Behavioural Processes,
10 (1985)
111
11 I-121
Elsevier
THE CCLE OF F!Ei FLAVORS KLAUS SCHNEIDER Psychology
and
Dept.,
3550 Marburg
IN THE AQUISITIOn
FRANK
OF ODOR AVERSIOP!*
LOEBELL
Fhilipps-Universitst
Marburg,
Gutenbergstr.
18,
(West-Fermany)
(Accepted 26 January
i?84)
ABSTRACT Schneider, K. and Loebell, F., 1985. The role of new flavors acquisition of odor aversion. Behav. Proc. 10: 111-121.
in the
In two experiments rats received either an odor together with a flavor (experiment I) or with tap water (experiment II) prior to lithium chloride-induced illness. The rats were then tested for the aversion of tap water in compound with the illness-paired odor offered together with an alternative new odor not paired with toxicosis. The two-odor-box-choice tests revealed that rats easily acquire an odor aversion even when the odor is not presented in a simultaneous compound with a new flavor and reject the drinking box, where the conditioned odor is presented, purely on the basis of that odor. Food Aversion
Learning,
Taste Aversion,
Odor Aversion,
Odor Fotentiation.
Acknowledgements We would like to thank M. Boes, J. Hupfeld, A. Foost and K.P.Wild for assisting in collecting the data and Stada Arzneimittel A.G., Bad Vilbel, Y.-fermany for the provision of cocoa extract and Haarmann & Reimer CmbH, Holzminden, W.-Germany for the provision of apricot and almond extracts. This research was supported in part by a grant from the ?equests for reprints should be send to geutsche Forschungsoemeinschaft, Klaus Schneider, Fachbereich Fsychologie, Philipps-UniversitXt, Gutenbergstr. 18, 3551: Yarburg (West-Germany)
0376-6357/85/$03.30 0 1985 Elsevier
Science
Publishers
B.V.
112
INTRODUCTIOPI Animals will avoid ingested The most important
novel food which
sense modality
is followed
in this kind of Pavlovian
seems to be taste. In rats, even odor, when presented of a new taste, is not readily associated Garcia & Rusiniak, presented
with non-gustatory
as well.
1979; Schneider,
In food aversion conditioning
by toxicosis
aversion
learning
(Mackintosh,
Rats, for example,
(Rusiniak,
unlike other paradigms
Hankins,
together
Garcia &
of Pavlovian
1971), the effect of a weaker
but "potentiated"
(Palmerino,
& Garcia,
Rusiniak
are becomes
1979).
is often not blocked
Gut-lath & Rescorla
(Hankins,
of other modalities
illness with a new odor when this odor is presented
with a new taste followed Brett,
with internal malaise
if stimuli
stimuli
conditioning
in the absence
together with the new taste, the conditioned
associated associate
1973). However,
by illness.
by the stronger
1980; Rusiniak
(1980) found evidence
the effect of an odor stimulus
odor stimulus taste stimulus
et al. 1979).
that this potentiation
is mediated
by sensory
of
preconditioning.
113
In our own previous study (Schneider, were offered solution)
and poisoned
saccharin
solution
No avoidance
either after 5 min or after
was observed
produce
in the control
of a saccharin
an avoidance
accompanied
solution.
after the ingestion
by a casein odor
some evidence
saccharin
aversion
solution
presented
test.
with intoxication
of illness following a casein
odor did not
In the latter condition of a saccharin
solution
not
of a casein
test, however, we found in subsequent
for a taste generalization
to a casein taste
Note 1). Such taste generalizations of food aversion trials
1 hr, avoided the
for the avoidance
and tested
(0.5%
subsequently.
Using the same one-bottle studies
without
taste
avoidance
condition
the experience
solution
of a casein
animals were poisoned
solution
odor in a one-bottle
after 20 hr. Moreover,
the consumption
with a saccharin
as well as a 2.5% casein hydrolysate
together with its specific
following
1979), we found that rats which
a casein odor in combination
(Domjan,
The present aversion
learning
investigation
presented
conditioning
to examine whether
conditioning
is associated
here for an odor choice.
by the consumption
by other students
1982).
at all. A two-bottle-two-drinking-box
the two studies was tested
Loebell & Weinrebe,
only after several
was designed
compound
from a conditioned
have been observed
- however,
1975; Parker & Revusky,
in taste-odor
odor stimulus
(Schneider,
of tap water
conditioned
with the
test was used in Odor avoidance
presented
in compound
with
the odor.
