Instructional Improvement of Secondary School Teachers through Effective Academic Supervision by the Vice-Principals

Orenaiya Solomon Adewale 1

Journal of Education and Human Development
June 2014, Vol. 3, No. 2, pp. 607-617
ISSN: 2334-296X (Print), 2334-2978 (Online)
Copyright © The Author(s). 2014. All Rights Reserved.
Published by American Research Institute for Policy Development

Astract
Academic  supervision  and  teachers’  classroom  instruction  are  two  instructional
activities  which  closely  related  with  the  intention  of  developing  teachers  to  the
required  higher  level  of  instructional  competencies.  Research  questions  and
hypotheses were formulated to provide insight into the instructional improvement
level of classroom teachers by the effective monitoring by  the vice-principal. The
role of vice-principal as instructional leaders is to influence the quality of secondary
school education. The teachers’ improvement level will be evaluated in mastery of
subject  matter,  teaching  skills,  and  use  of  teaching  resources.  From  the  internal
academic supervision, there are three levels namely; the upper level (principals/viceprincipals),  middle  level  (head  of  departments)  and  the  lower  level  (subject
heads).From  all  indications,  internal  academic  supervision  is  the  sure  best  for
improving the present quality and also maintaining higher standards because of its
ease  of  access,  cordial  relationship  to  teachers  for  monitoring,  correction  and
entrenchment  of  ideas  and  innovations.  The  implication  of  this  paper  is  to  be
manifested in instructional practices which will facilitate students’ learning status to
improve  to  higher  level  of  academic  achievement  which  we  all  desired  by  all
stakeholders in education.
Keywords:  Instructional  improvement,  secondary  school  teachers,  effective
supervision, vice-principals and Nigeria
Introduction
The  last  ten  to  twelve  years  of  educational  performance  and  evaluation  in
Ogun State, Nigeria had witnessed a drastic down trend in the academic performance
of  secondary  school  students,  dwindling  image  of  teachers  and  academic  and
economic values of secondary education in its entirety.
This  could  be  due  to  a  number  of  factors  from  the  parents,  students,
Governmenteducational policies, teachers highly accused, and Government’s agency
responsible  for  control,  monitoring  and  supervision  and  economic  recessio n  and
political  instability.  The  most  influential  and  impacting  to  the  existing  status  is  the
supervision  which  hither  to  had been  the  sole  responsibility  of  external  supervisors
from  the  Governmental  agencies  such  as  inspectorate  services  of  the  ministry  of
education and teaching service commission but their effects were not reflected in the
academic performance of students because of distance between them and teachers on
the  field,  thus  vice  principals  are  academically  and  professionally  qualified  to
effectively complement and further supervise classroom instruction for higher level
performance. An effective vice principal will develop teachers, while an effectiveness
in   teaching  will  produce  academically  and  economically  good  students  that  will  be
useful to themselves, parents ,government and society at large.
Therefore,  nature  of  academic  supervision  responsibility  required  from  the
vice-principals is to focus on the process of overseeing what the teachers teach, the
medium of teaching, how the teaching is done and giving solutions to challenges. The
processes encompasses spending quite number of hours/periods on teachers’ content
of instruction, usage of teaching materials and demonstrate the expected practices that
will improve academic achievement of students in examinations. This is because the
most  significant  criteria  or  factor  directly  influencing  the  quality  of  the  education  a
child receives is the quality of his teacher.
The principals and vice-principals have tailored their daily activities in schools
to  administrative  supervision,  leaving  the  academic  supervision  barely  open  to
external  supervisors  whose  efforts  have  no  continuity  and  constancy,  thereby
academic achievements of students under the responsibility of teachers have continue
to be declining. This has provided escape route for external supervisors to declare that
they have played their own part, what is now left is for the teachers to do their own
part.
And  to  be  practical,  there  is  a  wide  gap  between  external  supervisors  and
teachers,  which  the  vice  principals  can  academically  and  professionally  filled  as
connectors  and  implementers between  supervisors and  teachers of  which  my  paper
want  to  fill  the  missing  gap.  A  question  requiring  answer  is  “where  does  the  viceprincipal derive their positional role as instructional leader”?
The  simple  answer  is  that  the  teaching  service  ‘s  teachers  ‘manual  of  Ogun
State  teaching  service  commission  confers  the  position  of  principal  as  the
instructional leader, academic and administrative heads.  It further states that the vice
principal is to assist principal in the day to day activities of the school and act in the
absence  of  the  principal.  The  principal  is  the  headteacher,  instructionalsupervisor,
chief education officer, executor of instructional programme, teacher of teachers and
curriculum directorNakpodia( 2011)
Cawood&Gibbon (1990) opined academic supervision in terms of leadership
aims  at  renewal  of  objectives,  professional  growth  and  educational  improvements
also;  Gorton  (1983)  defined  academic  supervision  as  those  activities  engaged  by
individual,  groups  whose  main  purpose  is  the  improvement  of  person,  group  or
programme. I  will  end  this  introductory  review  with  Beach&Reinhartz  (2000)  while
emphasizing  that  supervisors  should  be  mentors  and  friends  in  relationships  to
support teachers and provide support in a relaxed atmosphere for providing learning
environment in the classroom.
Therefore, the various elements or constructs in the definitions above such as
interactions,/relationship  ,co-operative  behaviours  ,leaderships,mentors,support  to
teachers and improvement which the vice-principals can and will fill adequately and
efficiently in this paper.Moreover,the content of this paper will focus on the following
areas  of  academic  supervision  on  mastery  of  subject  matter,  usage  of  teaching
resources  and  teaching  skills.  The  effectiveness  of  instructional  supervision  implies
that a desired effect will be observed to take place as an improvement in the teachers’
teaching process supervised by the vice-principals in secondary schools.
Objectives of the Paper
1.To improve the quality of secondary school education through regular instructional
supervision in the classroom.
2.To measure effectiveness of instructional supervision in relation to teachers level of
instruction.
3.  To  find  out  the  contribution  of  the  frequency  of  vice  principals’  visitation  to
classrooms for instructional monitoring.
4.  To  find  out  if  there  is  a  relationship  between  vice  principals  and  teachers  in
instructional improvement of secondary schools.
5. To ascertain if vice-principals have portfolio documents for professional growth
of teachers.
Statement of Problem
Since the last ten years of academic achievement results of secondary school
students  released  by  the  internal  and  external  examination  bodies  in  Ogun  State,
Nigeria  has  not  been  impressive.  This  has  generated  negative  comments  and  poor
evaluation  on  the  part  of  teachers,  educationinspectors,  recruitment  agency  for
teachers and the government for not alive to their responsibility.
