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Clemen e Bellido, M.; Rod iguez O ega, A.; Rey, B.; Alcañiz Raya, ML. (2014). Assessmen
o he in luence o na iga ion con ol and sc een size on he sense o p esence in i ual
eali y using EEG. Expe Sys ems wi h Applica ions. 41(4):1584-1592.
doi:10.1016/j.eswa.2013.08.055.
Accep ed Manusc ip
Assessmen o he in luence o na iga ion con ol and sc een size on he sense
o p esence in i ual eali y using EEG
Mi iam Clemen e, Alejand o Rod íguez, Bea iz Rey, Ma iano Alcañiz
PII: S0957-4174(13)00676-3
DOI: h p://dx.doi.o g/10.1016/j.eswa.2013.08.055
Re e ence: ESWA 8859
To appea in: Expe Sys ems wi h Applica ions
Please ci e his a icle as: Clemen e, M., Rod íguez, A., Rey, B., Alcañiz, M., Assessmen o he in luence o
na iga ion con ol and sc een size on he sense o p esence in i ual eali y using EEG, Expe Sys ems wi h
Applica ions (2013), doi: h p://dx.doi.o g/10.1016/j.eswa.2013.08.055
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Assessmen o he in luence o na iga ion con ol and sc een size on he sense o
p esence in i ual eali y using EEG
Mi iam CLEMENTE1,*, Alejand o RODRÍGUEZ1, Bea iz REY1,2 and Ma iano ALCAÑIZ1,2
1 Uni e sidad Poli écnica de Valencia, I3BH/LabHuman, Valencia, Spain
2 Cibe , Fisiopa ología Obesidad y Nu ición, CB06/03 Ins i u o de Salud Ca los III, Spain
Co esponding au ho :
Mi iam Clemen e
Ins i u o In e uni e si a io de In es igación en Bioingenie ía y Tecnología O ien ada al Se Humano,
Uni e si a Poli ècnica de València
I3BH/LabHuman, Camino Ve a s/n, 46022, Valencia (Spain)
E-mail: mclemen [email protected]
Tel.: 0034-963877518
Abs ac : In he Vi ual Reali y ield, p esence e e s o he sense o “being he e” in he i ual wo ld.
Ou aim in his wo k is o e alua e he use ulness o he Emo i EPOC EEG de ice o measu e b ain
ac i a ions due o he sense o p esence in a Vi ual En i onmen (VE), using o he analysis he
sLORETA ool. We compa e be ween h ee expe imen al condi ions: pho og aphs, ideo and ee
na iga ion h ough a VE. We also compa e he di e ences in he sense o p esence due o he
isualiza ion o he VE in di e en sc eens: a common desk op sc een and a high- esolu ion powe wall
sc een. We moni o ed 20 heal hy subjec s, ob aining signi ican di e ences be ween he na iga ion and
ideo condi ions in he ac i i y o he igh insula o he The a band. We also ound a highe ac i a ion o
he insula o he Alpha and The a bands while na iga ing, when compa ing he wo sc een ypes. The
insula ac i a ion is ela ed o s imulus a en ion and sel -awa eness p ocesses, di ec ly ela ed wi h he
sense o p esence.
Keywo ds: EEG, Emo i EPOC, p esence, i ual eali y, na iga ion, sc een size
1. In oduc ion
In he Vi ual Reali y (VR) ield, p esence e e s o he eeling o being he e, inside he Vi ual
En i onmen (VE), while you body is physically loca ed elsewhe e (She idan, 1992). This concep is
undamen al o he success o he i ual expe ience, de e mining he in e ac ion be ween he compu e -
gene a ed wo ld and he subjec . In wo ds o Meehan e al. (2002), “ i ual en i onmen s a e he mos
sophis ica ed human-compu e in e aces ye de eloped”. In his s udy, ou main pu pose is o measu e
he le el o p esence expe ienced while na iga ing h ough a i ual en i onmen , in compa ison wi h
o he less imme si e condi ions, using a wi eless po able elec oencephalog am (EEG) de ice as an
objec i e indica o o b ain ac i a ion. Acco ding o Ri a e al. (2003), “as media becomes inc easingly
in e ac i e, pe cep ually ealis ic and imme si e, he expe ience o p esence becomes mo e ealis ic”. So
we expec o ind a highe sense o p esence while na iga ing han while pe o ming o he less imme si e
condi ions, in which he in e ac ion wi h he en i onmen is mo e es ic ed. Fo he measu e o b ain
ac i a ions, we will use an Emo i EPOC headse wi h which we expec o achie e ac i a ions in
conco dance wi h hose ob ained in p e ious s udies ca ied ou wi h mo e p ecise and expensi e de ices.
