EFFECTS OF RESTRAINT AND ISOLATION ON YELPING IN PUPPIES*

By SHERMAN ROSS, J. P. SCOTT, MARIA CHERNER AND VICTOR H . DENENBERGRoscoe B. Jackson

Scott & Marston (1950) report that youngpuppies below the age of twelve weeks are oftenobserved to give a rapid series of whines or yelpsat rates rising to over 100 per minute. This be-haviour appears to be associated with varioussituations of obvious discomfort : hunger, cold,_confinement, isolation, etc . It may be called` .`distress vocalization" and can be classified aset-epimiletic or care-soliciting behaviour . Yelp-ing can be easily quantified by counting thenumber of discrete sounds . The purpose of thisstudy was to explore the effects of some environ-mental factors which affect yelping .

Fredricson (1950) found that confinement ofan isolated puppy outside the home pen wouldproduce high rates of vocalization in puppies6 to 10 weeks of age . In a second paper (Fred-ricson, 1952) he showed that placing a secondpuppy in the box reduced the rate of yelping 50per cent. or more, and that substituting a smallbox in place of the puppy had no appreciableeffect. He also found a larger differential withpuppies that were first placed in confinementwith another puppy than with puppies firstplaced alone in the box . Causey (1956) obtainedpreliminary results with a small group of pup-pies which indicated that puppies isolated in astrange room showed more vocalization thanthose isolated in a familiar one .

From these studies a number of possible fac-tors which affect distress vocalization might beconsidered, such as confinement, isolation,strangeness of the test environment, previousexperience, and age . It also is clear that yelpingmay be a potential indicator of various sorts ofemotional distress in the puppy . It was ourpurpose to explore the characteristics of yelpingbehaviour: (1) by determining if reliable differ-ences in yelping could be secured which wouldreflect imposed variables of restraint and isola-'This study was supported in part by research grantsM-123 and M-522 from the National Institute of MentalHealth, U.S. Public Health Service, to the Division ofBehavior Studies, Roscoe B . Jackson Memorial Labor-atory. Miss Cherner was a Summer Research Appren-tice at the laboratory. Dr. V. H. Denenberg, PurdueUniversity, was a Vis~d

Scientist, and Dr. ShermanRoes, University of ryland, is a scientific Associateof the Labo glory. Dr. Scott is chairman of the Divisionof Behavior Studies,

Memorial Laboratory, Bar Harbor, Maine

I

tion, and (2) by determining if longer and con-tinued exposure to the distress producing situ-ation resulted in a decline in yelping . Two experi-ments were made.

Subjects and MethodsTwenty-nine hybrid and 6 pure bred puppies

from 3 to 6 weeks old were used as subjects .Details of breeding, sex, and age are shown inTable 1 .

The first experiment dealt with the effects ofrestraint, using yelping as the major measure ofdistress. Twenty-three puppies from 3 hybridlitters 4 weeks of age were randomly assignedinto two basic groups : Restraint (R) or Non-Restraint (NR) . We added the variables of beingalone (A), or together with a litter-mate (T),giving us four conditions under which to measureyelping: (1) alone in pen (NR-A) ; (2) alone inrestraint box (R-A) ; (3) together with a litter-mate in pen (NR-T) ; and (4) together with alitter-mate in restraint box (R-T) . The puppies ineach group were tested each day for 5 minutes inone of the following orders : ATTA and TAAT .The series was repeated once.

Prior to testing, the mother and all puppieswere removed from the home cage and placed ina large cart which was moved out of sight of thecage. The puppies to be tested were then re-placed singly or in pairs in the home cage andallowed to run around freely, or were placedinside the restraint box . The number of yelps wasrecorded by the observer, who stood quietlynearby and counted them with a hand counter .When puppies were tested in pairs it was easy todetermine which puppy was making the noise byobserving characteristic mouth and head move-ments .

For the second experiment, 12 puppies, aged3 to 6 weeks, were randomly assigned to theextreme groups of the first set of experimentalconditions : Restraint-Alone (R-A) and Non-Restraint-Together (NR-T). Testing durationwas 10 minutes with yelping scores tallied at theend of each 5-minute period . One trial a day wasmade for 10 consecutive days .The restraint box was made of wood in a

triangular shape : 17} in. long, 9,111 in. across thefront, and 6} in . deep. The lid was made of wire

mesh. This material also covered the front, sothat the restrained puppy was always able to"see" many familiar home objects . The majorityof the home pens were the standard weaningpens, approximately 6 feet square with openwire fronts. The cocker spaniel puppies werereared in large nursery rooms, 10 ft. x 17 ft. insize, and enclosed on all sides .

