Subgroup Formation in Human-Robot Teams
Subgroup Formation in Human–Robot
Teams
Completed Research Paper 
Sangseok You
HEC Paris
1 Rue de la Liberation, Jouy-en-Josas,
France
you@hec.fr 
Lionel P. Robert Jr.
University of Michigan
105 S. State St., Ann Arbor, Michigan,
USA
lprobert@umich.edu 
Abstract
Subgroup  formation  is  vital  in  understanding  teamwork.  It  was  not  clear  whether
subgroup formation takes place in human–robot teams and what the implications of the
subgroups might be for the team’s success. Therefore, we conducted an experiment with 44
teams  of  two  people  and  two  robots,  where  each  team  member  worked  with  a  robot  to
accomplish  a  team  task.  We  found  that  subgroups  were  formed  when  team  members
identified with their robots and were inhibited when they identified with their team as a
whole.  Robot  identification  and  team  identification  moderated  the  negative  impacts  of
subgroup formation on teamwork quality and subsequent team performance.  
Keywords: Robots, subgroup, human–robot collaboration, teamwork quality, performance
Introduction
The use of physical robots to support teamwork continues to increase (Gombolay et al. 2014). Robots are
employed  in  human–robot  teams  to  accomplish  teamwork  (You  and  Robert  2018).  The  National
Aeronautics and Space Administration (NASA) uses remote-controlled robots paired with humans to work
alongside astronauts on space missions (Hoffman and Breazeal 2007). Construction sites and urban search-
and-rescue teams are employing robots for dangerous and labor-intensive tasks. Robots are often viewed
as unique and distinct from other team technologies because of their physical embodiment (You and Robert
2018). Physical embodiment can cause individuals to project identities and personalities onto robots and
view them as humans (Groom and Nass 2007). As a result, individuals can develop strong emotional bonds
with robots (Hiolle et al. 2012).  
Emotional  bonds  with  technologies  have  received  much  attention  from  scholars  in  several  domains
including information systems (IS) and human–computer interaction (HCI) (Suh et al. 2011; Vincent 2006;
Zhang 2013). Generally, these emotional bonds have been viewed as beneficial because they promote the
adoption  and  the  continual  use  of  technology  (Kim  et  al.  2010;  Robert  2017).  Emotional  bonds  with
technology  have  also  been  associated  with  more  engagement,  enjoyment,  and  better  performance  with
using the technology (Li et al. 2006). Research suggests that individuals develop strong bonds with robots
(Hiolle et al. 2012). Yet, IS scholars have paid little attention to the impacts of emotional bonds with robots. 
Although much attention has been directed at the positive outcomes associated with humans’ emotional
bonds  with  robots  and  other  technologies,  little  attention  has  been  paid  to  understanding  the  potential
drawbacks in human–robot teams. The formation of faultlines may be one such drawback. Faultlines are
hypothetical divisions that can split teams into smaller subsets (Lau and Murnighan 2005). Research on
faultlines has consistently shown that strong bonds within a subdivision of the team relative to the bonds
among all team members can lead to subgroups (see Carton and Cummings 2012 for a review). Subgroups
can  divide  the  team  and  create  discord  among  team  members  (Bos  et  al.  2010).  This  explains  why  the
emergence  of  smaller  groups  (i.e.  subgroups)  within  teams  has  been  found  to  undermine  teamwork
(O’Leary and Mortensen 2010).  
Fortieth International Conference on Information Systems, Munich 2019
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Subgroup Formation in Human-Robot Teams
Is  it  possible  that  humans  can  form  bonds  with  robots  that  are  strong  enough  to  create  subgroups?
