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JOURNAL OF THERAPEUTIC HORTICULTURE 2017: VOLUME XXVII | ISSUE II1
The Use of Sensory Perception of
Plants in Horticultural Therapy
of Alcohol Addiction
Pétra Berger and Torsten W. Berger
Department of Forest-and Soil Sciences, Institute of Forest Ecology, University of Natural Resources
and Live Sciences (BOKU), Peter Jordan-Straße 82, 1190 Vienna, Austria
*
*Corresponding author: torsten.berger@boku.ac.at
JOURNAL OF THERAPEUTIC HORTICULTURE2017: VOLUME XXVII | ISSUE II 2
Positive emotions initiate upward spirals
toward enhanced emotional well-being.
Cultivation of plants as part of a strategy for
personal change proved to be an effective
rehabilitation tool for persons with alcohol use
disorders (addicted persons). We hypothesized
that only specific plants provoke positive
emotions via touching, seeing, smelling and
tasting, and ranked the sensory perception of
plants by alcohol addicted and healthy persons,
based upon the frequency of associated feelings.
Each participant selected one favored plant
per sensory group and expressed the plant-
induced emotions, desires and memories. A
preferential plant selection was recorded both
for the addicted as well as for the healthy
group. Alcohol addiction affected the selection
of specific plants within each sensory group
significantly. The most frequently selected
plant per sensory group for the addicted- and
healthy persons, respectively, was: sunflower
versus chili pepper (seeing); lavender versus
lemon balm (smelling); sweet basil versus wild
chive (tasting). Both addicted and healthy
persons favored the woolly hedgenettle via
tactile perception. For these plants associated
positive feelings (emotions, desires, memories)
dominated over negative feelings. However,
it is remarkable that the stinging nettle
(touching) and the chrysanthemum (smelling)
were preferentially selected (second rank) by
persons with alcohol use disorders, though
negative feelings dominated over the associated
positive feelings. Revisiting painful memories
via selection of these so-called indicator plants
may help the addicts to learn new, positive
behaviors. Healthy persons related the sensory
perception of the two favored plants with
significantly more positive but less negative
feelings and the number of total answers
(feelings) was significantly higher as well.
The fact that the felt emotions, desires and
memories, provoked by sensory perception of
plants, were not different between addicted and
healthy persons is considered a positive finding
of this study. This indicates that connectedness
to nature has not been disturbed by alcoholism.
Activating these resources in order to trigger
positive emotions is a main goal in horticultural
therapy with addicts. Hence, we conclude that
those plants, which provoke positive feelings,
should be used in therapeutic horticulture.
JOURNAL OF THERAPEUTIC HORTICULTURE 2017: VOLUME XXVII | ISSUE II3
Introduction
Alcohol is legal and widely accepted in society
(Schächtel, 2013). Hence, it can be hard to tell the
difference between casual use and abuse. Alcohol
addiction, also known as alcoholism, is marked by a
craving for alcohol and the inability to stop drinking,
even when it causes extreme personal or social harm
(Dachauer, 2009).
Cognitive behavioral therapy shows that many harmful
actions and emotions are not logical or rational.
These feelings and behaviors may come from past
experiences or environmental factors. When persons
with alcohol use disorders understand why they feel or
act a certain way – and how those feelings and actions
lead to substance use (e.g., alcohol) – they are better
equipped to overcome their action (Addiction Center,
2017). A substance dependence disorder practically
never appears in isolation, but is always associated
with other manifestations of disease, most frequently
with depression and anxiety disorders but also with
personality disorder and with psychoses (Angst &
Cassano, 2006; Scheibenbogen & Feselmayer, 2008). It
is difficult to find out whether a so-called “co-morbid”
disorder is a secondary effect of a primary substance
dependence or whether it was the starting point for the
addiction (Musalek & Scheibenbogen, 2008).
Therapeutic horticulture, the cultivation of plants as part
of a strategy for personal change, has long been seen as
an effective rehabilitation tool (Sandel, 2004). Positive
aspects of gardening have proven to be a significant
benefit to people with difficulties and hardships in
their lives, including those with addictive problems
(Feselmayer et al., 2008). Alcoholics drink alcohol in
order to avoid negative emotions (Knoll, 2014). Hence,
creating well-being may substitute negative emotions
and, as a consequence, substance dependent addiction
(Dachauer, 2009). Cervinka et al. (2016) found that
enjoyment of the garden scored highest as predictor
of perceived restorativeness of private gardens and
satisfaction was the second prominent predictor.
