Fred H. Previc Air Force Rereorth Loborofory, Flight Motion Effects Brriiidi,

Brooks AFB

Neuro sychological

Control Stations Guide r ines for Aircraft

Applying Knowledge of How Humans Inferact In Different Portions o f 3-0 Space

cspi~c ihe rigorous prnccss lor sclecl- D i n g ;iiitl iraitiiiig iiii1it:ir.y pilots, thcy ;ill too ul'leii xuccunib tu spntial disoricniii- tion (SD) aiid l oss u l xihiitinn ;iw:irci~cs~ (LSA) i n Ilight. [I i s eviiiiatcrl tli:iL SD Inishiips ticcur iiIicc cvery 300,000 Iiuirrs [ I ] m r l ilint an LSR rnixlia[i occurs aboirl threc times as nftcn 121. Ilericc, an cxpci.i. cncccl pilot with 3000 Iiu~u.soi'figIitexpc- ricncc has ii 1 % likcliliood of bcing itivolvcd in an SI)-rclaicd inishap ;uid at least ii 3% clinncc ofbciiig irivolvctl in ci- tlicr ;in Sn- nr LSA-rcloietl iniish;ip. Ilow- ever, tlic likelihood i ) C beitig invrdvcrl iri a n SD-rcliItetl i ticidcnt (hat poscc" ;I scriruia risk ro wt'cty or' iuission success i s riiiicli highcr.: t'or cxoniple, 26% of axperiencctl figli~cr pilots Ilyiiig F- I Os rcpor~crl lliai SI) hacl causcd n "iicru.-r~ccitlcnl" i n their flying careers 131.

A I hough tlic abnorniril nccclcrnlory ciiviroiiiiiciit or Ilight i s inhcrcnlly dati- gerntis aiid tinfoigiviiig, thc poor' ricsigii d i i i o> t aviation contml stations iugi iabl y coni poiinrls Ihc serisorimoic ~r liiriitationa of pilots i n thc aerial cnviroiinicnt. l'hc pirpow of i h i s ;irliclc i s lo provide aset of guidcliiics for aircmfl cntitrol slnlions (in- cludiiig ccickpils), based on Iicuropsycho- logic;il principles. l'licsc stations w i l l cxploil rtilly thc inl'oriiiatioti~~iroccssiiig ciipiibilitics til' pilots a i i d ;illow iheiii to cnpe tiertcr w i h theclciiwntls or rlyiiig ilnd erilioiiccrl t a c h 1 npcwtioiis.

Building U Better Conlrol Stution Idcall y, ;iircr>ill c n t ~ o l stiirioiis should

;dlow ttic operator to prc)ccss inloriiiiiticm in h c sariie w;iy 11i i i i llic tiiiinw bmiri l int- tiridly docs s o . 111 our evcrydap cxislcrice, l i i i i i ia i ix ordinirriiy process and act upoii an cncwioiis ainuuiit cif i i i l 'orinidioi~, Inucli o f it prccmscious. I h r iiisinrice, wc

IEEE ENGINEERING IN MEDICINE AND BIOLOGY

cnntiniioiisly iuonitor and i i pd~~ tc our prcscni i ind fuilire gcog'.;q>hic;d locations, lociil inctcomlogical ciwlitiunu, anrl 1hc signiliciiiice of various u h c r cxtertinl ob- jccts mid cvciirs, along with ( i t 1 1 4 posturc in space, i i i i td io i id status, anrl oillei. itifor- irintinn cm;in;il i iig from oiir butlily wises.

It i s nrguablc h i t , iii our iiorrnd lcnmtriiil cxistencc, wc pinccss truich nime 1nfo1- iriation than c I n eveii pilots i>lhigll-peifor- iiiiiricc aiumfi , despite thc r x l ttiat thc Iiiticr arc 1:isli-s;iitirnterl i i u h 0 1 their liuic. Morcovcr. oui' iintiiral iiitbriiintion processing occurb at high spd -e .g . , the optical flow iissoci:iierl wiih vchiculat loconioiioii on earth is usiially o f consid- ci.iibly highcr vclocity than thai eticniiii- lcretl tiy pilors oi' Iiigh-l~crforiiinricc flitcraft. ' lhc I'iiii(1ainciital prublcm fricing pilots wid olher nircrat't r ipc~iiors, thcn, i s no1 tlic amoun( arid npced ril'tlicirreqiiirctl it1fnrm;itioii pi"xsing, but ixtlicr the q~ialily :iiirl iiiluiiivcncss oC the infortnil- tioir provitlctl IO tticin.

IJnli~rItui;iicly, it i s iinpossiblc t o dupli- cate i i i i ic l i ui' h e inf(iriiiatiiin processing h i wc iiaturdly ciigagt: in as wc innvc ;ILXNI~ 011 the ~ ; I C C or h e earth. r:urollr, sig- niils coiicerriing ilic slniur of our iiiotinn Iplatliirin ( c g , the body) iirc t imsin i t tc r l by iiicans 0 1 inmwcptivc seiisnry systciiis that ciiriiiot lic ~iscd IO iiifei.tlic status ofthc iiircrtfi i ii tl ight. Sccoiirl, nonvisuii I wi-

sury syslcins (c.g., the vcstibdiir and soinatoscnsory otics) thiil providc riipkl iiiitl nccuratc iiirorinrrtinii c t " w i t i g our pnsition in spnce during niiitrral Iiiiwc- iiieiits arc less reliotilc iii rliglit cluc [U ilrc cxisieiice of gl.;ivito-irierti;il forcc vcctors ~h;it rlcviatefroin rhc rlir~ctionoTirut:gI.av- ity. Third, i l ic It111 three-rliiiiciisioiial (3-D) cxtcnt orltlr: m i r i d V~SLI~ I I world cannot bc cluplicatcd withiii the fiiiitc ctmhies of tlic

