Analysis

=**Odor** perception **influences human performance**=

This article explores four research papers to investigate how odors, more specifically how odor perception influences human performance, alertness, concentration and mood.

The Ilmberger //et al.// (2001) study shows that positive odor perception (cineole perceived relaxing and odorless water perceived stimulating) increased the speed of information processing (alertness), while ylang ylang rated as unpleasant, decreased it.

The research by Weber and Heuberger (2008) found that odors perceived pleasant and intense increased mood, calmness and alertness while unpleasant and intensive odors decreased it.

The Degel //et al.// (1999) study showed that implicit memory of odors truly exists and if odor is perceived pleasant (lavender vs. jasmine), it causes improved performance.

The Sakamoto //et al// (2001) study compared sedative and stimulating effect of odors and found that lavender vs. jasmine actually increases concentration contradicting earlier studies. Though this study has not measured odor perception we can assume that lavender had positive effect on performance because it was perceived pleasant. Lavender in other similar studies was perceived pleasant compared to stimulating aromas such as ylang ylang or jasmine.


 * Recommendations for educators:**

Check for existing emotional state before applying aroma. For instance, during test time when students are stressed, or late afternoon between 2:30-3:30 when they are tired, apply lavender or similar aroma for its balancing properties. During a long lecture, stimulate audience with an aroma with high cineole content, such as Eucalyptus. Make sure all class members perceive the selected odor pleasant and relaxing.

Your classroom should have pleasant odor or none to ensure optimal learning environment. Remember, odors perceived unpleasant, such as ylang ylang or jasmine, will impair attention and concentration.

===// Josef Ilmberger, Eva Heuberger , Claudia Mahrhofer , Heidrun Dessovic , Dietlinde Kowarik , and Gerhard Buchbauer, The Influence of Essential Oils on HumAttention. I: Alertness, Chemical Senses, Apr 2001; 26: 239 - 245. The online version of this article was downloaded by ilona lantos on July 4, 2010 from: http://chemse.oxfordjournals.org/cgi/reprint/26/3/239.pdf //===


 * Keywords**: ylang ylang, peppermint, 1,8 cineole, menthol, jasmine, alertness, attention

In this study about 420 healthy human subjects participated, aged between 16 and 67 years. Six experiments were conducted. In each experiment two experimental groups and one control group of 20 or 30 individuals participate. In the first and second experiments ylang-ylang and 1,8-cineole (eucalyptus) were used with two experimental groups and one control group of 20 subjects in each. In the third and fourth experiment 1,8-cineole (eucalyptus) and menthol (peppermint) were used with two experimental groups and one control group of 20 subjects in each. In the fifth and sixth experiment peppermint and jasmine absolute were used with two experimental groups and one control group of 30 subjects in each.
 * Subjects**

A-B design was used, that is two trials per session. In each trial the appropriate substance was applied on a surgical mask. This substance was water in both trials for the control group, and in the first trial for the experimental groups. Subjects were not told which substance was on the mask. In each trial after putting on the mask subjects were asked to fill out a questionnaire and rate the odor pleasantness (from “smells pleasant” to “smells unpleasant”), intensity (from “weak” to “strong”), effect (from “stimulating” to “tiring”) and degree of relaxation (from “I feel relaxed” to “I feel tense”). Then subjects had to perform a simple reaction time task for about 25 minutes. The stimuli, a red ellipse was presented randomly on the screen for about 220 times. Subjects had to release the go button and press another button as fast as they could when the red ellipse appeared. The time interval between the appearance of the ellipse and releasing the go button was recorded as reaction time, whereas the time interval between releasing the go button and pressing the second button was the motor time.
 * Methodology **

Reaction time was longer in second trials compared to first trials in all experimental and control groups, except for the cineole (100 ml) group. When compared the two cineole groups, the higher dosage cineole brought faster reaction time. However menthol and Peppermint did not produce difference in reaction.
 * Results**

Motor time in the second trial decreased for the cineole (100 ml) group and for the control groups. Peppermint, jasmine and ylang-ylang marginally increased the motor time in the second trial. Though water was rated as unpleasant and non-relaxing in the second trial, it resulted faster MT but not RT.

All fragrances were rated as more pleasant, more intense, more stimulating and more relaxing in the second trial than water in the first trial, except ylang-ylang, which together with water was rated less pleasant and less relaxing in the second trial.


