Mood

=Natural odors affect mood, alertness, calmness =  RESEARCH REVIEW by Ilona Lantos

 Reviewed: 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.pdf]


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


 * Introduction:**

//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


 * 1. **** Subjects and method of selection **

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.


 * 2. **** Size **

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.


 * 3. **** Length **

Experiments were conducted in June, July and August during daytime and nighttime. Each experiment lasted about 15 minutes.


 * 4. **** Methodology **

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.

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.


 * 5. **** The results **

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.

// Check for reversed order //

In experiment 2 (E-C design) 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) 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.

// Check for visual input //

In experiment 4 (at night) 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.

// Check for odor valence //

In experiment 5 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).

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.

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.

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.

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.

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.


 * 6. **** The authors/researchers conclusions **

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)


 * 7. **** Your own thoughts/analysis of the results **

The validity of this study is questionable since they used various numbers of subjects (it is assumed that the same individuals participated but not all of them all the time), various flowers, different time of the day and different months.

I conclude that pleasant or neutral odors positively affect mood, alertness and calmness while unpleasant odors negatively. But because the perception of an odor is subjective, neutral odor is preferred. Therefore, it is important to ensure that the learning environment is free of unpleasant odors or any odors since the presence of odors might impair the learning process, unless the appropriate odor is selected for the appropriate state.

References:

1. Thayer, Robert E. (1989). //The biopsychology of mood and arousal//. New York, NY: Oxford University Press. 2. []

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

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.