US GoveriimantVhrk Not Pmterted by US Copyright a i

nircraft. or any other ponablc plnll‘orni housing iii i ;iircraftcontrol display. Finally, the motor systems used in Iocumoling on wrth (i.c., the trunk and Irwcr liinlis) can- no1 as easily be used in conlrolliug thc mo- tion of the aircraft. Tlicrefore, operators are rorcetl to ovcr-rely on iiianuat-cnntrol sys- tems that are ordinarily used in reaching, object inniii~iiilation, mnd rithci snphisti- cnted visuotnotor intcractioiis unrc1;ited to locurnotion.

Allhough an idcnl aircraft control sta- tion slionld atternpt to duplicate the norinal terrestrial environmcnt w hcncver possible, it slioiild be even inore c~iniiicnsiiralc with Ihc iiieiital nindels uscd hy different brain system involved in carrying oul our ov- cryclay pcrceptual-motor interactions. A recent neuropsychololjical mridcl of how liumiiiis intcract with our 3-D spntinl eiivi- ronincnt 14J may provc cspecially fruitful in this regard. This iiiodel, shown inFig. I, proposcs lkal [our major brain systems ine- diate our percepiunl-motor intcriictions in 3-D spacc. A dorsolateral cortical system subserves o w interxlions in peripetxotid spice, i n which reaching arid objeclmnuip- ulation occiir. A vcnlroliitcfid cortical sys- Icm is iiscd i n f i ~ a l ex/n~per.wml space lo search [or mid rccognizc objects and other dclailcd infwnatioti (e.g., alptianomeric symbology)). A veiilromedial cortical sys- tcm is used to navigate nnrl nrient inlAori r?wrp.iper:wrd sl~aoc, which is defincd as our topugraphical (geogmlihicnl) enviry- ment. Finally, R dorsonicdial system is uscd to oricnt in ;id locoinnteabout in um- bierrf extraper,roriaL space, which is (IC- l‘incd in cartli-fixed or gravitational condiniilcs.

Peripersonal sensory

inputs help to align

gaze and limb position

with the object.

As rurrlicr Bclincatcrl it1 ‘Table I, each ol‘thcsc rour bri~i~i systems interacts with its own rcginn of the 3-D world, has :I uniqtic ctiniliinatiori of pretlomiiiwnl scii- sory and inotorsysterns, mtl iiscs ii unique coorclitiate system for carrying out per- ceptual-niotor i n l m c l ions wit hi n that spcc . Fur cxample, o~ir peripersonal sys- tcin is 1) biascd to the lower proxiirial vi- stiiit ficld; 2) relies mainly on visuel, vestitiular, and soilinlosensory scnsory iii- puts; 3) iiscs upper-linih rrinveinenls ;IS its imjor motoric instrument; mid 4) has :I

spatial coorrlin;itc systcm that is cciitered aroand the upper limbs ml lorsti. Con- versely, the RcLioii exlrapcrsund system is 1 ) biased Lo thc uppcr distant visual fielit; 2) relies on visir;il und auditory sensoryiri- puts; 3) iiscs priin;irily horizontnl head iiiovcinciits in oriciiting and navignting; and 4) h;is its coordinatc system centered around the position of gaze.

Before proceeding to discuss how air-

coin[iic~~siirate with tlic operations per- fi>rinerl in c d i rcalin or 3-D spncc, two general points will bc nnted aliout the ecology orour 3-U world. First,oneof thc factors that helps lo unify the four 3-D reelins is (Iic fiict that all rely on visiuii ;is

their primary sensory system, although lhc iypc ofvisual proccssiiig that preedoin- innks i i i c d i rcalin is not always thc same-e.g., “global” motiori processing is used cxtcnsively in peripersonal spacc, whcrcas sustained “lncal” visual proccss- ing is relied on i n local extrnpcrsonal space 141. Hciicc, ptirely visunl tlisplsys should be able to proviilc a good iiware- ness of the pusitinn nf the sirclnrt in rela- tionship to its surrotindiiig spice. Second, onc o f thc most fundarricnlal featuccs of rhe visual aiivironmctit is that the groiiiid planc slopes tip arid away ~ ~ O I U thc nh- scrvcr.’l’hus, the inore proxiinol and distal portions of the visual world arc Iriciiteil iii the lowcr and tipper visual fields, respec- tively. Not surprisingly, the preferIetl vicwing angle fnr a given display bc- comes elevated BS thc distnnce to it in- crea~es [SI, just ns o p t i d vcrgence and accmn inorlation bccorne more di stnn L with increasing elevalion or our cycs 161. A n y t r u l y well-designed worksla- lion--whether used for cortrolliiig air- crnft or nul-should cinhrace this cardinal fcntiire of our 3-r) enviroiiincnt 17:j.

