80 Copublished by the IEEE CS and the AIP 1521-9615/04/$20.00 © 2004 IEEE COMPUTING IN SCIENCE & ENGINEERING

Editors: Jim X. Chen, jchen@cs.gmu.edu

R. Bowen Loftin, bloftin@odu.edu

VISUALIZATIONV I S U A L I Z A T I O N C O R N E R

olfaction displays (devices that outputscented air) augment data visualization,that is, communicate information rel-evant to many fields?1 Perhaps incor-porating underutilized modalities suchas haptics (touch), olfaction, and gus-tation (taste) as data visualization aidsis the next logical step to optimizinghuman information processing.

It seems reasonable that adding thesense of smell to a virtual environment(VE) would enhance the environ-ment’s presence or “realness.” At-tempts have been made to include ol-factory displays in VEs (for example,John Cater’s Deep Immersion VirtualEnvironment Laboratory at theSouthwest Research Institute2), butmost have been unsuccessful. One rea-son is the lack of a standard to repre-sent and playback smells.

Olfactory effects could play a crucialrole in certain training environments,such as those for fire fighters and med-ical personnel.3 Current VEs includeadvanced visual and audio outputs, butsmell is either very limited or absent.Very few studies focus on this subject,with most discussing ambient (whole-room and long-duration) rather thanspecific (localized and short-duration)odors, which are relevant to data visu-alization and VR.

At Princeton University, GeorgeMiller suggested that each of our sen-sory modalities has processing limitsof seven (plus or minus two) informa-tion bits.4 Visualization Corner’scoeditor, Bowen Loftin, has men-tioned in a previous installment thatusing additional modalities might cir-cumvent the human information-pro-cessing limit and let us process an ad-ditional seven (plus or minus two)information bits for each modalityutilized.1 Conceptually, the increasein data-processing capabilities viamultimodal data visualization dis-plays, along with the enhanced visual-ization experience provided by themultimodal environment, might pro-vide a deeper, more sensitive, under-standing of data otherwise unattain-able through conventional visual andauditory displays. Another factor isthat human olfactory capabilities dif-fer by gender, age, number of odorsused, whether odors mix, and the timeit takes to detect an odor before auto-matically becoming desensitized or,worse yet, sickened by it.3

Olfactory BackgroundOlfaction, the sense of smell or the actof smelling, appears to be separate fromvisual–spatial or verbal–auditory modal-

ities.3 However, the literature remainsinconclusive about whether adding anolfactory component increases infor-mation processing without initiatingcognitive overload—the taxing of ourworking memories. That is, each of thetwo working memory modalities,visual–spatial and verbal–auditory, eachretains different types of information.Multiple same-modality tasks (for ex-ample, visual and visual) can clash, pro-ducing cognitive overload and reducedvisualization. Utilizing different modal-ities (for example, verbal and visual)might reduce cognitive overload andenhance learning and, presumably, datavisualization.

In addition to reduced interference(meaning cognitive overload), olfactorycomponents might possibly conveymessages (such as specific meanings forcertain odors) when our visual or audi-tory modalities were already employed.Researchers believe that olfactory–odormemory has reliable qualities, com-monly known as Proustian characteris-tics, which include resistance to inter-ference, uniqueness, and modalityindependence. Maria Larsson at Stock-holm University stated that, “verbal/se-mantic factors play a negligible role inolfactory memory.”5

However, olfaction has played asignificant role in human learningand memory. Adding an olfactorycomponent to an environment couldreduce stress, increase informationprocessing, enhance memory perfor-mance through better problem-solving, reduce response times, pro-duce fewer errors, increase recall,

COULD OLFACTORY DISPLAYSIMPROVE DATA VISUALIZATION?By Donald A. Washburn and Lauriann M. Jones

S MELL (OLFACTION) CAN BE CRITICAL TO OUR DAILY

LIVING—FOR EXAMPLE, SMELLING SMOKE FROM A FIRE IN

TIME TO LEAVE A BURNING BUILDING—BUT IT IS SELDOM USED IN

DATA VISUALIZATIONS OR VIRTUAL REALITY (VR) SYSTEMS. COULD

NOVEMBER/DECEMBER 2004 81

recognition, and retention, and en-hance productivity, alertness, andphysical performance.3

Sense of Presence StudiesUniversity of Central Florida’s (UCF)Institute for Simulation and Training(IST) conducted an olfactory study aspart of its Research in Augmented &Virtual Environment Systems (RAVES),a cross-disciplinary project researchingmultimodal VEs. The research testedolfaction’s impact on a human operator’ssense of immersion in a VE. The appli-cation was similar to military trainingenvironments that strive to optimizefield performance.