The state and federal government responded by conceiving and conceding to
re-organise  the  inspectorate  department  so  that  education  inspectors/external
supervisors  would  be  more  effective  in  their  duties  to  improve  instructions  in
secondary schools FGN(2006).
The  irregularity  and  low  frequency  of  visitation  to  schools  by  education
inspectors  because  of  transportation  challenges  and  low  numbers  of  staff  in  their
department  makes  the  problem  unresolved  thus  form  the  platform  to  look  inward
into  the  school  site  to  find  a  connector  who  will  continue  from  where  external
supervisors  stops  and  serve  as  a  bridge  between  education  inspectors  and  teachers
hence the reason underlying my resolve to conduct a study on the contributory role of
vice-principal  in  ensuring  instructional  improvement  of  teaching  workforce  in
secondary schools.
In  addition  to  the  above  justification,  is  that  the  principals  are  surrounded
with administrative and social matters justified their less concentration on academics
but  vice principals  who sits endlessly  in the office without any designated duties as
some principals exclude their vices or deputies from administrative duties support the
need for the principals to concede academic supervision to their vices while countersupervise or demand for daily or weekly report of instructional duties in the schools.
Instructional  supervision  is  less  monitored  or  not  done  at  all  in  secondary  schools
because the external supervisors such as the education inspectors, zonal secretaries are
not impacting positively over long period of time because their periods of visitations
is low or extremely scanty.
In addition, the quality of supervision may be doubtful because most external
supervisors are highly deficient in most subject mastery an d professional competence,
thus there is no guarantee for increased performance of teachers. This is in support of
Ogunlabi (2008).
Among  other  reasons  for  improving  instruction  in  schools  is  that  large
percentages  of  teaching  workforce  in  most  states  in  Nigeria  are  not  professionally
certified  unlike  in  the  developed  countries  where  no  one  can  teach  in  secondary
schools  except  you  are  academically  and  professionally  certified,  as  such  there  is
another opportunity to learn required teaching methodology while on the job.
Most  importantly,  there  is  a  missing  gap  in  the  implementation  of  policies,
practices and instructional innovations between external supervisors and teachers as
such vice principals would play a complimentary role to ensure effectiveness of  best
practices in the secondary school system.
Research Questions
This paper would attempt to provide answers to the following;
1. How is instructional supervision carried out in secondary schools in Ogun State,
Nigeria?
2. How is effective supervision going to be carried out in secondary schools?
3.  To  what  extent  does  vice  principals  monitoring/supervision  of  classroom
teachers’ instruction influencestudents’ performance?
4.  How  should  we  improve  instructional  supervision  by  vice  principals  in
secondary schools?
Significance of the Study
1.  To  ensure  accountability  and  increased  level  of  teachers  instructions  in  the
secondary school.
2. To encourage frequency of instructional supervision at the classroom level.
3. For achieving increased level of students’ academic performance in school.
4. To establish co-operative attitudes in teachers toward academic supervision.
5. To achieve educational effectiveness and quality improvement.
Theoretical  Construct:  Theory  of  Student-Centred  Accountability  and
Connection
A  theory  developed  by  Marzano  (2003)and  improved  upon  by  Reeves  (
2004).The focus of this theory is emphasized on instructional leaders, instruction and
students  in  order  to  improve  teaching  and  learning  processes.  For  fuller
understanding of instructional  supervision by supervisors, certain factors fundamental
for  coverage  by  this  theory  are  instructional  leaders,  frequency  of  supervision,
teachingskills, mastery of subject matter, curriculum, andinstruction. Accountability of
student  centered  learning  cannot  be  achieved  if  there  has  not  been  effective  input
from teachers, and for the students centered to improve vice supervisors must visits
classroom daily or regularly through observation and recognition of best practices.
Content
A  supervisor  is  a  person  engaged  in  conducting  instructional  monitoring  or
supervision. Those persons are education inspectors, zonalsecretaries, principals, vice
principals,  head  of  staff,  head  of  departments,  subjectheads,  form  cocoordinators/class  co-ordinators.The  concept  of  instructional  supervision  is  a
classroom based supervision conducted by external and internal supervision for the
purpose of provision of guidance, support and continuous evaluation of teachers for
improvement in teaching and learning process and profe ssional development through
collegial approach.(Beach&Reinhartz;2000 &Tyagi,2010).
Fullan(2007) stated why there is no effectiveness in supervision of instruction
in classrooms is because principals and vice principals spend most school time in their
offices  managing  facilities,  resolving  students’  indiscipline,  purchase  of  office  and
facilities materials thereby devoting less time or no time to instructional matters.
In a related development, Bloom et al(2003) echoed that principals and team
of  supervisors  who  receives  coaching  are  more  engaged  in  instructional  leadership,
spends more time on instructional issues, addressing those issues than those without
any knowledge of coaching.
UNESCO  (2007)&WORLD  BANK,(2011),reported  that  there  is  a  growing
conviction that empowerment of school-site supervision can make school respond to
needs of students. The monitoring of teachers is a guarantee for better qualities which
is  possible  with  co-operation  between  principals,  and  teachers  including  the  vice
principals.  This  author  is  of  the  view  that  with  vice  principals  always  available  in
classroom monitoring will ensure teachers ‘ usage of instructional time, check pupils
books,  give  classwork  and  assignments  which  automatically  discourages  perpentual
absentees and late comers.
The scope of the content of this paper will cover mastery of subject matter,
teaching materials and teaching skills which the vice principals will execute properly to
ensure increase level in academic achievement in secondary schools.
Mastery Of Subject Matter
Kimberly (2009) stated that teachers must have sufficient knowledge in their
areas of study. Therefore, effectiveness of teaching and learning can best be measured
by teachers’ level of teachers’ capability in subject mastery which  have direct impact
and a good predictor of students learning. In like manner, Adegbile&Adeyemi (2008)
confirmed  that  usage  of  highly  knowledgeable  in  his  area  of  specialization  in  low
performance  students  will  eventually  be  rewarding.  Competency  in  subject
matter/content in association with teaching skills,  while teacher-student relationship
are connecting variables that can improve academic achievement of secondary school
students.
Teaching Resources
Instructional  resources  or  teaching  resources  are  instructional  materials  for
conveying  essential  knowledge  and  skill  of  subject  in  school  curriculum.  Teaching
resources suitable and available for use in secondary school’s instructional process are
books,  workbooks,  computer  software,  maps,  wall  charts,  flip  charts  and  academic
libraries.  In  a  research  carried  out  by  Popoola  (1990)   investigated  the  effects  of
instructional  materials  on  the  academic  achievement of  students  in  some  secondary
schools. He compared the West African Examinations Council results fo r five years
and  compares  d  achievement  of  students  in  schools  with  inadequate  teaching
resources  and  found  a  significant  difference  in  the  achievement  of  the  two  sets  of
students.