This is in accordance with Fredrickson and Joiner
(2002), stating that positive emotions initiate upward
spirals toward enhanced emotional well-being.
According to this so-called broaden-and-build theory
(Fredrickson, 1998, 2001) “negative emotions narrow
people´s thought-action repertoires (e.g., fight or flight),
positive emotions broaden people´s thought or action”.
For example, enjoyment (see above) “creates the
urge to play; play builds physical, socioemotional, and
intellectual skills, and fuels brain development, and so
on.” In general terms, positive emotions “enlarge” the
cognitive context (Isen, 1987). This effect is probably
linked to increases in brain dopamine (Ashby et al.,
1999).
Nature environments include diverse sensory
stimulations, making them ideal places for working with
body awareness and mindful presence as a means to
restore emotional and physiological capacity (Corazon
et al., 2010; Berman et al., 2008; Tennesen & Cimprich,
1995). While there is a strong emphasis on sensory
perception and “hands-on” learning in the outdoor
environmental education of children, little attention
is placed on cognition through the physical senses at
later stages, though touching, seeing, smelling and
tasting would make them aware their own biological
connections to the environment (Auer, 2008).
We are not aware of any study that has ever tried to rank
sensory perception of plants by persons, based upon
the frequency of associated feelings. As pointed out
above, positive emotions can help facilitate a successful
horticultural therapy session. For that reason it is
important to work with plants that cause positive sensory
perception by persons with alcohol use disorders. We
hypothesized that only specific plants provoke positive
emotions via touching, seeing, smelling and tasting.
Hence, we tested persons with alcohol use disorders
(addicted persons) and healthy persons and asked the
following research questions:
1. Which plants are preferentially selected via the
tactile, visual, olfactory and gustatory senses?
2. Which plants trigger the most positive emotions?
3. Are plant induced emotions different between
alcohol addicted and healthy persons?
4. How can positive and negative sensory
perceptions of plants be used in therapeutic
horticulture?
Methods
Test plants
Four to five plants were selected within each sensory
group for testing the perception of the tactile, visual,
olfactory and gustatory senses. Since the interviews with
the participants were done in October 2016, the time of
the year had an influence on the selection of fresh test
plants, but the main reasons are given below. In general,
JOURNAL OF THERAPEUTIC HORTICULTURE2017: VOLUME XXVII | ISSUE II 4
we tried to choose plants with a high variety of surface
structure, color and forms, smell and taste. All selected
plants (common and scientific names) are listed in
Table 1. Pictures of the plants are given in the
supplementary Figures 1-4 (SFig. 1 to SFig. 4) of the
supplementary materials.
Plants for testing the perception of the tactile sense
(supplementary Figure 1)
Woolly hedgenettle: this species is probably the cuddly
toy of all plants, since its hairy leaves feel comparable
to a bunny.
Fountain grass: the leaves are sharp but the spadix
feels soft and causes a funny tickling.
Stinging nettle: everybody knows the painful burning
of the skin after touching this plant.
Moss: this inviting looking plant feels cuddly, soft and
slender.
Cushion bush: this hardly know plant looks interesting
and feels scratchy; the German name “barbwire” may
cause negative feelings.
Plants for testing the perception of the visual sense
(supplementary Figure 2)
Sunflower: everybody knows this beautiful plant with
its large, circular, shiny yellow bright flower, inevitably
remembering someone of the sun.
Rose: a red flourishing rose stands for love, as know
from many poems.
Cyclamen: this plant was selected, since the intensive
purple may arouse the interest of the participant.
Chili pepper: the gleaming red gives the chili an exotic
and striking appearance.
Ornamental cabbage: this, probably not well known,
cabbage looks very inconspicuous but may just
represent something new.
Plants for testing the perception of the olfactory sense
(supplementary Figure 3)
Lavender: the strong odor of this plant is probably
known by most people.
Chrysanthemum: this plant was chosen because of its
unpleasing smell.
Orange thyme: like other citrus fruits disseminates a
nice scent.
Lemon balm: this well-known plant spreads a very
likeable citrus fragrance.
