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Determining the Value of Social Companionship to Captive Tufted Capuchin Monkeys (Cebus apella)

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This study used a method similar to one introduced by Dawkins in 1990 to assess the magnitude of the psychological need for social companionship in pair-housed tufted capuchin monkeys (Cebus apella). This method permits classification of commodities as necessities or luxuries. The study directly compared the commodity of social companionship to the commodity of food, a known physiological necessity, in a series of preference tests following commodity deprivations. The majority of subjects chose their social companion over food at baseline and persisted in this preference even after several hours of food deprivation. In addition, subjects' preferences shifted from 1 commodity to the other with manipulation of social and food deprivation levels. Capuchin monkeys perceived social companionship as a necessity at a level similar to that of food.
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Determining the Value of Social
Companionship to Captive Tufted
Capuchin Monkeys (Cebus apella)
Elizabeth Dettmer and Dorothy Fragaszy
Department of Psychology
University of Georgia
This study used a method similar to one introduced by Dawkins in 1990 to assess the
magnitude of the psychological need for social companionship in pair-housed tufted
capuchin monkeys (Cebus apella). This method permits classification of commodi-
ties as necessities or luxuries. The study directly compared the commodity of social
companionship to the commodity of food, a known physiological necessity, in a se-
ries of preference tests following commodity deprivations. The majority of subjects
chose their social companion over food at baseline and persisted in this preference
evenafterseveralhoursoffooddeprivation.Inaddition,subjects’preferencesshifted
from 1 commodity to the other with manipulation of social and food deprivationlev-
els.Capuchinmonkeys perceived social companionshipasa necessity at alevelsimi
-
lar to that of food.
Recent animal use legislation (Animal Welfare Act, 1985, 1991) in the United
States requires that those responsible for the care of captive nonhuman primates
provide for their psychological well-being, including provisions to meet social
needs. Whereas physical well-being can be assessed as the absence of pathology
and on the basis of physical condition or physiological measures, the definition
of psychological well-being is more problematic. Although many parameters for
enrichment have been stipulated in regulations, no consensus on how to measure
psychological well-being presently exists (Committee on the Well-Being of
Nonhuman Primates, 1998; Dawkins, 1990; Novak & Suomi, 1988; Poole,
1992). Identification of basic needs might be a less elusive research goal than
identification of psychological well-being. If we can determine how to meet
JOURNAL OF APPLIED ANIMAL WELFARE SCIENCE, 3(4), 293–304
Copyright © 2000, Lawrence Erlbaum Associates, Inc.
Requests for reprints should be sent to Elizabeth Dettmer, Boston VAMC (116B), 150 South Hun
-
tington Avenue, Boston, MA 02130. E-mail: dettmer.elizabeth@boston.va.gov
needs, doing so will support physical and psychological well-being. We suggest
that a shift from the identification of psychological well-being to the identifica
-
tion of basic needs might bring us closer to current welfare goals.
How does one define basic needs? Maslow (1968) introduced a theory of basic
needs for Homo sapiens. He placed physiological needs such as hunger, thirst,
sleep, rest, exercise, and elimination at the base of the hierarchy. Individuals, he
postulated, must first meet these physiological needs before attending to needs of
safety, the next step in the hierarchy, or social needs, still another step higher.
Maslow’s hierarchy continues to levels of introspection that include self-esteem
needs and self-actualization and asserts thatwell individuals can fulfill all of these
needs—from nourishment to self-actualization: “If the essential core of the person
is denied or suppressed, he gets sick, sometimes in obvious ways, sometimes in
subtle ways, sometimes immediately, sometimes later” (p. 4). In free choice situa
-
tions, the need-deprived person gives basic needs priority over other satisfactions
(Maslow, 1968). This theory supports the use of choice tests to evaluate whether a
particular commodity fulfills a need.
Animal researchers have employed preference tests similar in theory to that
which Maslow (1968) termed choice situations. However, many of these tests
have been too simplistic in nature. An assumption, originating with Spencer
(1880), was made that animals experience subjective feelings of pleasure when
given access to reward or positive reinforcers. Therefore, many researchers have
presented subjects with a choice between two different environments, assuming
the animals would spend more time in the particular environments that they found
more reinforcing. Dawkins (1981) used such a method to demonstrate that bat-
tery-kept hens prefer larger cages to smaller ones and litter floors to wire floors.
When the two commodities were pitted against one another (the animal had to en
-
ter a smaller cage to gain access to litter or a wire cage to gain the larger area), litter
was given higher priority. According to Dawkins, battery hens “preferred the
smaller cage when this had a litter floor to the one four times larger with a wire
floor” (p. 255).
Duncan (1978) criticized such preference experiments for providing only rela
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tive conclusions: “The fact thatA is always chosen in preferenceto B tells us noth
-
ing of the absolute properties of A and B” (p. 198). In addition, many choice
experiments are based on the assumption that
in the natural environment, proximate and ultimate needs will generally go hand in
hand. For example, animals that experience a proximate need for food and start
searching for it when their reserves are low will be fulfilling the ultimate need of
avoiding death by starvation. (Dawkins, 1983, p. 1197).
Duncan argued that animals in laboratory settings often choose according to
short-term gains that do not correspond to long term gains. In view of such criti
-
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DETTMER AND FRAGASZY
cisms,Dawkins(1990)suggestedanoperanttrainingtechniquethatprovidesanob
-
jective wayfordeterminingwhatanimalsareexperiencing.Theparadigmrequires
subjects to demonstrate motivation toobtain certain rewards through operanttasks
for different commodities. An animal’s willingness to work for eachcommodity is
compared.Willingness toworkfor foodis usedtoanchor therelative measurement
allowing assignment of qualitative worth. If animals show that they regard being
without some commodity as aversive as being without food (a known basic need),
then one could argue that the animals suffer (as they surely would suffer without
food)withoutthatcommodity.Inotherwords,theneedforfoodisusedasayardstick
against which other less recognized needs are measured.