The use o a wi eless po able EEG de ice will allow a quicke placemen o he senso s and a highe
deg ee o mo emen in he subjec , hus a o ing a highe le el o p esence du ing he expe ience.
As Loomis (1992) ema ked, “p esence is a undamen al p ope y o consciousness”. Sanchez-Vi es and
Sla e (2005) also poin ed ou ha inside he i ual expe ience, you a e a he same ime conscious o he
“place” and he “e en s” and simul aneously conscious o ha he e a e no such place o e en s; howe e ,
you s ill beha e and hink as i he place we e eal and he e en s we e happening. As you consciousness
o he di e ences be ween he eal and i ual place and e en s blu s, he ba ie be ween you mind and
he VE diminishes, imp o ing you in e ac ion wi h he compu e -gene a ed wo ld. As Kobe e al. (2012)
ema ked, he g ea e he deg ee o p esence he pa icipan s eel, he g ea e he chance hey will beha e
in he VE as hey would do in a simila eal wo ld se ing. This ag ees wi h he iew o p esence as no
only he sense o “being he e”, bu also he abili y o “do he e” (Sanchez-Vi es and Sla e , 2005).
Ano he pu pose o he p esen s udy is o e alua e he in luence ha he isualiza ion sys em has o e he
le el o p esence in he di e en in e ac ion condi ions. The e a e p e ious s udies ha ha e analyzed
changes in he eeling o p esence due o he size and ealism o he sc een used o display he
en i onmen . Fo example, Kobe e al. (2012) compa ed he p esence elici ed by wo isualiza ion
sys ems: one based on a high-imme si e VR wall (3D) and ano he based on a low-imme si e 2D desk op
sc een. Simila ly o his, in he p esen wo k we di ided he subjec s in o wo g oups, based on he kind o
sc een used: he i s g oup pe o med he ask in a common desk op sc een (DS) and he second g oup
iewed he en i onmen s in a high- esolu ion powe wall sc een (PW). Acco ding o he p e ious
li e a u e, we expec o ind a highe s imula ion o he sense o p esence in he PW g oup han in he DS
g oup.
Fo he assessmen o he sense o p esence, we need a measu e eliable, alid, sensi i e, and objec i e
(Meehan e al., 2002). The adi ional me hods used ques ionnai es o his pu pose, ob aining alid ye
subjec i e esul s. Since he es s a e ca ied ou a e he i ual expe ience, hey do no p o ide
in o ma ion o he empo al e olu ion and a e in luenced by he subjec ’s opinion. This can be obse ed,
o example, in he s udy om Usoh e al. (2000), who used ques ionnai es o dis inguish be ween he
sense o p esence expe ienced while pe o ming a ask in he eal wo ld and inside a i ual en i onmen .
They passed di e en ques ionnai es o he subjec s a e bo h expe iences, ob aining only a ma ginally
highe p esence a e in he eal scene.
Ano he way o e alua ing p esence is he use o physiological measu es, aken du ing he i ual
expe ience and no a he end o i , so hey can be used as eal ime moni o ing du ing he ask. Be ween
he measu es a ailable, we can ema k echniques such as hea a e, skin conduc ance, eye mo emen o
su ace elec omyog aphy. Fo example, Meehan e al. (2002) used hea a e, skin conduc ance and skin
empe a u e o he measu e o p esence in a s ess ul i ual en i onmen . Thei hypo hesis was ha he
mo e eal he en i onmen seemed, he g ea e sense o p esence he subjec would eel. They concluded
ha he bes assessmen o he p esence expe ience was ob ained wi h he hea a e esponse.