Plants for testing the perception of the gustatory sense
(supplementary Figure 4)
Sweet basil: most people like the sweet-peppery taste
of this familiar herb.
tactile sense
woolly hedgenettle
Stachys byzantina
fountain grass
Pennisetum alopecuroides
stinging nettle
Urtica dioica
moss
Poytrichum formosum
cushion bush
Calocephalus brownii
visual sense
sunflower
Helianthus annuus
rose
Rosa hybrid
cyclamen
Cyclamen persicum
chili pepper
Capsicum annuum
ornamental cabbage
Brassica oleracea var. acephala
olfactory sense
lavender
Lavandula angustifolia
chrysanthemum
Chrysanthemum indicum
orange thyme
Thymus fragrantissimus
lemon balm
Melissa officinalis
gustatory sense
sweet basil
Ocimum basilicum
wild chive
Allium schoenoprasum
kitchen sage
Salvia officinalis
garden cress
Lepidium sativum
Table 1
Selected plants (common and scientific names) for testing the perception of the tactile, visual, olfactory and gustatory senses.
JOURNAL OF THERAPEUTIC HORTICULTURE 2017: VOLUME XXVII | ISSUE II5
Wild chive: everybody has eaten chive before and
knows its spicy, fresh, hot onion-like taste
Kitchen sage: not everybody knows this herb nor likes
its intensive, camphor-like, spicy flavor.
Garden cress: this common herb tastes a little bit spicy
like mustard or radish.
Participants
Persons with alcohol use disorders were staying at the
Anton Proksch Institute for a residential treatment
program, while we performed the survey at two
afternoons in October 2016. The Anton Proksch
Institute (Vienna, Austria) is one of Europe’s leading
addiction treatment clinics (this institute treats and
studies all forms of addiction, from dependence
on alcohol, prescription drugs and illegal drugs to
non-substance related addictions such as gambling
addiction, internet addiction, shopping addiction and
work addiction). We got the permission to perform
this survey, but we did not receive any personal data of
the participants. Hence, we estimated the age of them
between 30 and 55 years. All 20 persons participated
voluntarily at the survey, however, only 19 questionnaires
(11 male and 8 female participants) could be used for
this study.
The same test plants were used for the survey among
the healthy control group. The so-called healthy persons
comprise 13 friends and relatives which were visited or
invited individually or in small groups in private homes
to fill out the questionnaires within the same week in
October 2016. The age of the healthy control group
was between 19 and 60 years (5 male and 8 female
participants; all questionnaires could be used).
It must be pointed out that people with alcohol use
disorders are frequently called (alcohol) “addicted”
persons and people without alcohol use disorders
“healthy” persons throughout the paper to make it easy
to read.
Survey
The survey at the Anton Proksch Institute was done as
part of two regular group therapy sessions (so-called
experiencing pleasure meetings). Before each session
the test plants were nicely placed at a covered table.
The plants were grouped by the 4 senses to be tested
and labeled (see supplementary Figures 1-4). At the
beginning of each session the first author was introduced
by two permanent employees of the institute and
the purpose of the survey was explained. All alcohol
addicted persons enjoyed participating, and filling out
the questions generated intensive conversations with lots
of good and bad stories and emotions involved. Help for
filling out the questionnaire was provided if asked for.
The survey among the healthy persons was more straight
forward. After a short introduction, the participants
tested their sensory perception of the plants, which were
similarly presented as described above, and filled out the
questionnaire without any support needed.
Measures and data analyses
Each participant filled out a questionnaire. For each of
the tested four perceived senses it was asked,
1) Which plant do you like most (if touched, looked
at, smelled or tasted)? 2) What comes into your mind?
and 3) How do you feel (emotion), what does the plant
remind you of (memory), and what wishes are evoked
by this plant (desire)? Hence, each participant gave only
answers about one plant per sensory group. Finally, each
participant was asked, 4) if he would like to attend a
horticultural therapy.
Because of hygienic and therapeutic reasons it was not
allowed for persons with alcohol use disorders to taste
the plants. Hence, they had to answer questions about
the gustatory perception by means of the retrospective
taste before they started the therapy at the Anton
Proksch Institute. Therefore, related results must be
treated with caution.
We performed a Pearson’s chi-squared test (χ2 test)
to evaluate the null hypothesis that the selection of
a plant is independent of the tactile, visual, olfactory
or gustatory sensory perception within each group of
persons (addicted and healthy persons). Under the
assumption of independence the expected count per
plant would be the number of participants divided by
the number of plants. In case the null hypothesis was
rejected, there was a preferential selection within the
observed group of persons. Similar χ2 tests were done
to test selection differences between male and female
persons per group.