Demonstration of such commodity demand curves (demonstration of how hard
an animal will work for a commodity) requires a great deal of time. Researchers
have voiced concern about the large number of experiments that would need to be
done to plot demand functions of different animals, conditions, sexes, times of
year, and so on (Dawkins, 1990). In addition, the implementation of such a plan is
somewhat problematic in that operant responses such as pressing a lever are asso-
ciated preferentially with different stimuli. Animals seem to be prepared to make
certain associations and less prepared to make others. For example, Garcia and
Koelling (1966) showed long ago that rats readily associate an auditory–visual
stimulus with shock punishment but do not associate a taste stimulus with shock.
Such differential preparedness can alter performance and therefore complicate the
comparison of an animal’s motivation for different commodities with the use of
the same operant task.
This design, a simplification of Dawkins’s (1983, 1990) method, investigated
whether social companionship is a basic need for capuchin monkeys (Cebus
apella). Instead of comparing commodity demand curves, we directly compared
individuals’ needs for social companionship with the need for food.
METHODS
Design
Figure 1 illustrates the experimental design. Subjects were tested in a baseline
condition and two test phases. Baseline trials required subjects to choose be
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tween food and social companionship without prior deprivation. Following de
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termination of baseline preferences, subjects next were exposed to food depriva
-
tion trials (Phase 1, right arm of Figure 1). None of our subjects exhibited a
preference for food in baseline testing; therefore, the left side of Figure 1 was
not implemented in this study.
Phase 1 determined the duration of food deprivation required to produce a pref
-
erence for food.If the subject failed to choose food inat least 9 of 11 trials, the du
-
SOCIAL NEEDS IN CAPUCHINS 295
ration of food deprivation was increased and a new set of choice trials presented to
the subject. Once subjects switched to a food preference or reached 22 hr of food
deprivation, they moved to Phase 2. On advisement of the attending veterinarian,
no animal experienced more than 22 hr of food deprivation.
Phase 2 assessed the subjects’ need for socialcompanionshipin relation to their
need for food. Subjects were deprived of food for thedurationdetermined in Phase
1 to produce a preference for food.Concurrently, they also were deprived of social
companionship. The duration of social deprivation was increased until the subject
expressed a preference (9of 11 trials) for the social companion or until 24 hr of so
-
cial deprivation was implemented.
296
DETTMER AND FRAGASZY
FIGURE1 Thedesignof theexperiment.Subjectswere assignedtotheleft ortheright pathof
testingafter weevaluated theirpreference forfood orthe pairmatein achoice setting,under nor
-
mal conditions. In Phase 1, subjects experienced deprivation of the commodity they had ex
-
pressed preference for in the baseline condition. Testing in this phase was repeated with
increasing levels of deprivation until the subject switched its preference to the initially less pre
-
ferred commodity. Once its preference had shifted, the subject entered Phase 2. In thisphase of
testing,the subjectexperienceddeprivation ofboth commodities.The durationof deprivationof
the initially preferred commodity was increased until the subject reverted to its original prefer
-
ence.As no subject expressed apreference for food overthe social partner inthe baseline condi
-
tion, all subjects followed the path outlined on the right side of the figure.
Subjects
Seven capuchin monkeys, six males and one female, served as subjects. At the
onset of the procedures, these animals ranged in age from 19 to 88 months. The
subjects had lived as pairs in indoor pens (1.99 m × 1.07 m × 1.19 m) for at least
2 months prior to testing. All subjects but one were reared for at least 2 years in
species-typical groups. The only female subject, age 33 months, was paired with
the youngest male, 21 months. Both subjects were well below the age of sexual
maturity, estimated as 48 months (Fragaszy & Adams-Curtis, 1998). The ani
-
mals were maintained on Purina Monkey Chow 5045 (Richmond, IN) and daily
rations of fruit and vitamin supplements. Food was available ad libitum except
during testing periods. The light–dark cycle was set at 13:11 hr, with onset of
light at 6:30 a.m.
Materials
The testing apparatus was composed of three adjoining metal mesh chambers,
each 45.7 cm × 40.6 cm × 61.0 cm. The chambers were suspended 1.31 m from
the ground via a frame. Transparent doors provided access from the middle cage
SOCIAL NEEDS IN CAPUCHINS 297
FIGURE 2 The testing apparatus. (a) The subject sat in the center compartment of the three-
compartment apparatus. Transparent siding and doorsallowed the subject toview but nottouch
items in the outer two cages. (b) The monkey gained access to one of the adjoining cages by
pressing the appropriate knob, which caused displacement of a peg and allowed the separating
doorto drop. Theexperimenter then closedthe door tothe middle compartment,effectively per
-
mitting the subject a single choice.
to each of the outer cages (see Figure 2a). Each door was opened by a black
knob located in the middle cage to the right of the door. Pushing with a pressure
equivalent to 5 lb (2.3 kg) on either knob caused the corresponding door to drop
(see Figure 2b). Exertion of 5 lb of pressure was effortful but not difficult for the
subject to achieve.
Procedure
Training.
Subjects were placed individually into the testing apparatus for
15–30 min each session and hand fed. Agitation (vocalizations and intense watch
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ingbehavior)droppedrapidlyafterapproximately11days.Throughaseriesofsuc
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cessive approximations, the subjects were trained to operate the choice doors by
pushing on the appropriate knob. Subjects required from 7 to 17 (average = 12)
training sessions to master control of the doors.
The subjects then were presented with two types of choice trials. In the first
(Type A), more of one food item (fruits, nuts, and yogurt) was placed on one side
of the testingapparatusandlessofthesameitemontheother.Sideof placement of
the larger amount of food was randomized. Access doors were locked. Subjects
were released into the middle compartment where they could view the choices in
each adjoining compartment through Plexiglas doors. After 20 sec, a beeper sig-
naled the experimenter to unlock both choice doors and say the word “okay.” This
signaled the subject to make a choice. Pushing the knob to open a door provided
access to the corresponding compartment and any food item contained in it. The
experimenter immediately locked the opposite compartment. The subject was re-
quired to remain with the choice for 5 min, at which time the subject was removed
viaatransferbox.The animal remained in the box as the testing apparatuswaspre
-
pared for the next trial. Subjects underwent four trials of this type per training ses
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sion. Subjects were assumed to have gained an understanding of the choice
situation when in 100% of trials in two concurrent testing sessions (a total of 8 tri
-
als) they chose the larger over the smaller amounts of food in Type A trials.
