An Environmental Approach to Positive Emotion : Flowers

Evolutionary Psychology
human-nature.com/ep – 2005. 3: 104-132
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Original Article

An Environmental Approach to Positive Emotion: Flowers

Jeannette Haviland-Jones, Department of Psychology, Rutgers-The State University of New Jersey,
New Brunswick, NJ. 08903, USA. Email: baljones@rci.rutgers.edu.

Holly Hale Rosario, Department of Psychology, Rutgers-The State University of New Jersey, New
Brunswick, NJ. 08903, USA.

Patricia Wilson, Department of Psychology, La Salle University, Philadelphia, PA 19141, USA.

Terry R. McGuire, Department of Genetics, Rutgers-The State University of New Jersey, New
Brunswick, NJ. 08903, USA. Email: mcguire@biology.rutgers.edu.

Abstract: For more than 5000 years, people have cultivated flowers although there is
no known reward for this costly behavior. In three different studies we show that
flowers are a powerful positive emotion “inducer”. In Study 1, flowers, upon
presentation to women, always elicited the Duchenne or true smile. Women who
received flowers reported more positive moods 3 days later. In Study 2, a flower
given to men or women in an elevator elicited more positive social behavior than
other stimuli. In Study 3, flowers presented to elderly participants (55+ age) elicited
positive mood reports and improved episodic memory. Flowers have immediate and
long-term effects on emotional reactions, mood, social behaviors and even memory
for both males and females. There is little existing theory in any discipline that
explains these findings. We suggest that cultivated flowers are rewarding because
they have evolved to rapidly induce positive emotion in humans, just as other plants
have evolved to induce varying behavioral responses in a wide variety of species
leading to the dispersal or propagation of the plants.

Keywords: positive psychology; emotion; happiness; flowers; memory; social distance;
Duchenne smile.

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Introduction

“…[I]t was the flower that first ushered the idea of beauty into the
world the moment, long ago, when floral attraction emerged as a
evolutionary strategy” (p.xviii)…[one of]…”a handful of plants that
manage to manufacture chemicals with the precise molecular key

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An Environmental Approach to Positive Emotion: Flowers
needed to unlock the mechanism in our brain governing pleasure,
memory, and maybe even transcendence.” (p.xviii) I would be the last
person to make light of the power of the fragrant rose to raise one’s
spirits, summon memories, even in some not merely metaphorical
sense, to intoxicate”…(p. 177) (Pollan, 2002).

The proposition that “floral attraction emerged as a evolutionary strategy” for
“pleasure, memory and maybe even transcendence” (Pollan, 2002) is basically the
hypothesis that there is an evolutionary niche for emotional rewards, a niche to which
species far removed from mammals, even flowering plants, may adapt. Few
scientists have taken this hypothesis seriously and few studies question the effect that
flowering plants or other non-humans, (except dogs; Allen, 2003) have on human
emotions. Do flowering plants, in fact, increase positive emotional reaction by
influencing emotional displays such as smiling or, over a longer time period, do they
change moods and also influence socio-emotional functions such as social greeting
patterns or memories of social events? The following studies of social-emotional
responses to flowers begin to examine this proposition and to question the human
emotional environment outside that of human relationships.
Although we know that depriving humans or other social species of species-
specific social contact and emotional support is detrimental to health (Cacioppo et al.,
2000; Spitz, 1946), very little research has been directed to the effects of depriving
humans of other-species sources for emotional support. Humans are embedded in a
larger sensory and social environment than that occupied by their own species.
Depriving humans of non-species emotional support may be as detrimental to human
survival and fitness as depriving humans of any other resource.