The iicxt sactIoi~ of th is article will il- lustriitc 110w n ncii rnpsychological under- standing or thc w:iy iti which humans intcr;ici with their 3-D spatial envirou- mcnt can lead to specil‘ic prcdictions coil- ccrniiig the locnrioii aiid fcahrrcs of

Extrapersonal

Focal ’ Exlraoersonal Ambient

Action Ex t rapersonal

1. The iiciiropsyclinlogy of 3-1) spwct. Tlic four bcliavinral rcalms are showii at thc Icft, whilc thc Bur corticnl systcins nirrc- spundiiig to cach arc shown at the right. Adapted frnm rips. 3 aiirl 5 uf 141.

a2 IEB ENGINEERING IN MkOI[IYE AND BIOLOGY March/April?OOO

3-0 Spatinl Realms: Functional Characteristics and Relevante for

Aircroft Control Stations

Peripcrsonal Ttie prirnnry fiinctiona carried otil iii

peripersoiial spacc arc reaching h i - ob- ,jects and otliei, manipulihtis tlxit, at least in rlonhurnan priiiiates, arc c ~ u s e ~ y ticd IO

cunsumiuatory bclinvior. PcrIpersniial SCIISO i’y i 11 p 11 Is (visual , so 111 ntos c 11- sory/plnpl.ioccplive, and vcstibular) hclp to align g a m and liinh ptrsiiion with thc ohjccl. Peripcrsoiinl inntrir oulpu(s arc iisetl in grasping :lilt1 iiianipulnting the ob- jcct using thc ;ii’ni and h m l ;is well a s in tracking (Iisiiig tiend and smooth ociil:ir ninvcincnls) the ;ir111 alitl hand ;IS llley rciich for nritl in;iiiipul;ile thc ob,iccr 141. Thc v isua l spcc ia l iza i ions uf o u r pcripersonal system includc: I) “glot)al” iiioliari proccssing, which is nccersitated by rlie iinpossibility of proccssiiig tlrc rapid and optically dcgratlcil ruotioii LISII-

;illy found in this rcnliii hy %A“contniir iriecliaiiisms, i ~ i i d 2) “cuortliiiate” pro- cessing, wliich is reqiiircd Tor h e prccisc visuo-spatial distance j iirlgrricnts in- volvcil in reiicliitig aid grasping ohjccts. Uccause ofttie clow afl‘iiiity with Teetlitig, pcripcrsonnl 1)ch;iviors are also linkcd Ln homcostntic sign;ils coiiccrtiing thc skte of thc body itsclf.

The focal

extrapersonal system

is the primary one

involved in processing

alphanumeric

information from

control displays.

In lapping into thc! natural lmclivit ies o f our pci.iper.son;il brain xystcin, aircrall control stations should fncilitalc itic iiae

of “i inalog” (trajccrnry- o r move- tncnr.-based) vi siio- iiiaiiiial incchoni sins in iiiter;icting with visual displays. l ’ h i s i n a n d behavior shuultl occur in thc not- i i i d locntion trT pcripersoii;iI i ic l iv- i ty-nmnely, thc inid-io-Iowcr portion ill thc slntioii and wilhiii +30 tlcg of tlic

niidl i nc oC (lie control station. 111 hicl, most aircraft crintrol stations grossly violate thcsc giiitlclirics by: I ) rcqiiiring h t tlic iixiiiunl system hc iiscd primarily for con- trolling tlic aircraft in spacc (iiormnily a task ol’ 0111’ wholc-hotly locoinntory sys- Icrric); 2) h c i i i g inaiii id hehovior tu he ciirricd out well riutsidc of i t s normal riiiigc (e.g., control p;incls (hat extcntl 90 dcg or inore IO the sidc til‘ thc cockpit or ahiivc ttic pilot); and 3 ) using only ‘iligi- I S I ” reqionscs (e.g., “huuoti-1~~cssiiig”~ to interact with niMytr i ly Iociitctl switch scttings whose cn inh inahs 1’1111 illto tlic thousands.

Tlic first violnrjori can hc solvcd by al- lowing nircralt control tri hc partly iis-

sutncrl by the Vccct (tliscussetl later), wliicli woiiltl ihcrcby C1.w up ;it Ic;isl onc h i c l for in;iiiipulntinii rrTilispl;iy in~ol~niation. ’I’he secoiid i i i ic l third violations cotilrl be dcalt with by niiniiriizing tlic oveixll nuinbcr of swilclics and by locating tlicin in iiorinal reaching spncc. Onc way to (lo th is would hc i o iise touch-scrccti or ciirsiir (inousc) rccliriologics thal h i l i t a t e direct niitllnr “anahig” mnnunl iiiterxtions with rhc in- formalion that i s bcing inaiiipn1;itcrl ;it a pariiciilar inoiiiciii. I ,imited “itliillog” sys- teins Tor coiitmll ii ig LI i s l h y i iifot.ni;iiioii ;ire alimtly in existence iii arlv;incctl air- crat‘t such :IS the F- I X, which has a cursur knob 011 its ccnier-srick. Altcrnliiivcly, oiic cnulrl conlrol displays hy incans of

Table 1. Behavloral

Perlpersonal

Function Visual Grasping, Manipulation; Consumption

3-D LOCUS Lateral extont Vertical bias Radial extent

Central 60 deg Lower Field 0 - 2 m

Primary CO-Ordlnate System

Bod y-centered (upper-torso)

Sensory Systems

Vlsual Somatosensory! Proprloceptive Vestibular Gustatow

Motor Systems

Arm Movements Smooth €ye Movements Head Movements U ppe r-to rso M oli on

vstems Involved In 3- Extrapersonal (local)

Visual Search; Object, Face Recognition

Central 20-30 deg Upper Field 0.2 m - Distance

Retinotoaic -

Visual Proprioceptive

Saccades

Spatlal Interactions

Extra personal (actlon)

Navigation; Scene Memory; Target Orientation

-

-.

