Physiology & Behavior, Vol. 16, pp. 79-82. Pergamon Press and Brain Research Publ., 1976. Printed in the U.S.A.

Effects of Stimulus Displacement on Adjunctive Behaviour P. COOK AND G. SINGER

Department o f Psychology, La Trobe University, Bundoora, Victoria 3083, Australia (Received 18 March 1975) COOK, P. AND G. SINGER. Effects of stimulus displacement on adjunctive behaviour. PHYSIOL. BEHAV. 16(1) 79-82, 1976. - Food deprived animals were placed on an intermittent schedule (FI 60 sec) of food reinforcement and allowed to become polydipsic. When the drinking tube was empty animals showed a decrease but not complete cessation in licking. Animals whose drinking tube was empty or absent exhibited large increases in all other behaviours recorded (e.g. bar pressing, locomotor and exploratory behaviours, floor gnawing, grooming, attacking the drinking tube etc.) When a rifled drinking tube was reinstated aU behaviours returned to approximately their original levels. These changes were not observed in the normal wet tube group. The results are discussed in terms of current theories of adjunctive behaviours. Stimulus displacement

Adjunctive behaviour

Polydipsia

INTERMITTENT schedules of food delivery to food deprived animals have been shown to induce a variety of absurd or excessive behaviours [2, 8, 9, 11]. These behaviours occur as adjuncts to the behaviour under more direct schedule control and Falk has referred to them as adjunctive behaviours [4]. Schedule induced psychogenic polydipsia is a type of adjunctive behaviour in which animals are induced to drink excessive volumes of liquid. Explanations of this behaviour in terms of adventitious reinforcement [ 1, 12] or of timing behaviour [13] or as a direct result of thirst motivation have been suggested [7,16] but evidence presented by others [ 3, 5, 6, 10] make these explanations untenable. Wayner [18] proposes that adjunctive behaviours including schedule induced polydipsia result from a stimulation of the lateral hypothalamus produced by the schedules of reinforcement involved and the animal's food deprived condition. He further suggests that this LH stimulation leads to a state of general activation and that the responses exhibited by the animal are dependent upon the stimuli available in its environment. He also reports that if the drinking spout is made inaccessible then other types of activity occur more frequently. Stein [ 16] has presented observations which show that if an empty drinking tube replaces the normal water tube in a polydipsic's environment then the rat almost immediately stops licking the tube. If Wayner's hypothesis of general activation is correct it would be expected that the cessation of drinking behaviour should be followed by displacement to other activities since the excitability of the motor pathways remains unchanged. The present experiment was designed to test this hypothesis.

days old at the start of the experiment, were housed individually in a room kept at 23°C with a 12 hr light 12 hr dark (nonreversed) light cycle.

Apparatus A modified Skinner box with a lickometer tube present adjacent to the food bar was used. Animals received 45 mg food pellets [ 3].

Procedure Over a period of 7 days animals were food deprived and their body weights stabilised at 75% of their predeprivation levels. Animals were then shaped to bar press for 45 mg food pellets on a continuous reinforcement schedule for 3 days. Following this period, each day, animals were given a 30 min session of bar pressing for food pellets on a FI 60 sec schedule. Polydipsic behaviour was allowed to develop for 16 days at which time the animals were divided into 3 groups of 2. For the following 8 sessions Group 1 had a normal water filled drinking tube present, Group 2 an empty drinking tube and Group 3 had no drinking tube present. At Day 26 water filled drinking tubes were restored to all groups. At all stages throughout the experiment animals were observed during their thirty minute daily sessions and their behaviour recorded under the following categories: grooming behaviour, locomotor and exploratory behaviour, gnawing at the cage floor and attacks on the drinking tube. The volume of water consumed and the animals' bar pressing and number of licks were also recorded. To account for individual differences in the animals' response levels, each animal's responses were compared to its Day 16 response level and graphed as percentage differences.