Apa om pe iphe al physiological measu es, di e en neu oimagen echniques ha e been p oposed and
used o he assessmen o he sense o p esence inside a i ual en i onmen , such as unc ional magne ic
esonance imaging ( MRI), T ansc anial Dopple (TCD) o elec oencephalog aphy (EEG). Rega ding
MRI, Baumga ne e al. (2008) analyzed b ain ac i a ions associa ed wi h p esence in child en and
adul s while wa ching a VR ideo o an au oma ic na iga ion in a olle coas e scena io. They compa ed
he di e ences be ween a high p esence and a low p esence en i onmen . Resul s om he MRI analysis
showed ha he p esence expe ience e oked by he i ual olle coas e scena io was associa ed wi h an
inc ease in ac i a ion in a dis ibu ed ne wo k. As discussed la e by Jäncke e al. (2009), he dis ibu ed
ne wo k ha is ac i a ed du ing he p esence expe ience includes he do sal and en al isual s eam, he
pa ie al co ex, he p emo o co ex, he mesial empo al a eas (including he hippocampus, amygdala and
insula), he b ains em and he halamus. In a p e ious s udy ca ied ou by ou g oup (Clemen e e al., in
p ess), MRI was also used o he measu e o p esence in a i ual en i onmen , compa ing h ee
expe imen al condi ions: pho og aphs, ideos and ee na iga ion h ough he en i onmen . We ound
signi ican di e ences in he le el o p esence expe ienced while na iga ing compa ed wi h he o he wo
condi ions, mos ly in he insula, he cuneus and he pa ie al lobe. Wi h ega d o TCD, wo ecen s udies
(Alcañiz e al., 2009; Rey e al., 2010) p oposed ha TCD could be used as a b ain ac i i y measu emen
echnique o s udy p esence in i ual en i onmen s. Resul s o hese wo s udies showed changes in
blood low eloci y in he majo ce eb al a e ies o he pa icipan s du ing momen s associa ed wi h
di e en le els o p esence in di e en imme si e and na iga ional condi ions.
The o he echnique ha has been p oposed and applied o p esence measu emen is he
elec oencephalog aphy (EEG), due o he eedom o mo emen he subjec has once he elec odes a e
placed, especially in compa ison wi h echniques ha impose se e e es ic ions o mo emen s such as
MRI. EEG measu es he elec ic ac i i y in he b ain; mo e speci ically, i measu es he synap ic
po en ials in he ce eb al co ex. EEG signals show he di e ence in po en ial be ween wo elec odes, an
ac i e one and a e e ence one. The ime esolu ion o he echnique is o he o de o milliseconds,
allowing he measu e o he luc ua ions in he EEG signal due o he asks de eloped.
Un il now, se e al s udies ha e been made combining VR wi h EEG o measu e he sense o p esence
expe ienced by he subjec s. Fo example, Baumga ne e al. (2006) e alua ed he ce eb al ac i i y
ela ed o he sense o p esence using a mul ichannel EEG, applying he low- esolu ion b ain
elec omagne ic omog aphy (LORETA) me hod o s udy he co ical s uc u es ha p oduce he
neu ophysiologic ac i a ion. They compa ed ac i a ions be ween child en and adolescen s while iewing
a ideo o a olling coas e , and ound ac i a ion in he pa ie al a eas o he b ain.
Mo e ecen ly, o he s udies we e de eloped in in e ac i e en i onmen s whe e he na iga ion h ough he
i ual en i onmen s was allowed, in o de o inc ease he sense o “being he e”. In he p e iously
men ioned s udy om Kobe e al. (2012), which compa ed wo sys ems o he p esen a ion o he i ual
s imuli, one based on a high-imme si e VR wall (3D) and ano he based on a low-imme si e 2D desk op
sc een, i was obse ed ha he 3D sc een sys em showed a g ea e p esence sense associa ed wi h an
inc ease in he Alpha band o he pa ie al TRPD (“Task- ela ed powe dec ease”), ela ed o he pa ie al
ac i a ions. The lowe p esence expe ience in he 2D sc een was accompanied by a s ong unc ional
connec i i y be ween he on al and pa ie al a eas o he b ain, poin ing ou ha he communica ion
be ween hose a eas is c ucial o he expe ience o p esence.
In ano he s udy which ollowed a di e en EEG-based app oach o he e alua ion o p esence, Kobe
and Neupe (2012) s udied he E en -Rela ed b ain Po en ials (ERP) o he EEG signal, which we e
elici ed by ones ha we e no ela ed wi h he VR expe ience. They ound a co ela ion be ween he
inc ease in he p esence expe ience and he dec ease in he la e nega i e slow wa e ampli udes, ela ed o
he cen al s imulus p ocessing and he alloca ion o he a en ional esou ces. Acco ding o his
conclusion, an inc ease in p esence is ela ed o a g ea e pay o a en ion o he i ual en i onmen ,
which leads o a dec ease in he a en ion paid o he i ele an s imulus o he VR (dec ease in he ERP
componen s due o he ones).