To test the null hypothesis that the selection of a
specific plant or of all plants within one sensory group
is independent of the person’s addiction, additional
χ2 tests were performed. Under the assumption of
independence the expected count per specific plant (df
JOURNAL OF THERAPEUTIC HORTICULTURE2017: VOLUME XXVII | ISSUE II 6
= 2 groups of persons – 1 = 1) and the expected counts
for all plants within one sensory group [df = (2 groups
of persons – 1) x (number of plants within one sensory
group – 1)], respectively, would be the mean frequency,
weighed by the number of participants of the addicted
and healthy groups. In case the null hypothesis was
rejected, there was an impact of alcohol addiction on
the selection of a specific plant and on the general plant
selection within one sensory group, respectively.
It is difficult to put emotions, desires and memories
into numbers and statistics. However, we tried to
differentiate between positive and negative sensory
perceptions. According to question 2 the participants
had to write down all points which came into their mind.
This additional information helped to distinguish: e.g.,
“home” may be associated with positive- (joy about
home) or negative feelings (unfulfilled desire to be
home). The high number of different emotions, desires
and memories of the two most frequently selected
plants per sensory group was reduced by contributing
them to identical categories for addicted and healthy
persons. Finally, we summarized the numbers of answers
(positive vs. negative sensory perception; addicted
vs. healthy persons) and performed similar χ2 tests as
above for testing whether i) addiction had an impact on
the amount of positive or negative feelings and, ii) the
amount of answers is significantly higher for healthy
persons in accordance to the cited broaden-and-build
theory, cited above.
Data calculation (summations, percentage) and
computation of χ2 values were performed in simple
Excel sheets. Results of significance of the performed χ2
tests were obtained by comparison with table values.
Results
Selection of plants
Each participant selected one favored plant per sensory
group. The results of the plant selections by alcohol and
healthy persons via tactile, visual, olfactory and gustatory
perception are listed in the Tables 2 to 5. The questions,
whether there is i) a preferential plant selection within
each group of persons, ii) an impact of addiction on
general plant selection and iii) an impact of addiction on
the selection of a specific plant were answered for each
sense by means of χ2 tests. Similar χ2 tests were done
to test selection differences between male and female
persons per group, however, only in one out of 8 cases
(addicted persons via tactile perception) impact of sex
was significant. For that reason results and discussions
focus on differences between total (men and women)
addicted and healthy groups.
Table 2
Selection of plants by alcohol addicted and healthy persons via tactile perception
plant ------------- addicted ------------- -------------- healthy -------------- ----------------- total -----------------
(tactile group) male female male female addicted healthy impact on
N % N % N % N % % % specific plant
woolly hedgenettle 5 45 0 0 3 60 5 63 26 62 yes(*)
fountain grass 1 9 2 25 1 20 1 13 16 15 no
stinging nettle 1 9 3 38 0 0 0 0 21 0 no
moss 4 36 0 0 1 20 1 13 21 15 no
cushion bush 0 0 3 38 0 0 1 13 16 8 no
sum N / % 11 100 8 100 5 100 8 100 100 100
preferential selection within each group of persons no yes**
impact of addiction on general plant selection no
χ2 tests were performed to answer whether there is i) a preferential plant selection within each group of persons, ii) an impact of
addiction on general plant selection and iii) an impact of addiction on the selection of a specific plant. Significant results are given as:
(*): p < 0.10; *: p < 0.05; **: p < 0.01; ***: p < 0.001.
JOURNAL OF THERAPEUTIC HORTICULTURE 2017: VOLUME XXVII | ISSUE II7
Table 3
Selection of plants by alcohol addicted and healthy persons via visual perception
plant ------------- addicted ------------- -------------- healthy -------------- ----------------- total -----------------
(visual group) male female male female addicted healthy impact on
N % N % N % N % % % specific plant
sunflower 7 64 7 88 1 20 2 25 74 23 yes(*)
rose 1 9 0 0 0 0 1 13 5 8 no
cyclamen 1 9 0 0 1 20 1 13 5 15 no
chili pepper 2 18 1 13 3 60 4 50 16 54 no
ornam. cabbage 0 0 0 0 0 0 0 0 0 0 no
sum N / % 11 100 8 100 5 100 8 100 100 100
preferential selection within each group of persons yes*** yes*
impact of addiction on general plant selection no
χ2 tests were performed to answer whether there is i) a preferential plant selection within each group of persons, ii) an impact of
addiction on general plant selection and iii) an impact of addiction on the selection of a specific plant. Significant results are given as:
(*): p < 0.10; *: p < 0.05; **: p < 0.01; ***: p < 0.001.