 * Conclusions**
 * Odor intensity was more obvious across the experimental groups than water in the control groups in the second trial.
 * All odors were perceived as more pleasant in the second trial compared to water in the first trial, except ylang-ylang, which also resulted in longer reaction time.
 * Cineole got the highest rate for "relaxing" in the second trial and also led to faster reaction and motor time compared to all other groups.
 * Odors, except cineole (100) decreased alertness in all experiments acting as destraction.
 * Perception influenced outcome. Placebo effect can be best illustrated with the control groups inhaling water in both trials, The more stimulating was the water perceived in the second trial, the more the reaction and motor time decreased, that is alertness increased.
 * Besides individual perceptions there are other factors determining odor effects on behavior, such as individual differences, level of existing alertness, expectations of effects, and personality.

===

=== ===//Sandra T. Weber and Eva Heuberger, The Impact of Natural Odors on Affective States in Humans, Chemical Senses 33: 441–447, 2008. //=== ===//The online version of this article was downloaded by ilona lantos on July 4, 2010 from: [|http://chemse.oxfordjournals.org/cgi/reprint/33/5/441.pd] //===


 * Keywords**: odors, mood, alertness, calmness, affect, jasmine absolute rose oil, fragrant plants, ambient odor, vanillin

//Alertness//: speed of information processing (sleep to wakefulness) //Mood//: Compared to [|emotions] moods are less specific or intense, and less likely triggered by a particular stimulus or event and lasts longer. Moods generally have positive or negative valence (good mood, bad mood). 1 //Calmness//: is the mental state of being free from agitation, excitement, or disturbance.2

In this study 32 healthy human subjects participated, average age 24 years. Participants were recruited by advertisement at the University of Vienna. They were free to withdraw at any time and compensated for their time. Five experiments were conducted at two locations in natural outdoor settings with fragrant plants. The first four experiments took place at the Fragrant Garden. The fifth experiment was conducted at the Department of Clinical Pharmacy and Diagnostics. In each experiment the number of participants varied. In the first experiment 32 subjects participated, in the second experiment 29, in the third 25, in the fourth 30, in the fifth 22.
 * Subjects **

Experiments were conducted in June, July and August during daytime and nighttime. Each experiment lasted about 15 minutes. In each experiment 2 outdoor conditions were defined. The experimental (E) conditions at the Fragrant Garden subjects smelled selected blooming fragrant plants. In the control condition (C) at a different part of the garden subjects were not exposed to any blooming fragrant plants. Auditory and visual stimuli were identical between conditions. In this study both the C-E and E-C designs were used.
 * Methodology **

The first experiment using the C-E design was performed in May during daytime and started with the acquisition of personal data (5 minutes) followed by the control condition (15 minutes). Subjects were sitting on a bench, not talking to each other and asked to fill out a questionnaire and rate the odor pleasantness and intensity. Then subjects went to the experimental condition and asked to sniff at the selected plants 3 times each then fill out the same questionnaire.

To check for odor effects, 2 additional experiments were performed at the Fragrant Garden in June and July, the conditions were reversed using the E-C design. To check for possible visual effects (color and shape of the plants), the fourth experiment was conducted at night, when certain fragrant plants were releasing scent. To check for odor valence, habituation and order effects, the fifth experiment was performed in July at a garden at the Department of Clinical Pharmacy and Diagnostics. A counterbalanced design was employed with 3 experiments and a control condition. In the first two experiments pleasant odors (dilutions of vanillin and jasmine absolute or rose oil), in the third experiment unpleasant odor (sodium sulfide) and in the control condition odorless water were presented with plastic squeeze bottles 5 cm underneath the subject ’ s nose.

In experiment 1 (C-E design) there was significant difference between the experimental and control condition in affective states. The experimental condition showed increased mood, alertness, and calmness. The atmosphere at the Fragrant Garden was rated as more pleasant and more intense than in the control condition.
 * R **** esults **

In experiment 2 (E-C design // to check for reversed order // ) there was no significant difference between the experimental and control condition in affective states. The odorous atmosphere at the Fragrant Garden was rated as more intense but not more pleasant than in the experimental condition.

In experiment 3 (E-C design // to check for reversed order // ) there was no significant difference between the experimental and control condition in affective states. The odorous atmosphere at the Fragrant Garden was rated as more intense and more pleasant than in the experimental condition.

