine learning-based techniques. The aforementioned trends in leadership and organizing knowledge work welcome new forms of collaboration, and networking in general is highly valued by both organizations and individuals.

Consequently, we have recently witnessed the birth of commercial applications for browsing candidates for professional interaction (for example, Brella,c Grip,d and Shapre). Such applications tend to follow the so-called Tinder logic of user-based selection of seemingly interesting candidates based on simple profiles, often restricted to matching attendees at professional events. However, the simplistic and similarity-seeking nature of such applications calls for ethical reflection and expansion of the horizon in this area. We envision that future PSM systems could offer solutions on different levels of matching:

  • Identifying optimal combinations of professional qualities and aims in certain professional activities (that is, matching skills and goals).
  • Recommending partners for particular co-creative purposes, such as for business partnerships or mentoring relationships (that is, matching individuals).
  • Optimizing team formations for a project (that is, matching multiple actors).
  • Identifying suitably complementary actors for networked value creation (such as, matching at ecosystem level).
  • Balancing the supply and demand in the job market by suggesting dedicated trainings or new job openings (such as, matching on societal level).

To provide an early framework of PSM activities, we identify three main tracks of social matching in professional life: one-to-one, one-to-many, and many-to-many (Figure 2). These categories display different levels of decision-making complexity and varying numbers of qualities to analyze.

Figure 2. Main tracks of PSM, with examples of matching cases with different scales of cost upon a suboptimal matching decision. The complexity of matching decision-making increases as the number of actors increase.

Specific matching cases further vary in terms of the temporal nature of the decision: for example, long-term commitment in recruitment of a new employee vs. short-term perspective in forming a working group within an organization; intensity of collaboration: for example, choosing a new group member for a co-creative project vs. choosing a member for a young company's advisory board; and, probability and criticality of risk: for example, low-probability but high-cost risk of making an unsuccessful recruitment vs. high-probability but low-cost risk of extending one's personal network with new individuals. The bottom part of Figure 2 relates particularly to this latter aspect of the cost of suboptimal matching.

These qualities set boundaries and requirements for PSM system design, for example, in terms of the breadth of given alternatives (variety of matches), the need for transparency and explanatory capability of the logic behind recommendations, and the agency and role that a system has in the decision-making. In Figure 2, the recommendations related to increased complexity and cost of failure imply higher risks and require increased explanatory power of recommendations from PSM systems. Deciding whom to meet at an event has low risks as the interaction would be short term and of low intensity; therefore, a user might be satisfied with only a few algorithmic recommendations and superficial reasoning behind the recommendations. However, matching for which actor to choose for close business collaboration poses higher risks and costs of failure. For the user to trust and follow the recommendations, this requires both more in-depth algorithmic reasoning and better explanation capabilities in the user interface.

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Pitfalls in Computational PSM

A key argument of this article is the fundaments of state-of-the-art technologies and approaches that could be utilized to build PSM systemsfor example, item recommenders, social network analysis, and machine learningmust be reconsidered in this application area. Directly applying the prevailing analysis or design patterns to PSM can introduce new risks with detrimental effects on the performance and collaboration practices of knowledge workers. The following critically reviews the suitability of common computational approaches.

First, it is imperative to realize that recommendation does not equal prediction,26 particularly in PSM. To truly enhance professional collaboration, recommender algorithms should not reproduce or strengthen the biased human behavior. For example, in a recruitment system, using prior examples as training data for machine learning is expected to strengthen the demographic distribution that a certain organization or profession has traditionally had. As McNee et al.26 pointed out, an accurate recommender engine might produce recommendations that are formally relevant as predictions, yet not very useful as recommendations (for example, a well-connected person is recommended to most users).

Wallach gave a gender-related example of the same issue: "There is a substantial difference between a model that is 95% accurate because of noise and one that is 95% accurate because it performs perfectly for white men, but achieves only 50% accuracy when making predictions about women and minorities."39 Similarly, it would be straightforward to predict who someone might meet at an event based on their history of professional social encounters in similar situations. However, using that as a recommendation would strengthen their habitual behavior, which might be against their actual collaboration needs.