EXPERIMENT
I
In Experiment saccharin
solution
box attached of extinction identical
I, animals were made sick after exposure in compound
with a casein odor in a small drinking
to the back wall of the conditioning
chamber.
trials animals were provided with tap water
boxes attached
to a
10 cm apart to the back wall,
In a series in two
in which the
target odor (casein) and one other new odor were presented. aversion
was assessed
by the amount of tap water consumed
box with the target odor, in relation
In addition,
the approach
The
from the
to the total amount consumed.
of the animals
to the drinking
boxes was
114
detected
by two photobeams.
In a former study
& Loebell,
Note 2) we had observed
taste-odor
compound
the drinking
Weinrebe,
that rats after conditioning
to a
remain on testing days with their snouts near
spout without
allow examination
(Schneider,
drinking.
The arrangement
of how often animals
should therefore
sample an odor without
consuming
fluid.
Method
Subjects weighing weight
and apparatus.
Twenty naive, male albino
rats (Wistar),
between 310 and 500 g at the start of the experiment
406 g) were used. They were kept individually
and maintained
on dry laboratory
(mean
in plastic cages
food ad lib. Lights went on at 2.00 a.m
and off at 2.00 p.m. All training
and testing was done in the early
dark phase from 2.00 to 7.00 p.m.
A conditioning
chamber
used for training, were inserted
(80 by 30 by 30 cm) made from plywood was
conditioning
through 7.5 by 7.5 cm windows
wall of the conditioning sides of the midline exactly
and testing.
chamber
spout. One infrared parallel
photobeam
spout. The interruptions
with a micro-computer
The drinking
was situated
to lick
behind
were counted
by an exhaust
fan to the
via a 2 cm plastic tube inserted air was delivered
to polyethylene
via a copper
in the top
tube (6 mm)
tubing. The metal tube was arranged
semi circle below the drinking center of the semi circle). (diameter
photobeam
a round 3.7 cm chamber
just 2 mm in front of the
of both photobeams
boxes were ventilated
of the boxes. Odorized
26 holes
box through
(AIM 65/40).
of the building
connected
steel spout protruded
6 cm above the floor of the conditioning
from the drinking
outside
or one box
box from the back wall. Animals
had to thrust their heads into the drinking
the hole, a second
at both
boxes were made from transparent
8 mm into the center of the drinking
drinking
of the 80 cm long back
(10 cm apart from the midline)
(7.5 by 7.5 by 5 cm). A stainless
hole centered
boxes
4 cm above the floor either
at the midline.. The drinking
Plexiglas
The drinking
spout
Odorized
.5 mm), directed
(the drinking air streamed
in a
spout being in the at 1 l/min from
to the top of the drinking
box.
115
Procedure.
The animals were trained
in a 15 min drinking
period
5 days of the training
from a drinking
cap, which
from one drinking
room air (1 l/min) was delivered
solution
air was produced solution
in compound
by pumping dried and cleaned
group
matched
Acquisition
was followed
of the conditioning
extinction
trials
and changed
in the
box, and a different
new odor
from day to day for each animal.
odors were on day 15 an apple juice odor (150 ml
apple juice), solution)
on day 16 an apricot
odor
(a 2% (v/v)
and on day 17 a cocoa odor (a 5% (v/v) cocoa
One week after the last test, the animals were again placed
for two days on a 23 3/4-hr water deprivation on the third day for the aversion the apricot the odorized
shedule,
air was changed
after 3 trials).
and then tested
of the target odor compared with
odor used on day 16. The liquid odorant
apple juice after two trials, solutions
animals were
box, located
of the target odor was counterbalanced
apricot
solution).
days in which
5 min.
after 14 hr.
the target odor (almond) was present
of a commercial extract
within
and then by a series of 4
in one drinking
in the other. The position
The alternative
In the
the same treatment
in one drinking
chamber,
in which
with tap water
over animals
an
and delivered
to two groups.