In experiment 4 (conducted at night // to check for visual input // ) there was significant difference between the experimental and control condition. The experimental condition showed increased mood, alertness, and calmness. The odorous atmosphere at the Fragrant Garden was rated as more intense but not more pleasant than in the experimental condition.

In experiment 5 // to check for odor valence, // there were Paired Samples t-tests conducted (hydrogen sulfide-odorless water; vanillin- odorless water; floral- odorless water; vanillin- hydrogen sulfide; floral- hydrogen sulfide) to measure affect (mood, alertness, calmness).


 * 1) In the hydrogen sulfide-odorless water experiment there was a significant decrease in mood and calmness but not in alertness in the hydrogen sulfide condition. In the odor pleasantness and intensity rating hydrogen sulfide was rated as more unpleasant and more intense than odorless water.
 * 2) In the vanillin- odorless water experiment there was no significant difference in mood, calmness or alertness. In the odor pleasantness and intensity rating vanillin was rated as more unpleasant and more intense than odorless water.
 * 3) In the floral- odorless water experiment there was no significant difference in mood, calmness, however alertness was higher in the floral condition. In the odor pleasantness and intensity rating jasmine absolute and rose oil were rated as more pleasant and more intense than odorless water.
 * 4) In the vanillin-hydrogen sulfide experiment there was a significant increase in mood and calmness but not in alertness in the vanillin condition. In the odor pleasantness and intensity rating vanillin was rated as more pleasant but not more intense than hydrogen sulfide.
 * 5) In the floral-hydrogen sulfide experiment there was a significant increase in mood and calmness but not in alertness in the floral condition. In the odor pleasantness and intensity rating rose oil and jasmine absolute were rated as more pleasant but not more intense than hydrogen sulfide.


 * C **** onclusions **
 * Based on experiments 1 and 4 (C-E design), it is confirmed that pleasant odors from blooming plants improve affective states (mood, alertness and calmness) in humans in natural, outdoor setting independent of visual input.
 * Since in experiments 2 and 3 (E-C design) affective states did not show significant difference between the experimental and control condition, authors speculate that natural complex fragrances may cause long-lasting changes in mood, alertness and calmness.
 * From experiment 5 authors conclude that unpleasant odors impair the affective states in humans and reverse the enhancing effect of pleasant fragrances.
 * There was no difference between pleasant and neutral conditions regarding affective states, but there was an increased rating in neutral conditions if preceded by fragrant condition, which supports the idea that pleasant odors have long lasting effects.
 * Stimulating odors (pleasant or unpleasant) increase alertness. (Goel and Lao 2006)

//Joachim Degel and Egon Peter Köster: Odors: Implicit Memory and Performance Effects, Chemical Senses, 24: 317–325, 1999. //
===//The online version of this article was downloaded by Ilona Lantos on September 4, 2010 from:[| http://chemse.oxfordjournals.org/content/24/3/317.full.pdf] //===


 * Keywords**: lavender, jasmine, performance, creativity, mathematical, implicit memory

This study investigated the implicit influence of odors on human performance. Earlier studies showed that ambient odors (Gilbert et al., 1997) or suggested ambient odors (Knasko et al., 1990) did not influence performance. Other studies explicitly introduced odors during the learning phase (Schab et al., 1992). In another study (Torii et al., 1988) the stimulating and sedative effects of odors influenced the level of arousal but not performance. In the current study the subjects were not being told about the scents.The assumption was that subjects will be more productive, creative and make less errors under the stimulating odor condition than in the sedative or neutral odor conditions and that the fit between odors and visual contexts will be positively influenced by the implicitly learned odors in the test rooms.

In this study 108 healthy individuals (54 males, 54 females) participated, average age 30. Participants were randomly divided equally into two experimental and one control groups. The experiment took place in three different phases: performance testing, fit rating, pleasantness rating. The performance testing consisted of 3 types of tests: the creativity test (2 minutes), the concentration test (8 minutes), the mathematical test (8 minutes). The total duration of the tests was 45 minutes including 15 minutes of waiting and instruction time.
 * Subjects**

First subjects took three types of performance tests in the 2 testing rooms with odors of lavender and jasmine and in one odorless room. Each subject performed the tests individually assigned to one of the 3 interviewers. The 3 interviewers alternated among the 3 groups. Neither the subjects nor the interviewers were told about the odors. In the creativity test (2 minutes) subjects had to name as many members of a given class of objects as they could think of. For instance, things that are red or things that make noise. In the concentration test (8 minutes) subjects had to count the frequency of a specified letter in 25 rows of 50 randomly arranged mirror letters (b, p, d, q). The mathematical test (8 minutes) consisted of 5 blocks, each including 15 tasks (5 addition, 5 subtraction, and 5 multiplication).
 * Methodology**