Second, social matching systems tend to look for maximal similarity; in fact, dating scenarios have particularly been found to benefit from emotional similarity.13 A perfect match in dating services refers to the similarity of profiles, typically based on analyzing a simple user-defined, property-based profile content and clustering the pool of actors. This logic also seems to have affected the current vocational matching services: shared qualities tend to be highlighted in the user interface, and the brevity of profiles can lead the user to follow the natural tendency of seeking for similarity.

Third, from the perspective of social ties and networks, contemporary approaches for analyzing connections between individuals often utilize social network analysis and link prediction.24 Following the triadic closure hypothesis, new ties are more likely to be formed between friends-of-friends or colleagues-of-colleagues,10 that is, between actors that share a strong connection. The triadic closure mechanism can, however, enforce echo chambers and increase polarizationthe typical pitfalls of social networking services in the 2010s. In knowledge work, we argue the narrowed thinking due to echo chambers is bound to reduce exposure to novel information and decrease divergent thinking and innovation capability.

Fourth, PSM system designers must consider that good matches cannot be generalized across individuals. In content or item recommender systems, the same news article or product is often recommended to several users with corresponding consumption behavior and ratingsthat is, collaborative filtering.20 However, in PSM, person A being a good partner for person B does not imply that A would also be a good match for person C, even if B and C had similar qualities. An optimal match in professional life is very case specific and determined by, among other things, the matched actors' current needs, interests, personality, and availability for collaboration. Matches can be generalized only across similar cases. This means that narrowing down only to similar collaboration cases can lead to data sparsity and that the collaborative filtering approach would suffer from cold-start issues.

Finally, as professional activities are related to value creation for organizationsand, more broadly, communities and societiesPSM calls for a systemic perspective. For example, the same central and active individuals cannot practically be recommended to everybody (that is, the Matthew effect). The mechanism of preferential attachment5 tends to lead to power-law distribution across the population. A system might recommend excessive collaboration opportunities for people that already have plenty of connections while undervaluing other criteria, such as urgency of the need for collaboration or the actors' practical capacities for exploring new collaboration opportunities.

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New Design Directions

The limitations in human decision-making and the pitfalls in the traditional computational approaches essentially imply that PSM is far from trivial bulk predictions targeted to masses. Neither the matching mechanisms in dating applications nor the analytics methods in contemporary content recommender systems and link prediction algorithms seem to fit with the characteristics of PSM. To turn the focus from critique toward constructive thinking, we next propose high-level goals for the future generations of PSM systems. These are intended to advance this nascent research area toward socially meaningful and ethically sustainable design directions.

Goal: Balance diversity and similarity. Comparing to leisurely social matching applications or content recommenders, we argue that PSM systems should employ more diversity-enhancing approaches that shift the current aim for convergence toward divergence. While diversification has been recognized as a relevant aim for recommender systems in general,23 matching people for professional collaboration makes a particularly strong case for this.

At the same time, neither optimizing for similarity nor diversity should be taken as a maxim: the optimum is a moving goal somewhere between these extremes. Successful collaboration requires mutual trust and shared working culture (that is, similarity as a consolidating, convergent power) as well as openness for change and different perspectives (that is, diversity as a divergent power). Similarity is useful when the aim is to validate ideas or methods and there is a need for agility in short-term collaboration. Strong common denominators can also open minds to appreciate individual differences. Diversity is beneficial in developing novel ideas with the help of complementary perspectives, establishing long-term business ventures utilizing complementary social capital, or making well-informed strategic decisions based on diverse knowledge.

Identifying the optimal balance requires analysis and modeling of not only the actors but also the characteristics of the intended collaboration and the collaboration context. Compared to leisurely matching, professional life is more dynamic in terms of interaction needs, interests, and resources at different times.