2% of body weight),
received
by two recovery
again with tap water
together
room air through
box.
by weight,
of LiCl (.I5 M solution, group (CG) animals
middle
access to .05% (w/v)
(EG) animals were made sick by an intraperitoneal
The control
provided
to the
(150 ml of a .I% (v/v) extract solution)
Rats were assigned,
injection
chamber
with an almond odor. Odorized
the metal tube in the drinking
experimental
(4 cm) as the hole of
in a 15 min period in the conditioning
box. On day 12 animals were allowed
sodium saccharin
through
from the center of a metal
the same diameter
box located at the center of the back wall.
In these days purified
almond
for 15 min
On days 3 to 5 water was
box used later. From day 6 to 11 animals were trained
to drink their water
drinking
room.
spout protruding
had approximately
the drinking
colony
ration
for 11 days. On the first
period they were provided with water
in their home cages in the animal available
to drink their daily water
in the afternoon
regulary
used to produce
(almond solution
and the apricot
after 6 trials,
and cocoa extract
116
Results and Discussion
On the conditioning saccharin
solution
trial animals
drank on average
less of the new taste fluid presented they had consumed
chamber
and control
last three training
A preference preference
together with a new odor than
animals
on the acquisition
score was calculated
animals
between
trial and on the
days.
for each postconditioning
test. The amount of fluid taken from the drinking
the target stimulus
period
(14.5 ml). There were no differences
(almond) was presented
was divided
amount of fluid taken from both boxes. Figure experimental
consumed
tap water on the last 3 days of the training
in the conditioning experimental
11.3 ml of the
in compound with an almond odor. Animals
almost completely
target odor was presented, both boxes. This remained
whereas
1 reveals
avoided
control
true in the retention
by the total that
the box where
animals
odorbox where
the
sampled water
from
test after one week.
E z
W
a
W IL
w
E El
E2 DAYS
E3
Er,
Fig. 1. Average preference ratios for the consumption of water from the box where the target odor previously paired with illness was presented in a two-odor-box choice test for 3 consecutive extinction days and on a retention test after one week (E4). In the second box a new alternative odor not associated with poisoning was presented on each extinction day. Experimental animals (EG) were poisoned within 5 min after a I5-min exposure to a saccharin-taste, casein-odor compound, control animals (CG) after 14 hr.
117
These impressions between
groups
(Nann-Whitney E4: U=16.5,
were confirmed
by statistical
EG and CG were significant U Test
(Z-tailed),
p
10 (1985)
111
11 I-121
Elsevier
THE CCLE OF F!Ei FLAVORS KLAUS SCHNEIDER Psychology
and
Dept.,
3550 Marburg
IN THE AQUISITIOn
FRANK
OF ODOR AVERSIOP!*
LOEBELL
Fhilipps-Universitst
Marburg,
Gutenbergstr.
18,
(West-Fermany)
(Accepted 26 January
i?84)
ABSTRACT Schneider, K. and Loebell, F., 1985. The role of new flavors acquisition of odor aversion. Behav. Proc. 10: 111-121.
in the
In two experiments rats received either an odor together with a flavor (experiment I) or with tap water (experiment II) prior to lithium chloride-induced illness. The rats were then tested for the aversion of tap water in compound with the illness-paired odor offered together with an alternative new odor not paired with toxicosis. The two-odor-box-choice tests revealed that rats easily acquire an odor aversion even when the odor is not presented in a simultaneous compound with a new flavor and reject the drinking box, where the conditioned odor is presented, purely on the basis of that odor. Food Aversion
Learning,
Taste Aversion,
Odor Aversion,
Odor Fotentiation.
Acknowledgements We would like to thank M. Boes, J. Hupfeld, A. Foost and K.P.Wild for assisting in collecting the data and Stada Arzneimittel A.G., Bad Vilbel, Y.-fermany for the provision of cocoa extract and Haarmann & Reimer CmbH, Holzminden, W.-Germany for the provision of apricot and almond extracts. This research was supported in part by a grant from the ?equests for reprints should be send to geutsche Forschungsoemeinschaft, Klaus Schneider, Fachbereich Fsychologie, Philipps-UniversitXt, Gutenbergstr. 18, 3551: Yarburg (West-Germany)
0376-6357/85/$03.30 0 1985 Elsevier
Science
Publishers
B.V.
112
INTRODUCTIOPI Animals will avoid ingested The most important
novel food which
sense modality
is followed
in this kind of Pavlovian
seems to be taste. In rats, even odor, when presented of a new taste, is not readily associated Garcia & Rusiniak, presented
with non-gustatory
as well.