The  vice  principals  have  a  significant  role  to  monitor  usage  and  records  of
teaching resources in a pool or in school stores from school’s purchase or produce
teaching  aids  and  shared  among  teachers  for  use  in  the  classrooms.  Every  school
should keep an inventory of available teaching aids by quantity and conditions for use.
The  teaching aids inventory should be able to show frequency usage of each resource
on  a  weekly  basis.  It  must  be  emphasized  that  teaching  and  learning  materials  are
determinant of quality of education, thus it is essential for quality teaching materials to
be made available to teachers and students in adequate quantity to support teaching
and learning processes.
Teaching Skills
Reigner(2000)&Berry,B.(2011)  reiterates  that  teachers  needs  to  be
curious,imaginative,interesting,friendly  and  hard  working  in  order  to  be  effective  in
the  classroom,  thereby  creating  a  learning  environment  that  results  in  enhancing
learners  disposition.  Interesting  teachers  keep  students  alive,  attentive  and  focused based to hear and learn more from classroom instruction.
The  nature  of  effective  teaching  skills  is  that  the  teacher  should  renew  and
innovate,  and  enlighten  the  minds  of  students  so  that  linkage  can  be  established
between past, present and build positive hope by preparing them to build meaningful
knowledge for correct application.
An  effective  teacher  realize  that  students  learn  in  a  diverse  ways  hence,  a
skilled teacher should adjust lessons to reach all students, responding to multiples of
learning  in  classroom  in  addition  to  usage  of  remediation  and  enhancement,
responding to students need and getting students actively engaged in the lesson will
increase  rate  of  retention  and  reproduction  .Therefore,  effective  teaching  skills  are
essential  to  successful  school  outcomes  resulting  from  instructional  supervision  by
vice principals.
Researches  and  experiences  had  revealed  that  teachers’  actions  in  their
classroom especially teaching skills have twice impact on students’ achievement as do
school  policies  regarding  curriculum,  assessment,  staff  collegiality  and  community
involvement Marzano (2003).
Challenges
1.  The  vice  principal  knowledge  on  the  new  instructional  practices  gained  from
attending  conferences,  seminars  and  training  of  external  supervisors  may  be
limiting.
2.  Overburden  of  vice  principals  with  some  administrative  duties  of  conducting
examination, carrying out special duties  as  it is mandatory for vice principals to
carry out instructions from the principals as his role is that of assistants.
4.  There  may  not  be  absolute  authority  given  to  vice  principals  to  back-up  the
academic responsibility in order to deal with erring teachers and ensure realization
of goals and objectives of teaching.
5.  There  may  be  possibility  of  clash  of  interest  of  power  between  principals  to
absolutely hand over academic tasks to vice principals with power and authority as
some  teachers  might  play  themselves  in-between  the  two  power  personality  of
administering the school effectively.
6.. The vice principals’ overzealousness for absolute power and decisions regarding
instructional monitoring.
Conclusions
Teachers’  effectiveness  in  classroom  instruction  in  evaluated  with  their
mastery of subject matter, teaching resources, teaching skills and school records have
impacts on learners’ academic achievement.
This  is  in  agreement  with  Campbell,J.M.(2004)  that  teachers’  level  of
instruction  arising  from  instructional  supervision  under the  office of  vice  principals
will ensure effectiveness resulting in improved academic achievement of students in
the secondary schools in Ogun State, Nigeria.
Recommendations and Suggestions
1.vice  principals  should  co-opt  the  most  senior  members  of  staff/head  of  staff  as
workload shared is half-solved to avoid stress and excess burdens ,this will be a
breeding  ground  for  excellence  and  continuation  of  good  value.  More  so  that
most  senior  members  of  staff  will  soon  be  assigned  vice  principal-ship
position/duty –post.
2. Vice-principals should be given one or two periods per week in a lower class to
serve  as  good  role  models  so  that  instructions  will  b e  matched  with
action/activity.
3.Training  should  be  given  to  vice  principals  on  the  nature,  process,  roles  and
limitations of academic responsibility in relation to principals(superior boss) and
external  supervisors  from  ministry  of  education,  teaching  service  commission(
regulating  and  supervising  agencies).This  can  be  a  good  avenue  to  deploy
experienced  supervisors  on  ad-hoc(short)  and  permanent  position  and  use  vice
principals as resource-persons as those who performs such job are less ranked and
equipped with fewer experiences on instructional level of teachers.
4.Vice  principals  can  occasionally  be  part  of  supervision  or  inspection   team  as
observer  to  further  learn  the  rudiments  of  measuring  scales  and  check-list  for
application in their various schools to ensure effective connection between external
supervisors and teachers for effectiveness in academic activities for productiveness
towards students in secondary schools/secondary education.
5.Let  there  be  a  policy  in  place  to  deploy  experienced  vice  principals  to  the
inspectorate department of the ministry of education to give required experiences
to  new  and  inexperienced  education  inspectors  for  stability  and  quality
effectiveness of instructional supervision in schools.
6.There should be a policy statement for the vice principals to be given constitutional
duties in the school with authority for effectiveness of work assigned and to also
give good image to the office of vice principal.
References
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instruction.Boston:Allyn and Bacon.
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Leader Emergence Through Interpersonal Neural Synchronization Jing Jiang

Jing Jiang (蒋静)a,b,c,d, Chuansheng Chen (陈传升)e, Bohan Dai (代博涵)a,b,f,g, Guang Shi (时光)a,b, Guosheng Ding (丁国盛)a,b, Li Liu (刘丽)a,b, and Chunming Lu (卢春明)a,b,1
a) State Key Laboratory of Cognitive Neuroscience and Learning and IDG/McGovern Institute for Brain Research, Beijing Normal University, Beijing 100875,
China;
b) Center for Collaboration and Innovation in Brain and Learning Sciences, Beijing Normal University, Beijing 100875, China;
c) Berlin School of Mind and Brain, Humboldt University, 10117 Berlin, Germany;
d) Max Planck Institute for Human Cognitive and Brain Sciences, 04103 Leipzig, Germany;
e) Department of Psychology and Social Behavior, University of California, Irvine, CA 92697;
f) Max Planck Institute for Psycholinguistics, Nijmegen 6500 AH, The Netherlands; and
g) International Max Planck Research School for Language Sciences, Nijmegen 6500 AH, The Netherlands

Edited by Susan T. Fiske, Princeton University, Princeton, NJ, and approved March 2, 2015 (received for review December 1, 2014)
The neural mechanism of leader emergence is not well understood. This study investigated (i) whether interpersonal neural
synchronization (INS) plays an important role in leader emergence,
and (ii) whether INS and leader emergence are associated with the
frequency or the quality of communications. Eleven three-member
groups were asked to perform a leaderless group discussion (LGD)
task, and their brain activities were recorded via functional near
infrared spectroscopy (fNIRS)-based hyperscanning. Video recordings of the discussions were coded for leadership and communication. Results showed that the INS for the leader–follower (LF)
pairs was higher than that for the follower–follower (FF) pairs in
the left temporo-parietal junction (TPJ), an area important for social mentalizing. Although communication frequency was higher
for the LF pairs than for the FF pairs, the frequency of leaderinitiated and follower-initiated communication did not differ significantly. Moreover, INS for the LF pairs was significantly higher
during leader-initiated communication than during follower-initiated
communications. In addition, INS for the LF pairs during leaderinitiated communication was significantly correlated with the
leaders’ communication skills and competence, but not their communication frequency. Finally, leadership could be successfully
predicted based on INS as well as communication frequency early
during the LGD (before half a minute into the task). In sum, this
study found that leader emergence was characterized by highlevel neural synchronization between the leader and followers
and that the quality, rather than the frequency, of communications was associated with synchronization. These results suggest
that leaders emerge because they are able to say the right things
at the right time.