A Brief History

In cultures around the world as far back in history as we have any records,
flowers provided emotional information among peoples. Pollen was found in the
graves of Neanderthals suggesting that the flowers had a place in the burial (Solecki,
1971), although the significance of the pollen is still in dispute (Sommer, 1999).
Flowers are expected to convey sympathy, contrition (guilt), romance (sexual intent)
or celebration (pride and joy) (Heilmeyer, 2001). Flowers are also used to express
religious feelings and in some religions are considered the direct route for spiritual
communication. (Stenta, 1930). Of course, some flowers are used for personal
adornment, both the blossoms themselves and their essences in the form of perfumes.
The vast majority of personal commercial fragrances have a floral top- and/or mid-
note. In spite of some basic survival uses, such as edible or medicinal flowers, most
flowering plants grown in the flower industry in modern times are not used for any
purpose other than emotional. Floriculture crops in the United States accounted for at
least 4.9 billion dollars in sales in 2001 (USDA, 2003). This amount seriously
underestimates the floral economy because it does not include imports.
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An Environmental Approach to Positive Emotion: Flowers
Naive psychology argues that flowers are desired because of learned
associations with social events. However, the ubiquity of flower use across culture
and history and the lack of easy substitutes for the many uses of flowers suggest that
there may be something other than this simple association. Flowers may influence
social-emotional behavior more directly or may prime such behavior. That is,
flowering plants may have adapted to an emotional niche.

The Emotional Niche – Both the Positive and the Negative

Can one really argue that positive emotion usually has survival benefits or
conveys reproductive fitness? Despite early definitions of happiness or joy as a basic
emotion, the continuing science of the evolution of emotion has emphasized the
negative -- hostile and fearful emotions in animals and depression and hostility in
humans (McGuire, 1993). A larger research literature reports on the stimuli that
govern negative emotions as well as the patterns of response, secondary effects, and
individual differences that emerge in their expression (for reviews, see Lewis and
Haviland-Jones, 2000). It is clear that both plants and animals use defenses that elicit
emotional fear or disgust reactions through the sensory modes of taste and smell,
vision and audition. Snakes and spiders are not necessarily poisonous and the
stinking, slimy mushroom may even be edible. It is not necessary that defense
mechanisms be physically damaging, only that they produce an emotional reaction
leading to avoidance or withdrawal. A plant or animal that can frighten or disgust a
predator has gained fitness by exploiting an emotional niche. Withdrawal without
physical contact is better than an active physical defense, which might lead to damage
or death of the defending species. The ability to produce negative avoidant emotion in
a predator has long been considered a possible defense and could be seen as the
exploitation of an emotional niche.
That positive emotion could operate in a similar emotional niche has emerged
recently but the evidence remains exploratory (Grinde, 2002; Seligman, 2002).
Attraction mechanisms for plants have some socio-emotional features. For example,
Hawk moths (Manduca species.) repeatedly visit Datura flowers (jimsonweed) for a
hallucinogenic reward (Grant and Grant, 1983). Some species of orchids produce
very little nectar and attract pollinators with perfumes. Orchid bees (Eulaema,
Euplusia and Euglossa genera) collect perfumes/pheromones from these orchids into
specialized pouches; they then use the perfumes as sex attractants. Other species of
orchids mimic female sex pheromones and attract males who mate with the flower
(Scheistl, et al., 1999). Interestingly, after “mating” the flowers then produce an anti-
aphrodisiac pheromone (Schiestl and Ayasse, 2001). The well-known bower bird
decorates its nest with flowers (Uy and Borgia, 2000). A number of bat-pollinated
flowers emit a sulfur-like odor that mimics odors used in bat mating and social
recognition (von Helversen, Winkler, and Bestmann, 2000). Many other plants
provide non-nutritional chemical compounds, which insects can use for defense or
sexual attraction (Weller, Jacobson, and Conner, 2000). There does not appear to be
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An Environmental Approach to Positive Emotion: Flowers
a demonstration of plants providing socio-emotional benefits using similar chemical
or visual mechanisms to humans.
The attraction to flowering plants reflected above may be related to positive
emotion. Panskepp’s (2000b) research suggests that non-human species use positive
emotion similarly to humans. “Tickling” rodents elicits high pitched “laughter.” This
laughter is related to the appropriate neurological patterns for positive emotion, and is
attractive to other members of the same species. Rats will prefer to approach a
human caretaker who is a “tickler” over one who provides food and water. In other
words, the immediate elicitation and expression of emotion even coming from
another species is related to secondary social attraction effects. The secondary effects
of positive emotion are demonstrated in a large number of behavioral domains for
people as well as for rodents (Panksepp, 2000a). Positive emotion makes people
appear to be more attractive, even sexually attractive and arguably, more likely to be
approached socially. (Cunningham, Barbee, and Philhower, 2002; Otta, Abrosio, and
Hoshino, 1996).
Both short and long-term expressions of positive emotion are related to
secondary effects of positive mood. For example, cognitive processing that is
inclusive and exploratory (Isen, 1987) often accompanies or follows positive
expressions. Positive mood also improves memory processes (Isen, 1999; Levine and
Burgess, 1997) and serves as a buffer against stress. Those who are induced to be
positive will recover more rapidly from stressors (Folkman and Moskowitz, 2000;
Fredrickson, 2000). Also, the long-term expression of positive moods leads to a
prolonged involvement in an ongoing activity, and several researchers have argued
that happiness is related to feelings of safety and would therefore be associated with
social gathering and caring for infants (for reviews see Ekman and Davidson, 1994).
Finally, happy people are more likely to get married, thereby establishing families
(Mastekaasa, 1992).
Thus, happiness in humans facilitates both immediate and long-term social
and cognate functions (Fredrickson, 2002; Izard and Ackerman, 2000; Panksepp,
2000a) and may lead to long-term survival benefits. Health benefits are often
documented in laboratory studies of animals other than humans. For example, Poole
(1997) suggests that unhappy animals are often physiologically and immunologically
abnormal, and Hockly et al. (2002) found that the environmental enrichment of lab
mice slowed the progression of Huntington’s chorea in genetically engineered mice.
Environmental enrichment also is known to upregulate genes involved with neuronal
growth (Rampon et al., 2000). There is a growing body of evidence supporting the
need for a positive emotional environment for optimal health, social and cognitive
processes. If positive emotion has these effects, then human emotional needs are a
niche to which other species can adapt.
If flowering plants are exploiting a human emotional niche, it must be shown
that they directly influence emotional states and thereby, also beneficially influence
secondary cognitive and social behaviors. It is the goal of our research studies to
demonstrate that some plants, notably domesticated flowers, have a strong effect on
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An Environmental Approach to Positive Emotion: Flowers
emotional state and influence secondary cognitive and social behaviors.