Goal: Enable experiences of social serendipity. We call for systems that help people make professional matching decisions with positive long-term benefit. We argue that the experience of serendipity is an indicator of successful knowledge work, making it a desirable goal for designing PSM systems. Social serendipity can be considered as a strong experience of both unexpectedness and instrumental benefit from social encounters and collaboration.25

The unexpectedness can arise from encounters with people outside one's conventional social circles or with seemingly different qualities than oneself. However, turning such chance into serendipity calls for features that help the user to identify the possible benefits and gain advantage of the offered chance. The element of benefit can result from collaboration that provides value beyond what one could personally attain, for example, because of having complementary skills or knowledge or having formed an unparalleled team. Similar thinking can be identified in content recommenders where it is necessary to establish certain level of familiarity for the user and, at the same time, support the discovery of interesting new content.22 However, as social serendipity involves several actors, it is more challenging to design for it than for information serendipity, the more common aim of content recommender systems.

Goal: Support a systemic perspective in defining ideal matches. We argue that matching algorithms should not only optimize matches for an individual user but also consider what is ideal on a systemic level: across the user population and social structures like organizations. While social link prediction is typically based on relationships on the local scale, PSM systems introduce an opportunity to intervene the evolution of social networks to optimize for systemic diversity.

For example, in individual fields, a system should avoid reinforcing the processes of increasing homogeneity21 and preferential attachment5 by reproducing existing social network evolution mechanisms and recommending the same central actors to everyone. Instead, the recommendations need to be considered on an ecosystemic or even global level (for example, within a profession-based community). Organizations must balance the workload across employees; the most likable and versatile individuals cannot practically contribute to all the groups or organizational actions. Furthermore, the actors' interdependency demands bidirectional optimization: while person A could seem like a beneficial match to person B, person B might not perceive person A relevant enough. Matches that are optimized only for an individual can create collaboration proposals with asymmetric benefit and thus remain inefficient or be rejected.

Goal: Support the utilization of the existing social structures. We urge PSM developers to take advantage of existing social structures in organizations. First, existing weak or dormant ties (for example, people who already know each other but lack understanding of all the mutual collaboration opportunities) can be re-introduced through recommendations. Second, from an organizational perspective, diversity-enhancing matching should enable making use of existing echo chambers by identifying potential pairs of actors that are able to connect and bridge the flow of knowledge between established clusters (as illustrated in Figure 3).

Figure 3. Illustrative example of matchmaking potential within a community.

This objective differs fundamentally from the practices of straightforwardly predicting the likelihood of the formation of new social connections.24 We point to Burt7 who discussed social capital from two viewpoints: whether scarce or dense social networks produce social capital. Weak ties that gap structural holes can increase creativity and support the career development of those that occupy bridging roles. At the system level, these brokers serve as conduits of information flow. A related matching strategy that contributes to system-level diversity is identifying tertius jungens (or "third who joins"), that is, individuals that can serve as proxies in introducing "disconnected individuals or facilitating new coordination between connected individuals."28 Utilizing social proxies can be expected to facilitate building trust between the apparently diverse actors.

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PSM System Qualities and Future Directions

To address the aforementioned goals, we introduce a model of the analytical elements that we consider crucial for future PSM systems. Figure 4 outlines a high-level system architecture with key modules, inspired by Terveen,36 and their main functions. These are related to an analytics pipeline as well as general system qualities that need to be addressed across the presented modules. With this overview, we underline key requirements for future work and relevant research directions.

Figure 4. Key modules and functions in a high-level system architecture and the system qualities mapped to the different modules along the analytics pipeline.

Sensitivity for professional contexts and purposes. Perhaps the most analytically challenging requirement is that systems should model not only the potential actors and their social structure but also the context of the intended professional relationship. The produced models should drive tailoring of the matching logic accordingly (for example, changing priorities and weights of variables). The notions of context and context-awareness have been extensively discussed across the sciences, and various contextual variables have been investigated in relation to information systems in general and recommender systems in particular (for example, location, culture, user personality, task context).1 In what follows, we focus on a few aspects that are particularly relevant when considering the matching logic.

