Functional activity of the rat olfactory bulb related to different durations of odor exposure

We have studied the effects of different odor exposure durationson the functional activity of the rat olfactory bulb by usingthe 2-deoxyglucose (2-DG) method. This technique brings outodor-specific patterns of labeling in the glomerular layer ofthe bulb. In a first set of experiments, rats designated ascontrols were submitted to two stimulation conditions with cyclohexanonefor 40 min following 2-DG injection: group C-5—alternatestimulation (5 min odor–5 mm pure air); group C-20—continuousstimulation (20 mm odor-20 min pure air). In a second set ofexperiments, rats designated as ‘adapted’ were exposedfor 3 h to cyclohexanone before the 2-DG injection; then, threeconditions of stimulation were tested with the same odor duringthe post-injection period; group Adap-5—alternate stimulation;group Adap-20—continuous stimulation; group Adap-0—stimulationwith pure air only. In the two control groups, the total numbersof labeled glomerular foci were similar; however, group C-20showed a significant increase in the number of ‘heavily’labeled foci. This result suggests that under conditions of20 min continuous odor exposure, receptor cells do not adaptrapidly and totally. Results from the adapted groups showedthat only the group Adap-20 presented significant changes infunctional bulbar activity. An important decrease in the totalnumber of labeled glomerular foci and an absence of ‘heavily’labeled foci were noted in all rats of this group; their patternsof 2-DG uptake were greatly reduced in both complexity and contrast.These results highlight the importance of olfactory receptoradaptation under conditions of long-duration odor exposure.Fast recovery of receptor sensitivity when the stimulation isinterrupted is also suggested.     

Dynamics of dolphin porpoising revisited

Porpoising is the popular name for the high-speed surface piercingmotion of dolphins and other species, in which long, ballisticjumps are alternated with sections of swimming close to thesurface. The first analysis of this behavior (Au and Weihs,1980) showed that above a certain "crossover" speed this behavioris energetically advantageous, as the reduction in drag dueto movement in the air becomes greater than the added cost ofleaping. Since that publication several studies documented porpoisingbehavior at high speeds. The observations indicated that thebehavior was more complex than previously assumed. The leapswere interspersed with relatively long swimming bouts, of abouttwice the leap length. In the present paper, the possibilityof dolphins using a combination of leaping and burst and coastswimming is examined. A three-phase model is proposed, in whichthe dolphin leaps out of the water at a speed U_f, which is thefinal speed obtained at the end of the burst phase of burstand coast swimming. The leap is at constant speed and so theanimal returns to the water at U_f, goes to a shallow depth andstarts horizontal coasting while losing speed, till it reachesU_i. At that point it starts active swimming, accelerating toU_f. It then starts the next leap. Ranges of speeds for whichthis three-stage swimming is advantageous are calculated asa function of animal and physical parameters. Notation C—Constant defined in equation (12) C_D—Coasting drag coefficient D—Drag g—Gravitational acceleration H—Height of jump J—Energy required for jump k—Ratio of swim length to jump length l—Distance L—Total distance (eq. 28) m—Added mass M—Animal mass M₁—Total mass r—Coefficient defined in eq. (22) R—Ratio of energies, for three-phase swimming R₂—Ratio of energies, for burst and coast swimming t—Time T—Thrust U—Speed V—Body volume W—Weight     