METHOD

Animals Six La Trobe University strain rats approximately 120 79

80

COOK AND SINGER RESULTS PERCENTAGE

The removal of water from the drinking tube or complete removal o f the drinking tube resulted in large increases in other behaviours, in addition to the expected decrease in licking. Almost all behaviours recorded returned to close to their previous wet tube levels immediately following the return of the water. The percentage change in lickometer counts for the 3 groups is shown in Fig. t. It is interesting to note that although licking does substantially decrease, it does not stop completely. The 2 animals in the dry tube group were still licking at approximately 1500 licks per 30 min session even after 8 days with no water present in the tube. The return to near base preremoval levels is again seen; a similar situation occurs for the volume of water consumed per session (see Fig. 2.). Large increases were recorded for all animals in both the number of bar presses and the time spent bar pressing (see Figs. 3 and 4). The replacement of the filled drinking tube at Day 26 led to almost complete return to normal Day 16 levels. PERCENTAGE

CHANGE

IN LICKOMETER

COUNTS

CHANGE

IN BAR PRESSES

pERCB]

8U

60

2U

-20

D A Y / ]2 1'6 1~ 2'1 ~ :~ / CONTROL

DRY TUBE

NO TUBE

FIG. 3. The percentage change in the number of bar presses relative to Day 16 is shown for the 2 animals in each group.

20PERCENT 0

PERCENTAGE

IO0--

CHANGE

IN BAR PRESSING

TIME

PERCENT

-20

80 440

~0 -60

40 40

DAy8

I

'

12

I

'

'

1617

'

I

'

2125

I

2629

CONTROL

'

I

'

'

'

I

'

8 12 161721 252~ 29

I

'

8 12

DRY TUBE

I

'

'

1617

'

'

I

212526 Z9

20

NO TUBE

FIG. 1. The percentage change in lickometer counts relative to Day 16 is shown for the 2 animals in each group.

0

-20 I

PERCENTAGE

CHANGE

IN VOLUME

CONSUMED

DAY8

OF WATER

'

'

'

CONTROL

PER SESSION

'

'

I

12 16 ~/ 2125 ~6 27

I

,

,

,

,

'

8 12 16 ~ 21 25 25 ~7 DRY TUBE

,

,

,

'

'

~ 12 16 ~7 2125 26 2~ NO TUBE

1o

FIG. 4. The percentage change in the time spent at the bar relative to Day 16 is shown for the 2 animals in each group. o

-io

2O

-3(3

X

410. I

DAY8

'

'

I

'

'

'

I

12 1617 21 252629 CONTROL

'

J

I

'

'

'

I

12 1612 21 2525 29 DRY TUBE

1

I

,

I

812 161721

~

i

i

I

25 2629

NO TUBE

FIG. 2. The percentage change in the volume of water consumed per session relative to Day 16 is shown for the 2 animals in each group.

Figures 5, 6, 7 and 8 show changes in the other behaviours recorded. These are, respectively, locomotor and exploratory behaviour, floor gnawing, grooming and attacks on the drinking tube. There are quite large individual differences between the animals with regard to these behaviours, for instance, the dry tube group showed very large increases in locomotor and exploratory behaviours with little change in grooming, while the opposite is true for the no tube group. Despite these individual differences a pattern similar to the bar pressing data emerges, i.e. large increases in these behaviours during the no water period from Day 17 to Day 25 with almost immediate return to pre-Day 17 levels o f responding when the water filled drinking tube is reinstate d. The percentage change in 23 hr water consumption for the 3 groups is shown in Fig. 9. The extremely large

STIMULUS DISPLACEMENT AND ADJUNCTIVE BEHAVIOR PERCENTAGE CHANGE EXPLORATORY

IN LOCOMOTOR BEHAVIOURS

81

AND 25a

PERCENTAGE

CHANGE

IN GROOMING

BEHAVIOUR

200 pERCB¢ ]gJ

0o

-tl0.