leader emergence
|neural synchronization|
babble hypothesis|
quality of communication|
communication skill
L
eadership is a ubiquitous feature of all social species, including
human and nonhuman animals (1, 2). However, the neural
mechanism of leader emergence is still not well-understood.
Evolutionary theories suggest that, whereas both human and
nonhuman animals have evolved tendencies to compete for
dominance over access to survival-related resources (3–5), human leaders also play an important role in maintaining group
cohesion (6). Thus, human leaders need to take into account
not only their own needs but also the needs of their followers
to facilitate cooperation among group members (7–9). Interestingly, recent imaging evidence indicates that the neural activities
of two individuals are more synchronized when they perform
a cooperative rather than a competitive task (10). Moreover,
the level of interpersonal neural synchronization (INS) is closely
associated with the level of understanding between partners (11). It
is unknown, however, whether INS is involved in leader emergence.
Previous evidence has shown that communication plays an
important role in the increase of INS (12). However, the role
of communication in leader emergence has been extensively
debated. On the one hand, the so-called“babble”hypothesis
postulates that the most talkative member of a group often
becomes the group’s leader (13, 14). Indeed, there is evidence
that the frequency of communication (regardless of its usefulness) is a better predictor of leader emergence than other factors
such as the quality of communication (15). It is suggested that
communication frequency is probably one of the main factors
that increase the probability for initiating group action (16).
On the other hand, various recent studies have suggested that
the quality of communication is a more important predictor of
leader emergence than is the frequency of communication (17–
20). Consistent with this“quality-of-communication”hypothesis,
evidence shows that the frequency of communication has no
real effect on leader emergence (20). Although the frequency of
communication boosts leadership ratings, it does so only when
the content is of high quality (17). Furthermore, in task-oriented
groups, the quality rather than the quantity of communication is
a better predictor of leader emergence (18, 19). Research has
also suggested that high-quality communication tends to involve
a high level of mentalizing: i.e., the ability to read social situations and to alter one’s own behavior to fit in and act appropriately (21). Indeed, communication skills have been considered
to be an important part of leader competence in modern societies (22). It is likely that leaders emerge when they possess tactful
communication skills and competence: i.e., being able to say the
right things at the right time.
Research is needed to investigate how communications are
related to INS, which in turn may be related to leader emergence. Considering the interactive nature of leader emergence,
Significance
Great leaders are often great communicators. However, little is
known about the neural basis of leader–follower communication. Only recently have neuroscientists been able to examine
interpersonal neural synchronization (INS) between leaders
and followers during social interactions. Here, we show that
INS is significantly higher between leaders and followers than
between followers and followers, suggesting that leaders
emerge by synchronizing their brain activity with that of the
followers. Moreover, the quality rather than frequency of the
leaders’ communications makes a significant contribution to
theincreaseofINS.Thisresultsupportsthe“quality of communication” hypothesis in leader emergence. Finally, our results
show that leadership can be predicted shortly after the onset
of a task based on INS as well as communication behaviors.
Author contributions: J.J., C.C., G.D., L.L., and C.L. designed research; J.J., B.D., and G.S.
performed research; J.J., C.C., B.D., G.S., and C.L. analyzed data; and J.J., C.C., and C.L.
wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
1
To whom correspondence should be addressed. Email: luchunming@bnu.edu.cn.
This article contains supporting information online atwww.pnas.org/lookup/suppl/doi:10.
1073/pnas.1422930112/-/DCSupplemental.
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it is imperative to adopt the “second-person approach”:i.e.,
measuring two or more persons’ brain activities simultaneously
(23). This approach is also termed “hyperscanning” and has
proven to be promising in the field of social neuroscience (23–25).
By using an EEG-based hyperscanning approach, recent evidence
showed that, during guitar playing, the a priori-assigned leaders
showed higher levels of delta-phase locking than did the followers
and that INS from the leaders to the followers was stronger than
that from the followers to the leaders (26, 27). Evidence further
showed implicit synchronization of both body movements and
neural activity between a priori-assigned leaders and followers
during social interactions (28). However, previous hyperscanning
studies did not examine the neural mechanism of leader–follower
(LF) communications and did not compare the INS between the
LF and the follower–follower (FF) pairs. Thus, it is still unknown
whether and how INS is involved in leader emergence. In addition,
EEG is sensitive to motor artifacts and suffers from poor spatial
resolution. In contrast, functional near infrared spectroscopy
(fNIRS) is more tolerant of movements and is able to measure
local hemodynamic effect. These advantages make it particularly
suitable for testing the role of communication in leader emergence
in a realistic situation.
This study examined whether and how INS was involved in
leader emergence by using the fNIRS-based hyperscanning
approach. During the experiment, three-person groups were
recruited to perform a leaderless group discussion (LGD) task.
This task has been used successfully in many studies to induce
a discussion-oriented, problem-solving situation (19). INS of neural
activity was computed. It was hypothesized that INS of the LF pairs
would be higher than that of the FF pairs. Based on the babble
hypothesis, it was expected that (i) leaders would initiate more
communications than the followers and (ii) the increased INS
for the LF pairs would be mainly due to the emerging leaders’
communication frequency and would occur in language-related
brain areas. Alternatively, based on the quality-of-communication hypothesis, leaders would not initiate more communications
than the followers, and INS for the LF pairs would be associated
with the emerging leaders’ communication skills and competence, rather than the frequency, and would occur in brain areas
associated with social mentalizing. Finally, using a Fisher linear
discrimination analysis, we investigated how early during the
LGD session the INS data and communication behaviors could
predict the emergence of leaders.