Odor similarities in structurally related odorants

Similarity assessments against one or several references wereused to estimate "earthiness" in 7 pure cyclic alcohols. The "earthy" odor quality of 3 isomers (I, II, IV) of the moldmetabolite "geosmin" (1, 10dimethyl-9-decalol C₁₂H₂₂O) was foundto be present in 2 other alcohols possessing a partial geosminstructure: exo-2-ethyl-fenchol (C₁₁H₂₂O) (V) and cis-cis 2,6-di-methyl-cyclohexanol(C₈H₁₆O) (VI). All have in common an axial hydroxy group attachedto a 5 or 6 carbon ring with alpha methyls on both sides. The trans-cis and trans-trans isomers of 2,6 dimethyl cyclohexanol(VII, VIII) both with equatorial hydroxy groups, were rankedas different from the above group. Instead their odor resemblesmore that of their aromatic precursor — 2,4 dimethyl phenol(IX) — than that of their axial isomer (VI). The two trans-ring geosmin isomers (I,II) and 2-ethylfenchol(V) were still judged earthy at up to 1000x the lowest concentrationtested. However, the cis-ring geosmin isomer (IV) and the axial cyclohexanol(VI) were perceived by most subjects to change in quality: earthyat lower concentrations but increasingly different at higherones. Discrimination between earthy odorants decreased with decreasingconcentration. Geosmins I, IV and 2 ethyl-fenchol (V) were particularlyconfused. However, discrimination did not appear to be affectedby prior adaptation to geosmin IV. Subjects appeared to be able to focus on the earthy odor qualitycomponent in single odorants IV, V, VI in which several otherquality components could be discerned as well.     

Effects of ambient odors of lavender and cloves on cognition, memory, affect and mood

The effects of the odors of lavender and cloves on three cognitiveskills—memory, affective reaction to the experiment andmood—of college students are studied in two sessions,separated by 1 week. Essential oils of lavender or cloves werediffused throughout the laboratory, or no odor was presented.In the second session, approximately the same number of subjectsfrom each odor condition of the first session influenced arithmeticreasoning in the first session (3 x 3 factorial design). Lavenderadversely influenced arithmetic reasoning in the first session.At the same time, subjects' affective reactions to the experimentwere more favorable with lavender present, though cloves decreasedwillingness-to-return. In the second session, effects on cognitivefunctioning were not evident, and effects on affect were complex:relative to no-odor controls, groups that had odor in at leastone session expressed negative affect and unwillingness-to-return.Discussion concerned implications for the claim that lavenderis physiologically relaxing, the surprising absence of an effectof an effect of odor change on memory, and possible interactionsof odor and personality factors.     

Mechanistic Approaches to Community Ecology: A New Reductionism

Mechanistic approaches to community ecology are those whichemploy individual— ecological concepts—those ofbehavioral ecology, physiological ecology, and ecomorphology—as theoretical bases for understanding community patterns. Suchapproaches, which began explicitly about a decade ago, are justnow coming into prominence. They stand in contrast to more traditionalapproaches, such as MacArthur and Levins (1967),which interpretcommunity ecology almost strictly in terms of "megaparameters.". Mechanistic approaches can be divided into those which use populationdynamics as a major component of the theory and those whichdo not; examples of the two are about equally common. The firstapproach sacrifices a highly detailed representation of individual—ecological processes; the second sacrifices an explicit representationof the abundance and persistence of populations. Three subdisciplines of ecology—individual, populationand community ecology—form a "perfect" hierarchy in Beckner's(1974) sense. Two other subdisciplines—ecosystem ecologyand evolutionary ecology—lie somewhat laterally to thishierarchy. The modelling of community phenomena using sets ofpopulation-dynamical equations is argued as an attempt at explanationvia the reduction of community to population ecology. Much ofthe debate involving Florida State ecologists is over whetheror not such a relationship is additive (or conjunctive), a verystrong form of reduction. I argue that reduction of communityto individual ecology is plausible via a reduction of populationecology to individual ecology. Approaches that derive the population-dynamicalequations used in population and community ecology from individual-ecologicalconsiderations, and which provide a decomposition of megaparametersinto behavioral and physiological parameters, are cited as illustratinghow the reduction might be done. I argue that "sufficient parameters"generally will not enhance theoretical understanding in communityecology. A major advantage of the mechanistic approach is that variationin population and community patterns can be understood as variationin individual-ecological conditions. In addition to enrichingthe theory, this allows the best functional form to be chosenfor modeling higher-level phenomena, where "best" is definedas biologically most appropriate rather than mathematicallymost convenient. Disadvantages of the mechanistic approach arethat it may portend an overly complex, massive and special theory,and that it naturally tends to avoid many-species phenomenasuch as indirect effects. The paper ends with a scenario fora mechanistic-ecological utopia.     