In one trial per session, the subjects were presented with the second type of
choice trial (Type B), a choice between two different food items instead of differ
-
ent amounts of the same food item. This procedure was implemented to give the
animals experience with the consequence of choice when choosing between two
different items.
Testing.
The first two trials of each testing session were designed to confirm
that subjects were willing to go to either side of the apparatus. The subject was pre
-
sented with a choice between 1 tsp of flavored sugar water and nothing. The place
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mentofthe flavored sugar waterwasalternatedfrom side to side.Animalscontinued
with testing if on each of these trials they chose the side containing the sugar water
over the empty side. Only once did a subject refuse to choose both doors.
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DETTMER AND FRAGASZY
The two sugar water trials were followed by one test trial in which the subjects
were presented with a choice between the home-cage partnerandtwo Purina Mon
-
key Chow biscuits (the basis of their normal diet). The side placement of these
stimuli was systematically varied using the Fellows (1967) testing sequence. The
subjects’ choice was followed by a 5-min waiting period where they remained in
the testing apparatus with the chosen object, the biscuits or social companion. If
the subject chose the social companion, the biscuits immediately were removed
fromtheroom. If thesubjectchose the biscuits, thesocialcompanion was removed
from the testing apparatus and placed on the floor in the same room. After 5 min,
the subjects were transferred to the home cage, where they had access only to the
chosen stimulus. If the subject chose food in the test trial, the home cage was sup
-
plied with food biscuits but the social partner remained outside the cage (although
still in view) for 5 min. If, instead, the subject chose the social partner during the
test trial, both subject and social partner were returned to the home cage together
but waited 5 min for access to food.
Test sessions were conducted in baseline, Phase 1, and Phase 2 conditions. In
the baseline, subjects were tested in the choice apparatuswith no prior deprivation
of food or social companionship for 11 trials (one per day). In Phase 1, the animals
were deprived of food initially for 3 hrbefore eachtrial.If the subject chose the so-
cial companion 3 times at that level of deprivation over an 11 trial sequence, the
subject’s next trial would be the first of another session of trials following a longer
period of food deprivation. Subjects were exposed to a different sequence of depri-
vation hours, dependent on their preceding performance. For example, Be began
Phase 1 trials following 3 hr of food deprivation. On 3 days, she chose her social
companion. She then wasdeprived of food for 5 hr and tested againuntil she chose
her social companion three times. She was then subjected to yet a higher depriva
-
tion level (7 hr). Subjects continued in this manner until they chose food on 9 of 11
SOCIAL NEEDS IN CAPUCHINS 299
TABLE 1
Testing Specifics
Subject Baseline Trials
Food
Deprivation
Trials
Range of Food
Deprivation
Hours
Food and
Social
Deprivation
Trials
Range of
Social
Deprivation
Hours
Be 11 (11) 38 (24) 3–17 (3–5) 21 (13) 17–24 (22–24)
Ch 11 30 3–13 22 22–23
Jo 11 20 3–15 11 17
Qu 11 27 3–13 32 22–24
Xa 11 61 3–22 11 22
Xe 11 41 3–18 11 22
Wi 11 44 13–19 37 22–24
Note. Be was tested twice. The values in parentheses are from her second testing sequence.
trials or reached 22 hr of food deprivation. See Table 1 forthe rangeof hoursof de
-
privation and the total number of trials each individual completed.
In Phase 2 trials, the level of food deprivation required to reach criterion in
Phase 1 was continued. Additionally,subjects were deprived of socialcompanion
-
ship for 17–22 hr. If the subjects did not chose their social companion on 9 of 11
trials, following the initial period of social deprivation, it was increased by 1 hr
(see Table 1). As soon as a significant preference for the social companion was
demonstrated or the animal failed to display a preference after 24 hr of social de
-
privation, testing was terminated. In Phases 1 and 2, subjects were tested on 5 con
-
secutive days, then given 2 days on their standard feeding schedule and without
social separation. Testing occurred over a 15-week period.
Welfare Implications
Subjects in the study were deprived of food for up to 22 hr. The attending veteri
-
narian advised that 22 hr of food deprivation was not life threatening and would
have no long-lasting effects on the animals. We monitored the subjects carefully
when feeding them after periods of food deprivation to make certain they did not
eat too quickly, which could contribute to bloating and stomach problems.
Subjects also were deprived of their social companions for up to 24 hr at a time.
Past research has shown that primates subjected to social separations are likely to
experience an increase in cortisol (Lyons et al., 1999). This physiological response
isa normal reaction ofthe body that facilitatescoping with stress andis expected to
occur in any new situation characterizedby uncertainty. Short-term stressors, such
as separation of juvenile rhesus from their natal social group and resulting in-
creased cortisol have been correlated to decrements in some immune parameters
(Gordonetal., 1992). However, it stillisnot clear if such changesoccurinall sepa
-
rations and how such specific changes, especially short-term changes, might affect
overall health. Chronic elevations of cortisol have been linked more clearly than
short-term elevations with detrimental health effects in past research. The separa
-
tions for this study were relatively brief (less than 24 hr). All subjects remained in
good health and exhibited normal behaviors during and after the study.
RESULTS
Baseline
Five of the seven subjects displayed a significant preference for their social
companion in baseline sessions, and all seven chose their social companions
more often than food in this phase (binomial probability of .008). Three subjects
chose their social companion on all 11 baseline trials (see Table 2).
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DETTMER AND FRAGASZY
Phase 1
The duration of food deprivation required to produce a preference for food over
social companionship was 12–19 hr for six of the seven subjects. The seventh
animal (Xa), following 22 hr of food deprivation, still chose his social compan-
ion more often than food (7 out of 11 trials). The two animals who failed to
demonstrate a statistically significant preference for their social partners at base-
line required 19 and 12 hr of food deprivation before they exhibited a preference
for food.
Phase 2
Of the five animals who displayed a social preference at baseline, four again dis
-
playedapreferencefortheircompanioninPhase2whentheyweredeprivedbothof
food (12–22 hr) and social companionship (17–23 hr). The fifth animal, Be, never
exhibited a significant preference for social companionship in this phase. When24
hr of social deprivation was added to the 17 hr of food deprivation, she chose ran
-
domly between the two commodities. The two subjects who showedno significant
preferenceinbaselinechoserandomly betweenthetwocommoditieswhen 24hrof
social deprivation was coupled with food deprivation.