According to the literature on robots, people develop emotional bonds with their robots in much the same
way they do with other people (Hiolle et al. 2012; Robert 2018; You and Robert 2018). This suggests that
the human–robot relationships within a team could act as the basis for a faultline. If this is true, would the
emergence  of  subgroups  be  detrimental  to  the  success  of  human–robot  teams?  Although  no  study  has
explicitly  examined  faultlines  in  human–robot  teams,  one  study  has  found  evidence  that  attachment  to
robots  can  be  detrimental  to  the  success  of  human–robot  teams.  In  explosive  ordnance  disposal  (EOD)
teams, attachment to a robot made operators hesitant to deploy the robot to dangerous missions, and, as a
result,  the  effectiveness  of  the  EOD  team  was  decreased  (Carpenter  2013).  These  findings  suggest  that
strong bonds with robots do not always result in positive outcomes.  
Despite the importance of faultlines and the subgroups they create in traditional teams, the consequences
of  faultlines  in  human–robot  teams  remain  relatively  unexplored.  Yet,  as  robots  are  increasingly  being
designed  to  elicit  social  and  psychological  responses,  this  becomes  vital  to  understanding  how  such
reactions are likely to manifest themselves in human–robot teams. We believe this calls for IS scholars to
broaden  our  view  of  the  role  of  technology.  In  this  paper,  we  began  to  explore  the  concept  of  subgroup
formation in human–robot teams with the following research question. 
RQ) How does a bond between a human and his or her robot influence the formation of human–
robot subgroups and the subsequent team outcomes? 
Our goal is to determine whether the bonds between team members and their robots can act as a faultline
and have negative effects on team outcomes as they do in traditional teams. We examined 44 human–robot
teams. Results offer evidence for both the existence and impacts of subgroups in human–robot teams. 
Background
Robots in the Current Study
Although definitions of robots vary widely across disciplines, we highlight the most common characteristic
for  this  study:  the  physical  embodiment.  The  physical  embodiment  distinguishes  robots  from  other
technological agents, such as chatbots, recommendation agents, and avatars (Ziemke et al. 2015). Due to
robots’  physical  embodiment,  interactions  with  these  robots  are  qualitatively  different  from  those  with
other technological agents because they allow for more visceral and tangible experiences, such as touching
and hitting (Lee et al. 2006). Existing in the same physical space enables people to interact with a robot
“real-time and real-space, here and now” (Dourish 2001, p. 235). We believe that the physical embodiment
is a key property of robots that creates strong bonds between an individual and a robot. Thus, the robots in
this paper were chosen primarily to manifest physical embodiment rather than intelligence, autonomy, or
human-likeness. 
Bonds with Technology and Robots
Research  has  shown  that  strong  bonds  with  a  technology  artifact  can  have  important  implications  for
understanding technology use. The basic premise behind the importance of bonds with technology is that
the stronger the bonds individuals feel to a technology artifact, the more they prefer to use it and enjoy
using  it.  Typically,  the  consequences  of  the  bonds  with  technology  are  positive.  For  instance,  emotional
attachment  has  been  positively  related  to  individuals’  willingness  to  use  and  continue  to  use  their
technology, such as a mobile phone and an online avatar (Kim et al. 2010; Suh et al. 2011). Emotional bonds
with technology can also enhance the quality of interaction. Individuals who built an emotional bond with
avatars felt higher levels of social presence in videogames and a better shopping experience in virtual worlds
(Kim  et  al.  2015;  Suh  et  al.  2011).  Also,  emotional  bonds  with  robots  were  shown  to  increase  the
performance and viability of human–robot teams (You and Robert 2018). However, emotional bonds with
technology can also have adverse effects. People sometimes hesitate to adopt new technology when they
develop strong bonds with their current technology (Read et al. 2011). 
Emotional bonds have been crucial to understanding the interaction between humans and robots because
of the embodied presence of robots (Groom and Nass 2007). Physically embodied objects (as opposed to
digital objects) tend to elicit visceral interactions (Schifferstein and Zwartkruis-Pelgrim 2008). Individuals
are often more engaged with physical objects and exert more effort to maintain relationships with them 
Fortieth International Conference on Information Systems, Munich 2019 2
Subgroup Formation in Human-Robot Teams
(Lee et al. 2006). This explains, in part, why people can build emotional bonds with physically embodied
agents like robots more easily than virtual avatars (Groom and Nass 2007; Lee et al. 2006). 