Results
Interpersonal Neural Synchronization. The experimental setup is
illustrated in Fig. 1A. For each session, three participants sat
face-to-face in a triangle and were given a topic for an LGD
(see Materials and Methodsfor details). Their brain activities
were simultaneously recorded with an fNIRS system (Fig. 1B).
The discussion was video-taped and coded by independent
judges for leadership, communication skills and competence,
initiation of communications, and frequencies of verbal and
nonverbal communications.
For the LF pairs, a significant INS increase compared with
the resting-state condition was identified at channel 6 (CH6),
which roughly covered the left temporo-parietal junction (TPJ)
[t
(10) =4.62,P=0.001, false discovery rate (FDR) correction]
(Fig. 1C). No INS increase was found for any channel of the FF
pairs (Fig. 1D). Group differences between the LF and FF pairs
were significant for CH6 (t
(20)=3.51,P=0.002), but not for any
other CHs.
To validate that the above results could not have been obtained
by chance, we assessed the likelihood of obtaining significant INS increases for any random pairings of the participants.
Specifically, we reanalyzed the data after randomizing the LF
pairing both within and between discussion groups. The first was
the within-group permutation: Each of the two followers was
assigned to be the“leader”and the INS data were reanalyzed.
The second approach was the between-group permutation: All
33 participants were randomly assigned to 11 three-member
groups, and the INS analysis was then reconducted. This permutation was conducted 1,000 times. Both approaches showed
no significant INS increases for any CHs. Fig. 1EandFandG
andHshows the results of typical within- and between-group
validation analyses, respectively. Complete results for CH6 from
1,000 permutations of between-group validation analyses are
shown inFig. S1. These results suggested that the significant INS
increase in the left TPJ was specific to the particular LF relationship in the LGD context.
Who Synchronized with Whom?Granger causality analysis (GCA)
was conducted on the time series of CH6 to determine whether
it was the leader who synchronized with the followers or whether
it was the other way around. One-sample t tests on the pairwiseconditional causalities showed that the mean causalities of both
directions were significantly higher than zero: from the leaders to
the followers (t
(10)=10.001,P<0 .001="" and="" br="" followers="" from="" the="" to="">the leaders (t
(10)=7.272,P<0 .001="" br="" however="" test="" two-samplet="">showed that the mean causality from the leaders to the followers
was significantly higher than that from the followers to the
leaders (t
(10)=2.177,P=0.027). These results indicated a more
important role of the leaders than the followers in the INS increase in the LF pairs at CH6.
Communication Behaviors and INS. Both verbal and nonverbal
communication frequencies were significantly higher for the LF
pairs than for the FF pairs: (t
(20) =3.873,P=0.001) for verbal
and (t
(20)=4.565,P<0 .001="" br="" communications="" for="" ig.="" nonverbal="">2A). However, the leaders did not differ significantly from the
followers in the frequency of communication initiation (t
(10) =
−1.602,P=0.125). To investigate whether the role of leaders in
communication initiation might have changed as the discussion
progressed, the initiation data were reanalyzed by the first and
the second halves of the LGD session. Still, no differences were
found between the LF and FF pairs: (t
(10) =−0.433,P=0.674)
Fig. 1. Experimental procedure and the increase of interpersonal neural
synchronization (INS). (A) For each group, three persons sat in a triangle.
Two cameras were placed in opposite positions. The figure shows two sample
frames from the cameras in the opposite directions. Participants were asked to
discuss a topic for 5 min and then to choose a leader to report their conclusion.
(B) The optode probe set was placed on the left frontal, temporal, and parietal
cortices. T3 corresponds to a position in the international 10–20 system.
(CandD) Shown are tmaps for results of the original pairs (i.e., real data).
(EandF) Shown aretmaps for the permutation results of pairs with a follower
from the same group randomly assigned as the leader. (GandH) Shown aret
maps for the permutation results of randomized pairs from across groups. [C,E,
andGaretmaps for averaged leader–follower (LF) pairs;D,F,andHaretmaps
for the follower–follower (FF) pairs.]
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PSYCHOLOGICAL AND
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for the first half and (t
(10) =−0.858,P=0.411) for the second
half of the LGD session (Fig. 2B). These results suggested that,
although communication frequency was higher for the LF pairs
than for the FF pairs, leaders and followers contributed equally
throughout the LGD session.
We next examined INS that accompanied different types of
communications (verbal, nonverbal, and no communications).
For the LF pairs, INS during verbal communications (INS-V)
differed significantly from both INS during nonverbal communication (INS-NV) (t
(10) =2.951,P=0.015) and INS when no
communications occurred (INS-NC) (t
(10)=2.758,P=0.02) (Fig.
2C). Fig. 3 shows the correspondence between INS (coherence
value) and video frame for a typical LF pair at CH6. No significant results were found for the FF pairs. Group difference in
INS-V between the LF and FF pairs was also significant (t
(20) =
3.178,P=0.005). No significant group differences were found
for INS-NV (t
(20)=−0.24,P=0.813) and INS-NC (t
(20)=0.982,
P=0.338). These results indicated that the INS difference was
specific for verbal communication between the leaders and
the followers.
In terms of the role of communication initiation, leaderinitiated communications induced a higher level of INS than the
ones initiated by the followers (t
(20)=2.176,P=0.042) (Fig. 2D).
This result suggested that leader-initiated communications were
likely to be of higher quality (and thus led to increased INS).
This conjecture was further supported by two other results. First,
leaders’ communication skills and competence were more highly
rated (M=25.279, SD=0.800) than those of the followers (M=
22.020, SD=1.112) (t
(20) =7.894,P<0 .001="" 2e="" br="" ig.="" second="">there was a significant correlation between INS during leaderinitiated communications and judge-rated leaders’ communication skills and competence (r=0.697,P=0.017) (Fig. 2F). The
correlation between INS during leader-initiated communications
and the leaders’ initiation frequency was not significant (r =
0.247,P=0.465). This difference in correlation coefficients was
in favor of the quality-of-communication hypothesis over the
babble hypothesis although a larger sample of leaders would be
needed to allow for a statistical test of the difference.