In sum, four different patterns of response were demonstrated:
1. Three animals displayedabaseline preference for social companionship fol
-
lowedbyafoodpreferenceafter12,15,or18hr offood deprivationonly, thena so
-
SOCIAL NEEDS IN CAPUCHINS 301
TABLE 2
Summary Table of the Results of Each Subject
Subject
Baseline: Social
Choices Out of
11 Trials
Did Animal
Display a
Baseline
Preference for
Social
Companion?
Hours of Food
Deprivation
Required to
Create Food
Preference
Did Animal
Switch Back to
Social
Preference With
Addition of
Social
Deprivation?
Social
Deprivation
Hours Required
to Shift
Preference Back
to Social
Be 11 yes 17 (5) no N/A
Ch 11 yes 12 yes 23
Jo 10 yes 15 yes 17
Qu 7 no 12 no N/A
Xa 9 yes > 22
a
yes 22
Xe 11 yes 18 yes 22
Wi 8 no 19 no N/A
a
Xafailedtoreachcriterionforfoodpreferenceevenat22hroffooddeprivation,choosingfoodononlyfourtrials.
cialpreferencefollowingfooddeprivation of12,15,or18 hrandsocialdeprivation
of 23, 17, or 22 hr (social–food–social).
2. One animal showed a baseline preference for social companionship and no
preferences after 22 hr of food deprivation. When social deprivation (22 hr) was
added to 22 hr of food deprivation, he switched back to his preference for social
companionship (social–neutral–social).
3. Two animals showed no baseline preference, a food preference after 12 or
19 hr offood deprivation (but no socialdeprivation), and no preference whenboth
food and socially deprived (neutral–food–neutral).
4. One animal showed a baseline preference for her social companion, a food
preferenceafter 17 hroffood deprivation, butnopreference when deprivedofboth
food (17 hr) and social companion (24 hr; social–food–neutral).
DISCUSSION
To measure the need for social companionship, subjects were asked—following
a host of commodity deprivations—to choose between two commodities: food
and social companionship. The only time subjects showed a food preference was
when they were provided with a social companion but deprived of food for at
least 12 hr prior to testing trials. None of the subjects showed an initial food
preference over social companionship, and four of the seven subjects chose the
social partner significantly more often than food, even following lengthy periods
(22 hr) of food deprivation.
These results show that social companionship and food are valued similarly by
tufted capuchins. This was demonstrated by the manipulation ofdeprivation levels
and the resulting preference shifts that indicate the “need” status of the two com
-
modities as very similar. Because capuchins treat social companionship as if it
were at the same need level as food, we propose that these monkeys can be consid
-
ered psychologically well only if they maintain their access to their companions.
Having said that, we also point out that our resultssay nothing of the scalar val
-
uesof the tested commodities(23 hr of socialdeprivation is notclaimedto be equal
to 17 hr of food deprivation). No parametric comparison of the amounts of food
and social companionship deprivation can be made. Moreover, the extent towhich
these findings may be generalized across species, ages, sexes, and housing condi
-
tions is unknown. For example, these subjects had a history of social housing. It
may be that animals housed singly from an early age would perform very differ
-
ently in this paradigm. As a second example, the quality of the relationship be
-
tween the subject animal and the social companion may be an important variable.
In this study, the subject’s familiar cage mate was used as the social companion. It
may be that only familiar individuals fulfill the basic need for companionship.
302
DETTMER AND FRAGASZY
CONCLUSIONS
Despite the caveats arising from our particular sample of subjects and our inabil
-
ity to address the scalar values for different needs, the results are clearly inter
-
pretable. Tufted capuchin monkeys value social companionship as they value
food: It is a necessity, not a luxury. This paradigm creates a conservative esti
-
mate of what animals deem as essential to their well-being as the physiological
necessity of food. It avoids time-consuming creation of demand curves and asso
-
ciated problems of equating different operant tasks that must be specific to each
commodity. Instead, commodities can be classified in one of two categories: ba
-
sic needs and luxuries, where no level of deprivation will offset deprivation of a
basic need. Future research using this paradigm could investigate relationships
or specific inanimate features of the environment such as those often targeted for
“enrichment.” This method can provide convergent validation for claims that
various alterations of housing or handling improve the psychological well-being
of animals. It can show that animals regard some object, environment, or event
as necessary to their well-being.
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... Research has shown that some social species place companionship equally as high as food, indicating that for these species, companionship may not be a luxury but a requirement (Dettmer & Fragaszy, 2000). In more recent years, researchers have begun to investigate the effect of personality on mate compatibility (Martin-Wintle et al., 2017;Tetley & O'Hara, 2012) and social group success (Chadwick, 2014;Stoinski et al., 2004). ...
... The value animals place on companionship can be high. Capuchin monkeys (Cebus paella) choose social companions over food, even after a period of food deprivation (Dettmer & Fragaszy, 2000), and calves (Bos primigenius) are more motivated to get full, unrestricted access to conspecifics rather than settling for more limited access (Holm et al., 2002). For a number of species, we are yet to adequately provide an appropriate social environment that facilitates unrestricted species-typical interactions. ...
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Social structures of animals are important at both individual and population level. Maintaining biologically functional and compatible social groups is a primary welfare concern for zoo-housed animals. Indeed, appropriate management of social groups is considered one of the most important, but difficult tasks to achieve in captivity. The ability of individuals to adapt to captivity is extremely varied, with some species showing little to no negative effects or signs of poor welfare (e.g., ring-tailed lemurs). Whilst others reportedly show abnormal behaviours (e.g., stereotypies in elephants or self-injurious behaviour in non-human primates) or struggle to breed successfully (e.g., giant panda). Animal welfare is now at the forefront of decision making in zoos, evidenced by the ongoing evolution of zoo animal environments through enclosure design, provision of enrichment, research and adaptive management guidelines, and implementation of welfare assessment programmes. A current unanswered question is whether the needs of social species can be adequately met within zoo environments. Understanding how social structures affect zoo-housed animals enables opportunities to examine the constraints acting upon group composition. Identification of factors that impact social groupings and subsequent welfare issues can allow for improved management and target areas for change in designing zoo environments. In this chapter, an overview of the welfare impact of social groupings of a number of zoo-housed animals is presented, and the extent to which zoos are able to cater for individual species needs is discussed. We conclude by outlining areas for further research into factors that may affect the social compatibility of zoo-housed animals, and discuss the potential long-term implications for housing socially complex animals.