Porosity of the Avian Eggshell

The avian eggshell is considered as a mediating boundary thatoperates along with the nest microenvironment and the behaviourof the brooding parent(s) to isolate the embryo from the externalenvironment. Particular importance is attached to shell modificationsthat could assure that the pores are not flooded or blockedwith debris. It is proposed that the mechanical properties ofthe shell that ensure the integrity of the diffusion pathwaysthroughout incubation are of equal importance to those thatprotect the embryo from mechanical dimage. Five broad categoriesof pore types in avian eggshells have been defined. 1) simplepore systems—a tube open at both ends traverses the trueshell, 2) occluded pore systems—the outer surface of theshell is coated with featureless material of unknown originand chemical composition fissures in this material presumablypermit gaseous diffusion, 3) plugged pore systems—theouter orifice of the pore orifice contains a plug of organicor crystalline inorganic material, 4) capped pore systems—theouter surface of the true shell and pore orifices are coveredwith a stratum of spheres formed from organic material, vateriteor non crystalline materials rich in calcium and phosporus,5) reticulate pores—the outer portion of the palisadelayer is modified so that a plexus of tubules comprises muchof the shell. Although five pore systems have been defined sofar, all probably share a common origin in that cones formedin the distal part of the isthmus provide not only the opportunityfor pore formation but also foundation for the palisade layer.     

Receptor site analysis using neurosensory responses of the boll weevil to analogs of the cyclohexylideneethanol of its aggregation pheromone

The active sites of II neurons (Dickens, 1990c) in both sexesof the boll weevil, Anthonomus grandis Boh., were investigatedusing structure—activity relationship studies. Hectrophysiologicalresponses of antennal olfactory receptors in male and femaleboll weevils were recorded in response to components II andIII of its aggregation pheromone and various functional, geometric,and 2-fluoroalkenyl analogs. Dose—response curves forelectroantennogram responses of both sexes to both the 2-fluoroanalog of II (E-II-F) and II (Z-II) were essentially identical.Correspondingly, dose—response curves for the geometricisomer of II (E-II), and its 2-fluoro analog (Z-II-F), had similarshapes but responses to E-II were significantly greater at severaldoses. Responses of single neurons associated with type I sensillato 1 µg stimulus loads of various analogs of II showedsignificant differences in the numbers of impulses elicitedby each during a 500 ms stimulation period: Z-II > E-II-F> III--F, III > Z-II-F, E-II, IV. These results demonstratedthe importance of the cis geometry between the dimethyl groupat the 3-position on the six-carbon ring, and the functionalmoiety at the 1-position. The limited activity of E-II and Z-II-Fon II neurons indicates these compounds may be stimulating otherreceptor types, since EAGs to these compounds were large. Dose—responsecurves for an II neuron were similar for Z-D and E-II-F, aswere curves for III and III--F, indicating that the fluorineatom at the 2-position had little effect on receptor binding.Our data support a previous hypothesis that II neurons haveseparate receptors sites for pheromone components II and III.     

The effect of meat consumption on body odor attractiveness

Axillary body odor is individually specific and potentially a rich source of information about its producer. Odor individuality partly results from genetic individuality, but the influence of ecological factors such as eating habits are another main source of odor variability. However, we know very little about how particular dietary components shape our body odor. Here we tested the effect of red meat consumption on body odor attractiveness. We used a balanced within-subject experimental design. Seventeen male odor donors were on "meat" or "nonmeat" diet for 2 weeks wearing axillary pads to collect body odor during the final 24 h of the diet. Fresh odor samples were assessed for their pleasantness, attractiveness, masculinity, and intensity by 30 women not using hormonal contraceptives. We repeated the same procedure a month later with the same odor donors, each on the opposite diet than before. Results of repeated measures analysis of variance showed that the odor of donors when on the nonmeat diet was judged as significantly more attractive, more pleasant, and less intense. This suggests that red meat consumption has a negative impact on perceived body odor hedonicity.     