Next, the subjects were taken another room and asked to rate the fit of odors between a provided 12 jars pf odorants (sandalwood, coffee, leather, lavender, jasmine, cedar wood, laundry, aftershave, ambient odors) and the presented pictures of various everyday surroundings including the testing rooms (train compartments, train lavatory, kitchen, bank, canteen, office, car). Three of them contained visual cues for leather or coffee. Pictures were presented randomly and the alternated between the ones that had visual cues or those that did not. Subjects had to rate the fit between all odors to each picture on a scale of 100 mm visual analog scale with the end labels "fit" and "does not fit". To prevent olfactory adaptation, subjects were asked to smell the inside of their arms after each rating, as well as a 45 second pause was held before showing a new visual context.

5 minutes after the ratings of fit test, subjects were asked to rate each odor for pleasantness, to write down the name of the odor and the place and time where and when they last time smelled the odor.


 * Results**
 * In the mathematical test, the jasmine group made significantly more errors than the other two groups.
 * In the letter counting test the lavender group produced the least amount of errors.
 * In the creativity test, interviewer A had a significant affect on performance.
 * In the ratings of fit test, the jasmine test room received the highest fit to jasmine by the jasmine group compared to the lavender or control groups. The control test room got the highest control odor rating by the control group while there was no difference in ratings by the lavender and jasmine groups for the control room.
 * In the pleasantness rating, lavender was rated more pleasant than jasmine and coffee more pleasant than leather. The three groups did not differ in their ratings of pleasantness.
 * Lavender had positive effect on performance while jasmine had negative.

The authors of this study concluded that implicit perception of the odor of lavender significantly affect performance in the mathematical and letter counting tests. Subjects in the lavender room made the least number of errors compared to the jasmine or control groups.This might sound contradicting to what Torii et al. (1988) measured, namely that there is a correlation between alertness and performance, and jasmine is stimulating and increase performance while lavender is sedative and decrease performance. This contradiction can be explained by the Yerkes-Dodson law which says that there is an optimal arousal level for optimal performance. Below this level stimulating odor would raise performance and sedative odor would decrease it. Above the optimal arousal level these odors would have the opposite effect.
 * Conclusions**

The second conclusion was that If odor source is visually present then odor and source will be easily connected.

The authors of this study also concluded that implicit memory for odors exists. When a person is exposed to some odor unknowingly he/she will connect that odor with that place later on. This implicit memory works especially for those who are unfamiliar with the odor and unable to specify the name of the odor. This was the case with the control group (they gave the highest score for the odorless sample fit to the control room) and the jasmine group (gave highest score for jasmine fit to the jasmine scented test room) and the non-identifiers in the lavender group. Those in the lavender group who were able to name the odor of lavender, did not rate lavender higher to the lavender test room than those in the control or jasmine groups.

The fact the non-identifiers have better implicit memory of odors contradicts with earlier findings according to which knowing the odor name has a better result in odor recognition tests (Lyman and McDaniel, 1986, 1990). Explanation is that those experiments introduce odors explicitly in the learning phase so the name and smell of the odor are stored in multiple memory pathways, in the semantic memory and the odor memory.

===//Reiko Sakamoto, Kazuya Minoura, Akira Usui, Yoshikazu Ishizuka and Shigenobu Kanba: Effectiveness of Aroma on Work Efficiency: Lavender Aroma during Recesses Prevents Deterioration of Work Performance, Chemical Senses, Apr 2001; 26: 239 - 245. //=== ===// The online version of this article was downloaded by ilona lantos on July 4, 2010 from: [] //===


 * Keywords**: lavender, jasmine, concentration

Previous studies examined essential oils for their sedative (lavender) and stimulatory (jasmine, peppermint) qualities and their effects on work performance. In one study electroencephalography (EEG) showed increased activity in the frontal lobe during excited states (jasmine) and decreased activity during sedated states. In previous studies lavender decreased calculation rates (Ludvigson and Rottman, 1989) or work performance (Moss et al, 2003), but conversely in another study lavender increased accuracy in arithmetical calculations compared to the jasmine and control groups. (Degel and Koster, 1999) While former studies indicated that lavender reduces work efficiency, this latter indicates that during stressful periods lavender has the opposite effect that is increases work performance. The current study further investigated the effect of lavender which was introduced during recess time between work sessions in this study as opposed to former studies when lavender was introduced during work performance.