Table 4
Selection of plants by alcohol addicted and healthy persons via olfactory perception
plant ------------- addicted ------------- -------------- healthy -------------- ----------------- total -----------------
(olfactory group) male female male female addicted healthy impact on
N % N % N % N % % % specific plant
lavender 6 55 6 75 1 20 1 13 63 15 yes*
chrysanthemum 2 18 1 13 0 0 0 0 16 0 no
orange thyme 1 9 0 0 0 0 1 13 5 8 no
lemon balm 2 18 1 13 4 80 6 75 16 77 yes*
sum N / % 11 100 8 100 5 100 8 100 100 100
preferential selection within each group of persons yes** yes***
impact of addiction on general plant selection yes*
χ2 tests were performed to answer whether there is i) a preferential plant selection within each group of persons, ii) an impact of
addiction on general plant selection and iii) an impact of addiction on the selection of a specific plant. Significant results are given as:
(*): p < 0.10; *: p < 0.05; **: p < 0.01; ***: p < 0.001.
JOURNAL OF THERAPEUTIC HORTICULTURE2017: VOLUME XXVII | ISSUE II 8
Tactile sense
Within the alcohol addicted group, men preferred the
wooly hedgenettle (45%) and the moss (36%), while
women liked the stinging nettle (38%) and the cushion
bush (38%) most (Table 2). Because of this significant
difference (χ2 test, p < 0.05) between male and female
persons, there was no preferential selection of plants
within the total addicted group. The wooly hedgenettle
was selected by 62% of the healthy persons, indicating a
clear selection preference (p < 0.01), but there were no
differences between male and female persons. Not any
single healthy person preferred the stinging nettle. The
general plant selection was not affected by the addiction,
however, the wolly hedgenettle was favored (p < 0.10) by
the healthy group.
Visual sense
The addicted persons preferred the sunflower (74%),
while the healthy persons favored the chilli pepper
(54%; Table 3). The same plants ranked on the second
place, but vice versa (chili pepper, addicted persons:
16%; sunflower, healthy persons: 23%). While each
group showed a significant (addicted: p < 0.001; healthy:
p < 0.01) selection pattern, there was no impact of the
addiction on the general plant selection. However, the
addiction had an impact, when specifically looked at the
choice of the sunflower (p < 0.10). Visually, nobody was
attracted by the inconspicuous look of the ornamental
cabbage.
Olfactory sense
There was a clear (p < 0.01) preferential selection
among the addicted persons: lavender (63%),
chrysanthemum (16%) and lemon balm (16%; Table 4).
The healthy group showed an even higher preference
(p < 0.001) towards lemon balm (77%) and lavender
(15%). The addiction had an impact (p < 0.05) on the
general plant selection, because of significant (p < 0.05)
impacts on the specific plants lavender and lemon balm.
Not any healthy person was attracted by the unpleasing
smell of the chrysanthemum.
Gustatory sense
Though the alcoholics had to answer questions about the
gustatory perception by means of the retrospective taste,
the results showed a significant (p < 0.05) preference:
sweet basil (53%), followed by wild chive
(32%; Table 5). The healthy persons favored wild chive
(69%) and garden cress (15%), causing a clear (p < 0.01)
selection preference as well. Obviously (p < 0.10), the
alcohol addiction had an impact on the general plant
selection, based upon the individual impacts on sweet
basil (p < 0.05) and wild chive (p < 0.10).
Plant induced emotions, desires and memories
We tried to differentiate between positive and negative
sensory perceptions as described in the methods section.
Thereafter, the diversity of different emotions, desires
and memories of the two most frequently selected plants
Table 5
Selection of plants by alcohol addicted and healthy persons via gustatory perception
plant ------------- addicted ------------- -------------- healthy -------------- ----------------- total -----------------
(gustatory group) male female male female addicted healthy impact on
N % N % N % N % % % specific plant
sweet basil 6 55 4 50 1 20 0 0 53 8 yes*
wild chive 4 36 2 25 3 60 6 75 32 69 yes(*)
kitchen sage 0 0 1 13 0 0 1 13 5 8 no
garden cress 1 9 1 13 1 20 1 13 11 15 no
sum N / % 11 100 8 100 5 100 8 100 100 100
preferential selection within each group of persons yes* yes**
impact of addiction on general plant selection yes(*)
χ2 tests were performed to answer whether there is i) a preferential plant selection within each group of persons, ii) an impact of
addiction on general plant selection and iii) an impact of addiction on the selection of a specific plant. Significant results are given as:
(*): p < 0.10; *: p < 0.05; **: p < 0.01; ***: p < 0.001.