The importance of human–technology bonds has prompted both IS and HRI researchers to investigate the
conditions that promote these bonds. The degree to which people believe that a technology artifact is a part
of them or represents them has been found to be a facilitator of emotional bonds with technology (Lee and
Sundar  2015).  This  can  come  in  the  form  of  perception  of  shared  identity  between  people  and  their
technology  in  terms  of  characteristics  (Vincent  2006),  personality  (Govers  and  Mugge  2004),  and
appearance (Suh et al. 2011). Such bonds can be facilitated when users build, personalize, or customize their
technology artifacts and robots (Lee and Sundar 2015). This is because people often view the artifacts they
create or personalize as representations of themselves (Ahuvia 2005).  
Subgroup Formation in Teams
Although  the  implications  of  faultlines  and  subgroup  formation  have  not  been  studied  in  the  context  of
human–robot teams, both have an extensive literature base (Thatcher and Patel 2012). Next, we review the
literature on faultlines and subgroups within teams. We also introduce the idea of faultlines and subgroup
formation in human–robot teams. Specifically, we discuss how the human–robot relationship can act as a
faultline in human–robot teams and lead to subgroup formation.  
Faultlines — which represent potential breaks within teams — have been used to explain the formation of
subgroups  within  teams.  These  potential  breaks  can  be  the  basis  for  division  within  teams  (Lau  and
Murnighan  2005).  Faultlines  have  been  based  on  variables  such  as  race,  gender,  age,  and  occupation
(Thatcher  and  Patel  2012).  Theories  related  to  faultlines  suggest  that  team  members  are  likely  to  form
stronger bonds with those they are more similar to (Lau and Murnighan 2005; Li and Hambrick 2005). For
example, in a team with two engineers and two accountants, occupations could potentially be a faultline.
Faultlines increase in strength as the number of similar attributes between members within a subdivision
increases  relative  to  the  number  of  differences  across  subdivisions  (Polzer  et  al.  2006).  In  the  previous
example, if the two engineers were men and the two accountants were women, the strength of the potential
faultline would increase because it would include gender and occupation. 
Subgroups  can  form  when  faultlines  are  activated  (Bezrukova  et  al.  2009;  Thatcher  and  Patel  2012).
Subgroups are a subset of the team consisting of two or more members (Carton and Cummings 2012). The
presence of subgroups has been associated with negative implications. Subgroup formation has been found
to reduce variables that promote teamwork, such as trust and satisfaction, while increasing variables that
are  harmful  to  teamwork,  such  as  conflict  (Cronin  et  al.  2011;  Pearsall  et  al.  2008;  Robert  2016a).
Traditionally, subgroup formation has been studied in collocated teams, but recent studies have found the
evidence  in  virtual  teams  (Robert  2016b).  In  many  cases,  subgroups  are  formed  in  geographically
distributed  teams  when  team  members  form  stronger  bonds  with  collocated  team  members  than  with
dispersed members (Polzer et al. 2006). Subgroups in virtual teams have been associated with more conflict
and  coordination  problems,  lower  trust,  lower  team  identification,  and  lower-functioning  transactive
memory systems (O’Leary and Mortensen 2010; Spell et al. 2011). 
Although there are many ways to measure faultlines, the underlying core logic remains similar. When team
members  form  stronger  bonds  within  subdivisions  than  with  the  team  as  a  whole,  the  team  is  likely  to
fracture into subgroups. The word likely should be emphasized because faultlines do not always lead to
subgroup formation (Homan et al. 2007). Faultlines do, however, provide the basis for which subgroup
formation occurs within teams (Lau and Murnighan 2005). There is still much ongoing research into what
activates faultlines from potential to actual subgroup formation (Jehn and Bezrukova 2010; Pearsall et al.
2008). Most scholars seem to agree that once activated, subgroups can be harmful to effective teamwork
(Jehn and Bezrukova 2010; Thatcher and Patel 2012). 