In this study about 36 healthy male university students participated, average age 24. Participants were randomly divided into two experimental groups and one control group. Five experiments were conducted between 0930 and 1700 for 1 day, each of them was a 60 minute-long computer task requiring concentration. Each experimental group was exposed to the selected aroma during a 30 min recess between each session.
 * Subjects**

Participants were asked to have sufficient sleep and avoid alcohol, cigarettes, medications, cosmetics or caffeinated drinks starting 2 days before the experiment to prevent fatigue. Each control group was exposed to the selected aromas (lavender and jasmine) while the control group was not exposed to any aroma during recesses. All participants worked in the same area but during recess each group used its group room. During the work session participants performed some monotonous work on the computer using a performance efficiency assessment program which provided two indicators tracking errors and response time.
 * Methodology**


 * Results**
 * The indicator of concentration displayed a U shaped curve in each work session gradually declining from start then climbing up what is called "The Last Spurt Effect" (Kuraishi at al, 1957).
 * Significant decrease of concentration occurred in the control group during the work session between 1430 and 1530, which is known as the time when work efficiency usually decline (Monk et al, 1996).
 * Significant inter-group differences occurred during work session between 1430 and 1530. Concentration in the lavender group was the highest compared to both the control group and the Jasmin group.

The authors of this study suggest that though lavender generally is considered sedative, when mental fatigue is present, smelling lavender can prevent deterioration of performance. They also acknowledged some limitations, such as the extent aroma preferences might have influenced the results or the short length of the study.
 * Conclusions**


 * References:**

Degel, J. and Koster, E.P. (1999) Odors: implicit memory and performance effects. Chem. Senses, 24, 317–325.

Gilbert, A. N., Knasko, S.C. and Sabini, J. (1997) Sex differences in task performance associated with attention to ambient odor. Arch. Environ. Health, 52, 195–199.

Goel N, Lao RP. 2006. Sleep changes vary by odor perception in young adults. Biol Psychol. 71:341–349.

Knasko, S. C. (1992) Ambient odor’s effect on creativity, mood, and perceived health. Chemical Senses, 17, 27-35.

Knasko, S.C., Gilbert, A.N. and Sabini, J. (1990) Emotional state, physical well being, and performance in the presence of feigned ambient odor. J. Appl. Soc. Psychol., 20, 1345–1357.

Kuraishi, S., Kato, M. and Tsujioka, B. (1957) Development of ‘‘Uchida–Kraepelin psychodiagnostic test’’ in Japan. Psychologia, 1, 104–109.

Ludvigson, H. W., Rottman, T. R. (1989) Effects of ambient odors of lavender and cloves on cognition, memory, affect and mood. Chemical Senses, 14, 525-536.

Lyman, B.J. and McDaniel, M.A. (1986) Effects of encoding strategy on long-term memory for odors. Quart. J. Exp. Psychol., 38, 753–765.

Lyman, B.J. and McDaniel, M.A. (1990) Memory for odors and odor names: modalities of elaboration and imagery. J. Exp. Psychol.: Learn., Mem. Cogn., 16, 656–664.

Monk, T.H., Buyesse, D.J., Reynolds, C.F. and Kupfer, D.J. (1996) Circa- dian determinants of the mid-afternoon dip in performance. Chronobiol. Int., 13, 123–133.

Moss M, Cook J, Wesnes K, Duckett P. (2003) Aromas of rosemary and lavender essential oils differentially affect cognition and mood in healthy adults. International Journal of Neuroscience 113(1):15-38.

Schab, F.R. and Crowder, R.G. (1995) Implicit measures of odor memory. In Crowder, R.G. and Schab, F.R. (eds), Memory for Odors. Erlbaum, New York, pp. 71–91.

Torii, S., Fukuda, H., Kanemoto, H., Miyanchi R., Hamauzu, Y. and Kawasaki M. (1988) Contingent negative variation and the psycho- logical effects of odour. In Van Toller, S. and Dodd, G.H. (eds), Perfumery. Chapman & Hall, London, pp. 107–120.

Yerkes, R.M. and Dodson, J.D. (1908) The relation of strength of stimulus to rapidity of habit formation. J. Comp. Neurol. Psychol., 18, 459–482.