Full 360 deg Uppor Field 2 m - Distance

Gaze- (view-) centered

. .-

Vlsual Audltory Olfactory

Head movements (horizontal) Saccades Upper-Torso Motion

Extrapersonal (amblent)

Spatial Orientation; Postural Control; Locomotion

Front 180-deg Lower Field Most Distant

Gravitationall Earlh-fixed

_.

Vlsual Somatosensory/ Proprioceptive Vestibular

Leg Movements Head movements

Mortli/ADril 2000 IEEE ENGINEERING IN MED111HEAllD BIOLOGY a3

voliiiitnry siiccatlic cyc I I ~ U V C I ~ I C I ~ ~ S , vol- untary hcad inow”ciits, .or V U C ; ~ cuiii- inmds. Howevcr, the saccadic mid vociil syxteius are not nurmally tiscd i n peripersnnd space, mid both ai^ subjcct io signal-to-noise problcnis in psychulogi-

enviroiinien~iilIy s h m s r d (e.g. , noisy) kiir- cri~fl coiilrol cnvirrinmcnts.

Altlioiigh sinoorh Read iiiovetnetits arc nattil.;illy tiscd incon,junctinn with srnnnrli pursuit antl vergcncc inovcinentx iu Iperipersonal space and are being used in spccific applications such ns tracking out-the-window tai’gets using hel- met-inountcd displays, hciid-timking dunc is ritrcly iiscd tindcr natural ciwiin- sinnccs. I t is much lcss likcly to he used in vcrlical t ~ i c k i n g 181; irioreover, liead muvcinents can lcad to SD at high-Ci lev- els 19 ]. Hence, optiitial helmet-inoontcd

MI I y stressrui (e.g., i11gi1-worIt ioild) nllci

2. Visiitil suiircli pcrforniniicc as a Ctlnc- tion or target lociitiun hi thc four qiintl- rants of the visiial ficld. l b t t ~ iirc cxprcsscd as pcrcciitage of trials in which nii cyc riinvcmcnt was not ncctletl to luciitc thc targct (abnvc) and mcnn i-caction timc (in msec) tn locntc tlic target (liclow), Rasctl on data from cxptriiiiciit 2 nf [13].

piirsirit tracking systems sliould no1 rcly on hcad-tracking alone.

Uccause glolxtl Inotion niirl coordinate processing are iiripoiltlnt iii pcii~~crsu~id visuo-in;iid activity, they are also tied IO

thc proxiinal lower visual field 141. llius, anothcr iicurol’sychnlflgicijl giidelinc cuii- ccrning peripersonal operations would bc to plnce inany “ w i g or coordinntc-type displays (e.g., pictori;il noiwerl~al) re- ln~eil lo wc;ipons and iiircraft status in the inid-to-lowcr p o r h ofthc control station. For cxumplc, tratisicnt wrmiing cues slioultl alsohccfl‘cctivc i n this rcgion ni‘the coiilrcll stalion, givcii thc antiiral role nT tmnsicnt visual ciics in pcriper,sonal pro- cessing [4]. Inlcgriitcd status displays, which h a w 1101 only proven supcrior i n many psychologicid stiidics [ IO1 but have also incl with guod xccptance hy pilots [ I 13 antl arc witlcly used iii coininei~cinl lmducts, shciuld also lie placed iownrtl ilic Iowcr hulfol’ihe displny console. Allhough nlany pictorial displays involvc, lo s u m cxtctit, ohject-based recognilion proccsscs t h a t are normally npplictl i n focd exlrrqwsonal spice, a knowledge of air- craft status itselfix (like hodily pliysiologi- cal status) a rtinrlarnenlally ~pcripcimiiiil activity. Anoher reaswii fur placing tbc eii- gine and olher stillus displtiys i n tlic lnwcr poition nf il ie console is that thcy do not have to be as conlinuously inoiiitoretl as criticnl alphmimeric 2nd global siiii;ttioii infnrinatiori, which is much murc advant;\- geoiisly pIesen~ctl in Ihc tippcr pr)Ition of tlic console (scc bcluw).

Focal Extrnpcrsonal l‘lic main f i incr joi i of‘ l‘ocal ex-

trnpcrsoiial uperat ions is to scarch fnr ob- jccki i d other detniled shapes and 10 ~~ccognizc thcm. ‘The focal extrapei~soiinl system is t l x primary onc invnlvcd in pro- cessi ng alphanumeric iu f(irm;~lion froin

. . . .. .. . . . . . . . . . ... . . . . . . .. .. . .... . .. .. . . . .... . .. . .. . . .. . . _.’

Original Reproduction

3. Wiclc-ali& topographical iiiciiiory rcprcscntation iii huninns. Originill ilbstrn- t i m is shown s l left; rcprodllcccl tlmwing frnm mcmnry i s shown tit riglit. Adiiptct from Fig, I or [ 191, wiili parmission.

84 IBE ENGINEERING IH MEDIIINE AND BIOLOGY

Operations in the

action extrapersonal

realm are support

navigation and other

types of orientation in

topographically

defined space.

control d i s p l a y s . Gcncrii l ly, , its “rcrinoiopic” cuordinnte nysteiri i s tied IO ilic ~iosiiion cif thc eyes i n their orbils ;ind moves wiih ihc cycs in depth. The imst inlporlnnt ssiisriry input by far is vision, whilc ihc main motoric instrtunenl ~iscd by the focal cxtriq~crsuni11 systcm is saccadic cye ~iiovcmcnts.