Human Ecology for Introductory Biology Courses: An Overview

Human ecology, specifically the population—resource—environmentdilemma, should be given thorough coverage in every introductorybiology course. To aid educators in integrating it into thecourse, the subject is outlined here and suggestions are givenon what topics should be emphasized and how they might be introducedto students. Special attention is given to the fundamental roleof population growth in the dilemma, and to the complex interactionsamong population growth, depletion of resources, and environmentaldeterioration. Today's human population size appears to be abovethe long-term carrying capacity of Earth, and is only maintained(albeit often badly) by the exploitation of a "one-time bonanza"of fertile soils, fossil fuels, concentrated ores, ground water,and other species of organisms. If current trends continue,the depletion of these resources will progressively degradethe human environment, destroying the capacity ofnatural ecosystemsto supply civilization with indispensible services. The resultswill be in increasing frequency and severity of disasters, especiallyfamines, that will at first most seriously affect the poor.But the rich will increasingly be impoverished, and be engulfedalso. The basic solution to the dilemma is reduction of thesize of the human population to one well below the long-termcarrying capacity (one living on resource "income" rather than"capital") and establishing an equitable society with a sustainableeconomic system.     

DE- AND RE-GENERATION OF CHLOROPLASTS IN THE CELLS OF CHLORELLA PROTOTHECOIDES: I. SYNTHESES OF NUCLEIC ACIDS AND PROTEIN IN RELATION TO THE PROCESS OF REGENERATION OF CHLOROPLAST

When Chlorella protothecoides is grown mixotrophically in thelight in a medium rich in glucose and poor in nitrogen source(urea), one obtains the cells that are entirely devoid of chlorophylland containing only little RNA and protein. When these cells—referredto as "glucose-bleached" cells—are further grown in thelight with provision of nitrogen source, but without glucose,sequential syntheses of RNA, protein and chlorophyll take place.If the glucose-bleached cells are incubated in the dark underthe same nutritional condition, RNA, protein and chlorophyllare also successively formed in relatively small amounts. Thecells obtained under such a condition are, in many respects,similar to the cells that are obtained when the alga is grownin the dark in a medium poor in glucose and rich in the nitrogensource. These cells, which are called the "etiolated cells",are faintly green in color and contain larger amounts of RNAand protein compared with the chlorophyll-less glucose-bleachedcells. The glucose-bleached cells and the etiolated cells showapproximately the same content of DNA per cell. When the etiolatedcells are incubated in the light with provision of nitrogensource, but without glucose, they become green with active synthesisof chlorophyll and additional syntheses of RNA and protein. Based on these results and those to be reported later, it wasconcluded that the greening of the glucose-bleached cells involvesa light-independent phase followed by a light-requiring phasewhich entails the greening of cells and full organization ofchloroplasts, and that the latter process is essentially thesame as that taking place when the etiolated cells are incubatedin the light with provision of nitrogen source in the absenceof glucose. (Received September 5, 1964; )     

Context-dependent changes in the perception of odor quality

Ambiguous odor compounds, partly citrus-like and partly woodyin odor character, were seen to change in odor quality whenevaluated in the same session as more prototypical odors. Whentested with characteristically citrus odors, the ambiguous compoundsseemed more woody, and when tested with characteristically woodyodors, the ambiguous odorants were higher in citrus character,an example of perceptual contrast. Response frequency biaseswere ruled out as an explanation for this shift by an experimentin which responses other than citrus and woody ratings wereasked of the subjects during the contextual exposure. Simplesensory adaptation was found to be a potential contributor tothe effect, and a sufficient condition to produce similar shiftsin odor quality. However, adaptation was not a necessary conditionto produce the effect. This was seen in reversed pair experimentsin which the contextual odors were presented after the ambiguousstimuli. The contextual shift was robust—it was obtainedwith different ambiguous odors, contextual (conditioning) odors,numbers of contextual odors, orders of presentation of contextualodors relative to ambiguous odors, scale types, and rating tasksduring the presentation of contextual odors.     