... Conceptualizing social release in terms of social reinforcement has several advantages. First, it is consistent with a longstanding body of literature showing that contingent access to social stimuli can function as a reinforcer across a variety of procedures, including T-maze and operant tasks, and in a range of species, including chimpanzees (Mason et al., 1962), capuchin monkeys (Dettmer and Fragaszy, 2000), horses (Søndergaard et al., 2011), foxes (Hovland et al., 2011), calves (Holm et al., 2002), sows (Kirkden and Pajor, 2006), mice (Martin et al., 2014), and rats (Evans et al., 1994;Humphreys and Einon, 1981;Wilsoncroft, 1968). ...
... Similarly, foxes (Hovland et al., 2011) and mice (Martin et al., 2014) paid higher prices for food than for social access to a same-sex conspecific. Other studies, however, with capuchin monkeys (Dettmer and Fragaszy, 2000) and rats (Ben-Ami Bartal et al., 2011;Evans et al., 1994;Sato et al., 2015), have reported comparable value of social and food reinforcers. ...
Article
The present research measured social reinforcement in rats, using a social-release procedure in which lever presses permitted 10-s access to a familiar social partner. The work requirements for reinforcement increased systematically according to progressive-ratio (PR) schedules. Social and food reinforcement value were compared across blocks of sessions (Experiment 1) and concurrently within the same sessions (Experiment 2). To assess motivational effects, response and reinforcer rates for both reinforcer types were studied under food restriction, social restriction, and combined food and social restriction. Responding was maintained by both reinforcers, albeit at substantially higher levels for food than for social access. Responding for social access decreased to low levels under extinction conditions, demonstrating functional control by the social-reinforcement contingency. Sensitivity to social restriction was seen in some conditions in Experiment 2, in which social reinforcers were earned earlier in the session (at lower food prices) under social restriction than under the other deprivation conditions. Altogether, results are consistent with a social reinforcement conceptualization, and demonstrate an important role for social contact in social release behavior. The study demonstrates a promising set of methods for analyzing and quantifying social reinforcement.
... Moreover, data indicate that when an individual has not been groomed for some time, this lowers the level of endorphins in its brain and increases its motivation to be groomed; while, correspondingly, grooming increases the level of endorphins in the brain and alleviates the motivation to groom (Fabre-Nys et al., 1982;Martel et al., 1995). Accordingly, capuchin monkeys (Cebus apella) showed higher preferences for social companionship over food, demonstrating the high motivation for social contact (Dettmer and Fragaszy, 2000). ...
Article
Across captive settings, nonhuman primates may develop an array of abnormal behaviors including stereotypic and self-injurious behavior. Abnormal behavior can indicate a state of poor welfare, since it is often associated with a suboptimal environment. However, this may not always be the case as some behaviors can develop independently of any psychological distress, be triggered in environments known to promote welfare, and be part of an animal's coping mechanism. Furthermore, not all animals develop abnormal behavior, which has led researchers to assess risk factors that differentiate individuals in the display of these behaviors. Intrinsic risk factors that have been identified include the animal's species and genetics, age, sex, temperament, and clinical condition, while environmental risk factors include variables such as the animal's rearing, housing condition, husbandry procedures, and research experiences. To identify specific triggers and at-risk animals, the expression of abnormal behavior in captive nonhuman primates should be routinely addressed in a consistent manner by appropriately trained staff. Which behaviors to assess, what assessment methods to use, which primates to monitor, and the aims of data collection should all be identified before proceeding to an intervention and/or treatment. This article provides guidance for this process, by presenting an overview of known triggers and risk factors that should be considered, steps to design a comprehensive evaluation plan, and strategies that might be used for prevention or treatment. It also outlines the tools and processes for assessing and evaluating behavior in an appendix. This process will lead to a better understanding of abnormal behavior in captive primate colonies and ultimately to improved welfare.
... 257-258). One important type of reinforcing consequence mediated by another organism is the opportunity to engage in social interaction; and indeed, social reinforcement effects have been reported in a range of species, including humans (Jones et al., 2011) chimpanzees (Mason et al., 1962), capuchin monkeys (Dettmer & Fragaszy, 2000), horses (Søndergaard et al., 2011), foxes (Hovland et al., 2011), calves (Holm et al., 2002), pigs (Kirkden & Pajor, 2006), mice (Martin et al., 2014), and rats (Evans et al., 1994;Wilsoncroft, 1968) (see review by (Trezza et al., 2011). ...
Article
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Rats were given repeated choices between social and nonsocial outcomes, and between familiar and unfamiliar social outcomes. Lever presses on either of 2 levers in the middle chamber of a 3‐chamber apparatus opened a door adjacent to the lever, permitting 45‐s access to social interaction with the rat in the chosen side chamber. In Experiment 1, rats preferred (a) social over nonsocial options, choosing their cagemate rat over an empty chamber, and (b) an unfamiliar over a familiar rat, choosing a non‐cagemate over their cagemate. These findings were replicated in Experiment 2 with 2 different non‐cagemate rats. Rats preferred both non‐cagemate rats to a similar degree when pitted against their cagemate, but were indifferent when the 2 non‐cagemates were pitted against each other. Similar preference for social over nonsocial and non‐cagemate over cagemate was seen in Experiment 3, with new non‐cagemate rats introduced after every third session. Response rates (for both cagemate and non‐cagemate rats) were elevated under conditions of nonsocial (isolated) housing compared to conditions of social (paired) housing, demonstrating a social deprivation effect. Together, the experiments contribute to an experimental analysis of social preference within a social reinforcement framework, drawing on methods with proven efficacy in the analysis of reinforcement more generally.