The quest for a sweet spot between maximal diversity and similarity is already challenging per se. Furthermore, it is a moving, context-dependent target. The optimal degree of diversity depends on individuals and the targeted collaboration in question. For example, the end user's personality has been found to affect the readiness for accepting diversity of recommendations in content and item recommenders,41 and we expect that such inherent human factors also have an equally significant role in people recommenders. As for organizations, characteristics like openness, tolerance of difference, and the different purposes of collaboration presumably also have an effect.

Similarly, an understanding of the current social structures is needed to identify meaningful configurations of the matching logic. Our premise is that a typical structure is composed of clusters that are densely interconnected but loosely connected to other clusters. Consequently, we suggest that PSM developers draw from the diversity-bandwidth trade-off theory4 to navigate the design space. Ties of different strengths (weak-strong) all have potential as conduits of novel information but in different ways in different domains of work. For example, the highly dynamic environment of a startup company highlights the importance of strong ties as high-bandwidth sources of relevant information. At the other end of the spectrum, an academic research group produces new knowledge over years rather than days. Therefore, the actors are able to invest in utilizing low-bandwidth weak ties due to their potential in serving nonredundant, novel knowledge.

In sum, many of the these aspects represent largely unobservable contextual factors that are subjectively defined. This forms a cyclical relationship between context and collaboration where the collaboration activity gives rise to context and the context influences activity.1 Moreover, the context forms as a mixture of several individuals' and organizations' contextual characteristics. Formalizing this contextual variance requires new methods and frameworks for conceptualizing PSM in more detail. This also means the plethora of data needed to reach certain analytical targets is unpractical without new mechanisms of granting access to personal data. PSM development endeavors need to carefully consider which practically available data can best support the context-specific analytical goals and how to compensate missing data.

We suggest there are two alternative design strategies to enable context sensitivity in PSM systems. Reactive design leaves the active user in charge of driving the system in a way that contextual requirements are met. Proactive design follows the logic of prescriptive analytics where the system suggests actions or even takes them on behalf of the active user. Whereas the proactive design introduces higher requirements for data availability and quality, it also provides a stronger basis for pursuing serendipity and diversity.

Multi-dimensional analytics. As noted, contextuality and the goal of supporting systemic perspective call for multidimensional analysis with several parallel relevance algorithms and various data about the actors. Extant research on recommender systems shows that the perceived relevance of recommendations and the perceived usefulness of the recommender system increase when multiple different recommendation strategies are in parallel play. For example, Hupa et al.18 discuss the advantages of multidimensional social-network recommenders to increase interdisciplinary collaboration. Tsai and Brusilovsky37 used four different recommender engines to support identifying new academic collaborators using conference data (topic similarity, social similarity, interest similarity, and geographical distance) and showed that the users who are able and willing to use multiple engines in parallel receive more relevant recommendations.

Although the triangulation of these approaches can already help identification of relevant matches, we call for consideration of additional perspectives in the prescriptive analytics for people recommendations. For example, geographical distance must be considered, especially in long-term collaboration. Level of seniority (or expertise) can affect the preferred symmetry of benefit and trust: matching for mentoring or advisory relationships calls for high difference in expertise, while matching for a production team often demands relatively equal levels of seniority. The personalities and organization cultures need to be similar enough to enable matches that are sustainable in the long term (for example, no conflicts due to drastically different ways of working or level of commitment).

Overall, developing analytics procedures and recommender engines for different perspectives is a step toward so-called hybrid recommender systems.37 At the same time, this introduces practical challenges. In addition to the axiomatic data availability issue, defining the logic in which the different analytical functions are combined in a context-sensitive manner requires deliberate research. Because PSM can potentially be affected by such a broad range of human features, all of them cannot practically be embedded in the algorithm design. We can only call for multidisciplinary research collaboration where social scientific understanding would support the identification of top-priority factors and formalizing this vast space.