Despite the rich evidence of the effects of subgroups in teams, researchers are only beginning to examine
how  robots  can  contribute  to  the  formation  of  subgroups  and  how  this  can  influence  team  outcomes.
Faultlines are often anchored on the perception of relatively stronger bonds with one than another. Thus,
it  is  possible  that a team of two humans each working with a robot can fracture  into  two  human–robot
subgroups based on the team members’ strong bonds with the robots. We learned from prior research that
people  often  develop  strong  emotional  bonds  with  their  robots  (Friedman  et  al.  2003;  You  and  Robert
2018). The bonds are as strong as or stronger than the ones people develop with other humans and pets 
Fortieth International Conference on Information Systems, Munich 2019 3
Subgroup Formation in Human-Robot Teams
(Krämer  et  al.  2011;  Melson  et  al.  2009).  Therefore,  we  believe  that  human–robot  bonds  can  act  as  a
faultline and, when triggered, lead to subgroup formation. Thus, we investigated the existence of human–
robot subgroups and the implications associated with the outcomes of human–robot teams.  
Hypotheses Development
To understand the implications of subgroup formation in human–robot teams, we developed a theoretical
model (Figure 1). The model posits that the relationship between an individual and a robot can be the basis
of a faultline. In particular, this faultline can become activated when individuals in teams establish stronger
bonds with their robots than with a human teammate. The model draws from social identity theory (Hogg
et al. 2004) to describe how identity-based bonds can result in subgroups in human–robot teams. Robot
identification (i.e. identifying oneself with a robot) is likely to engender subgroups based on human–robot
bonds,  while  team  identification  (i.e.  identifying  oneself  with  the  whole  team)  is  likely  to  reduce  the
formation  of  subgroups.  The  model  also  illustrates  the  moderation  effects  of  both  robot  and  team
identification  for  teamwork  quality.  Specifically,  subgroup  formation  decreases  teamwork  quality  when
robot identification is higher than low, whereas it increases teamwork quality when team identification is
higher than low. 
Robot
Identification
+ H1
– H3
Human
Robot
Subgroup
– H2
+H4
Team
Identification
Human	Robot
Teamwork
Quality
H5
Human	Robot
Team
Performance
Figure	 1.	Research	Model
Figure 1 Research Model 
Robot Identification and Subgroup Formation
Robot  identification  is  associated  with  increases  in  subgroup  formation  in  human–robot  teams.  Robot
identification can be defined as the extent to which individuals believe their robot is a part of the self (You
and Robert 2018). This can happen because individuals believe that an object and themselves share the
same  qualities  (Connell  and  Schau  2013).  Robot  identification  can  be  viewed  as  a  specific  instance  of
material  identification.  Material  identification  can  be  represented  by  the  concept  of  self-extension  and
occurs when an individual becomes attached to a material object  (Mugge et al. 2009). Self-extension, as it
pertains to material identification, literally means to extend one’s self to include a material object (Belk
2013). Self-extension has been used to explain brand identification (Kim et al. 2001), digital goods (Belk
2013), and avatars (Suh et al. 2011; You and Sundar 2013). 
Robot  identification  represents  a  strong  attachment  to  the  robot  when  individuals  have  extended
themselves to include the robot (You and Robert 2018). In the first place, robot identification speaks to the
individual-level psychological process based on the individual’s relationship with his or her robot. However,
in  teams  working  with  multiple  robots,  team  members  use  and  control  their  own  robot  as  part  of  the
collaboration with other teammates (Yanco and Drury 2004). Thus, the shared experience of identification
with a robot can also be viewed as a team-level phenomenon. In such cases, subgroup formation is likely to
occur when individuals have a stronger relationship within their subdivision than across the team as a whole
(Cronin et al. 2011). In a human–robot team, the relationship between an individual and his or her robot
engenders the subdivision of the whole team. All things being equal, the likelihood of subgroup formation
increases as an individual’s identification with his or her robot increases. 
Hypothesis 1: Robot identification increases subgroup formation in human–robot teams.