’I’hc most critical control-stalion guidclines based un ;in undcrstmding nf focal cxtrn~>crsotial nperatinns rel;iic to the sizeand posiiioiiingnfva~ious display clcmcnts. Foc:il extrapersonal opefiilioiis ;ire limited In the cenh-iil 30 tlcg of the vi- suat field, in which 0111’ visual acuity is ad- etlti;ilc to support the high-resoltilion “lociil” contour nnalysis reqliilwl for a - pliari ii!iicric m r l urhcr sliopc processing [4]. Lvcn i n ti uncl~itieretl visual ricltl, targcts presented iiiore h i n I S tlcg away frorti the i‘ixnlion point cannot bc reliably dctcctctl without rnoving tlic cycs. In a cluttered visiinl hid, cyc movctiicnts m y bc rcqtiircd when lncnl forin iriCorriiation exceeds inorcih;ui ii fcwdegrees in eccen- tricily, ;incl hcacl tiiovenieiils niay w w r when the target exceeds 15 dcg in ccccn- lricily [ 121. Uascd 011 visual search studies 113,141, focal extrapcrsoiinl vision gcncr- ally extends much rtlrthcr into the upper visiial I‘icld (piiriiciilwly the upper right quadrant) than into Ihc luwcr I‘iclrl (cspc- cinlly the lower 1er1 qiiadl.;liit) (sec Fig. 2.). ‘I’hc tippcr-t’icld bins of the foc;il cxirapeIsnnnl xysteni is atiribukiblc io: 1) thc fact that focal-iiiorle operntions are iisually canied 0111 ;11 ii grciitcr distance

rroiu 1 he itidivitlual thm ;ire pei~ipcIsoniil opct'*tdioris, and 2) thc nccrl to ni'fset thc pcripcrsonsl iitlentional i i n d oculorriotor biases towml thc lower field.

Thus, a givcn display shotild iiol cx- cccd 3U (leg in dianictcr to avoid costly hcad iuoverrients, ntid iiidivitlti:il readouts nti tlic d i s p l q pincl slaould not cxcccrl I O de6 (to :illow thi: inrorniation to bc p"o cessed in a siiiglc rixntiori). For II typical 10rleg rriultifiincticintlisplay, hereshould normally hc ti0 niurc thari about I2 s y n - bok nr' alphnniimcric scts, giveti that vi- S ~ I R ~ search tinic incrcascs dr;unaticnlly whcii innre than this aiiiounl ol' Coco1 cxtrapersonal infiirination i s presented at onc chic 1131. The most critical clouts slioulrl be located above the ccntcr o f tlic display i l d towncrl (he upper portirin of the control station. Whereas transient or muvi iy inlorniation may bcttcr siinulaic the n;iLural v isua l ciics Found i n periperxonal spacc, such ii inorle of prc- seiitatioii is less dcsiruble in focal ex- t r n p c 1x0 ii a 1 be C R u se higtl-rcsolul ioii in formation pruwssinng i s dcgr;idcrl when prescntccl Ir;insient ly. (Onc cxainple 0 1 tiow fncd c ~ l r ; i p c r ~ o ~ i d information c m bc skhilized is providctl tly a forwiirtl-looki ng- infrared-i nmgi ng (FLIR) rlisplxy, wliicli xtahilizcs thc tiirgcl and thus helps the b(in?sight to be placcd on it.) f i i cniitriut, color is ;I siiliciit c i ic for thc Focal cxtrapersontil brain p;ilhw:iys and i s hest iiscd in dcpicting solid display ohjccts. Colur i s less desirahlc for linc ancl clinractcr syiiibols 1 I I, giveri the p(iorcr spatial resolution l i~ purely ctirotnatic as opposcd to actwoinatic sliniuli 1151.

op er ;I i i o n s

Action Extrapersonal Opcr;ilior\s jii the action cxtrapcrsoniil

rcdii i suppurl iiavigation irnd otlicr typcs of or icn tnh i in lopnglaphic;illy dcl'ined sp;icc! 1:4]. Altlinugh the coordinatc sysieni used in tnpogriipliic;d space is ultimately bascd on the position of g i z c ( i . ~ , view- point), iictina extrapcrsonal ol~cc;itions arc most closely linked to i ~ i ~ ~ c i i i c n l s 01: the herd. 'lhcsc hex1 movements gcncriilly prcccde cliangcs in heeding tluriiig loco- iiintion I x i d prctlominnte in oricnting LO targets heyorid ?(I-40 dcg iii eccentricity 1\71. The two major scnsury systcins used l'nr humans iii actiun cxlmpcrsonal space-thc visual illid autlilory-require the iritcgration or Ivnt l positinti sigmils to dcfiinc target orientn\ioii in rclationship to one's vicwpoiiit in topographicnl sp;icc. Thc pmlomin;inl role or head irioveineiit in topographical spacc i s consistent with the

Moving-Aircraft Moving-Horizon

4 , An i l luslmlioii cit'lhc "niuvin~-aii*cr~Ttt ("cwtsidc-in") iittitridc tliuphy concept vs. tlic moving.Iiorizon ("iii~ide-aiit") cnnccpl. Prnin 1321, with pcrmissiuii.

increasing use of Iwlmet-mnuatcd sys- tems for localizing tacliciil ttirgets.