Prediction of Leadership.To investigate how early the leaders
emerged during the LGD, Fisher linear discrimination analyses
were conducted. Fig. 4Ashows the time course of the prediction
accuracy in the discriminant analysis based on the INS data,
which differentiated the LF pairs from the FF pairs. The analysis
included three indexes: sensitivity (percentage of LF pairs correctly predicted, red line), specificity (percentage of FF pairs
correctly predicted, blue line), and the generalization rate of
accuracy (overall proportions of LF and FF pairs correctly predicted, green line). A moving-window analysis (window size=9s)
revealed that the prediction accuracy was sporadic during the
initial period, but the prediction accuracy of all three indexes was
stably higher than the chance level starting at 23 s (P<0 .05="" br="">corrected by FDR) [see the purple section above the chancelevel (0.50) line in Fig. 4A)]. A similar discriminant analysis was
conducted based on the communication frequency (Fig. 4B). The
results showed that the prediction accuracy of all three indexes
was stably higher than the chance level starting at 29 s (P<0 .05="" br="">corrected by FDR) (see the purple section above the chancelevel line in Fig. 4B). In sum, the INS and communication frequency data were able to discriminate the leaders from the followers less than half a minute into the LGD task.
Discussion
This study used an fNIRS-based hyperscanning approach to test
the hypothesis that INS was involved in leader emergence. The
results demonstrated that INS increased from the baseline more
significantly for the LF pairs than for the FF pairs. Further
analysis revealed that, although the communication initiation
frequency of leaders and followers did not differ significantly,
leader-initiated communication induced greater INS than did
follower-initiated communication. The INS increase during leaderinitiated communications was also associated with leaders’
communication skills and competence. These results suggest that
quality rather than quantity (or frequency) of communication is
more important in leader emergence. These results are discussed
sequentially below.
First, results of this study confirmed our hypothesis that the
LF relationship in the LGD context would be characterized by
a high level of INS. We derived our hypothesis from integrating
Fig. 2. (A) Verbal and nonverbal communication frequencies during the
task. The averaged frequency of the two leader–follower (LF) pairs (black)
was higher than the frequency of the follower–follower (FF) pairs (white).
(B) There were no significant differences in leader-initiated (L→F) vs. follower-initiated (F→L) verbal communications. (C) LF pairs’ INS during verbal
communication (INS-V) was higher than INS for all other situations. NC, no
communication occurred; NV, nonverbal communication; V, verbal communication. (D) INS during leader-initiated communication was higher than
that during follower-initiated communication. (E) Leaders’ communication
skills and competence were more highly rated than those of the followers.
(F) INS during leader-initiated communication was positively associated with
ratings of communication skills and competence (Upper), but not with
leader-initiated communication frequency (Lower). *P<0 .05.="" br="">Fig. 3. The correspondence between INS at CH6 and coded communication
behaviors. (A) A time course of INS for one randomly selected LF pair. (B)The
corresponding communication behaviors coded from video frames. Blue
points, follower-initiated verbal communications; green points, nonverbal
communications; red points, leader-initiated verbal communications. The
sections of the line without color points represent no communications. The
numbers 1, 2, and 3 inAhighlight time points that correspond to videoframe examples inB.
4276 | www.pnas.org/cgi/doi/10.1073/pnas.1422930112 Jiang et al.
recent imaging evidence that cooperation between persons led to
a high level of INS (10, 28) with recent perspectives about human
leaders’ role as the coordinators who help their groups to solve
various tasks, including resource sharing and decision making
(9, 29). According to the service-for-prestige theory of leadership
(9), human leaders and followers are involved in reciprocal exchange: Leaders may incur costs to provide followers with public
goods, and, in return, followers incur costs to provide leaders
with prestige, particularly in a relatively small group. We interpret
the higher INS for the LF pairs as a reflection of their closer
cooperation and social exchange.
Second, we found that the level of INS was increased specifically during verbal communications between the leaders and
followers, not during nonverbal or no communications, nor for
any type of communications involving the FF pairs. This result
was consistent with previous studies showing that verbal communication was one of the main factors that affected leader
emergence (13, 17–19). The present results further suggest that
verbal communication affects leader emergence by modulating
the neural synchronization. Because of the importance of verbal
communications in INS, this particular route of leader emergence
may be specific to humans (e.g., the service-for-prestige theory) (9).
Nonhuman animals typically establish leadership via dominance
(e.g., displays of physical strength), so it would be interesting to
investigate whether they also show INS.
Third, although the leaders and followers contributed equal
numbers of communications, leader-initiated verbal communications were found to lead to higher INS than did followerinitiated ones. Moreover, the GCA results showed that INS was
bidirectional but was significantly stronger from the leaders to
the followers than the other direction. These results suggested
that dynamic social interactions played an important role in
leader emergence. Indeed, as Schilbach et al. (23) suggested,
dynamic social interaction is a key constituent of grasping the
minds of others. An action by an“initiator”may lead to closer
monitoring of the outcome of the interaction, including the
responses by other individuals (23). In our study, the leaders initiated the communications, monitored the followers’ responses,
and closely synchronized their brain activities with those of the
followers. This speculation was further supported by the significant correlation between communication skills and competence
and INS. It seems that a leader is someone who would say the
right things at the right time to increase neural synchronization with the followers.
Fourth, the increased INS for the LF pairs was found in the
left TPJ, but not in the language area [i.e., left inferior frontal
cortex (IFC)]. This result was consistent with previous evidence
that high quality of communication is associated with high-level
mentalizing (21), which was partly subserved by the left TPJ.
Specifically, previous evidence has shown that interpersonal coordination or communication is facilitated by the mutual abilities
to predict each other’s subsequent action (i.e., high-level mentalizing) (30). Researchers have debated about which specific
parts of the left or right TPJ or both are involved in mentalizing
and understanding and reasoning about the beliefs and intentions of others (31–33). In one study, a lesion in the left TPJ was
found to affect the representations of someone else’s beliefs
(33). In another study, the posterior part of the right TPJ and the
parietal cortex were found to be involved in social cognition and
memory retrieval whereas the anterior part of the right TPJ as
well as the motor cortex and insula were involved in attention
(32). Although the poor spatial resolution of fNIRS did not allow
us to precisely locate the position of the INS increase, the most
likely area would be the posterior part of the left TPJ (for highlevel mentalizing) because no motor cortex was involved in
this study.
Finally, discriminant analyses showed that, shortly after the
start of the LGD task, the INS data and communication
behaviors could successfully distinguish the LF from the FF
pairs. These results further supported the quality-of-communication hypothesis by suggesting that the communication
frequency matters when the quality is of high level (17). These
results also confirmed previous findings (26–28, 34) that
neural activity (as well as interactive communication behaviors)
could be used to differentiate reliably the leaders from the followers. It is worth noting that different studies have found different earliest time points for successful discrimination based on
neural activity: before the onset of the interactions in Sänger
et al. (26, 27) and Konvalinka et al. (34) and about half a minute
into the interaction in our study. One possible explanation of
these variations is that the time point for successful discrimination depends on how the leaders emerge. In Sänger et al. (26,
27), leaders were assigned a priori; in Konvalinka et al. (34),
leaders emerged through a number of repeated trials; and, in the
present study, leaders emerged during a single LGD task. Future
research should specifically examine the role of neural activity or
INS in predicting different types of leader emergence.