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Subgroup Formation in Human-Robot Teams
Team Identification and Subgroup Formation
Team  identification  is  associated  with  decreases  in  subgroup  formation  in  human–robot  teams.  Team
identification is defined as “the extent to which members are psychologically identified with a group” (Scott
1997, p. 120). Team identification is derived from social identity theory (Hogg et al. 2004). Social identity
theory helps to explain who we are in comparison to others (Hogg et al. 2004). Team identification occurs
when  individuals  believe  their  identity  overlaps  with  the  team’s  identity  (Van  Der  Vegt  and  Bunderson
2005). When this occurs, their membership in the team becomes self-defining (Janssen and Huang 2008). 
Team identification has been described as the glue that binds team members together (Bezrukova et al.
2009). This is because team identification promotes strong inter-team relationships, in part by leading team
members  to  view  their  teammates  more  positively  (Gibson  and  Vermeulen  2003).  For  example,  team
identification  has  been  found  to  increase  trust  toward  team  members  (Han  and  Harms  2010).  Trust  is
associated  with  strong  interpersonal  bonds  among  all  team  members  while  team  identification  also
facilitates inter-team relationships by reducing conflict and promoting cohesion and a sense of a shared
faith (Robert and You 2018; You and Robert 2018).  
Team identification represents a strong bond to one’s team. Teams with members who are psychologically
bonded to the team as a whole have less chance of fracturing into subgroups (Ren et al. 2014). Conversely,
fractures are likely to occur when individuals  have a stronger relationship within their subdivision than
across  the  team  (Dovidio  and  Gaertner  2000).  Thus,  when  human–robot  teams  are  high  in  team
identification, there is a greater chance that the relationship between an individual and his or her robot will
be  offset  by  the  relationship  between  the  individual  and  the  team.  As  a  result,  increases  in  team
identification should reduce the likelihood of subgroup formation in human–robot teams. 
Hypothesis 2: Team identification decreases subgroup formation in human–robot teams.
Moderation Effects of Robot Identification and Team Identification
In this study, we built and tested a theoretical model to explain the impacts of human–robot subgroups in
human–robot  teams.  We  drew  on  theories  related  to  intra-group  bias,  subgroup  formation,  and  dual
identification. Theories on the intra-group bias, subgroup formation, and dual identification suggest that a
subgroup’s strength and the presence of a collective identity might help dictate the influence of a subgroup.
Empirically,  several  meta-analyses  offer  strong  evidence  to  support  these  assertions  (see  Carton  and
Cummings 2012 for a review). Taken together, both theory and empirical evidence suggest that the presence
of a collective identity alters how subgroup formation influences teamwork and performance.  
Negative Impacts of Subgroup Formation on Teamwork Quality
Generally, the subgroup formation has been found to reduce teamwork quality by increasing divisiveness
within teams (Robert 2016a). Divisiveness degrades teamwork quality by negatively influencing members’
perception  of  their  teammates  and  the  work  experience  with  them.  Subgroup  formation  can  lead  team
members to make negative attributions about members who are perceived to be outside the subgroup. The
same  actions  taken  by  outgroup  teammates  is  likely  to  be  viewed  more  negatively  when  subgroups  are
formed (Cronin et al. 2011). This reduces intergroup relationships among team members and heightens the
potential  for  conflict  (Bezrukova  et  al.  2009).  When  this  occurs,  team  members  are  likely  to  experience
more frustration, anxiety, and discomfort (Lipponen et al. 2003; Polzer 2004). Increases in these factors
should degrade teamwork quality. 
Subgroup formation is also likely to reduce the motivation of team members. Team members are less likely
to exert much effort when they do not trust the actions taken by outgroup teammates (Kameda et al. 1992).
Research on effort-withholding in teams has repeatedly shown that negative attributions to one’s teammate
or poor inter-team relationships are largely associated with members putting less effort toward the team’s
objectives (Srinivasan et al. 2012).  