1979; Schneider,
In food aversion conditioning
by toxicosis
aversion
learning
(Mackintosh,
Rats, for example,
(Rusiniak,
unlike other paradigms
Hankins,
together
Garcia &
of Pavlovian
1971), the effect of a weaker
but "potentiated"
(Palmerino,
& Garcia,
Rusiniak
are becomes
1979).
is often not blocked
Gut-lath & Rescorla
(Hankins,
of other modalities
illness with a new odor when this odor is presented
with a new taste followed Brett,
with internal malaise
if stimuli
stimuli
conditioning
in the absence
together with the new taste, the conditioned
associated associate
1973). However,
by illness.
by the stronger
1980; Rusiniak
(1980) found evidence
the effect of an odor stimulus
odor stimulus taste stimulus
et al. 1979).
that this potentiation
is mediated
by sensory
of
preconditioning.
113
In our own previous study (Schneider, were offered solution)
and poisoned
saccharin
solution
No avoidance
either after 5 min or after
was observed
produce
in the control
of a saccharin
an avoidance
accompanied
solution.
after the ingestion
by a casein odor
some evidence
saccharin
aversion
solution
presented
test.
with intoxication
of illness following a casein
odor did not
In the latter condition of a saccharin
solution
not
of a casein
test, however, we found in subsequent
for a taste generalization
to a casein taste
Note 1). Such taste generalizations of food aversion trials
1 hr, avoided the
for the avoidance
and tested
(0.5%
subsequently.
Using the same one-bottle studies
without
taste
avoidance
condition
the experience
solution
of a casein
animals were poisoned
solution
odor in a one-bottle
after 20 hr. Moreover,
the consumption
with a saccharin
as well as a 2.5% casein hydrolysate
together with its specific
following
1979), we found that rats which
a casein odor in combination
(Domjan,
The present aversion
learning
investigation
presented
conditioning
to examine whether
conditioning
is associated
here for an odor choice.
by the consumption
by other students
1982).
at all. A two-bottle-two-drinking-box
the two studies was tested
Loebell & Weinrebe,
only after several
was designed
compound
from a conditioned
have been observed
- however,
1975; Parker & Revusky,
in taste-odor
odor stimulus
(Schneider,
of tap water
conditioned
with the
test was used in Odor avoidance
presented
in compound
with
the odor.
EXPERIMENT
I
In Experiment saccharin
solution
box attached of extinction identical
I, animals were made sick after exposure in compound
with a casein odor in a small drinking
to the back wall of the conditioning
chamber.
trials animals were provided with tap water
boxes attached
to a
10 cm apart to the back wall,
In a series in two
in which the
target odor (casein) and one other new odor were presented. aversion
was assessed
by the amount of tap water consumed
box with the target odor, in relation
In addition,
the approach
The
from the
to the total amount consumed.
of the animals
to the drinking
boxes was
114
detected
by two photobeams.
In a former study
& Loebell,
Note 2) we had observed
taste-odor
compound
the drinking
Weinrebe,
that rats after conditioning
to a
remain on testing days with their snouts near
spout without
allow examination
(Schneider,
drinking.
The arrangement
of how often animals
should therefore
sample an odor without
consuming
fluid.
Method
Subjects weighing weight
and apparatus.
Twenty naive, male albino
rats (Wistar),
between 310 and 500 g at the start of the experiment
406 g) were used. They were kept individually
and maintained
on dry laboratory
(mean
in plastic cages
food ad lib. Lights went on at 2.00 a.m
and off at 2.00 p.m. All training
and testing was done in the early
dark phase from 2.00 to 7.00 p.m.
A conditioning
chamber
used for training, were inserted
(80 by 30 by 30 cm) made from plywood was
conditioning
through 7.5 by 7.5 cm windows
wall of the conditioning sides of the midline exactly
and testing.
chamber
spout. One infrared parallel
photobeam
spout. The interruptions
with a micro-computer
The drinking
was situated
to lick
behind
were counted
by an exhaust
fan to the
via a 2 cm plastic tube inserted air was delivered
to polyethylene
via a copper
in the top
tube (6 mm)
tubing. The metal tube was arranged
semi circle below the drinking center of the semi circle). (diameter
photobeam
a round 3.7 cm chamber
just 2 mm in front of the
of both photobeams
boxes were ventilated
of the boxes. Odorized
26 holes
box through
(AIM 65/40).