JOURNAL OF THERAPEUTIC HORTICULTURE 2017: VOLUME XXVII | ISSUE II9
per sensory group were categorized and the numbers of
answers per category were summarized. The results of
the attempt to put feelings into numbers and statistics
are plotted in Figure 1 (addicted persons) and Figure 2
(healthy persons).
Persons with alcohol use disorders
Positive sensory perception of the addicted persons
(Figure 1) were often related to a nice vacation,
summer feelings, good meals and situations, when they
were laughing, feeling happy, enthusiastic and full of
energy; they thought about hiking in nature, forests and
gardens. Negative sensory perception was connected
to unfulfilled desires to be home (with friends), to
sleep in the own bed and to cook the own meal (note
that the addicted persons were staying at a residential
treatment). In addition, bad memories of childhood,
reminder of better times, sorrow and desire for summer
are listed on the negative side of Figure 1.
Based upon the interviews of 19 alcohol addicted
persons 104 answers (feelings) were recorded and most
of them (72) were connected to positive emotions,
desires and memories (Figure 1). However, almost one
third (32) of the feelings were negative, though these
feelings were related to sensory perception of the two
most favored plants. It is striking that the stinging nettle
(touching) and the chrysanthemum (smelling) were
preferentially selected (second rank), though negative
feelings dominated over the associated positive feelings.
Figure 1. Felt positive and negative emotions, desires and memories provoked by sensory perception (touching,
seeing, smelling, tasting) of the two most frequently selected plants per sensory group among 19 alcohol
addicted persons. Similar feelings were grouped into categories, and answers per category were counted.
JOURNAL OF THERAPEUTIC HORTICULTURE2017: VOLUME XXVII | ISSUE II 10
Persons without alcohol use disorders
Comparing Figure 2 (healthy persons) with Figure 1
(addicted persons), it is remarkable that the number
of total answers (feelings) amounted 125 and was
significantly higher (p < 0.001), taking into consideration
that only 13 healthy persons were interviewed. Healthy
persons related the sensory perception of the two
favored plants with significantly (p < 0.01) more positive
(118) but less negative (7) feelings.
In most cases, it was possible to put the felt emotions,
desires and memories into the same categories,
indicating a similar sensory perception of plants by
addicted and healthy persons (Figure 2). However,
the categories “home-family-friends”, “childhood” and
the “wish to take the favored plant home” had to be
added on the positive side of Figure 2 for the healthy
persons. In a few cases, new unfulfilled desires had to be
complemented on the negative side. In general, healthy
persons did not select a plant, which was dominated by
associated negative feelings.
Figure 2. Felt positive and negative emotions, desires and memories provoked by sensory perception
(touching, seeing, smelling, tasting) of the two most frequently selected plants per sensory group among
13 healthy persons. Similar feelings were grouped into the same categories as set up for the alcohol addicted
persons (see Figure 1), and answers per category were counted. Feelings, which were not reported by the
addicted persons, are given in bold letters.
JOURNAL OF THERAPEUTIC HORTICULTURE 2017: VOLUME XXVII | ISSUE II11
Discussion
Question 1) Which plants are preferentially selected via
the tactile, visual, olfactory and gustatory senses?
A preferential plant selection via the visual, olfactory and
gustatory perception was recorded both for the alcohol
addicted as well as for the healthy group. Tactile plant
perception caused a rejection of the null hypothesis
(expected counts per plant equal the number of
participants divided by the number of plants per sensory
group) only for the healthy group but not for the total
addicted group. In the latter case, there was a significant
difference between male and female addicted persons,
cancelling out selection preferences of the total (men
and women) group. In all other cases, sex did not affect
preferential plant selection.
Alcohol addiction affected the selection of specific
plants within each sensory group (touching, seeing,
smelling, tasting) significantly. The most frequently
selected plant per sensory group for the addicted- and
healthy persons, respectively, was: sunflower versus chili
pepper (seeing); lavender versus lemon balm (smelling);
sweet basil versus wild chive (tasting). Both addicted
and healthy persons favored the woolly hedgenettle via
tactile perception. However, the stinging nettle seemed
to be a good separation indicator via touching, which was
the second choice among the addicted group but not
selected at all among the healthy group.
We are not aware of any study that has ever tried to
rank sensory perception of plants by persons, not to
mention by alcohol addicted and healthy persons. We
suggest (see below) that the recorded preferential plant
selection and the impact of alcohol addiction on this
selection were driven by provoked emotions, desires and
memories via touching, seeing, smelling and tasting.
Question 2) Which plants trigger the most positive
emotions?