Other indications of distress recorded duringthe experimental trials included degree ofactivity, defaecation, and urination :

ResultsThe results of .the first experiment, in which

yelping was measured under each of four experi-mental conditions, are shown in Table II andFig. 1 . The major variables were the effects ofrestraint against non-restraint and being con-fined alone against together with a litter mate. Inaddition, the dogs were tested in one of twoorders, starting either under the alone conditionor under the together condition of confinement .

Because of the unequal numbers of subjects (6puppies in each cell except the NR-T first, wherethere were 5) an analysis of unweighted meanswas used. In this procedure the mean for each ofthe 8 cells was com~~tted and an analysis of vari-ance was performed on these means . The two-error term sums of squares subjects within cellsand A x S) were computed y from the rawscores and were then reduced to a mean valueby dividing by the harmonic mean. The method

ANIMAL BEHAVIOUR, VIII, 1 -2

Table J . Characteristics of Subjects

is essentially the same as that described byWalker & Lev (1953, pp. 381-382).

The analysis shows that yelping was signific-antly more frequent when the subjects wererestricted than when non-restricted (p<0 .01),

W

RE$fl AINED "11111.111ts 11AptEp.

Fig. 1 . The mean number ofyes for each of the grottosrestraint and non-restraint under the aloneandtosietherconditions .

ExperimentNumberin litter Sex, M/F

Weight rangeParentage

Kg.Age in daysat first test

1 7

8

8

4/3

2/6

4/4

Scottie-Cocker-Beagle x Elkhound-

Basenji

Scottie-

le xSchipperk

ocker

Scottie-Beagle-,Schipperke xScottie-Dachshund-Beagle

I

3 .76-4 .50

2.00--4 .38

2 .00-4.08

28

27

28

2 3/0 Pug-Dachshund xPug-Dachshund

1 .00-1 .16 21

1 0/1 Cocker Spaniel 1 .46 38

2 0/2 Cocker Spaniel 2 .01-3 .20 44

3 3/0 Cocker Spaniel 1 .54-1 .76 25

1/2 Cocker x Basenji 1 .44-1 .78 38

ROSS, ET AL : EFFECTS OF RESTRAINT AND ISOLATION ON YELPING IN PUPPIES

Table U. Nu bar of V

Under Condlllsas of Ieelatiea ad RembsW

and that the alone condition brought about asignificantly greater number of yelps than thetogether condition (p. <0-01). Further, these twovariables interacted significantly at the 0 .05level . Fig. I shows that the combined effects ofbeing alone and in a restricted environmentapparently acted to increase differentially thenumber of yelps . The order of testing was notsignificant, nor did this variable interact witheither of the other two main effects either singlyor in combination .

The nature of the observed effects is clear .Undisturbed puppies in the home cage withtheir mother and litter-mates ordinarily showlittle or no distress vocalization. The puppieswhich were placed alone in the pens-gave someyelps in every case . In the non-restrained puppiesthe range was from 7 to 687 in a 5-minute period .In the restrained puppies the range was from 485to 969. Being alone in the home pen produces adefinite reaction, though not as great as beingalone under other conditions .

Placing a litter-mate with the puppy reducesthe amount of emotional distress as indicated byyelping, but does not bring it back down to zeroin all cases, as does restoring the mother and alllitter-mates. The effect of adding a companionis highly significant statistically . In the 12 re-strained puppies every one showed more yelpsalone than when together with a littermate .

Restraint produces similar highly significanteffects . Each animal in the restrained group canbe compared with a non-restrained litter-matetested in the same way . In every one of the I Ipairs the restrained puppy showed more totalyelps than the non-restrained litter-mate, whetherthe testing was done alone or together . There islittle doubt that restraint produced large andsignificant increases of yelping.

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The relationship between the experimentalfactors is obviously not a simple additive one, ascan be seen in Fig . 1. In non-restrained puppies,adding the second puppy reduces the averagenumber of yelps by 286 . The effect of the secondpuppy upon a restrained littermate is to reducethe average number of yelps by 783 . The secondpuppy has more than twice the effect that it hadunder the first condition . However, the per-centage of reduction compared to the total isapproximately the same, being 60 per cent . forthe non-restrained puppies and 52 per cent . forthe restrained ones . In other words, the presenceof a second animal appears to reduce the over-allexcitement by a proportional amount rather thanby an absolute amount, and this agrees withFredericson's (1950 ; 1952) results . This relation-ship probably explains the interaction effectbrought out by analysis of variance .The second experiment was designed to study

the effect of adaptation to the two extreme con-ditions of Experiment 1, viz . restricted*aloneagainst non-restricted-together. Four subjectsunder the first condition and eight under thelatter were given one 10-minute test per day for10 consecutive days . The means and standarddeviations are presented in Table 111, and ;Fig . 2is a graphic presentation of the findings . Thehighly significant difference between the twogroups confirms the findings of the first experi-ment that the conditions of restricted-aloele,andnon-restricted-together bring about major differ-ences in yelping behaviour. The significant trialseffect indicates that yelping decreased over the10-day interval, presumably due to adaptation tothe experimental conditions. The lack of asignificant interaction between groups and trialsshows that this adaptation was the same foi • bothgroups ;