Measurement of Positive Emotion

The measurement of emotion, particularly positive emotion, is reliably done
in several ways. Positive expressive movements among humans are reliably measured
with facial movement, particularly smiles. The smile is the easiest facial movement to
recognize. This is especially important when the movement is brief and embedded in
ongoing activity. Self-reports of moods are also reliable when longer mood states are
measured.
The Duchenne smile is consistently related to positive emotion in humans and
is a reliable indicator of happiness, whether or not the happiness can be self-reported
(Dimberg, Thunberg, and Elmehed, 2000). For example, Messinger, Fogel and
Dickson (2001) showed that the Duchenne smile is associated with reciprocal positive
emotion because it is displayed by infants when their mothers are also smiling.
Williams et al (2001) argue that the Duchenne smile elicits a hardwired reciprocal
response in observers. The Duchenne smile functions both as a shared
communication as well as an individual response to positive stimuli. It is a reliable
indicator of the ability of a stimulus to elicit immediate positive emotion.
In the course of research on fear stimuli Dimberg and Thell (1988) used
pictures of snakes for fear stimuli, and pictures of flowers for neutral stimuli. They
found that flowers were not neutral but had effects on rapid changes in facial
musculature. They reported that the facial EMG reaction to the flower stimuli is
zygomatic muscle activity (smile), which they refer to as a positive response.
Dimberg and Thell did not conclude that the study participants exposed to the flower
picture were happy because a genuine, or “true” smile (the Duchenne smile) also
requires orbicularis oris movement (movement around the eye), which they did not
measure. It is possible that they inadvertently discovered a positive emotional
stimulus in flowers. This immediate response needs to be tested with further study of
the facial response to determine whether the response is indeed the Duchenne smile.
This will be one of the first tests we use in Study 1.
If people respond to cultivated flowers with a Duchenne smile, it would be a
strong indicator that flowers are an immediate stimulus for positive emotions. Then if
interviews and self-reports corroborate the positive effects, this is evidence for long
term or secondary effects on mood.