In the following, we build on the prior literature on identity theory and subgroup formation to explain the
moderation effect of subgroup formation for the relationship between different identification mechanisms
and team outcomes in Hypotheses 3 and 4. Specifically, although subgroup formation generally decreases
teamwork quality, the adverse effects of subgroup formation can be harnessed by different identification 
Fortieth International Conference on Information Systems, Munich 2019 5
Subgroup Formation in Human-Robot Teams
mechanisms in teams working with robots. As discussed, the negative effects of subgroup formation have
been observed in research on teamwork (see Carton and Cummings 2012 for a review). The evidence from
research on teamwork offers an explanation to the negative relationship between the subgroup formation
and performance in human–robot teams (Homan et al. 2007; O’Leary and Mortensen 2010).  
Robot Identification, Subgroups, and Teamwork Quality
Scholars have identified the strength of subgroups as a critical element in understanding the relationship
between subgroups and teamwork. The logic is simple. As the strength of subgroups increases, so does the
divisiveness  in  the  team.  This  divisiveness  manifests  itself  in  many  forms,  such  as  conflict  and  discord
(Goyal  et  al.  2008).  The  subgroup  strength  has  also  been  shown  to  alter  variables  like  satisfaction  and
performance (Cronin et al. 2011).  Subgroups can have positive impacts on teamwork quality by providing
emotional and psychological support to its members. This view of subgroups was originally put forth by
Gibson and Vermeulen (2003). They found empirical evidence that moderate levels of subgroup strength
facilitate learning in teams. They argued that moderate levels of subgroup strength provide team members
with a safe space to engage in the learning process. This was in contrast to when subgroup formation was
weak  or  strong.  When  subgroup  strength  was  weak,  subgroups  had  little  or  no  relationship  with  team
learning. When subgroup strength was strong, subgroups actually decreased team learning by creating a
divisive  environment.  Other  scholars  have  found  evidence  that  subgroup  formation  can  have  positive
impacts on teamwork in the form of social integration, open communications, and perceptions of fairness
(Robert 2016b; Spell et al. 2011).  
In a similar vein, robot identification should moderate the relationship between subgroup formation and
teamwork quality in human–robot teams. Specifically, subgroups should hurt teamwork quality when robot
identification is high. When subgroups are formed, increases in robot identification result in increases in
the strength of the subgroup. High levels of robot identification coupled with subgroup formation lead to
the divisiveness associated with subgroups by reinforcing the subgroup boundaries. As many studies have
shown, divisiveness is likely to be associated with decreases in teamwork quality (Thatcher and Patel 2012).
We believe this condition best represents the high levels of subgroup formation observed by Gibson and
Vermeulen (2003). Studies have shown that individuals can build a strong bond with a robot that surpasses
teamwork among human teammates. For instance, because of strong bonds with a bomb disposal robot,
soldiers sometimes do not want to deploy the robot to dangerous missions that expose the robot to the risk
of destruction (Carpenter 2013). 
Conversely, subgroups should have a positive impact on teamwork quality when robot identification is low.
We  believe  this  condition  represents  the  low  levels  of  subgroup  formation  observed  by  Gibson  and
Vermeulen  (2003).  In  their  study,  subgroup  formation  revealed  positive  effects  on  the  team  learning
experience. We expected a similar mechanism to be at play in teams with subgroups and low levels of robot
identification.  Subgroups  based  on  human–robot  bonds  might  provide  a  comfortable  and  enjoyable
interaction with robots without interfering with the team’s collective, collaborative effort. Therefore, when
robot identification is low, increases in subgroup formation should lead to increases in teamwork quality. 
Hypothesis  3:  Robot  identification  moderates  the  impact  of  subgroup  formation  on  teamwork
quality. Subgroup formation decreases teamwork quality when robot identification is high and
increases teamwork quality when robot identification is low. 