Although topogrnphicnl visual space can extend to thc cdgcs d i h e visual field, and topq,riipliicul d i t o r y spnce cnri conipldcly aicoiiipass thc individiiiil, our incnt;il repi.csentatioii of sucli s p x c i s :ic- tiiirlly quite cotnpresscd, cspccidly i n its nnnvisihlc prirtioiis [ 181. Studies nfsccnc mcruory Il!)], Tor cx;irnple, have shnwn thnt irnrnediatc iricniory iqmseiitnlions iirc scvcr'cly t l istortcil, sticli t l i i i t a witlc-iinglc, gamcenteretl Iprotiitypic;rl view i s ilssunicd (scc Fig. 3). l l u s , in an iiirtixlt, the glnhal sitiiatiiin display that i s dcsigiierl to present geoglaphic:iI, twticiiI, ;ind otlier tnpogritphical inrorin;iliuii should prubahly adopt the s:iiuc wide-anglc pcrspcclivc ilirougla which thc pilnt would noriiinlly iinnge the world in his or Iicr mind--froin abuvc iilltl beh i i d Ucc;iiisc 0111' wctinii cxtrapcrsunal system apparcnlly inoven in yaw hut not pitch iiiid

roll--as cvidencetl hy tlic scnsihity 01' p;ir;iliippocniiipnl curons i nvolvcd i i i iopographical incinory to horixontnl licr~d inovciiiciirx but not to pitch :ind roll Iicatl t i l t s [20]-lhe global situation display shritild ideally adopt a track-up (v;irialile heading) depiction ilint shnws stahlc 110- riznn. In fact, this depiction seeins tn Iw most consistent with oiir mental iiiodelsof heading changes during fi)rwalrl lucoiiiu- tion [:21j :iind i s geiieixlly prcfcrrctl by pi- lots and othcr operators 1221.

1.ike focal cxtrapcrsoriai space, action extraperson;rl space i s biased toward thc uppcr distiuit pur1ioIi of the visual world. One way to s im i i l n te the d is tan t wide-angle inental rcprcscnt;it.inn d topn- graphical space i s to i isc ii pinnocoilvex

IEfE €NGIBEERING IN MEDlIINt AMD BIOLOGY

coll inii i t i i~g (e.g., Fresnel) lens iii front ol tiic glubiil siIu;ition disphy. Such a Icns, wlieii pl:icerl over a stantlard vidco moni- lor 01' difriising screen, crentcs an ex- Ixil1dcri (by about 50%) and ijpticnlly distant inwgc th;rt c;in casily depict x IHO dcgvicw rrfthc world within i t s boundary. 111 gcnci-"1, global situation displays slioiiltl be placed near tlic top riE thc coii- trul station, wliicla in an aircraft wuuld be just bci\c;itti I l ic cockpit shroud.

Recause tlic auditury systcii~ providcs kcy inputs to the nctinri cxttxpcrsonal lieu- nil syslcm, Ihc rcceiil use of 3-D auditory cuing clcviccs to riricnt tu out-thc-window tactical targcts 123 I is conitii~nsiir';i~e witti the iinturnl rolc o f ;ititlitory inputs i n nlrer- ing tis to dkfarit sources. H o ~ ~ c v c r , 3-TI auditury cuing i ~ n y be. nT ICSS valtic in il c n r ! f i l i c d aircrnrt coiitlal srntioii lor tlic following rciisoiis: 1) audiiury cuing tlc- vices arc tnucli lcsscflixlivc insitlethe fo- MI extrapcrsijn:il v i s d rcalin (i 30 (leg ofcccentricity) (241; 2 ) :iiiditory cues arc no iiinrc salient than visi ial ocieiitiltion ciics (c.g.. pulsing or t;ii-gets) in cliciting licnd nitrvcmcnts at cccentricities <40 deg [ZSl; ancl 3 ) thc ~ p & l rcsolution ot' the niwlitnry systciu(- I dcg) isiiboiit50tiincs pr)oi.cr than that of the visaal syslcin in- side Ihc central visual ficltl 1261.

Finally, thc action cxtviipcrsorinl systein scnds iiiiporlaiit predictive navigirtional in- f(irmiition conccriiiiig 011r' heading in space to thc rcst oltl ie brain, as illustratcd by the :ititicip;itoi-y role or Iiend i i invc~i i~ i i ts ilur- ing lucoinolion 1 lh1. Hcnce, i t is rlcsilnhle tu pruvitlepredictive aircraft Ipatli intoima- tion in i I i l nirclxl't control display. Although thc flight piith marker on current Imtl-tip

displays provitlcs predictive infortntitiun

85

Pilots flying with this

cockpit console would

experience enhanced

situation awareness,

greater motor

flexibility, and

reduced cognitive

stress.

coiiccmiiig the current trnjcctory or the air- craft i n earth-fixed spmcc, flight-pathclir~cc- tors arc also rcquired in topogIaptiicnl space for iiwigationd purposcs. ‘lhc most well knnwa of such dircctors is thc “high- way-in-the-sky,” which reportcdly Icads to iiiiprovcd situillion awareness and naviga- tionnl pcrtbriniincc rclativc to trorlilional stecring hars 127 I .

Ambient Bxtrapersnnal The innjor function pert’omiecl tiy our

ainbicnt cxti~i~pai-so~u~l systcni is to orient our hc;ds and burlics slmtially wilhin w co- ordinate [mine defiiied by the ginvity vec- tor imd thc hurizoiital plaiic of ihe earth. Spitial uricntiitiun infurmalion is used Tor pristurril ciintrul (invulviiig prctbninaiitly ttie lower limbs) and to peiceptually stabi- lize tlic world up to roll angles of 60 deg. These activities hen greatly simplify the perceptiiml operations carrictl out by IIIC other systems [41. In out terrestrial envi- ro n tile n t , tr nn s i en, t vest i b U 1 R I . i in d soni;itosensory itpiis are coinpIetnented byruorestuggishvisuRlinputs i n achievitig effective spatial orientntion. However, ttie lwu nonvisual systems arc rentlererl uiireli- able iii thc iibnorinal accc1cr;itory ciiviron- Iiient of tlight because the grwiraticinal Iorce that they ordinnrily sense is replaced by a i~csultant gravihiiicrtinl forcc vector that ciiii dcviatc quite substnntially Trom the dircction nf true gravity. Hcncc, pilots tcnd tn be murc visually field-ilcpcntlcnt