... En general, los resultados sugieren que el comportamiento reforzado socialmente comparte propiedades funcionales con otros reforzadores, e ilustra un conjunto prometedor de métodos para cuantificar el valor del refuerzo social. Palabras clave: reforzamiento social, análisis de demanda, procedimiento de ayuda, ratas There is ample evidence from both field and laboratory research that social contact can serve as a potent source of reinforcement in a broad range of species, including chimpanzees (Mason, Hollis, & Sharpe, 1962), capuchin monkeys (Dettmer & Fragaszy, 2000), horses (Søndergaard, Jensen, & Nicol, 2011), foxes (Hovland et al., 2011), calves (Holm, Jensen, & Jeppesen, 2002), sows (Kirkden & Pajor, 2006), hamsters (Borland et al., 2017), prairie voles (Beery, Christensen, Lee, & Blandino, 2018), mice (Martin, Sample, Gregg, & Wood, 2014), and rats (Evans et al., 1994;Wilsoncroft, 1968) (see review by Trezza, Campolongo, & Vanderschuren, 2011). ...
Article
Full-text available
Rats were studied in social-release procedures, in which lever presses by one rat released a second rat from a tube restraint for a period of social interaction. Both the fixed-ratio price and the duration of social contact were varied systematically on a within-subject basis, generating a total of 27 demand functions across six subjects. Overall, the data were well accounted for by the essential value model (96% VAF), supporting a social reinforcement view, according to which social-release behavior is maintained by social contact with another rat. Response rates and parameter fitswere comparable in 25-min and 120-min sessions, showing little evidence of satiation.Overall, the findings suggest that socially-reinforced behavior shares functionalproperties with other reinforcers, and illustrate a promising set of methods for quantifying social reinforcement value.
... For example, adult rhesus macaques chose to remain in the same cage as their social companions despite tradeoffs in available space (Basile, Hampton, Chaudry, & Murray, 2007). Also, captive tufted capuchin monkeys (Cebus apella) often chose their companions over food, even several hours after food deprivation (Dettmer & Fragaszy, 2000). Lastly, access to social partners buffers physiological stress during stressful procedures in captivity (Hennessy, Kaiser, & Sachser, 2009;Kikusui, Winslow, & Mori, 2006;Truelove et al., 2017), such as witnessing the anesthesia of another animal in the room (Gilbert & Baker, 2011). ...
Article
Laboratory rhesus macaques are often housed in pairs and may be temporarily or permanently separated for research, health, or management reasons. While both long‐term social separations and introductions can stimulate a stress response that impacts inflammation and immune function, the effects of short‐term overnight separations and whether qualities of the pair relationship mediate these effects are unknown. In this study, we investigated the effects of overnight separations on the urinary cortisol concentration of 20 differentially paired adult female rhesus macaques (Macaca mulatta) at the California National Primate Research Center. These females were initially kept in either continuous (no overnight separation) or intermittent (with overnight separation) pair‐housing and then switched to the alternate pair‐housing condition part way through the study. Each study subject was observed for 5 weeks, during which we collected measures of affiliative, aggressive, anxious, abnormal, and activity‐state behaviors in both pair‐housing conditions. Additionally, up to three urine samples were collected from each subject per week and assayed for urinary free cortisol and creatinine. Lastly, the behavioral observer scored each pair on four relationship quality attributes (“Anxious,” “Tense,” “Well‐meshed,” and “Friendly”) using a seven‐point scale. Data were analyzed using a generalized linear model with gamma distribution and an information theoretic approach to determine the best model set. An interaction between the intermittent pairing condition and tense pair adjective rating was in the top three models of the best model set. Dominance and rates of affiliation were also important for explaining urinary cortisol variation. Our results suggest that to prevent significant changes in HPA‐axis activation in rhesus macaque females, which could have unintended effects on research outcomes, pairs with “Tense” relationships and overnight separations preventing tactile contact should be avoided.
... The expressions of behaviors with such dramatic influence on the animals' fitness has been suggested to be accompanied by high motivation (Dawkins, 1990). For example, when tested on a series of preference tests, capuchin monkeys (Cebus apella) equally valued social companionship and food (Dettmer & Fragaszy, 2000). Accordingly, among zoohoused NHP the chronic inability to express highly motivated behaviors have been linked to poor welfare (Pomerantz, Meiri, & Terkel, 2013). ...
Article
Full-text available
Social housing of rhesus macaques (Macaca mulatta) is considered to be the cornerstone of behavioral management programs in biomedical facilities. However, it also involves the risk of socially inflicted trauma. The ability to avoid such trauma would contribute to the animals' well-being and alleviate staff's concerns, thus paving the path for more introductions. Here, we sought to address the conflict between the need to socially house rhesus macaques and the need to bring social wounding to a minimum by identifying behaviors expressed early in social introductions, that may serve as predictors of later wounding events. We employed logistic regression analysis to predict the occurrence of wounding for 39 iso-sexual, adult pairs in the 30 days following the introduction into full contact using the levels of behaviors that were observed at the onset of the introduction. The results show that the levels of submissive behaviors were the only significant predictor to later stage wounding. Higher levels of submissive behaviors expressed during the early phases of the introduction were associated with a decreased likelihood of wounding. Interestingly, levels of affiliative behaviors have not added any power to the predictability of the statistical model. Therefore, it may be suggested that the exchange of submissive signals at the earliest stages of the introduction is critical in the determination of relative rank and preclude the need to establish dominance via aggression when allowed full contact. While the observation of clear-cut dominance relationships is commonly considered a harbinger of success, our findings suggest that it is the acknowledgment of subordination, rather than the expression of dominance that underlies this observed pattern. The value of our findings for guiding social housing decision-making may be strongest in situations in which the composition of potential partners is constrained, and therefore requiring that wise decisions be relied upon early behaviors.
... In a forced choice study pitting an emotional pain (social separation) against an aversive physical affect (hunger) in pair-housed tufted capuchin monkeys (Cebus apella), monkeys that had lived as pairs for a minimum of two months were separated and given the choice of food or rejoining their companion [144]. The majority (4 of 7) of subjects chose their social companion over food even after lengthy periods of food deprivation (22 h, the maximum time food was withheld), suggesting that social deprivation was more aversive than hunger to most of the monkeys. ...