Team Identification, Subgroups, and Teamwork Quality
Theories related to dual identification posit that individuals seek to be a part of smaller subgroup while
being a part of a larger collective identity (Hogg et al. 2004; Richter et al. 2006). According to these theories,
a collective identity could alter the effects of a subgroup. A collective identity can act as a unifying force that
can bridge the divide between subgroups (Lau and Murnighan 2005; Ren et al. 2014). The bridging can
allow  both  subgroups  to  exist  along  with  a  broader  collective  identity  without  the  negative  effects
traditionally  associated  with  subgroups  (Ren  et  al.  2014).  Several  studies  examining  the  influence  of
subgroups have found evidence of the benefits of a collective identity in teams with subgroups (Thatcher
and Patel 2012).  
It is important to note that, in this paper, we go further than simply stating that team identification can
reduce the negative impacts of the subgroup formation. We propose that team identification determines 
Fortieth International Conference on Information Systems, Munich 2019 6
Subgroup Formation in Human-Robot Teams
when subgroup formation can have a positive or negative impact on teamwork quality. To do so, we draw
attention to the literature on dual identification. Theories around multiple identifications in organizations
assert that identification with a workgroup can have a positive impact when that identity is nested within a
larger  superordinate  organizational  identity.  Richter  et  al.  (2006)  examined  the  impact  of  workgroup
identification on inter-work group conflict and productivity. They found that when employees identified
with their organization, work identification was associated with decreases in conflict and increases in inter-
work  productivity.  Van  Dick  et  al.  (2008)  found  that  workgroup  identification  only  leads  to  more  job
satisfaction and extra-role behavior when employees also identify with their organization.  
Richter et al. (2006) and Van Dick et al. (2008) did not examine subgroup formation. However, given these
findings, we expect that team identification should moderate the impact of subgroup formation in human–
robot teams. Subgroup formation should increase teamwork quality when team identification is high. When
this occurs, teams should benefit from both the emotional support of a subgroup member (i.e. robot) and a
collective  identity.  However,  when  team  identification  is  low,  the  subgroup  formation  represents  the
divisiveness associated with subgroups. 
Hypothesis  4:  Team  identification  moderates  the  impact  of  subgroup  formation  on  teamwork
quality by increasing teamwork quality when high and decreasing teamwork quality when low. 
Teamwork Quality and Human–Robot Team Performance
Last, we posit that teamwork quality increases the performance of human–robot teams. Teamwork quality
is a team’s perception of the interactions involved during the teamwork. Teamwork quality, thus, includes
the degree to which team members enjoy and are satisfied with teamwork and the perceived support from
teammates (Dayan and Di Benedetto 2008; Easley et al. 2003). Prior literature demonstrates the positive
link between the quality of teamwork and the team’s performance (Hoegl and Gemuenden 2001). 
Prior studies have not examined the impacts of teamwork quality on performance in human–robot teams
(Oriz et al. 2010). However, they at least provide evidence by examining constructs similar to the perception
of teamwork quality. Hoffman and Breazeal (2007) reported perceived efficiency of collaboration with a
robot as a measure of successful teamwork.  
We believe that the general mechanism of teamwork quality increasing team performance can also apply to
human–robot teams. Specifically, positive teamwork quality can lead team members to be more committed
to the teamwork to maintain the ongoing positive experience. Also, good teamwork quality often indicates
good interaction, coordination, and communication among teammates and the effective use of the robots,
all of which contributes to better team performance (Hoegl and Gemuenden 2001). 
Hypothesis 5: Teamwork quality increases team performance in human–robot teams.
Method
As part of a larger research project, we conducted a 3 x 1 between-subjects lab experiment with individuals
recruited at a large university in the United States. We randomly assigned 88 individuals (mean age = 23.6,
standard deviation [SD] = 4.1, 42 females) to 44 teams, each of which consisted of two humans and two
robots. Teams were randomly assigned to one of the three conditions in the experiment: robot identification
(15 teams), team identification (14 teams), and control (15 teams). Each participant was paired with a robot
to accomplish a team task. Participants were paid $20 and received additional compensation based on their
team performance against other teams in the experiment. 
Experimental Task and Robots
The objective of the task was to move water bottles from one point to another point (Figure 2). There were
marks on the experimental setting area, indicated as Points A, B, and C. Participants were asked to control
their robots to move five water bottles from Point A t