Recen ly, se e al s udies ha e been ca ied ou using he Emo i EPOC headse , ying o demons a e i s
use ulness and p ac ical applica ions. Gi en i s po abili y and i s low-cos in compa ison wi h o he EEG
de ices, i is widely being used (especially in BCI applica ions) due o i s high empo al esolu ion
compa ed o o he non-in asi e echniques such as MEG, MRI o he adi ional EEG (Du inage e al.,
2012). Fo example, Campbell e al. (2010) used i as an in e ace o communica e he b ain wi h a mobile
phone applica ion, in o de o command i jus wi h men al o de s. Mo e p ecisely, in his s udy he e
appea a sequence o pho os o con ac s in he phone and when he showed pho o ma ches ha o he
con ac he use wan s o dial, a P300 b ain po en ial is elici ed. In ano he s udy, Khushaba e al. (2012)
explo ed he b ain ac i a ions elici ed while pe o ming a ask whe e decision making is in ol ed. They

used an Emo i EPOC headse o measu e he b ain ac i i y, as well as a Tobii-S udio eye acke sys em
o cap u e he pa icipan s’ choice based on hei p e e ence in looking a . In a pos e io s udy, he same
g oup (Khushaba e al., 2013) explo ed he comme cial applica ions o his decision making measu es o
he guidance o choose he ma ke ing ha be e i s he consume p e e ences. In his conc e e s udy, hey
used again he Emo i EPOC headse o measu e b ain ac i i y while pe o ming a choice ask o choose
among he use ’s p e e ed shape, la o and opping in biscui s.
The Emo i e EPOC has also been applied o e alua e b ain ac i a ions ela ed o emo ional induc ion. In
he s udy om Rod íguez e al. (2013a), i ual en i onmen s we e used o p o oke a nega i e mood
(sadness) in he subjec s while hei b ain ac i a ion was measu ed be o e and a e he nega i e induc ion
by means o an Emo i EPOC headse . In ano he s udy (Rod íguez e al., 2013b), hey also applied his
low-cos EEG de ice, o moni o b ain ac i i y du ing a posi i e emo ional induc ion ( iew o alida ed
images om he IAPS sys em).
Taking in o accoun all his p e ious esea ch, and since he in luence o use -con olled na iga ion on he
p esence expe ience and on he associa ed b ain ac i a ions has no been di ec ly e alua ed ye , he main
goal o he p esen s udy will be o compa e b ain ac i i y due o p esence be ween h ee expe imen al
condi ions associa ed wi h di e en le els o na iga ion con ol: he iew o s ill pho og aphs o he
i ual en i onmen , he iew o a ideo o an au oma ic na iga ion h ough he en i onmen and a ee
na iga ion h ough he VE. We expec ha he sense o p esence will be g ea e in he na iga ion
condi ion han in he o he wo condi ions, and ha he e will be di e ences in b ain ac i a ion in a eas
ela ed o p esence. Mo eo e , we will compa e he b ain ac i a ions due o di e ence in p esence
depending on he sc een used o he isualiza ion o he en i onmen s. We expec ha he mo e
imme si e and ealis ic sc een will gene a e a highe sense o p esence.
2. Ma e ial and Me hods
2.1. Subjec s
Fo he s udy, 20 heal hy subjec s we e ec ui ed; being di ided in o wo g oups o 10 subjec s each. The
i s g oup iewed he VR en i onmen s by means o a common desk op sc een (DS), while he second
g oup iewed he en i onmen s on a Powe Wall (PW) sc een. Fo he i s g oup (DS), 6 men and 4
women we e e alua ed, wi h ages be ween 22-29 yea s old. Fo he second g oup (PW), 5 men and 5
women ca ied ou he s udy, wi h ages be ween 21 and 29 yea s old. All he subjec s we e igh -handed.