J

-120 I

DAY8

'

'

I

'

'

'

1

]2 16 1] 212s 26 ~9

I

DAY

'

832

I

161223

DRY

CONTROL

'

'

I

I

25 2629

i

,

I

8121G

TUBE

'

,

t

~ 12 16 17 2125 2629

I

1723. 2526

8 12 ~ 1] 2J 25 26 29

CONTROL

29

DRY

FIG. 7. The percentage change in the number of grooming behaviours relative to Day 16 is shown for the 2 animals in each group. PERCENTAGE

CHANGE

GNAWING

NO TUBE

NO TUBE

FIG. 5. The percentage change in the number of locomotor and exploratory behaviours relative to Day 16 is shown for the 2 animals in each group. PERCENTAGE

~ 1216 1.72.l ~ 26

TUBE

1290

IN FLOOR

CHANGE

ON THE

IN ATTACKS

DRINKING

TUBE

BEHAVIOUR l(~(J PERCen 80O

(W]D 2t~-

~0

0. -1[11,

-2~ I

DAYB DAY

12 16 I CONTROL

n

2S~ I

t"" , t ' ' , t 8 ]216 172.!.25 2629 DRY

TUBE

k

,

'

121E

]}

,

,

,

t

'

'

I

12161/

'

'

'

Z1~5 2 6 ~

CONTROL

I

r

,

,

81215

DRY

i

,

,

,

32 21 2 5 2 6 2 9

TUBE

t

I

'

832

~

I

'

'

'

NO TUBE

Z?L 25 2G 29

NO TUBE

FIG. 6. The percentage change in the number of floor gnawing behaviours relative to Day 16 is shown for the 2 animals in each group. increase for the dry tube group relative to the smaller increase above controls for the no tube group may reflect a thirst provoking effect of excessive dry licking. DISCUSSION

The results from the present experiment s h o w that an animal's prevalent adjunctive behaviour m a y be displaced following appropriate changes in its environment; this is consistent with observations that w h e n drinking is thwarted the probability o f other responses occurring increases [ 18]. When the drinking tube is removed or a dry tube placed in a

I

JG]? 2]25 2629

FIG. 8. The percentage change in the number of attacks on the drinking tube relative to Day 16 is shown for the 2 animals in each group. polydipsic animal's environment, licking decreases and significant increases occur in other forms of activity (e.g. grooming, l o c o m o t o r and exploratory behaviour and floor gnawing). Furthermore, the increase in these activities cannot be explained by the fact that the animals have more time at their disposal (see Table 1). The failure in our experiment of animals to cease licking c o m p l e t e l y as reported by Stein [ 1 6 ] , may be due to the rewarding effects of the lickometer current [ 1 5 ] . This m a y be a contributing factor to all normal polydipsic behaviour as it has been s h o w n that stimulation of oral sensory receptors m a y alter LH activation [ 17], however, polydipsia still occurs in the absence of lickometer currents [ 14].

82

COOK ANDSINGER PERCENTAGE

2(3o

CHANGE

WATER

IN

23

HOUR

TABLE1

CONSUMPTION

AVERAGE TIME (IN MINUTES) SPENT BAR PRESSING AND LICKING AND THEIR TOTAL FOR THE 2 ANIMALS IN EACH GROUP ON DAY 25

150 PeRcENT 100

~3

Time at bar Time spent licking Total Time I

DAYs~

'

'

I

'

'

'