Several limitations of this study need to be noted. First, our
findings from the LGD task may not be generalized to other
types of situations for leader emergence. The process of leader
emergence from a free discussion among equals (all college
students) may be different from one involving members who are
of different ages, genders, social status, etc. In addition, the
phenomenon of INS may also be different for leader emergence
than for situations with a leader assigned a priori, as discussed
earlier. Second, our sample size was adequate for the examination of group differences, but not as satisfactory for individual
differences in leaders. Similarly, the statistical power was limited
when we tested the babble hypothesis because of both the small
sample size and the somewhat limited verbal behaviors from the
short period of the LGD task. Third, we did not measure other
important characteristics of leadership, such as charisma (35),
which should be considered in future research for their role in
INS. Finally, because of the poor spatial resolution of fNIRS,
it was difficult to identify exactly which brain areas were responsible for the responses at CH6.
In summary, leadership is an important feature of human society, but little is known about the neural basis of leader emergence. Using the fNIRS-based hyperscanning approach in a
realistic interpersonal-communication context, the current study
found evidence that human leaders cooperated with their followers to achieve group decision by synchronizing their brain
Fig. 4. Time course of prediction accuracy. (A) Prediction results based on
the cumulative INS data. (B) Prediction results based on cumulative communication frequency. There were a total of 274 time points forAafter
shifting 6 s toward the left due to fNIRS signal delay (Materials and Methods) and 280 time points for B. The time courses were smoothed by using
a moving average method (span=9 s). The purple line above the chancelevel line indicates the time points where all three accuracy indexes were
significantly higher than the chance level (0.50).
Jiang et al. PNAS | April 7, 2015 | vol. 112 | no. 14 | 4277
PSYCHOLOGICAL AND
COGNITIVE SCIENCES
activities with those of the followers through their tactful communication skills and competence. We further found that it was
possible to predict leadership based on the INS data as well
as communication behaviors early in their interactions. These
findings contribute to the theoretical discussion about the importance of communications in leader emergence and advance our
understanding of the neural mechanism of leaderemergence. The
results also potentially may be used in neuro-feedback or neurointervention during leadership training.
Materials and Methods
Participants.Thirty-six healthy adults (mean age 22±2 y) participated in this
study. They were pseudorandomly split into 12 three-person groups. For
each group, the members had to be of the same sex (to avoid a potential
confound of intergender interactions) and were total strangers to one another. There were 6 female groups and 6 male groups. One female group
was excluded because of data collection failure.
Written informed consent was obtained from all participants. The study
protocol was approved by the Institutional Review Board of the State Key
Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University.
Tasks and Procedures.For each group, an initial resting-state session of 5 min
served as the baseline. During this session, the participants were required to
remain as motionless as possible with their eyes closed and mind relaxed (36).
After the resting-state session, each group was instructed to perform the
LGD task. Two additional 30-s resting-state periods (one at the initial phase
and the other at the ending phase of the LGD) were used to allow the imaging instrument to reach a steady state.
During the LGD, the three participants of each group sat face-to-face in
a triangle. Two digital video cameras were placed at opposite positions so
that all three participants could be recorded (see Fig. 1Afor two sample
frames). Participants received the following topic for discussion: “An airplane crash-landed on a deserted island. Only 6 persons survived: A pregnant
woman, an inventor, a doctor, an astronaut, an ecologist, and a vagrant.
Whom do you think should be given the only one-person hot-air balloon to
leave the island?”The participants were asked to read and think about the
topic for 5 min without interacting with one another. Afterward, each
group was instructed to discuss the topic for 5 min. Each group was then
required to choose a member to report their conclusion to the experimenter.
The reporting session lasted 1 min. The whole procedure was video recorded
for subsequent coding.
Determination of the Leaders and Evaluation of Communication Skills and
Competence.After the experiment, an additional group of eight graduate
students was recruited to view the video recordings of the discussion session
and to judge who the leader was for each group. Judges were asked to use
their own criteria to make the judgment. For each group, the member with
votes from more than half of eight judges was defined as the leader. The
average vote for the leaders was 77.3±15.6%. The intraclass reliability (ICC)
among judges was 0.874 (P<0 .001="" 11="" 9="" br="" for="" groups="" judges="" of="" the="">choice of the leader agreed with the group members’ own choice (i.e., the
person who gave the report). For subsequent analyses, we used the more
objective choices by the judges.
Judges were also asked to evaluate the communication skills and competence of each group member on a 5-point scale (Table S1). There were
seven aspects of communication skills and competence (group coordination,
active participation, new perspectives, input quality, logic and analytic
ability, verbal communication, and nonverbal communication). Judges were
given explanations of the above categories and a scoring guide (seeTable
S1for details). Interjudge reliability was determined by ICC, and it was satisfactory to high (ranging from 0.773 to 0.926) for all but one item (new
perspectives, ICC=0.412). Possible reasons for the judges’ lack of consensus
on“new perspectives”might be the low frequencies of relevant behavior or
ambiguity of this construct. This item was removed from further analyses.
For the remaining items, ratings from the eight judges were averaged for
each item. The final scale of communication skills and competence included
six items with high internal consistency (Cronbach alpha=0.930).
Coding of Communication Behaviors.Two additional coders, who were not
involved in the voting of leaders and the evaluations of communication skills
and competence, coded communication behaviors. We used new coders
to avoid the leader voting’s potential contamination of behavior coding.
Communication behaviors included verbal communications, such as turntaking and interjections, and nonverbal communications, such as orofacial
movements, facial expressions, and sign gestures. Each of the 280 s during
the LGD was coded as having either verbal communication, nonverbal
communication, or no communications. If both verbal and nonverbal behaviors occurred for a given second, the dominant behavior was coded.
The frequencies of verbal and nonverbal communications were calculated
as the proportions of time (out of the 280 s) when verbal and nonverbal
communications occurred, respectively. The intercoder reliability (based on
ICC) was 0.930 for verbal communications (vs. no communications) and 0.952
for nonverbal communications (vs. no communications).
In addition, the initiator of each occurrence of verbal communication was
also coded. The frequency of initiations for each member was calculated as
the ratio of time points where a member initiated a communication over the
total number of that member’s verbal communications (ICC=0.949).
FNIRS Data Acquisition.During the experiment, the participants sat in a quiet
room. An ETG-4000 optical topography system (Hitachi Medical Company)
was used to collect imaging data from the three participants of each group
simultaneously. Three sets of the same customized optode probes were used.