Condition ATTA TAAT

Alone Together

Alone Together

Restraint Mean 1506 .5 785 .0 1480 .3 636 .6

SD 247-8 290 .7 326 .5 454-5

N 6

No-Restraint Mean 460 . 1 83-5 470-6 294 .0

SD 292-0 287 .0 89-8 436 .4

N 6 5

4

1100+

1000

400

tiao

ALONE -RESTRAINED

A N I M A L III- H A V I O U R, VIII, 1- 2

'fable IH . Results for Experiment 2

oI

T

aTRIALS

Fig . 2 . The mean number of yelps for 10 trials for theAlone-Restraint and the Together-Non-restraint groups .

As a check upon the adaptation hypothesis,the number of yelps emitted during the first 5minutes of testing was compared to the numberemitted during the last 5 minutes for trials 1 and10. Significant differences at the 0.05 level (one-tailed tests) were found for each of the trials .

DiscussionThe results of the first experiment demonstrate

that the yelping behaviour of puppies can beproduced by placing them alone in the home pen .Restraint added to isolation markedly increasesthe amount of yelping. Adding a littermate hasthe effect of reducing the total amount of yelpingby approximately 50-60 per cent . These findingsconfirm those of Fredericson (1950 ; 1952) and, inaddition, indicate that physical restraint is oneof the factors that contributes to emotionaldistress . Support is also given to the preliminary

finding of Causey (1956), that isolation pro-duces less distress in the home pen 'than in un-familiar surroundings .As can be seen from Table II, yelping be-

haviour is highly variable between individuals .The behaviour of individual puppies is muchmore consistent, there being "high" yelpers and"low" yelpers. Individual reaction to the ex-perimental factors is consistent. The possibilitythat the results could be obtained by accidentof sampling of genetically different individuals isextremely small . That such clear-cut results canbe obtained with a group of hybrids may in-dicate that the phenomena are characteristic ofall dogs rather than one particular breed.

The finding that the order of testing producesno significant effects is contrary to Fredericson'sresults that a puppy first confined with a litter-mate away from the home pen is less upset bysubsequent isolation in the same situation . Thisdifference is probably explained by the shortperiod of testing used in the present experiment(5 minutes). The amount of yelping dies downchiefly in the second 5 minutes (Experiment 2,Fig. 2), and Fredericson's puppies were testedfor 10 minutes .

The second experiment chiefly dealt with theeffects of the duration factor on the yelping be-haviour shown under the two extreme experi-mental conditions. Over the period of 10 trials,the mean number of yelps for both the restrainedalone and non-restrained-together groups ,show-ed a significant though gradual decrease . It ismore likely that this decrease is due to adapta-tion to the situaton and learning rather than tomaturation, since the decrease was obtainedwithin trials as well as between trials. The mostlikely explanation is that the puppy learns thatit will be released after a short time, and hencebecomes less disturbed emotionally .

Defaecation and urination were not important

Condition Trials

1

2

1

3

4

5 6

7

8 9 10

Mean 1128 .75 1348 . 75 1182-00 : 1167-251 1154 .50 1090 . 75 1041 . 75 1017 .75-

884 .00 920 .25R-A(N=4) 5 .0 341-22 , 399 .45 390 .81 1 601 .34 567 . 18 725 . 12 297 . 33 392 .83 572 . 99 512 .93

Mean 348 .25 ~ 281 .87 397.501 439 .00 214 .87 234 .12 1 290 . 12 i 50 .00 67 .00 128 .00

NR-T I(N=8) . D. 478 .37 296 .86 450 .731 391 .04 254 .76 294 .561 308 .24

43 .80 110 .40 147 .54

ROSS, ET AL : EFFECTS OF RESTRAINT AND ISOLATION ON YELPING IN PUPPIES

5

dependent variables in either experiment . Yelp-ing was greatest in the stress condition of R-A,but of 40 tests made with the restraint box, inonly two were there signs of eliminative be-haviour. This behaviour was exhibited morefrequently by puppies in the least stress produc-ing situation, that of NR-T . Among restrainedpuppies there was an observable amount of in-creased activity, which usually included biting,licking and clawing the front mesh of the rc-straint box. Play behaviour was exhibited often(and only) by puppies in the NR-T condition .