Article
The natural forces of attraction constitute a basic foundation within the field of physics. Each of the four known forces–gravitational, electromagnetic, and the strong and weak nuclear forces–act invisibly to draw physical structures together and maintain their proximity. In the field of biology, another force acts in a very similar way. This force, exerting its effect on the brains and biology of social animals, draws living organisms together to formsocial organizations connecting animals in simple and complex ways. Like the other attractive forces of nature, this force operating between living beings cannot be observed directly but is open to scientific inquiry by studying the effects on the interactions between individuals. The social attractive force bears a fundamental difference from nature's other forces of attraction in that evidence indicates the social force to be a product of an evolutionary process. The behavioral, neural, hormonal, cellular, and genetic mechanisms underlying social bonds evolved to elicit social behaviors which would help organisms survive, reproduce, and care for offspring sufficiently long that they too reproduced [2]. It is the underlying processes driving this force that play a critical role in the well-being of the organisms under its influence. The goal of social neuroscience is to fully understand the processes that generate and influence this drawing power between living beings, and in so doing be able to maximize the well-being of the individuals experiencing the effects of these forces. To that end, this paper presents a review of the current knowledge of the functions and mechanisms of social bonding, then describe the implications of this knowledge for the well-being of social animals with particular emphasis on the domestic dog.
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Primates are highly social animals and appropriate enrichment is required to ensure their psychological well-being. Mirrors are sometimes used as social or sensory environmental enrichment. In this paper we investigate the suitability of mirrors as enrichment for captive primates, by reviewing the literature on mirror implementation in captive primate environments. Mirror-directed responses are mainly social as the mirror self-image is often seen as a conspecific. Although positive exploration and affiliative behaviours are observed, negative aggressive behaviours towards the mirror are most frequently recorded, and abnormal behaviours in primates do not decrease in mirror-enriched environments. There appear to be differences in habituation rates to mirrors amongst primates. While habituation to enrichment is generally perceived to be undesirable, this criterion should not apply when mirrors elicit negative behaviours. Primates that show mirror self-recognition, which are mostly great apes, may be best suitable for mirror enrichment, as they do not perceive the mirror self-image as a threatening conspecific. Increasing the understanding of the reflective properties of a mirror might help primates to understand that the image in the mirror is not real. This could be attained by using small, mobile mirrors. We suggest that mirrors can make decent primate enrichment if the primate understands its reflective properties, which should be evaluated on an individual level. Appropriate use of mirrors as sensory enrichment can improve primate well-being and prevent suffering.
Chapter
Biological overviewSources of supplyUses in the laboratoryLaboratory management and breedingLaboratory proceduresAnaesthesiaEuthanasiaDiseases and treatmentsReferences
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To study animal welfare empirically we need an objective basis for deciding when an animal is suffering. Suffering includes a wide range ofunpleasant emotional states such as fear, boredom, pain, and hunger. Suffering has evolved as a mechanism for avoiding sources ofdanger and threats to fitness. Captive animals often suffer in situations in which they are prevented from doing something that they are highly motivated to do. The “price” an animal is prepared to pay to attain or to escape a situation is an index ofhow the animal “feels” about that situation. Withholding conditions or commodities for which an animal shows “inelastic demand” (i.e., for which it continues to work despite increasing costs) is very likely to cause suffering. In designing environments for animals in zoos, farms, and laboratories, priority should be given to features for which animals show inelastic demand. The care ofanimals can thereby be based on an objective, animal-centered assessment of their needs.
Book
• The four parts of which this work consists, though intimately related to each other as different views of the same great aggregate of phenomena, are yet, in the main, severally independent and complete in themselves. The General Analysis is an inquiry concerning the basis of our intelligence. Its object is to ascertain the fundamental peculiarity of all modes of consciousness constituting knowledge proper—knowledge of the highest validity. The Special Analysis has for its aim, to resolve each species of cognition into its components. Commencing with the most involved ones, it seeks by successive decompositions to reduce cognitions of every order to those of the simplest kind; and so, finally to make apparent the common nature of all thought, and disclose its ultimate constituents. The General Synthesis, setting out with an abstract statement of the relation subsisting between every living organism and the external world, and arguing that all vital actions whatever, mental and bodily, must be expressible in terms of this relation; proceeds to formulate, in such terms, the successive phases of progressing Life, considered apart from our conventional classifications of them. And the Special Synthesis, after exhibiting that gradual differentiation of the psychical from the physical life which accompanies the evolution of Life in general, goes on to develop, in its application to psychical life in particular, the doctrine which the previous part sets forth: describing the nature and genesis of the different modes of Intelligence, in terms of the relation which obtains between inner and outer phenomena. (PsycINFO Database Record (c) 2012 APA, all rights reserved) • The four parts of which this work consists, though intimately related to each other as different views of the same great aggregate of phenomena, are yet, in the main, severally independent and complete in themselves. The General Analysis is an inquiry concerning the basis of our intelligence. Its object is to ascertain the fundamental peculiarity of all modes of consciousness constituting knowledge proper—knowledge of the highest validity. The Special Analysis has for its aim, to resolve each species of cognition into its components. Commencing with the most involved ones, it seeks by successive decompositions to reduce cognitions of every order to those of the simplest kind; and so, finally to make apparent the common nature of all thought, and disclose its ultimate constituents. The General Synthesis, setting out with an abstract statement of the relation subsisting between every living organism and the external world, and arguing that all vital actions whatever, mental and bodily, must be expressible in terms of this relation; proceeds to formulate, in such terms, the successive phases of progressing Life, considered apart from our conventional classifications of them. And the Special Synthesis, after exhibiting that gradual differentiation of the psychical from the physical life which accompanies the evolution of Life in general, goes on to develop, in its application to psychical life in particular, the doctrine which the previous part sets forth: describing the nature and genesis of the different modes of Intelligence, in terms of the relation which obtains between inner and outer phenomena. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Article
An audiovisual stimulus was made contingent upon the rat’s licking at the water spout, thus making it analogous with a gustatory stimulus. When the audiovisual stimulus and the gustatory stimulus were paired with electric shock the avoidance reactions transferred to the audiovisual stimulus, but not the gustatory stimulus. Conversely, when both stimuli were paired with toxin or x-ray the avoidance reactions transferred to the gustatory stimulus, but not the audiovisual stimulus. Apparently stimuli are selected as cues dependent upon the nature of the subsequent reinforcer.