The Coordination of Organ Growth in Developing Citrus Flowers: A Possibility for Sink Type Regulation

The interrelationships between simultaneously developing organsof citrus flowers were investigated. Examination of flower organgrowth kinetics shows that petals grow mainly through enhancedwater absorption whereas ovaries accumulate a high percentageof dry matter. Using excised flowers implanted in an agar—sucrose mediumand supplied with [¹⁴C]-sucrose, [³H]-acetate, and [¹⁴C]-acetate,a characteristic distribution of label among organs could beestablished for each isotope. Wounding or application of -naphthaleneacetic acid (NAA) toa single petal completely changed the normal distribution patterns,shifting the bulk of [¹⁴C]-sucrose towards the treated organs. The findings are interpreted in the light of the ‘sink’hypothesis. It is proposed that each flower organ meristem createsa sink of its own which acts in a typical manner according toits specific endogenous hormonal balance. The sink activityof all meristems in concert results in a sensitive regulatorymechanism which is responsible for the coordination observedin flower development.     

Effects of olfactory stimuli on arm-reaching duration

The aim of the present study was to investigate the effects of olfactory stimuli on visually guided reaching. In Experiment 1, participants reached toward and grasped either a small (almond/strawberry) or a large (apple/orange) visual target. Any 1 of 4 odors corresponding to the visual stimuli or odorless air was administered before movement initiation. Within the same block of trials, participants smelled 1) an odor associated with an object of a different size than the target, 2) an odor associated with an object of a size equal to that of the target, or 3) odorless air. Results indicated that reaching duration was longer for trials in which the odor "size" and the visual target did not match than when they matched. In Experiment 2, the same procedures were applied but the "no-odor" trials were administered in a separate block to the "odor" trials. Similar results as for Experiment 1 were found. However, in contrast to Experiment 1, the presence of an odor increased the level of alertness resulting in a shortening of reaching duration. We contend that olfactory stimuli have the capacity to elicit motor plans interfering with those programmed for a movement toward a visual stimulus.     

CHANGES IN CONTENTS OF CARBOHYDRATE AND FATTY ACID IN THE CELLS OF CHLORELLA PROTOTHECOIDES DURING THE PROCESSES OF DE- AND RE-GENERATION OF CHLOROPLASTS

1. Previous work has demonstrated that when cells of Chlorellaprotothecoides are grown mixotrophically under illuminationin a medium rich in nitrogen source (urea) and poor in glucose,normal green cells are obtained, while in a medium rich in glucoseand poor in the nitrogen source, strongly bleached cells containingapparently no discernible chloroplast structures — called"glucose-bleached" cells — are produced either in thelight or in darkness. When the green cells are incubated ina glucose-enriched mineral medium without added nitrogen source,they are fairly rapidly bleached with concomitant degenerationof chloroplast structures (" bleaching "). When, on the otherhand, the "glucose-bleached" cells are transferred in a nitrogen-enrichedmedium without added glucose under illumination, they turn greenwith regeneration of chloroplasts (" greening "). In the presentstudy changes in contents of carbohydrate and fatty acid inalgal cells were followed during these processes of "bleaching"and "greening.".
2. During the process of "bleaching", the quantityof glucose existingin the insoluble carbohydrate fraction ofalgal cells increasedrapidly and markedly. A considerable increasewas also observedin the contents of cells in oleic, linoleicand palmitic acids.It was noted, however, that linolenic aciddecreased in quantityduring the most active phase of cell bleaching.
3. During the process of "greening", the glucose in the insolublecarbohydrate fraction rapidly decreased, suggesting that itis utilized, as carbon and energy sources, for the chloroplastregeneration. Linolenic acid was found to be synthesized inparallel with formation of chlorophyll. A peculiar pattern ofchange in contents was observed with oleic and palmitic acids,which was interpreted as being related with the process of cellulardivision occurring incidentally during the process of greening.