The experimental group (scents thatwere concordant to the VE), controlgroup (no scent), and discordant group(incorrect scent for the VE) differedsignificantly on their ratings of the aug-mented VE; genders also differed sig-nificantly in their experience in theaugmented VE, but not in the pre-dicted olfactory direction. Possibly inan attempt to create an immersed en-vironment (for example, a panoramicscreen with realistic graphics andsound), an overall “wow” effect mighthave overwhelmed the addition of anolfactory component.6

Georgia Tech conducted experi-ments on the effects of tactile, olfac-tory, audio, and visual sensory cues onparticipants’ sense of presence in a VE,specifically, on their memory of the en-vironment and the objects in it. Theresults indicated that introducing ol-factory cues increased the realism rat-ing from 64.7 to 68.1 on a 100-pointscale; however, it was not a statisticallysignificant trend.7

Olfactory Research FocusAs we’ve discussed, the olfaction topichas major challenges but limited re-search. Another key challenge is re-

moving an old scent before introduc-ing a new one, without interaction,which is especially difficult when awhole room is filled (ambient order).Based on this concern, our experimentsat IST focused on providing a userwith a small amount of scent (specificodor) near his or her nose.

Creating a scent is a challenge. Anodorant’s chemical composition createsthe olfactory effects, but no one knowswhether we can generate any smellfrom a combination of basic smells, aswe can do with color. Initial researchindicates the contrary.2

Large perfume laboratories seem tobe the best at creating scents. We haveworked with two different scent com-panies that use perfume labs becausethey already have hundreds of scentsavailable. We needed the scent of a re-cently fired gun, which one companycreated for our research because itwasn’t on their current list.

Most of these scents contain a rela-tively low percentage of the real item;for example, orange scent has only alittle bit of real orange in it because thescents must last for a long time, and thereal product can lose its scent quickly.

Olfactory Display DevicesWe can add olfaction to many differentsystems—for example, some majortheme parks have added olfaction totheir attractions by using the theaterseating to emit scents. Similar olfac-tory-seated systems are available fromDigital Tech Frontier (www.dtf.net).

Most data visualizations use projec-tion systems such as Cave AutomaticVirtual Environments (CAVEs) or, aswith most of our research, head-mounted displays (HMDs). We foundthat connecting a hose near a user’sface has a negligible impact on theuser’s comfort.

For large projection-based systems

and CAVEs, an external hose wouldbe inconvenient. Unfortunately, nounencumbered olfactory systems arecurrently available, but we’ll describeseveral prototype systems. Based onour focus of specific odor (smallamounts of scent near a user), we re-searched personalized olfaction de-vices because of their small size andthe ease of dissipation and control ofodors.

DigiScentsA pioneer in this area, DigiScents de-veloped iSmell, a device consisting ofpots of oils infused with differentscents. The developers believed theycould generate any smell from a com-bination of a few basic smells, but it isunclear whether anyone has scientifi-cally proven this claim. Unfortunately,the iSmell device was never commer-cially available, and DigiScents de-clared bankruptcy and closed down inApril 2001.

AromajetAromajet (www.aromajet.com) alsodeveloped a prototype aroma-dis-pensing device. Users could wear orplace a small device called Pinoke infront of a monitor. Aromajet also hasa kiosk system that lets users createtheir own fragrances from a customcombination of scents.

ScentAirScentAir Technologies (www.scentair.com) has created many olfactory systems,but its primary focus is on retail-space, orambient, odors. Recently, it developedtechnology for providing multiple scentson cue in coordination with training orsimulation systems. Called the Scen-tKiosk Scent Dispenser (see Figure 1),the system dispenses precise fragrancevolumes direct to a user via a tube. Theend of the hose must be within 18

82 COMPUTING IN SCIENCE & ENGINEERING

inches of a user’s nose, thus we con-nected it to a microphone boom.

The ScentKiosk Scent Dispensersystem uses single scent cartridges(see Figure 2). These cartridges aresealed when not in use, so the systemdoesn’t leak any scents, which ad-dresses a common problem for manyolfactory systems.

This system worked very well for allour current applications and is an ex-cellent olfactory system for data visual-ization and VR. We can easily changethe scent cartridge for different sce-narios. We also have a system with anextended (30-foot) hose connected tothe ScentKiosk system to let usersmove more freely. We are investigatingconverting the system to battery powerfor untethered use.

TrisenxTrisenx (www.trisenx.com) released abeta unit of its Scent Dome system in2003 (see Figure 3). The device is smalland has 20 different scents in its scentcartridge. Users can mix the scents inany amounts to create different odors.The scents disperse from the top of thescent cartridge via a small fan, but the

company doesn’t have a way to directthe scent to the user for data visualiza-tion and VR applications. The Senx-Ware Scent Design Studio white paper(www.trisenx.com/senxwhitepaperrev3.0.x.pdf) describes the system’s capabil-ities in detail.

Scent CollarThe Institute for Creative Technolo-gies (ICT; www.ict.usc.edu/disp.php)and AnthroTronix (www.anthrotronix.com) have developed the Scent Collar(see Figure 4), which fits around auser’s neck.8 It holds four scent car-tridges and is controlled by a wirelessinterface.