The pa icipan s’ hand dominance was es ed using he Edinbu gh Handedness In en o y (Old ield,
1971). All o hem p o ided signed consen o allowing hei da a being used in his s udy. One subjec
(a woman) om he DS g oup had o be excluded due o mo emen du ing he scan. The expe imen s
we e conduc ed in a labo a o y inside he LabHuman g oup. The EEG signal was moni o ed by means o
a mul ichannel wi eless po able EEG de ice (Emo i EPOC) (Rey e al., 2012), which has 14 da a-
collec ing elec odes and 2 e e ence ones. The handse ansmi s wi elessly he EEG da a o he
compu e .
2.2. P esence Ques ionnai e
A e he EEG session, subjec s had o answe he ques ions o a SUS ques ionnai e (Usoh e al., 2000) o
e alua e he le el o p esence ha hey el du ing each ask (one ques ionnai e o each expe imen al
condi ion). The ques ionnai e consis ed in six 7-poin Like ype ques ions ha had o be answe ed
depending on he s eng h o he “being he e” sensa ion expe ienced, whe e 1 co esponded o no eeling
he e a all and 7 o he highes sense o being he e (as expe ienced in he eal wo ld).
2.3. En i onmen s
The i ual en i onmen s we e p og ammed using GameS udio so wa e (Coni ec Da ensys eme GmbH,
Ge many), which allowed us o de elop 3D objec s and i ual wo lds wi h which we could in e ac and
na iga e. Ou i ual en i onmen (VE) consis ed o an e e yday, clean bed oom (wi h a bed, a close ,
and a desk wi h some books on i ) whe e pa icipan s could na iga e eely.
To allow us o iden i y he speci ic a eas o he b ain ha we e ac i a ed o each ask, we di ided he
pa adigm in o h ee condi ions de eloped wi h he same i ual en i onmen : in he i s , pho og aphs o
he en i onmen we e shown; in he second, a ideo o an au oma ic na iga ion h ough he oom is
obse ed; in he hi d, he pa icipan can na iga e eely in he VE. A scheme o he p o ocol can be seen
in Figu e 1.
Figu e 1. Diag am o he expe imen al design. In he bo om pa o he image, he scheme o he p o ocol
ollowed in he expe imen is shown. Abo e i , i can be obse ed a cap u e o he en i onmen .
Each condi ion was epea ed six imes. To lea n abou he asks ha had o be pe o med inside he
scanne oom, subjec s unde wen a p io aining session. In o de o p e en di e ences in ac i a ion
caused by he mo o ask, subjec s we e ins uc ed o mo e he joys ick con inuously du ing he
pho og aphs and ideo asks in he same way as hey did du ing he na iga ion pe iod.
2.4. Da a Analysis
We analyzed he esul s o he SUS ques ionnai es using he p og am SPSS 17.0 (IBM Co po a ion,
Some s, New Yo k, USA). Apa om he indi idual esponses o he six ques ions associa ed wi h each
o he pe iods (pho og aphs, ideo and na iga ion), we calcula ed an addi ional measu emen : SUS mean.
This is he mean sco e ac oss he six ques ions ha has al eady been desc ibed in p e ious s udies (Usoh
e al., 2000). We ca ied ou a non-pa ame ic F iedman Tes o compa e SUS esponses (dependen
a iables: ques ions 1-6 and SUS mean) o he di e en expe imen al condi ions: pho og aphs, ideo and
na iga ion. Pos -hoc es s we e made wi h a Wilcoxon Signed-Rank es wi h Bon e oni co ec ion.
The p ep ocessing o he signals was made by means o he EEGLAB p og am (Delo me and Makeig,
2004). All eco ded EEG epochs we e checked o a i ac s. Fi s o all, da a we e digi ally il e ed using
a linea FIR band pass il e (0.5-45 Hz). Then, he elec ooculog aphic (EOG) a i ac s we e emo ed
applying Blind Sou ce Sepa a ion (BSS), using a window leng h o 10s, wi h 5s be ween windows. The
elec omyog aphic (EMG) a i ac s we e emo ed using also he BSS me hod.
Fo he analysis o he ac i a ed b ain a eas, he sLORETA (s anda dized low- esolu ion elec omagne ic
omog aphy) ool was used (Pascual-Ma qui e al., 1994, 1999; Pascual-Ma qui, 1999; F ei e al., 2001).