(Received September 24, 1966; )     

Development of Air Blisters in Pilea cadierei Gagnep. and Guillaumin

An ultrastructural study was conducted to determine the originand development of the air blisters in leaves of Pilea cadierei.At early developmental stages (characterized visually by ananthocyanin flush to the blistered region, in leaves 0.5–1.8cm long) two epidermal layers separated by a small intracellularspace from a sub-epidermal layer of phenolic cells are observed.Osmiophilic phenol aggregates occur in the central vacuole,minivacuoles (or provacuoles) and in the endoplasmic reticulaof the phenol cells. Plastids in the phenol-containing cellshave extremely osmiophilic thylakoids, perhaps indicative ofphenol—caffeine complexes in the plastid. Later developmentalstages (characterized by a silver coloration in the air blisters)show an increase in the intracellular space, due at least inpart to the apparent collapse of the second epidermal layerand breaking of cell connexions. Phenol-containing cells havetwo different types of electron-opaque deposit: a grey granulardeposit and a continuous caffeine—phenol agglutination.Plastids are shade type and are much less opaque than in earlierstages. Several possible reasons for the presence of air blistersin many genera are discussed. Pilea cadierei, air blisters, ultrastructure, phenolics, tannin     

"Culture shock" from the bone cell's perspective: emulating physiological conditions for mechanobiological investigations

Bone physiology can be examined on multiple length scales. Results of cell-level studies, typically carried out in vitro, are often extrapolated to attempt to understand tissue and organ physiology. Results of organ- or organism-level studies are often analyzed to deduce the state(s) of the cells within the larger system(s). Although phenomena on all of these scales—cell, tissue, organ, system, organism—are interlinked and contribute to the overall health and function of bone tissue, it is difficult to relate research among these scales. For example, groups of cells in an exogenous, in vitro environment that is well defined by the researcher would not be expected to function similarly to those in a dynamic, endogenous environment, dictated by systemic as well as organismal physiology. This review of the literature on bone cell culture describes potential causes and components of cell "culture shock," i.e., behavioral variations associated with the transition from in vivo to in vitro environment, focusing on investigations of mechanotransduction and experimental approaches to mimic aspects of bone tissue on a macroscopic scale. The state of the art is reviewed, and new paradigms are suggested to begin bridging the gap between two-dimensional cell cultures in petri dishes and the three-dimensional environment of living bone tissue. osteoblast; osteocyte; tissue engineering; mechanobiology; mechanochemical transduction; fluid flow     