As stated above, addicted and healthy persons selected
different plants at the first rank via the visual, olfactory
and gustatory sense, but the same plant via the tactile
sense. In all these cases, associated positive feelings
(emotions, desires, memories) dominated over negative
feelings. These results support our hypothesis (see
introduction), that only specific plants provoke positive
emotions via touching, seeing, smelling and tasting.
In general, healthy persons did not select a plant, which
was dominated by associated negative feelings. However,
it is remarkable that the stinging nettle (touching) and
the chrysanthemum (smelling) were preferentially
selected (second rank) by addicted persons, though
negative feelings dominated over the associated positive
feelings. These species are considered indicator plants
for separating the selection preference of addicted and
healthy persons (that is why, these plants were included
in Figure 1, though moss and lemon balm ranked
similarly with stinging nettle and chrysanthemum,
respectively). We assume that the healthy persons
sensed the same negative feelings and, as a consequence,
nobody of them selected these plants (Tables 2 and 4).
Question 3) Are plant induced emotions different
between alcohol addicted and healthy persons?
Our results justify the conclusion that sensory
perception of plants induced similar emotions, desires
and memories for alcohol addicted and healthy persons
(see Figures 1 and 2). However, the selection procedure
of addicted persons partly focused on negative feelings,
while healthy persons avoided negative feelings.
This may be seen as an indication that a substance
dependence disorder is frequently associated with
depression and anxiety (Angst & Cassano, 2006;
Scheibenbogen & Feselmayer, 2008). In addition,
sensory perception of the favored plant provoked much
more (positive) feelings among the healthy group. This
is in accordance to the so-called broaden-and-build
theory by Fredrickson (1998, 2001), stating that positive
emotions broaden people´s thought and enlarge the
cognitive context.
Our results are in accordance with Schächtel (2013),
who could prove that alcohol addicted and healthy
persons reflected similar emotional experiences, when
presented with 60 realistic situations they had to
empathize with and assign the corresponding feeling
thereto (sensory perception of plants was not part of
her study). However, she challenged the perception and
reflection of the emotional states of alcohol addicted
patients due to the alcohol related depressant effect,
matching with significantly lower overall emotional
experiences but relatively higher negative perceptions
of our study. In accordance to the broaden-and-build
theory (see above) negative emotions narrow people´s
thought-action repertoires.
At this point it is worthwhile to mention that each
participant was asked to answer question 4 of the
questionnaire, if he would like to attend a horticultural
therapy (see methods section). Significantly (χ2 tests;
p < 0.10) more healthy persons (75%) were interested in
JOURNAL OF THERAPEUTIC HORTICULTURE2017: VOLUME XXVII | ISSUE II 12
this kind of therapy than addicted persons (63%), though
there seemed to be no need for it. This result underlines
that positive emotions simply broaden people´s action.
The fact that the felt emotions, desires and memories,
provoked by sensory perception of plants, were not
different between addicted and healthy persons is
considered a very positive result of this study. This
means that connectedness to nature has not been
disturbed by alcoholism. According to Nestmann
(1996) these feelings represent important resources,
e.i., everything what is appreciated and helpful for a
person in a specific situation. Activating these resources
in order to trigger positive emotions is a main goal in
horticultural therapy of addicts.
Question 4) How can positive and negative sensory
perceptions of plants be used in therapeutic horticulture?
Positive emotions initiate upward spirals toward
enhanced emotional well-being (Fredrickson 1998,
2001) and enjoyment of the garden scored highest as
predictor of perceived restorativeness (Cervinka et al.,
2016). Hence, we conclude that those plants, which
provoked positive feelings should be used in therapeutic
horticulture. Cultivation of plants as part of a strategy for
personal change proved to be an effective rehabilitation
tool for people with alcohol use disorders (Feselmayer et
al., 2008), which may be raised, if addicted persons are
allowed to work with plants they like most. All plants,
preferentially (first rank) selected via sensory perception
by alcoholics, triggered the most positive emotions in
this study. Creating well-being may substitute negative
emotions and, as a consequence, substance dependent
addiction.
On the other hand, a major part of the alcoholics (in
contrast to healthy persons) preferred plants, like the
stinging nettle and the chrysanthemum which induced
more negative than positive feelings. This fact seemed
to be in contrast to Knoll (2014), stating that alcoholics
drink alcohol in order to avoid negative emotions.