Goals of the Studies

In the following studies we first (Study 1) compare the emotional influence of
cultivated flowers with that resulting from comparable objects which supply more
basic needs such as food or warmth. We predict that the influence of cultivated
flowers on human mood should be powerful both immediately and long term. To
measure immediate emotional change we observe smiling behaviors; to measure
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longer-term mood change we measure mood before receiving a floral bouquet and 3
days afterwards.
In Study 1 we use only female participants; however, if the flowering plants
fill a human emotional niche, the effect should, at least partly, overcome local social
convention such as gender. Though women are the usual recipients of flowers in 21st
Century North America and thought to be more responsive to flowers, this may be
related to the perception (or bias) that women are more emotionally responsive
generally (Brody and Hall, 2000). Such a bias only reinforces the hypothesis that
flowers influence emotion, but does not eliminate the possibility that men can be
influenced similarly. In Study 2 we hypothesize that the positive emotional effects of
flowers should generalize to men. Finally, if the effect on emotional state is
powerful, we predict that the moods produced by cultivated flowers would have
positive effects on social behaviors. In Study 2 we measure emotional and social
behavior in a naturalistic observation.
The goal of Study 3 is to expand our information about secondary effects to
the cognitive area. It also examines the long-term impact of repeated exposure to
flowers (i.e. the dose effect). In the third study we provide people living in senior
living residences with flowers. We predict that the flowers will have both a long-
term effect and a short-term effect on mood. Further we predict that the secondary or
spiraling mood changes will influence social behavior and episodic memory.

Study 1 – Immediate Smiles and Long Term Mood Change

To test the effects of flowers, we compared the immediate and long-term
emotional behavior of participants who received floral bouquets to the behavior of
participants who were presented with flower-irrelevant control stimuli.

Method

Participants

The participants were 147 adult women evenly distributed across three age
groups (20-39; 40-59, 60+). Nearly all participants were white (n = 137); 2 were
“African Americans”, 5 were “Asian Americans”, and 3 were “other”. Women were
chosen for several reasons: (1) they are more facially expressive, making the coding
of their immediate emotional response more reliable; (2) they are more likely to
report shifts in moods, especially negative moods (Brody and Hall, 2000) and (3)
women are the more common recipients of flowers in the local culture. The
participants were recruited through alumnae newsletters, newspaper advertisements
and postings in grocery stores and churches in the New York-New Jersey
Metropolitan Area.


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Stimuli

The mixed-flower bouquet (including roses, lilies and stocks) was chosen
after consultation with the Society of American Florists about the most popular
bouquets. A mixed-flower bouquet has a variety of colors and odors and should
maximize the effect across a diverse group of participants. An initial focus group of
15 women, ages similar to those of the experimental participants, listed stimuli that
could substitute for flowers. This initial group was joined by an additional 15 women
and these 30 women rated all the stimuli on similarity to flowers. The focus groups
selected (1) a fruit and sweets basket (food) and (2) a large, multi-wicked candle
(light, heat) on a stand. The selected stimuli had some of the traditional traits of
domesticated plants -- food and fuel. Chocolate sweets were not selected because
ratings were split, either very high (desirable) or very low (undesirable due to
allergies or weight consciousness). The selected stimuli were uniformly rated high.
The stimuli all had the same economic value, had some pleasant odor, had variation
in color, and were wrapped similarly for presentation in clear plastic with colorful
bows.