The whole b ain was analyzed using oxel-wise - es s o examining he na iga ion s. ideo and
na iga ion s. pho og aphs condi ions in he six equency bands. Mo eo e , he same oxel-wise - es s
we e used o compa ing be ween he na iga ion condi ions o he wo g oups (DS s. PW) in he six
equency bands.
3. Resul s
3.1. Ques ionnai e Resul s
The answe s o he SUS ques ionnai e showed be ween subjec a ia ions. Mean alues in each condi ion
a e shown in Table 1. Resul s om applying he non-pa ame ic F iedman Tes showed ha he e we e
signi ican di e ences be ween he h ee expe imen al condi ions o all he ques ions and he SUS mean
( esul s can be obse ed in Table 1, columns 5 and 6). I we obse e he esul s o each ques ion, we can
see ha o he DS g oup, he g ea es Chi-squa e alue (χ2 = 16.222, p < 0.001) was obse ed o
ques ions 1 and SUS mean; while o he PW g oup, he g ea es Chi-squa e alue (χ2 = 13.556, p <
0.001) was obse ed o ques ions 1 and 3.
Pos -hoc analyses based on Wilcoxon Signed-Rank Tes s we e conduc ed on he SUS mean esul s wi h
Bon e oni co ec ion, esul ing in a signi icance le el se a p < 0.0167. Fo he DS g oup, he e we e no
signi ican di e ences be ween he pho og aph and ideo asks (Z=2.082, p=0.037>0.0167), bu he e
we e o he compa isons na iga ion s. ideo (Z=2.668, p=0.008<0.0167) and na iga ion s. pho og aph
(Z=2.668, p=0.008<0.0167). Fo he PW g oup, he e we e no signi ican di e ences be ween he
pho og aph and he ideo asks (Z =2.380, p = 0.017 > 0.0167) and be ween he pho og aphs and
na iga ion asks (Z=2.366, p=0.018>0.0167). Howe e , he e was a s a is ically signi ican inc emen in
he SUS mean in he na iga ion condi ion compa ed wi h he ideo condi ion (Z =2.521, p = 0.012 <
0.0167). Those esul s a e con ained in Table 2. Finally, we should men ion ha no signi ican di e ence
was ound o he ques ionnai e answe s be ween g oups (DS s. PW) o any o he h ee expe imen al
condi ions.
Table 1. SUS esponses o ques ionnai es o each ask (mean sco e and s anda d e o o he mean) and
esul s o he F iedman Tes o each ques ion and he mean sco e
Pho og aph Video Na iga ion χ2 P
DS 1.89±0.35 3.11±0.31 4.89±0.39 16.222 0.000 SUS ques ion 1:
eeling o “being he e” PW 2.90±0.33 3.80±0.26 4.80±0.41 13.556 0.001
DS 2.22±0.43 3.00±0.33 4.78±0.40 12.400 0.002 SUS ques ion 2:
eeling ha he oom is
eal PW 2.40±0.23 3.70±0.35 4.30±0.39 12.286 0.002
DS 1.56±0.24 2.67±0.24 4.11±0.39 15.548 0.000 SUS ques ion 3:
how eal do you
emembe he oom? PW 2.20±0.34 3.40±0.32 4.50±0.39 13.556 0.001
DS 2.00±0.37 2.89±0.51 4.78±0.49 14.813 0.001 SUS ques ion 4:
eeling o being inside
he oom o obse ing i PW 2.50±0.28 3.40±0.28 4.80±0.44 12.600 0.002
DS 2.89±0.42 2.89±0.39 3.78±0.49 10.800 0.005
SUS ques ion 5:
memo y o he oom as
simila o being in o he
places PW 2.90±0.46 3.70±0.32 4.70±0.39 9.680 0.008
DS 2.33±0.37 3.22±0.28 4.78±0.47 9.800 0.007 SUS ques ion 6: did
you hink you we e
eally in he oom? PW 2.60±0.48 3.40±0.36 4.40±0.48 10.000 0.007
DS 2.15±0.28 2.96±0.24 4.52±0.35 16.222 0.000 SUS mean
PW 2.58±0.27 3.57±0.23 4.59±0.36 12.839 0.002
Table 2. Resul s o he Wilcoxon Signed-Rank Tes o he compa ison o he SUS mean esul s be ween
expe imen al condi ions
DS PW
SUS mean Z P Z P
Na iga ion>Video 2.668 0.008 2.521 0.012
Na iga ion>Pho og aphs 2.668 0.008 2.366 0.018
Video>Pho og aphs 2.082 0.037 2.380 0.017
3.2. EEG Resul s
Fo he DS g oup, he compa ison be ween he Na iga ion and Video condi ions using oxel-wise - es
o all he equency bands e ealed signi ican di e ences in he Alpha-band (8-12 Hz) and The a-band
(4-7 Hz), o p<0.05. Alpha and The a band powe was dec eased in he Na iga ion condi ion in he igh
Insula (BA 13), indica ing inc eased ac i i y in his egion du ing he ee na iga ion ask.