We postulate that these plants may help to identify
their negative “automatic thoughts”. An automatic
thought is based on impulse and often comes from
misconceptions and internalized feelings of self-doubt
and fear (Addiction Center, 2017). Instead of trying to
self-medicate these painful thoughts and feelings by
drinking, a part of the alcoholic participants obviously
tried to revisit painful memories via selection of these
so-called indicator plants. This is exactly the way, how
cognitive behavioral therapy works: the addicts can learn
new, positive behaviors by continually revisiting these
painful emotions, desires and memories. For example,
negative feelings related to home, family, childhood,
friends, freedom were listed on the negative side of
Figure 1 (addicted persons) and hopefully will switch
eventually on the positive side as listed in Figure 2
(healthy persons).
Conclusions
We ranked sensory perception (touching, seeing,
smelling, tasting) of plants by persons with alcohol use
disorders (addicted persons) and healthy persons, based
upon the frequency of associated feelings. A preferential
plant selection was recorded both for the addicted as
well as for the healthy group. Alcohol addiction affected
the selection of specific plants within each sensory
group significantly. For the most frequently selected
plants associated positive feelings (emotions, desires,
memories) dominated over negative feelings. However,
it is remarkable that the stinging nettle (touching) and
the chrysanthemum (smelling) were preferentially
selected (second rank) by a part of the addicted
persons, though negative feelings dominated over the
associated positive feelings. We postulate that these
plants may help to identify their negative “automatic
thoughts”. Revisiting painful memories via selection
of these so-called indicator plants may help addicts to
learn new, positive behaviors in certain cases. The fact
that the felt emotions, desires and memories, provoked
by sensory perception of plants, were not different
between addicted and healthy persons is considered
a very positive result of this study. This means that
connectedness to nature has not been disturbed by
alcoholism. Activating these resources in order to trigger
positive emotions is a main goal in horticultural therapy
of addicts. Hence, on the other hand, we conclude that
primarily those plants, which provoked positive feelings,
should be used in therapeutic horticulture.
We recommend to repeat similar studies with two
test groups of persons with- and without alcohol use
disorders, which are more similar in regard to age
and sex with higher subject numbers. The gustatory
perception of alcohol addicted person should rely on
the actual taste instead on the retrospective taste before
they started the therapy, as had to be done in this study.
Finally, sensory perception of additional plant species
should be tested.
JOURNAL OF THERAPEUTIC HORTICULTURE 2017: VOLUME XXVII | ISSUE II13
ACKNOWLEDGEMENTS
We thank all participants of this study. Oliver
Scheibenbogen granted the permission to perform part
of this research at the Anton Proksch Institute (Vienna,
Austria). We thank Selina Franzke and Margret Kuderer
for mentoring the first author during the survey as part
of two regular group therapy sessions at the Anton
Proksch Institute. This research did not receive any
specific grant from funding agencies in the public,
commercial, or not-for-profit sectors.
JOURNAL OF THERAPEUTIC HORTICULTURE2017: VOLUME XXVII | ISSUE II 14
SFig. 1. Plants for testing the perception of the tactile sense
SFig. 2. Plants for testing the perception of the visual sense
Supplementary Material
woolly hedgenettle
sunflower
fountain grass
rose
moss
chili pepper cushion bush
ornamental
cabbage
stinging nettle
cyclamen
JOURNAL OF THERAPEUTIC HORTICULTURE 2017: VOLUME XXVII | ISSUE II15
SFig. 3. Plants for testing the perception of the olfactory sense
SFig. 4. Plants for testing the perception of the gustatory sense
lavender
garden cress
chrysanthemum
kitchen sage
orange thyme
wild chive
lemon balm
sweet basil
JOURNAL OF THERAPEUTIC HORTICULTURE2017: VOLUME XXVII | ISSUE II 16
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JOURNAL OF THERAPEUTIC HORTICULTURE 2017: VOLUME XXVII | ISSUE II17
BIOGRAPHY
Pétra Berger is a trained flower gardener. Presently,
she is a research assistant at the Institute of Forest
Ecology (University of Natural Resources and Live
Sciences, Vienna). In June 2017, she received a degree
in Horticultural Therapy in Austria.
Torsten W. Berger is professor at the Institute of
Forest Ecology, University of Natural Resources and
Live Sciences (BOKU), Vienna. His research interests
are: deposition of atmospheric constituents and its
impact on nutrient budgets of forest ecosystems,
biogeochemistry, forest nutrition, chemical
manipulations of forest ecosystems for evaluating human
environmental impacts and plant-soil feedback. Hence,
therapeutic horticulture is a very new interest of him.
He got fascinated by this topic, while supporting his
wife Pétra, working on her final thesis for her degree in
Horticultural Therapy.