The probe was placed on the left hemisphere so as to cover both the left
inferior frontal cortex (an area important for language) (37) and the temporal-parietal junction (TPJ) (an area closely associated with social mentalizing) (31, 33).
The optode probes consisted of 10 measurement channels (four emitters
and four detectors, 30 mm optode separation). CH9 was placed just at T3 in
accordance with the international 10–20 system (Fig. 1B). The probe set was
examined and adjusted to ensure consistency of the positions among the
participants of each group and across the groups.
The absorption of near-infrared light at two wavelengths (695 and 830 nm)
was measured with a sampling rate of 10 Hz. The changes in the oxyhemoglobin (HbO) and deoxy-hemoglobin (HbR) concentrations were recorded
in each channel based on the modified Beer–Lambert law. This study focused
only on the changes in the HbO concentration, which was demonstrated to
be the most sensitive indicator of changes in the regional cerebral blood
flow in fNIRS measurements (38).
Imaging-Data Analysis.
Interpersonal neural synchronization.Data collected during the resting-state and
LGD sessions were entered into the analysis. During preprocessing, data in the
initial and ending periods (30 s resting state plus 10 s LGD, respectively) were
removed, leaving 280 s of data for each session. Wavelet transform coherence
(WTC) was used to assess the cross-correlation between two fNIRS time series
generated by pairs of participants as a function of frequency and time (39).
The wavelet coherence MatLab package was used (40) [for more thorough
information, please see Grinsted et al. (40) and Chang and Glover (41)].
Briefly, three HbO time series were obtained simultaneously for each CH
from the three participants of each group. WTC was applied to each pair of
the time series to generate 2D coherence maps. According to previous
studies (10, 12), the coherence value increases when there are interactions
between persons, compared with that during the resting state. Based on the
same rationale, the average coherence value between 0.02 and 0.2 Hz was
calculated. This frequency band also excluded the high- and low-frequency
noises, such as those associated with respiration (about 0.2–0.3 Hz) and
cardiac pulsation (about 1 Hz), all of which would lead to artificial coherence. Finally, the coherence value was time-averaged.
The averaged coherence value of the resting-state session was subtracted
from that of the LGD session, and the difference was used as an index of the
INS increase between two persons. Because each group had two LF pairs and
only one FF pair, the INS increases for the two LF pairs were averaged for
matched-samplet tests (SI TextandFig. S2). For each channel, after converting the INS increase into azvalue, a one-samplettest was performed on
thezvalue across the participant pairs, and twotmaps of the INS increase
(P<0 .05="" and="" br="" by="" corrected="" fdr="" for="" generated="" lf="" one="" pairs="" the="" were="">other for the FF pairs. Thetmaps were smoothed using the spline method.
Validation by randomizing the data.To verify that the INS increase was specific to
the LF relationship that emerged during the LGD, two validation approaches
were applied. The first was the within-group permutation: Each of the two
followers was assigned to be the“leader,”and the INS data were reanalyzed.
The second approach was the between-group permutation: All 33 participants were randomly assigned to 11 three-member groups, and the INS
analysis was then reconducted. This permutation was conducted 1,000 times.
Who synchronized with whom?For CHs that showed significant INS increases,
GCA was conducted to determine the direction of synchronization (i.e.,
whether it was the leaders who synchronized with the followers or the other
way around). GCA is a method that uses vector autoregressive models to
measure the causal relationship (i.e., pairwise-conditional causalities from the
4278 | www.pnas.org/cgi/doi/10.1073/pnas.1422930112 Jiang et al.
source to the target) between time series such as the fNIRS data (42). We
computed the pairwise-conditional causalities of both directions: from the
leaders to the followers and from the followers to the leaders. These two
causality indices were statistically tested to see whether they differed from
zero and from each other.
Communication Behaviors and INS.To confirm the contribution of communication to the INS increase during the LGD, the CHs that showed significantly
greater INS increases for the LF pairs than for the FF pairs were selected. First,
the time courses of INS in the selected CHs were downsampled to 1 Hz to
obtain point-to-frame correspondence between the signal’s time course and
video recordings. Second, the time points of the video were marked as
having either verbal or nonverbal or no communications. Third, the corresponding INSs were separately averaged to obtain three indexes: i.e., INS-V,
INS-NV, and INS-NC, for INS during verbal, nonverbal, and no communications, respectively. The INS data were adjusted for the delay-to-peak effect
in the fNIRS signal (about 6 s) (43). Finally, these indexes were statistically
compared for the LF and FF pairs separately (using a paired two-samplet
test), as well as between the LF and FF pairs (using an independent twosamplettest).
To examine the role of the leaders, further analyses were conducted
to clarify whether the results were driven by leader-initiated or followerinitiated communications and whether the increase of INS was associated
with the leaders’ communication skills and competence or communication
frequency. The results were threshholded atP<0 .05="" br="" corrected="" level="">Prediction of Leadership.The time course of INS for the LF and FF pairs during
the LGD session was baseline-corrected by subtracting their respective averaged INS during the resting state. Cumulative INS across the time was
calculated and then used as the neural-classification feature to classify the LF
and FF pairs: i.e., the type of relationship (i.e., LF or FL) was the classification
label. The cumulative INS at time pointnwas computed as a sum of the INS at
time points from 1 to n−1. The discriminant analysis was conducted for
each time point. A leave-one-out cross-validation method was used to obtain the prediction accuracy. Time courses were generated for three indexes
of prediction accuracy: sensitivity, specificity, and the generalization rate of
accuracy. Because the fNIRS signal needs 6 s to reach a peak value after the
presentation of a stimulus (43), the recorded time points did not match the
brain-activity time points (or behavioral time points, such as communications). To adjust for the delay, we deleted the first 6 time points, yielding
a total of 274 time points for INS. Then, a moving window of 9 s was used to
identify the time points when the prediction accuracy differed significantly
from a chance level (0.50). Similar analyses were conducted based on the communication frequency at each time point. Finally, a moving average method
(span =9 s) was used to smooth the time courses of prediction accuracy.
The prediction results based on moment-to-moment INS data and communication frequency are provided inFig. S3, which suggested that the cumulative data provided more stable prediction accuracy than the moment-tomoment data.
ACKNOWLEDGMENTS.This work was supported by National Natural Science
Foundation of China (31270023), National Key Basic Research Program of
China (973 Program, 2012CB720704), National Natural Science Foundation
of China (30900393), Fundamental Research Funds for the Central Universities (2013YB24), the Beijing Higher Education Young Elite Teacher Project, and
the Open Research Fund of the State Key Laboratory of Cognitive Neuroscience
and Learning.
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