Figu e 2. Resul s o he Na iga ion> ideo con as o bo h expe imen al g oups. Cap u es o sLORETA
ac i a ion o he na iga ion> ideo con as in he The a band o : a) DS g oup, b) PW g oup
Fo he PW g oup, he same compa ison be ween he Na iga ion and Video condi ions, again using
oxel-wise - es o all equency bands, e ealed signi ican di e ences in he The a-band (4-7 Hz), o
p<0.05. The a band powe was dec eased in he Na iga ion condi ion in he igh Insula (BA 13),
indica ing inc eased ac i i y in his egion du ing he ee na iga ion ask. The e has been also ound a
end (p<0.1) o inc eased ac i i y in he Insula (BA 13) and in he Pa ie al Lobe (BA 40) o he Alpha-
band. A compa ison be ween he esul s o he na iga ion> ideo con as in he he a band can be seen in
Figu e 2. All he esul s o his con as a e con ained in Table 3.
Table 3. Compa ison o he esul s o he DS and PW g oups o he na iga ion> ideo con as
G oup B ain A ea Band Hemisphe e p
DS Sub-Loba , Insula (BA13) The a Righ <0.05
DS Sub-Loba , Insula (BA13) Alpha Righ <0.05
PW Sub-Loba , Insula (BA13) The a Righ <0.05
PW Pa ie al Lobe, In e io Pa ie al Lobule (BA40, 39, 7) Alpha Righ <0.1
PW Pa ie al Lobe, P ecuneus (BA19) Alpha Righ <0.1
PW Pa ie al Lobe, Angula Gy us (BA39) Alpha Righ <0.1
PW Pa ie al Lobe, Supe io Pa ie al Lobule (BA7) Alpha Righ <0.1
PW Sub-Loba , Insula (BA13) Alpha Righ <0.1
Rega ding he esul s o he compa ison be ween he condi ions o Na iga ion and Pho og aphs, we did
no ound any signi ican esul s o any g oup, bu we ound se e al a eas wi h endency o signi icance
in he PW g oup. Fo he Alpha band, he DS g oup p esen ed a end o ac i a ion o p>0.1 in se e al
on al and empo al a eas, as well as in he pa ahippocampal gy us. Fo he PW g oup, also in he Alpha
band, we ound he majo signi icance esul in he Uncus o he pa ahippocampal gy us, pa o he
Limbic Lobe; and endency o signi icance in o he a eas o he empo al and on al a eas. The comple e
esul s o his con as a e con ained in Table 4.
Table 4. Compa ison o he esul s o he DS and PW g oups o he na iga ion>pho og aphs con as
G oup B ain A ea Band Hemisphe e p
DS Sub-Loba , Insula (BA13) Alpha Righ >0.1
DS F on al Lobe, Subcallosal Gy us (BA34, 13) Alpha Righ >0.1
DS F on al Lobe, In e io F on al Gy us (BA47, 13, 11) Alpha Righ >0.1
DS F on al Lobe, O bi al Gy us (BA47) Alpha Righ >0.1
DS F on al Lobe, Middle F on al Gy us (BA11) Alpha Righ >0.1
DS F on al Lobe, Medial F on al Gy us (BA25) Alpha Righ >0.1
DS Limbic Lobe, Uncus (BA20, 28, 34) Alpha Righ >0.1
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Highligh s
> We analyzed he sense o p esence expe ienced in a i ual en i onmen using EEG. > F ee
na iga ion in a i ual en i onmen was compa ed wi h ideo and pho og aphs. > We compa ed he
esul s ob ained using wo di e en sc eens. > A common Desk op sc een and a high- esolu ion powe
wall sc een we e compa ed. > We used an Emo i EPOC headse , ob aining ac i a ion mainly in he
Insula.