16 ~ ~2s~s CONTROL

I

I ' 8 12

i 16

DRY

I ' ' ' I 17 21 25 26 29 TUBE

812

Control

Dry Tube

No Tube

8.5

12.1

17.6

10.2 18.7

4.2 16.3

-17.6

16 1,7 2 1 2 5 2 6 2 9 NO

TUBE

FIG. 9. The percentage change in 23 hr water consumption relative to Day 16 is shown for the 2 animals in each group. The findings f r o m the p r e s e n t e x p e r i m e n t are in accordance w i t h W a y n e r ' s h y p o t h e s i s t h a t a d j u n c t i v e b e h a v i o u r s are t h e result o f a n increase in general activity following LH s t i m u l a t i o n [ 18]. It appears f r o m this a n d earlier observa-

t i o n s o f SI w h e e l r u n n i n g , air ticking a n d p a p e r chewing [5, 8, 9 ] t h a t s c h e d u l e - i n d u c e d p o l y d i p s i a is n o t a p u r e l y t h i r s t related b e h a v i o u r and t h a t it is simply o n e o f a n u m b e r of highly active b e h a v i o u r s resulting f r o m i n t e r m i t t e n t schedules o f s t i m u l u s p r e s e n t a t i o n . T h a t s c h e d u l e - i n d u c e d polydipsia is, o f all the possible h e h a v i o u r s available t o t h e animal, one o f very h i g h p r o b a b i l i t y m a y be related t o e i t h e r n o r m a l p o s t p r a n d i a l d r i n k i n g a n d / o r t h e highly r e w a r d i n g effect o f oral sensory f e e d b a c k t o the LH.

REFERENCES

1. Clark, F. C. Some observations on the adventitious reinforcement of drinking under food reinforcement. J. exp. Analysis Behav. 5: 6 1 - 6 3 , 1962. 2. Falk, J. L. Production of polydipsia in normal rats by an intermittent food schedule. Science 133: 195-196, 1961. 3. Falk, J. L. Conditions producing psychogenic polydipsia in animals. Ann. N. Y. Acad. Sci. 157: 569-593, 1969. 4. Falk, J. L. The nature and determinants of adjunctive behaviour. Physiol. Behav. 6: 5 7 7 - 5 8 8 , 1971. 5. Freed, E. X. and N. Hymowitz. A fortuitous observation regarding "psychogenic" polydipsia. PsychoL Rep. 24: 224-226, 1969. 6. Gilbert, R. M. Ubiquity of schedule-induced polydipsia. J. exp. AnalysisBehav. 21: 277-284, 1974. 7. Grace, J. E. Schedule-induced polydipsia: Conditioned inhibition of salivation. Psychon. Sci. 17: 28-29, 1969. 8. Levitsky, D. and G. Collier. Schedule-induced wheel running. PhysioL Behav. 3: 571-573, 1968. 9. Mendelson, J. and D. Chillag. Schedule-induced air-licking in rats. PhysioL Behav. 5: 5 3 5 - 5 3 7 , 1970.

10. Porter, J. H. and D. R. Kenshalo, Jr. Schedule-induced drinking following omission of reinforcement in the Rhesus monkey. PhysioL Behav. 12: 1075-1077, 1974. 11. Schuster, C. R. and J. H. Woods: Schedule-induced polydipsia in the monkey. PsychoL Rep. 19: 823-828, 1966. 12. Segal, E. F. The development of water drinking on a dry-food free-reinforcement schedule. Psychon. Sci. 2: 29-30, 1965. 13. Segal, E. F. and S. M. Holloway. Timing behaviour in rats with water drinking as a mediator. Science 140: 888-889, 1963. 14. Segal, E. F. and D. L. Oden. Effects of drinkometer current and of foot shock on psychogenic polydipsia. Psychon. Sci. 14: 14-15, 1969. 15. Slangen, J. L. and J. A. W. M. Weijnen. The reinforcing effect of electrical stimulation of the tongue in thirsty rats. Physiol. Behav. 8: 565-568, 1972. 16. Stein, L. Excessive drinking in the rat: superstition or thirst? J. comp. physioL Psych. 58: 237-242, 1964. 17. Wayner, M. J. Motor control functions of the lateral hypothalamus and adjunctive behaviour. Physiol. Behav. 5: 1319-1325, 1970. 18. Wayner, M. J. Specifity of behavioural regulation. Physiol. Behav. 12: 851-869, 1974.