t l i ~ ~ i i nnviccs 12K1, ;IS thcy r d y on thc most critical sources of spiitial oricntatioii (titti- iurle) iii€oim”oti nvnilnlllc to then-Lc., the gi~ound plane nnd horizon. I t has hccn sliowo in iiiiiiiernus stirdies that tlic visual stimulus chnmcteristics tlint are inost criti- cal I’or achievitig “visual doniindncc” in spatial orientation ni‘c a largc pcrccivctl distance ll-om the otiserver atid ii rield-or-view that tiiiriiiiially cxtcnds bc- yontl50 (leg [2!4.

Although i m n y errorts lo duplicate the ainbicnt visual rcnlm have been innde in aircmfl coiilrol woikstntions-ranging froin pcriphcral visual devices to ~ ~ i ~ e - ~ i e ~ d - [ ) ~ - v ~ c ~ ~ hcli~~ct-inouiik~ (lis- plays I301-it has hcrctoforc provcn iin- possible to provide the full coinplemcnt of cues 1lintallowascerietnhc trulyst;ibilized perccpkinlIy. It tins been argued, thereforc, that thc artihAd horizon in atiilude (lis- plays shoultl not iiiove i t i concert with the iinnge 01 the nctunl horizon on tlic rctina but ratlicr t1i;it it slioidrl be perceptually sta- bilizcd :is is the achial horizon in niir ”psy- chic rekcrion” of 3-D space 1:3 I]. The stabilized horizon ntliiurle coiicept--alsn known tis thc uutsidc-in ntritiide iridicntor (sec Fig. 4) hccilusc it irssuiiics ii vicw h i t lies directly behind thc aircrdt [321, iis is consistent with the way wc vicw oursclvcs i n spacc 133 [-is cspcci;illy dcsiriblc in controlling aircriift rcinotcly. licg;irdlcss of: which type of attitude rlispliiy is sc- lectcd, howevcr, the primacy or nttittidc awareness i n nitcraft control nnd otlicr flight opcrntions rcqtiircs th;it the atlittide display bc present iit dl times, m r l prcfcra- tdy at or imir thc ccntcr ot‘lhc consola.

13cc;liisc ofthc trcincntluus dcinands on visual processing in the cockpit, t twc have

bccii scvcr:il i~ttciupts to LISC nonvisu;il SCII-

sory systciiis t o rclay attitudc informaticin to pilots. Onc cf’fort has heeii to usc audi- tory ciics to provide primary flight infor- ination, iiiiiclias oldcrairclaftrlid hy virttic nfchangcs in tlie a~iiplitucle and frequency ofairlkmc noise with cliangcs in airspcetl xd attitudc. While hciicficiid in thc a b seiicc of visual ciics [34], auditory oriefita- r i m dcviccs :ire liintlcrcd by thc fact that ambicnt iiuditury ctics ilr) i i r i t normdly coiitrihote greatly to rntlintni ni ng spatini nricntution oneartli 1351. A more reccnt cf- for1 has becii to UHC tactile infnriiiation to convey changes in pitch atid batik attitude viaa vcst worn by tlic pilul[36]. While the soinatoscusory sysicin is oiic that is iiaiii- rally uscd i n spatial orientation {sec ‘Triblc I), thc orily txtilc oricntntion vcst so I’m prototypcd docs not recreatc tlic niiLurril

stimulation patterns relayed by the soinatoscnsory systeni with changes in griivitational riricntatirm and so may not create a truly ninbient (precotiscious) orientationnl percept.

Froin tbc standpoint of riiotor contrcil, the iri+ior guideline would he tn use the priniary systeni irwolvetl in postural con- trol niid tocomoiion on earth-thc lower liinbs (feet). Allhough thc diih a r ~ ? 1101 CX-

tcnsivc, foot conlrul is very alkclive in thc control oudisplays, and it is coinpara- blc to I ~ i i t l coiitrol in this rcspcct [37 ] . Historicirily, thc fcct havc bccii tiscd tu control aircrari yaw by mm or the rud- der pcdals, but this is 110 Inngcr ncccssiiry with fly-by-wirc control syslcnis. Ad- vawxt l hrcc-sensI~ivc fuut pcrlals c o ~ ~ l d oilhcr bc ~iscd lo conlrol x t w l atlilude io spncc (;IS is done by skicrs) 01’ to coiitiol speed (as i n autnnnol~ilcs, scwing tna-

Path Indicator I

GI

Foot Controls Aircraft Status

5. An “ideal” rircrnft worltslation hascrl an ncumpsycholngical principlcs.

86 IBEEBGINEERING IN MEOICINE AND aatow Maithj’April2000

chines, ctc.). Yaw control could ihcit bc cnsily integriited with bank tiiovetncnts iii ii single control stick. l‘his would ficc up at least one Iiand at il given inomelit for control opcrerioiis nf a pcripcrsonal i ia- turc (c.g.,cursor’rtiovenientsoii iiscrceii).