Measures

Mood Measures. The 24-item Differential Emotion Scale (DES)-long form
(Izard, 1971) is divided into 8 subscales representing 8 primary emotions. Each item
expresses a feeling, such as "felt like what you're doing or watching is interesting."
The DES was developed to measure changes in normal moods rather than
dysfunctional ones. A participant was asked to indicate how often she had felt "each
of these feelings" in the past 2-4 days, ranging from "0" (Never) to "4" (very often).
The Life Satisfaction Scale (LSS; Diener and Larson, 1984) is a 5-item scale
including statements such as "So far, I have gotten the important things I want in
life." The participant was asked to indicate the extent of her agreement with each
statement on a 5-point bipolar scale ranging from "Strongly disagree" to "Strongly
agree."
Assessment of Secondary Behaviors. A series of open-ended questions
assessed the possible influence of the floral bouquets on secondary behaviors. During
the last interview, participants rated the extent and type of social support they had
experienced within the last 2-3 days. These included questions about intimate
contacts (i.e., people with whom participants had close relationships such as family or
friends), relaxation activities, creative activities, and amusements. This interview
also included questions about the placement of the stimulus in the home and the use
of the stimulus.
Coding the Immediate Positive Emotion. In the first 5 sec after presentation
of the stimulus, the coder recorded the presence of (a) the Duchenne smile
(zygomatic and orbicularis oris movement), or (b) the zygomatic smile alone (no
movement of the muscle orbiting the eye) or (c) no smile. The duration of the
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movements within the 5 sec was not coded, only their occurrence. These facial
muscles are easily discerned and coded even by untrained people. With training, the
coding is highly reliable (Ekman, Friesen, and Davidson, 1990; Frank, Ekman, and
Friesen, 1993).

Procedure

Participants were recruited for a study about normal daily moods. At initial
contact, participants answered demographic questions and scheduled the delivery of
the stimulus to their homes. They were told they would receive a gift for their
participation, one of 10 possibilities, but were not told which one. All participants
agreed to be interviewed by phone three times, including the initial contact. Both
interviewers and participants were blind to the stimuli.
Initial Interview Prior to Stimulus. About 10 days before the presentation of
the stimulus, the participant was interviewed by an experimenter who had no
knowledge of which stimulus would be given to that participant. The experimenter
asked the participant to respond to items on both the DES and the LSS.
Stimulus Delivery. Two experimenters delivered the stimuli to the homes of
the participants on a prearranged schedule. One presented the stimulus and the other
coded the type of smile. The presentation was double blind -- blind to the participant
until the moment of presentation and to the coder before and during the presentation.
The person holding the box with the stimulus had her entire upper body and face
blocked by the box so she was unlikely to give any cue as to the contents. The
stimulus was in a large box with one open side. This side was turned away from the
participant and from the coder. When the participant had her attention on the box, the
open side was turned towards her but the contents were still not visible to the coder.
This method of presentation allowed us to focus on the response activated by the
stimulus rather than the response to the delivery people. The coder noted the type of
smile in the initial 4-5 seconds after the stimulus was uncovered.
Follow-up Interviews. The second interview occurred 2-4 days after the
delivery of the stimulus. The interviewer was neither a coder nor a presenter of the
stimuli and remained blind to which stimulus the participant had received. The
participant again responded to the DES and the LSS. This interview also included
open-ended questions to assess social support as a possible secondary effect and to
determine use of the stimulus.

Results

Immediate emotional reaction

In the 5 sec following the presentation of the stimulus, 100% of the
participants in the flower group responded with the Duchenne smile indicating
happiness. The Duchenne smile was common in response to all the stimuli but there
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was some variation in response to the other stimuli; 10% of participants receiving
fruit and 23% of participants receiving the candle did not respond with a Duchenne
smile. The differences between the groups is very significant (?2 (2, N = 147) =
14.21, p = .007). There were age-related preferences to the control items. Older
participants were more likely to display the Duchenne smile when presented with
fruit baskets than the younger (?2 (4, N = 98) = 9.74, p = .045). For the candle, age
differences were marginally significant. Younger participants were more likely to
smile than the older ones (?2 (4, N = 98) = 8.99, p = .061). In a few cases, we became
aware during interviews that some participants preferred another stimulus. However,
stated preferences apparently had no effect on the universal Duchenne response to the
flowers.