Article
Mammals are unique among vertebrates in experiencing a need to carry out behaviours which are not necessary for their immediate survival. This poses questions as to the nature of these behavioural needs, how they evolved and their implications for the welfare of mammals in captivity. Evidence is provided to show that mammals carry out daily programmes of activity which meet four kinds of requirement, namely, for security, appropriate environmental complexity, novelty and opportunities for achievement. Within their programmes mammals perform two kinds of activity: work, which relates to day to day survival, and leisure, in the form of curiosity or play, which provides experience which may prove to be of value in the long term. The existence of behavioural needs is consistent with our knowledge of mammalian evolution. Even the earliest known mammals, living over 120 million years ago, differed from reptiles in having brain to body size ratios four to five times greater. The increase in brain size resulted largely from the massive expansion of a region of the cerebral cortex, known as the neopallium, which acts as a co-ordinating centre for sensory data, and creates a model of the world which determines subsequent action. During the 60 million year tertiary era, relative brain size increased in most orders of eutherian mammals, so that only the more intelligent survived. Because mammals rely for their survival on collecting and analyzing data and acting intelligently, they need facilities to search for information to establish and monitor their concept of the real world; their psychological well-being depends on an environment which offers such facilities. There are two kinds of behavioural needs; psychological needs, which appear to be unique to mammals, and ethological needs which are experienced by all vertebrates. It is concluded that environmental quality for captive mammals should not just be assessed negatively, by the absence of abnormal behaviours, but more positively by the extent to which it meets their psychological needs.
Article
1. Battery‐kept hens (Sykes Tints) showed a preference for a large (0.76 x 0.86 m) over a small (0.38 x 0.43 m) cage, but preferred the smaller cage when this had a litter floor to the one 4 times larger with a wire floor.2. The hens still showed a preference for litter when they could obtain access to it only by entering an even smaller cage (0.38 x 0.215 m) in which they could hardly turn round. This cage gave far less space than that recommended by the UK Welfare Codes (1971).3. The experiments described demonstrate that hens prefer larger to smaller cages and litter floors to wire ones, but that they give highest priority to flooring. Increasing the space allowed to battery‐kept hens may not therefore be as “valuable” to them as giving them access to litter.
Article
SEQUENCES OF POSITIONS FOR THE PLACING OF THE POSITIVE STIMULUS IN A 2-CHOICE VISUAL DISCRIMINATION TASK AS CONSTRUCTED BY GELLERMAN ARE EXAMINED BY MEANS OF A HYPOTHESIS-ANALYSIS TECHNIQUE AND ARE FOUND TO BE UNSATISFACTORY ON 2 COUNTS: (1) THEY FAIL TO ENSURE THAT NO POSITION HYPOTHESIS WILL PRODUCE OTHER THAN CHANCE PERFORMANCE ON THE LEARNING CURVE, AND (2) THEY FAIL TO PREVENT THE DIFFERENTIAL REINFORCEMENT OF POSITION HYPOTHESES. A NEW SET OF SEQUENCES IS PROPOSED WHICH SATISFY THESE CONDITIONS. SUGGESTIONS ARE MADE AS TO THE COMBINATION OF THESE SEQUENCES FOR USE IN RELATIVELY LONG DISCRIMINATION TASKS. (22 REF.) (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Article
This book is a continuation of my Motivation and Personality, published in 1954. It was constructed in about the same way, that is, by doing one piece at a time of the larger theoretical structure. It is a predecessor to work yet to be done toward the construction of a comprehensive, systematic and empirically based general psychology and philosophy which includes both the depths and the heights of human nature. The last chapter is to some extent a program for this future work, and serves as a bridge to it. It is a first attempt to integrate the "health-and-growth psychology" with psychopathology and psychoanalytic dynamics, the dynamic with the holistic, Becoming with Being, good with evil, positive with negative. Phrased in another way, it is an effort to build on the general psychoanalytic base and on the scientific-positivistic base of experimental psychology, the Eupsychian, B-psychological and metamotivational superstructure which these two systems lack, going beyond their limits. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Article
The concept of an ‘ethological need’ has assumed a prominent place in recent discussions of animal welfare, although the term itself is surrounded by confusion. It is here argued that some of this confusion might be overcome by applying consumer demand theory to some of the problems of animal welfare. As an example, the postulated ‘need’ of battery-caged hens to scratch and dustbathe is reinterpreted in this light, using the economic definition of a ‘necessity’. Two attempts to measure the value that hens put on access to litter are reported. In experiment 1, birds were required to make an instantaneous choice between food and litter under different degrees of food deprivation. In experiment 2, choices were observed over longer periods of time under changes of income (time available). In neither case was there evidence of hens regarding litter as a necessity but these results should be regarded only as preliminary.
Article
Removal of juvenile rhesus monkeys from their natal social group to indoor individual caging resulted in increased basal cortisol secretion and significant decrements in the frequency of lymphoid subpopulations. Fourteen juvenile rhesus monkeys, which had never been removed from the group, were studied. Baseline immune and cortisol measurements were obtained before seven of the subjects were removed from social housing to standard individual cages. The remaining seven subjects, matched for age, sex, weight, and rank, remained in the social group throughout the study serving as controls. Blood samples were taken 24 hours after removal of the test subjects from the group and at specific intervals thereafter through 11 weeks. At 24 hours after the separation test subjects showed a significant increase in basal cortisol levels (40%) and a significant decrease in several immune parameters, with absolute numbers of total T cells declining 72 +/- 12%. Significant group differences in immune parameters persisted through 11 weeks. Eighteen weeks following removal, the test subjects were returned to the group which produced a cortisol rise in both test and controls at the 24-hour postreturn sample. Although there were no group differences in the frequency of lymphoid subsets 24 hours after return, some test subjects showed marked decrements which were inversely related to cortisol and were predicted by behavioral events. These data demonstrate that the removal of naive juvenile rhesus monkeys from their natal social group to individual indoor caging is a potent psychosocial stressor and that the behavioral interactions which characterize the return of the individual subjects to the natal group may predict physiological response.