User-system cooperation for decision support. Due to the dynamic and inherently complex nature of PSM, we argue that the matching decisions cannot merely be automated or offloaded to algorithms. For example, machine learning generally produces relevant results only if initialized with good-quality training data and well-defined goals, whereas human reasoning is suited for multi-faceted challenges where the desired pattern is unknown a priori. The different limitations and strengths in the human and computational analytical capabilities call for effective collaboration between computational intelligence (deep yet narrow) and human intelligence (broad yet shallow). This relates to the general notions of augmented intelligence and human-in-the-loop thinking. As this approach has already shown its power in, for example, classification problems, the complexity of PSM offers an even more opportune application area.

The human-in-the-loop approach has been envisionedf as useful, for example, when: (a) the cases that need to be identified are rare (class imbalance, for example, rare type of collaboration); (b) the cost of error is high (for example, time spent on browsing irrelevant matching options); (c) human annotations are already used (for example, recruiting processes); and (d) generic pre-trained models exist but need to be customized. The holistic thinking and contextual adaptability of the user are needed, for example, to steer the deep yet narrow algorithms (for example, refinement of what an ideal match is, or prioritizing the sought features for each matching case) and to make sense of and choose between the resulting recommendations. Particularly when considering non-experts as users of recommender systems, we need user interface solutions that support decision-making with alternative options, a multi-dimensional systemic viewpoint, and ways to communicate and deal with the algorithmic uncertainty that this application area entails.

Figure 5 outlines the potential collaboration points along the computational analytics process. First, we need methods that guide the user in selecting appropriate training data and analytical goals to enable accurate profiling and, eventually, predictions. Semi-supervised approaches could allow training with a very small amount of labeled training data, minimizing both the cold start problem and need for manual work by the user. Second, we need feedback from the user regarding which factors are of top priority in the current matching case. Third, we need to support user exploration for enacted sensemaking, which has been found to be important both in visual analytics in general6 and visual network analytics in particular.17

Figure 5. Outlining relevant user interactions in the human-in-the-loop analytics process. Typical research and design challenges in italics.

Subscribing to the call for transparency in AI and algorithmic systems, we argue that also PSMs should be able to better explain the reasoning behind the recommendations. For example, the uncertainty of the prediction should be translated into human-comprehensible forms so that the user can trust them, is able to assess the factual relevance of the recommendation, and can adjust their preferences accordingly.

Throughout the process, the cost in terms of burdening the user must be in line with the benefits of using the system. This raises the question of what user input and feedback is sufficient to hone the algorithms while causing minimal burden with tedious tasks for the user. In other words, it introduces a trade-off between the certainty of the matching decision and invested user effort.

An example of interactive visualization that can support exploration of relevant other people is the Conference Navigator.38 The recommended conference talks are presented as sets, each of which are identified by a recommendation engine. The active user is able to explore different recommendation strategies and their combinations through an interactive interface. This kind of hybrid recommender system with several visualization approaches supports user-driven exploration.

In the long term, following Leifer's Hu-mimesis epiphany,g we envision future PSM systems taking the form of collaborative robots, that is, cobots or socially interactive agents working alongside the user. The user could delegate some of the decision making to a personal agent that, over time, builds an increasingly accurate model of the user and their preferences and typical cognitive biases. This could allow maximally automated tasks (for example, continuous pre-selection of relevant candidates among the whole population and recommending them at an opportune moment), implementing the idea of prescriptive analytics.9 Such automatic modeling of other people and their suitability naturally poses challenges considering not only data availability but also data protection regulations and other ethical issues, which can become greater hindrances than the engineering of such mechanisms.

Proactive nudging for behavioral change. While the previous section revolved around how the user steers the system, user-system cooperation also touches the system's influence on user behavior. To address the goals regarding serendipity, optimal diversity, and systemic perspective, we expect that typical end users need to be nudged away from their habitual and individually oriented preferences in networking. The notion of diversity-sensitive design can be considered to mitigate trust issues in exposing the user to diversity.16 To this end, the concepts of persuasive computing12 and gamification have been long studied in human-computer interaction as mechanisms for supporting behavioral change. While the general approaches have been successfully applied in application areas like exercising and education, it remains an open question how user interfaces could meaningfully support and affect the rather intimate decisions around professional collaboration.