Mood Interviews

All groups of participants showed an expected decline in the intensity of
emotions from the first interview to the second. All ts on negative emotion were
greater than 2.02; all ps were less than .05; there were only marginal effects for
positive emotions (see Diener and Larson, 1984, on retesting moods). Only the
Participants who received the flowers reported an increase in positive emotion on the
DES inventory (i.e., enjoyment, M = 0.22, -0.44, and -0.54 for flowers, fruit, and
candle respectively; F(2, 139) = 3.95, p = .02).
All three groups had higher scores on the LSS at the second interview than at
baseline (t(146) = -4.32, p = .001). This is an overall study effect and there was no
significant interaction by stimuli.
During the second interview we also asked questions about the use of the
stimuli. The flowers were at least twice as likely to be placed in communal space, that
is, places such as the foyer, the living room or dining room. Flowers were not very
likely to be placed in the most private spaces such as baths, bedrooms or inside
cupboards, whereas the other stimuli were more likely to be in private space than in
communal space (?2 (2, N = 147) = 20.35, p < 0.001). Participants who received
flowers were more likely than those receiving the other stimuli to answer positively to
social support questions (e.g. contacting people, talking intimately) after they
received the flowers than before (?2 (2, N = 147) = 7.35, p = .05). On the other hand,
there were no changes in responses to questions about engaging in amusements or
relaxation. These results from the interviews suggest that the flowers influence
secondary socio-emotional behaviors as well as having a strong effect on immediate
emotional behavioral expression. However, these were post-hoc analyses requiring
further study.

Discussion

The Duchenne smile is common on the presentation of all the stimuli as
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expected; however, the highest (100%) response rate occurred to flowers. The only
longer term increase in positive moods reported was for those who received flowers.
There were additional indications that flowers were different from other stimuli.
Follow-up interviews indicated that people who received flowers placed them in
communal spaces more often and slightly changed their social behavior.

Study 2 – Social Behavior and Flowers: The Elevator Study

In Study 1, we only included female participants and we only observed one
behavior, the smile. It appeared from post-hoc analyses that a broader range of social
behaviors might be affected. To expand and confirm the results, in Study 2 we
included men as well as women as recipients of flowers. We collected data on the
Duchenne smile and other social indicators such as proximity and initiation of
conversation. We believed it would be difficult to obtain self-reports of any positive
effect of flowers on men in this society when flowers are viewed as very feminine
and are seldom presented to men. In the second study we observed Participants being
handed single flowers or an alternate stimulus in a constrained social situation - an
elevator. The norms for social distance are well established (see Hall, 1966; Sussman
and Rosenfeld, 1982), and this is certainly true of public spaces (Burgess, 1983)
including elevators. Popular knowledge suggests that the most typical behavior for
elevators that are sparsely occupied is for strangers to retreat to opposite corners. We
predicted that the smile would occur more for the flower while social distance would
decrease, and that the behavior of men and women would be comparable.

Method

Participants

Participants were 122 individuals (60 males, 62 females) who entered a
university library elevator alone. Because of the study’s focus on naturalistic
observation, participants were not made aware that they were being observed. Thus,
no age or ethnicity data were obtained; however, the ages of people in a university
library will tend to be towards the early 20s, but not exclusively. In this large East
Coast University, there are representatives of many ethnic groups.

Stimuli

By random assignment, participants were observed in one of four conditions.
(1) In the flower condition, participants received one Gerber Daisy. Gerber or
Transvaal daisies are characterized by bold colors and blooms 4-5" across, although
there is little odor. (2) In the exposure condition, participants were exposed to a
basket of Gerber Daisies, but did not receive anything. (3) In the alternate stimulus
condition, participants were not exposed to flowers, but received a pen with a
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Document Outline

• Evolutionary Psychology
  • ??
    • • • • • Measurement of Positive Emotion
    • Goals of the Studies
    • ??
      • • • • Method
            • Discussion
            • Method
            • Results
      • TSS Scores
        • • • Discussion
            • Method
            • Results
        • Mood Interview
        • ??
          • • Discussion
        • Theoretical Explanations
    • References

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