Finally, the nculrrpsycliolofiicnl rrindcl uC 3-D space alsrr I c ~ l s to pretlictiniis conccruitig how nricnti\iioii inlomation shoiiltl be presciited in hclinel-nioutited displays when tlie pilot Imks away l‘lnin thc sircmlt ’ s lo tigi tud i nal axi s. Because sp;iiial orietitntion is rcrcrcncetl tnairily to thc pusiliori or the torso and lcgs in spnce 141, licarl inweinelits rclativc io llie bndy should iiat alter the way thc burly is per- ccivcd as heing oricntcd in ihc pilot’s inciitnl representat ioii. ‘L’hus, nttiliide in- Comalion should Iw lcss slavcd to where thc pilot is looking than to whcrc thc iir- craft (;uid the pilot’s torso) ;ire pointctl [38 1. hlihougli pilots have anccdutiiliy tinted that tr;itlitiuiiiil aiicmft-teferciicctl insirlc-out atlitutlc syinhohgics arc murc difficult to inlcrpret whcti thc hcad is innvcd off-axis, [his inny tint bc as truc ul’ uutsidc-in atd other displ;iys that do nnt allcinpi IO conform to thc rerind projec- tion ol rhc outside world.

An ”Ideal“ Aircraft Workstation Based on

Neurops ycholagicd Principles A depiction or an nctiinl aircraft coil-

trol station thal gcnorally adheres to tlic ncuropsychologifnl guidelines piit forth in thc prcvious section is shown in Fig. 5. It features a sloping cotisulc, i i large global situation (tnpogriiphic;il) display iri its iippet’inoqt pnrtion, nn ouisitle-in atti- lude display iti tlic cctitcr, tlcdiciitctl tar- geti rig and “God’s-cyc” topograptiicnl (IIMP) displays ,just bclow, ai iiiccraft sir- 111s display locntetl in thc lower, portion ol Ihc console, R ringlc control stick stir- i.oundetl by pntiels that Fall within normal rcacliing space, and foot pcd;~ls h r n l least airspeed cnntrol. This control siwiinri could he transferred io iilanosi nny eiivi- roninenr, with rootii nvidnble for addi- tional visual displiiys above 11ie console, arid it could bc cnsily built with existing tect~tinlogics.

A1 rivq1 glatice, this “ncuropsycho- logically compatihlc” cuckpii inny not all- pcitr to rcpi’csent a mjnr dcparturc Troiu curreill advanced cockpil st;ilions. wtiicli alrently iricolpolatc inmy of its kalures, such :IS the Roeing (Scattlc, WA) Ad- vanced Technology Crew Stnlion. Nor wollltl such a control s t a h eliminate all

MartldApriI2000

of the task-salurnlion problem’; facing pi- 101s of single-scat figtitcr airccari. With minimal training, however, pilots flying with this cockpit console woiilcl cxpcl.i- CHCC etitinncerl situarion awnrenew, grcalcr ~riolor flexihility, :inti rctluced cofiiiitivc stress. Siich I,eiicfits cotild lriinslatc into major improvements in both in i s si0 I 1 pe I fo I_ in an cc and sa Tc t y , wit 11 subsianlidly reduced nuinbcrs olmislinps caused by SD and [,SA. Thc ability tu in- corporate liirgc nrriouiits of elcctronic flight inforiniilion into control station< ihal ciiii be managccl with grciit eiiae and miiiirrial training could nlsu rcvoluiioiiize thc gciicral aviation wurld. hirthcrmore, thc sdc iiiid clfective control of pilot-lcss coinhat :wid vcliicles could hc coil- dnctcd from mobile platforms using “no~ipilnt” operators.

Dr. P F ~ C is ii civili;iii rePearch psycliulogist with Litton-‘L‘ASC iii San Antonio, TX. His .speciatizaiiuns arc iri the areiis of cnjiriitivc iieiiroscieiice nnd spa- tial oricnlation, a i d he has coiiducted research

in i i m s ranging from advaticed visud fligtii displays to vcstibular~autonomic in- tctwliotis. Dr. Prcvic rcccivcil liix PIID. h r n thc Uiiivcrsily OK North Carolinii iit Cireeiishoro i n 1982 i l l id later w o k d as a ~-esetilcli sciciilisE Tor KRUG Triiei rialiuiuil l‘rum 1982 to 1986. He joincrl thc Unitctl Sintcs Schonl ( IF Acrospacc Medicine ill 1986 as a civil SCVvitllt ;iiirI coriiinuetl iri

that s a n w posikm Tor the Air Forcc Rc- search Labricitory tinlii 1999.

Addrcss for Correspondence: Di.. Fred 11. Piwic, I.ittcin-‘t’ASC, 4241 Wootlcock Suite U-100, Sfin Antoiiiu TX 78228. Phone: + I 21 0 536 4779. Fax: + L 210 534 0420. E-iunil: fretl. previc @ brooks. aT.iniI

References I . Ercnliiic WK, DcVilbiss CA, mid I,yoiisT.I: Ti.ciitls in USAF rpiitird rliaoricimtinn xci- dciith--1958- 1992, 111: Lcwniidowhki K J , StCpl1cns W, Hswortli I .A ( Ids ) : SPIL CfJrfPrflc 2218:257-260, 1994.

2. GilIhi~l~iin I M : ‘Hie slintiiil ilisoricnta[ion prohien1 iii Hin I Initcrl SI:IIPL:A~~FO~L~C. J V r r l X ~ t 2:297-30h, 1992.

1. Kuipcrs A, Kiippcrs A, vnn 1InMcn CH, viiii

Dcrgcn JHW, nnB Oosleryeld W.1: Spalial (lis- oricntiilioii incidcnts 111 thcR.N.I,.A.F. F16 ad F5 aircraft and suggcstiuns for prcvcntinn. hi: S i h 1 iotmi A ivnwii PS.I iri A cra.rpice 0prrotiori.v.

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