Projection-Based Olfactory DisplayThe Advanced Telecommunications Re-search Media Information Science Lab-oratories(www.mis.atr.jp/~yanagida/scent/) wanted to create an unencum-bered olfactory display. The projection-based olfactory device (see Figure 5)emits a clump of scented air from a loca-tion near a user’s nose through free spacerather than scattering scented air by sim-ply diffusing it into the atmosphere. Toimplement this concept, the labs used an“air cannon” to generate toroidal vor-tices of scented air.9 During demonstra-tions, the company found several com-plex problems:

• The fragrance density wasn’t suffi-cient for perfect distinction.

• The temporal duration in whichusers could detect the smell was soshort that they couldn’t find anysmell if they exhaled when a scentedvortex ring reached their noses.

• Although the system could switchscents, continuous use caused aslight mixture of odors, since thescent adhered to the inner wall ofthe cylinder.

V I S U A L I Z A T I O N C O R N E R

Figure 1. ScentAir ScentKiosk Scent Dispenser. This system can deliver three scentsto a user for data visualization or virtual reality applications.

Figure 3. Trisenx Scent Dome. Thissystem produces a mixture of 20 scents,but currently has no way to direct scentsto a user.

Figure 2. ScentKiosk scent cartridges.These units are small and don’t leakscent, which is a common problem inolfactory systems.

NOVEMBER/DECEMBER 2004 83

The company is working on systemimprovements to solve these problems.

A lthough there has been littleolfactory research, this seems to

be changing. Just as haptics has grownfrom a very small research segment,olfaction is ready to mimic thisgrowth pattern in the near future.Currently, we’re working on an olfac-tory experiment based on improvingperformance in a VR training situa-tion. If there are critical cues or alarmsthat a user must notice during a datavisualization task for your own re-search, we recommend using a scentto complement the other modalitycues. If you would like more informa-tion or want to discuss your olfactoryideas, please contact us.

References1. R.B. Loftin, “Multisensory Perception: Beyond

the Visual in Visualization,” Computing in Sci-ence & Eng., vol. 5, no. 4, 2003, pp. 56–58.

2. J.N. Kaye, Symbolic Olfactory Display, master’sthesis, Media Arts and Sciences School of Ar-chitecture and Planning, Massachusetts Inst.of Technology, 2001.

3. D.A. Washburn et al., “Olfactory Use in Vir-tual Environment Training,” Modeling & Sim-ulation, vol. 2, no. 3, 2003, pp. 19–25.

4. G.A. Miller, “The Magical Number Seven,Plus or Minus Two: Some Limits on Our Ca-pacity for Processing Information,” Psycho-logical Rev., vol. 63, 1956, pp. 81–97;http://psychclassics.yorku.ca/Miller.

5. M. Larsson et al., “Demographic and Cogni

tive Predictors of Cued Odor Identification: Evi-dence from a Population-Based Study,” Chemi-cal Senses, vol. 29, no. 6, 2004, pp. 547–554.

6. L.M. Jones et al., “The Effect of Olfaction onImmersion into Virtual Environments,” Hu-man Performance, Situation Awareness and Au-tomation: Issues and Considerations for the21st Century, Lawrence Erlbaum Associates,2004, pp. 282–285.

7. H.Q. Dinh et al., “Evaluating the Importanceof Multi-Sensory Input on Memory and theSense of Presence in Virtual environments,”Proc. IEEE Virtual Reality Conf., IEEE CS Press,1999, pp. 222–228.

8. J.F. Morie et al.,“Sensory Design for VirtualEnvironments,” SIGGRAPH 2003 Sketch, July2003; www.ict.usc.edu/publications/SensDesign4VE.pdf.

9. Y. Yanagida et al., “Personal Olfactory Displaywith Nose Tracking,” Proc. IEEE Virtual RealityConf., IEEE CS Press, 2004, pp. 43–50.

Donald A. Washburn is a senior research sci-

entist at the Institute for Simulation and Train-

ing, University of Central Florida, coprincipal in-

vestigator for the Army Research Institute

Virtual Environment Research Testbed Project,

and principal Investigator for several haptics

and olfactory research projects. His research in-

terests include haptics, olfaction, voice interac-

tion, and virtual environments. He is pursuing

a PhD in industrial engineering in the interac-

tive simulation specialty at the University of

Central Florida. He is a member of the IEEE

Computer Society, ACM, and the Institute of

Industrial Engineers. Contact him at dwash-

bur@ist.ucf.edu.

Lauriann M. Jones is a graduate research as-

sistant and a doctoral student in the Applied

Experimental Human Factors PhD program at

the University of Central Florida. She is a

member of The Human Factors and Er-

gonomics Society, The American Psychologi-

cal Association, and The Southeastern Psy-

chological Association. Contact her at

ljojo@bellsouth.net.

Figure 4. ICT Scent Collar. This wireless olfactory display system is worn aroundthe neck and is shown here with four scent cartridges. (Image courtesy JackiMorie, Institute for Creative Technologies.)

Figure 5. Third prototype of a projection-based olfactory display system. It sends apuff of scent air to a user. (Imagecourtesy Dr. Yasuyuki Yanagida,Advanced Telecommunications ResearchMedia Information Science Labs.)