of the building
connected
steel spout protruded
6 cm above the floor of the conditioning
from the drinking
outside
or one box
box from the back wall. Animals
had to thrust their heads into the drinking
the hole, a second
at both
boxes were made from transparent
8 mm into the center of the drinking
drinking
of the 80 cm long back
(10 cm apart from the midline)
(7.5 by 7.5 by 5 cm). A stainless
hole centered
boxes
4 cm above the floor either
at the midline.. The drinking
Plexiglas
The drinking
spout
Odorized
.5 mm), directed
(the drinking air streamed
in a
spout being in the at 1 l/min from
to the top of the drinking
box.
115
Procedure.
The animals were trained
in a 15 min drinking
period
5 days of the training
from a drinking
cap, which
from one drinking
room air (1 l/min) was delivered
solution
air was produced solution
in compound
by pumping dried and cleaned
group
matched
Acquisition
was followed
of the conditioning
extinction
trials
and changed
in the
box, and a different
new odor
from day to day for each animal.
odors were on day 15 an apple juice odor (150 ml
apple juice), solution)
on day 16 an apricot
odor
(a 2% (v/v)
and on day 17 a cocoa odor (a 5% (v/v) cocoa
One week after the last test, the animals were again placed
for two days on a 23 3/4-hr water deprivation on the third day for the aversion the apricot the odorized
shedule,
air was changed
after 3 trials).
and then tested
of the target odor compared with
odor used on day 16. The liquid odorant
apple juice after two trials, solutions
animals were
box, located
of the target odor was counterbalanced
apricot
solution).
days in which
5 min.
after 14 hr.
the target odor (almond) was present
of a commercial extract
within
and then by a series of 4
in one drinking
in the other. The position
The alternative
In the
the same treatment
in one drinking
chamber,
in which
with tap water
over animals
an
and delivered
to two groups.
2% of body weight),
received
by two recovery
again with tap water
together
room air through
box.
by weight,
of LiCl (.I5 M solution, group (CG) animals
middle
access to .05% (w/v)
(EG) animals were made sick by an intraperitoneal
The control
provided
to the
(150 ml of a .I% (v/v) extract solution)
Rats were assigned,
injection
chamber
with an almond odor. Odorized
the metal tube in the drinking
experimental
(4 cm) as the hole of
in a 15 min period in the conditioning
box. On day 12 animals were allowed
sodium saccharin
through
from the center of a metal
the same diameter
box located at the center of the back wall.
In these days purified
almond
for 15 min
On days 3 to 5 water was
box used later. From day 6 to 11 animals were trained
to drink their water
drinking
room.
spout protruding
had approximately
the drinking
colony
ration
for 11 days. On the first
period they were provided with water
in their home cages in the animal available
to drink their daily water
in the afternoon
regulary
used to produce
(almond solution
and the apricot
after 6 trials,
and cocoa extract
116
Results and Discussion
On the conditioning saccharin
solution
trial animals
drank on average
less of the new taste fluid presented they had consumed
chamber
and control
last three training
A preference preference
together with a new odor than
animals
on the acquisition
score was calculated
animals
between
trial and on the
days.
for each postconditioning
test. The amount of fluid taken from the drinking
the target stimulus
period
(14.5 ml). There were no differences
(almond) was presented
was divided
amount of fluid taken from both boxes. Figure experimental
consumed
tap water on the last 3 days of the training
in the conditioning experimental
11.3 ml of the
in compound with an almond odor. Animals
almost completely
target odor was presented, both boxes. This remained
whereas
1 reveals
avoided
control
true in the retention
by the total that
the box where
animals
odorbox where
the
sampled water
from
test after one week.
E z
W
a
W IL
w
E El
E2 DAYS
E3
Er,
Fig. 1. Average preference ratios for the consumption of water from the box where the target odor previously paired with illness was presented in a two-odor-box choice test for 3 consecutive extinction days and on a retention test after one week (E4). In the second box a new alternative odor not associated with poisoning was presented on each extinction day. Experimental animals (EG) were poisoned within 5 min after a I5-min exposure to a saccharin-taste, casein-odor compound, control animals (CG) after 14 hr.
117
These impressions between
groups
(Nann-Whitney E4: U=16.5,
were confirmed
by statistical
EG and CG were significant U Test
(Z-tailed),
p