The question might be raised as to whether ornot the conditions of restraint and isolation areinnate releasing mechanisms. The reaction ofYelping or whining is a primary one, appearingat bir, and some of the adequate stimuli orreleasers are pain, cold and hunger. However, thereaction of excessive vocalization does not ap-pear in older puppies which have been rearedalone in small boxes from before the time of thecritical period of socialization (Fisher, 1955) .Such animals are both restrained and isolated .We are dealing here with something more com-plex than a simple IRM : an interaction of en-vironmental situations, organization of be-haviour through learning, and innate organisa-tion of behaviour . The yelping response ismodifiable by hereditary factors (Scott, 1957),and it is likely that there is a tendency to developthis response to isolation and restraint undernormal conditions of rearing .

As et-epimeletic or care-soliciting behaviour,the yelping of puppies is equivalent to the dis-tress vocalization of other animals. Such be-haviour offers many experimental possibilities,both as a measure of the strength of social re-lationships involved in imprinting and primarysocialization, and as a measure of emotional dis-tress in young animals, including human babies,where separation from the mother has beenfound to have important psychological effects(Bowlby, 1951) . Further, yelping behaviourmay prove to be a reliable and sensitive measureof a variety of imposed experimental variables .

SummaryThis study dealt with the effects of restraint,

isolation and companionship on the yelping be-haviour of puppies. Thirty-five puppies ofvarious complex hybrid and pure breeds, aged3 to 6 weeks, were used . The condition ofrestraint was produced with a small triangularwooden box, open at the top and front, whichwas covered with wire mesh . All tests were in thehome pen, and yelps were recorded with a handtally counter.

In the first experiment the effects of restraint(R) against non restraint (NR) weree tested asmodified by the condition of alone (A) and to-gether (T) . Twenty-three puppies, aged 4 weeks,were randomly assigned to one of the 'basicgroups of R or NR. They were . then given aseries of 5 minute tests, ATTA or TAAT, underthe basic conditions of R or NR . The yelpingbehaviour of the restrained (R) group was foundto be significantly higher than the non-restrained(NR) group, and the alone (A) condition pro-duced more yelping, than the together (T) con-dition. Both of these differences were significantbeyond the 0 .01 level. Both isolation and. re-straint increase yelping . Adding a companionreduces yelping by 50-60 .per cent .The second experiment was performed with

twelve puppies, aged 3 to 6 weeks, randomlyassigned to the extreme conditions of the firstexperiment, those of R-A and NR-T. The effectsof test duration upon yelping behaviour wasstudied with 10 trials, one per day, of 10 minuteseach. Statistical analysis of these results on-strated that there was a similar and significantdecrease (0 .01 level) in the mean number ofyelps in both the R-A and the NR-T groups .Comparison of means for the first 5 minutesagainst the second 5 minutes made on trialsI and 10, showed a decrease in yelping behavioursignificant at the 0 . 05 level. It was concludedthat repetition of the experience reduces yelping,probably because of learning and adjustment tothe situation.

REFERENCESBowlby, J . (1951). Maternal care and mental health .

Geneva : World Health Organization .Causey, Anne (1956) . A developmental study of emotion-

ality in puppies under conditions of stress.Unpublished ms ., E. B . Jackson MemorialLaboratory, Bar Harbor, Maine.

Fisher, A. E. (1955). The effects of differential, earlytreatment on the social and exploratory behpviourof puppies . Ph.D. thesis, Pennsylvania StateUniversity .

Fredric son, E . (1950). Distributed versus massed ex-perience in a traumatic situation . J. abnornt. sac.Psychol., 45, 259-266.

Fredricson, E. (1952). Perceptual homeostasis and dis-tress vocalization in puppies. J. Personal., 20,427-477 .

Scott, J. P., & Marston, Mary V . (1950). Critical periodsaffecting the development of normal and inalad-ustiyve social2 behaviourviour of puppies. JA genet.

Scott, J . P. (1957). The genetic and environmental pltlbr-entiation of behaviour. In : he Concept of de-velopneent, D. Harris (Ed.). Minneap is:' Uni-versity of Minnesota Press.

Walker H. & Lev, J. (1953). Stalstdcal inference. NewFork: Henry Holt & Company.Accepted for publication 14th July, 1959 .