Development of Ethylene Biosynthesis in Pear Fruits at --1 {degrees}C

Knee, M. 1987. Development of ethylene biosynthesis in pearfruits at — 1 °C.—J. exp. Bot. 38: 1724–1733. The regulation of ethylene synthesis in pear fruits was investigated.During storage for 60 d at — 1 °C the rate of ethylenesynthesis increased 100-fold but the concentration of 1-aminocyclopropane-l-carboxylicacid (ACC) increased only 2-fold and ACC synthase activity waslow. On transfer to 15 °C after storage at — 1 °Cethylene synthesis increased 10-fold within 10 h but ACC synthaseactivity only increased rapidly after 24 h; the decline in ACClevels during the first 16 h at 15 °C was insufficient tosustain ethylene synthesis. Ethylene synthesis was further investigatedusing discs cut from the mid cortex of pear fruits. Synthesiswas inhibited by aminoethoxyvinylglycine (AVG) and amino-oxyaceticacid at all stages of ripening. The rate of synthesis and ACCsynthase activity increased rapidly after slicing of pears heldat — 1 °C but more slowly in discs cut from pearsimmediately after harvest. Cycloheximide (CHI) inhibited theseincreases and reversed increases resulting from pre-incubationof discs. A combination of CHI and AVG abolished the capacityof discs to synthesize ACC and ethylene production was curtailed.Cordycepin and actinomycin-D were less effective as inhibitorsof the development of ethylene synthesis and ACC synthase activitythan as inhibitors of incorporation of 5-[³H] uridine into totalRNA or poly A rich RNA. The ability of discs to develop ethylenesynthesis and ACC synthase activity in the presence and absenceof cordycepin increased concurrently during storage of wholefruits at — 1 °C. This suggested that mRNA for ACCsynthase was formed at — 1 °C. Key words: 1-Aminocyclopropane-l-carboxylic acid, ethylene, fruit ripening, Pyrus communis L. (fruit ripening)     

Twitching and quivering of the tentacles during snail olfactory orientation

In Helix aspersa the posterior tentacles house a sensitive olfactory organ. We studied two types of tentacular movements, twitch and quiver. A twitch is a brief retraction (mean duration, 4.1 s); a quiver is a rapid lateral movement (350 ms) unaccompanied by retraction. We videotaped the tentacles while snails explored an open field. When an attractive odor source, linalool, was present at one side of the arena, the snails consistently moved towards it. By contrast, if only the carrier substance was present the snails moved in random directions. Twitching was 50 times more frequent during linalool trials than during control trials, while quivering was 1.4 times more frequent. Twitching increased steadily and dramatically as snails approached the linalool source and, in the temporal dimension, the maximum rate of twitching occurred when the snails arrived at the odor source. Quivers occurred at a fairly constant rate. Twitching is interpreted as a mechanism to remove odor molecules trapped in the liquid covering of the olfactory epithelium, thus resulting in better temporal resolution for olfactory perception. Quivering may be a mechanism to increase access of odor molecules to receptors by decreasing the boundary layer at the surface of the tentacle. Accepted: 24 May 1997     

No Effect of Ambient Odor on the Affective Appraisal of a Desktop Virtual Environment with Signs of Disorder

Background

Desktop virtual environments (VEs) are increasingly deployed to study the effects of environmental qualities and interventions on human behavior and safety related concerns in built environments. For these applications it is essential that users appraise the affective qualities of the VE similar to those of its real world counterpart. Previous studies have shown that factors like simulated lighting, sound and dynamic elements all contribute to the affective appraisal of a desktop VE. Since ambient odor is known to affect the affective appraisal of real environments, and has been shown to increase the sense of presence in immersive VEs, it may also be an effective tool to tune the affective appraisal of desktop VEs. This study investigated if exposure to ambient odor can modulate the affective appraisal of a desktop VE with signs of public disorder.

Method

Participants explored a desktop VE representing a suburban neighborhood with signs of public disorder (neglect, vandalism and crime), while being exposed to either room air or subliminal levels of unpleasant (tar) or pleasant (cut grass) ambient odor. Whenever they encountered signs of disorder they reported their safety related concerns and associated affective feelings.

Results

Signs of crime in the desktop VE were associated with negative affective feelings and concerns for personal safety and personal property. However, there was no significant difference between reported safety related concerns and affective connotations in the control (no-odor) and in each of the two ambient odor conditions.

Conclusion

Ambient odor did not affect safety related concerns and affective connotations associated with signs of disorder in the desktop VE. Thus, semantic congruency between ambient odor and a desktop VE may not be sufficient to influence its affective appraisal, and a more realistic simulation in which simulated objects appear to emit scents may be required to achieve this goal.