Proactive systems for PSM pose new challenges for user interface design as they manifest design ethics beyond the will of a userthe traditional fundament in human-computer interaction.

Matching people and interests is already enabled by various digital platforms and social media. However, to date, there are few solutions that would take a more explicit and proactive role in social matching (for example, recommending a person to meet someone when the situation is opportune). In content recommender systems, the recommendations are typically provided while the user is actively using the service. However, PSM calls for technology that takes a more active role and has its own judgment of what are optimal matchesthat is, a moral stanceas well as when and where to present the recommendations.

Proactive systems for PSM pose new challenges for user interface design as they manifest design ethics beyond the will of a userthe traditional fundament in human-computer interaction. The computational design ethics would need to balance between an individual's preferences (that is, their habitual behavior) and the greater good for an organization, business ecosystem, or other social entity (that is, systemic perspective). This requires careful encoding of the ideals and mechanisms for the user to adjust them when necessary. Proactive PSM also requires new interface design solutions that sufficiently preserve the user's agency to maintain trust and acceptance.

The conventional subtle ways of enabling serendipity in content recommenders, such as adding randomness to the results or removing top-ranked results, might not be enough for PSM systems. Rather, this application area calls for solutions that avoid bias and prejudice. For example, relevant approaches could include hiding a recommended person's profile picture or name (as strong indicators of gender, ethnicity, and socioeconomical stance) or hiding details about professional background and education. Revealing some commonalities is important for building interpersonal trust, whereas the relevance of the complementary qualities needs to be considered with respect to the collaboration need at hand. Rankings and ratings tend to encode human bias,29 which means the presentation of the matches should focus on qualitative descriptions rather than numeric ones.

Persuasion can also manifest itself via facilitation of forming the connection. For example, in an event context with low-risk matching, the matched actors can be given a playful challenge to explore the commonalities and complementariness by not revealing the exact reason behind the recommendation, such as in Chen et al.8 Here, the human capabilities in identifying possible matches could also be harnessed beyond the primary end user, for example, encouraging a third party to serve as a matchmaker between people they know, thus facilitating newly recommended connections and validating the ill-reasoned recommendations that an algorithm might provide.

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Social matching is ubiquitous in professional life, yet suboptimally supported by computational systems. Based on a multidisciplinary review of the literature, we outline the complex problem space of Professional Social Matching, and we define design goals for computer-supported PSM and requirements for developing next-generation systems.

We suggest that many conventional approaches in recommender systems and social link prediction, when applied to PSM, could have detrimental long-term implications for organizations' and individuals' performance. Conventional mechanisms, such as optimizing for similarity and triadic closure, involve risks of strengthening the human biases of homophily and echo chambering. We call for diversity-enhancing and contextually sensitive designs of future PSM systems, tapping on multi-dimensional analytics of not only the potential matched actors but also the intended type of collaboration and organizational context. Further, we call for a paradigmatic shift from automated recommender systems toward decision-support systems that are based on meaningful user-system cooperation.

All in all, analysis of this application area underlines the importance and urgency of rethinking some paradigmatic algorithmic approaches. In such a complex and interdisciplinary area as PSM, reconsidering the conventions is not only beneficial; it is a necessity.

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Thomas Olsson ([email protected]) is an associate professor at Tampere University, Finland.

Jukka Huhtamäki ([email protected]) is a postdoctoral researcher at Tampere University, Finland.

Hannu Kärkkäinen ([email protected]) is a professor of information knowledge and management at Tampere University, Finland.

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a. https://tinder.com/

b. https://www.happn.com/en/

c. https://www.brella.io/

d. https://grip.events/

e. www.shapr.co

f. http://bit.ly/2mvBU5m

g. Hu-mimesis: Design Requirements for Personal Relevance, https://www.youtube.com/watch?v=pg0xU-6PQII

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