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Effects of deprivation on exercise play in nursery school children
AnOn.Behav.,1980,28, 922-928
EFFECTS OF DEPRIVATION ON EXERCISE PLAY IN NURSERY SCHOOL CHILDREN BY PETER K. SMITH & TERESA H A G A N
Department of Psychology, University of Sheffield, Sheffield S10 2TN Abstract. The incidence of exercise play outdoors was observed in nursery school children aged three to four years, after a short or long period of confinement indoors. For both boys and girls there was a greater incidence of exercise play after the long period of confinement, the levels of exercise play decreasing with time. No sex differences were obtained. The results are considered in relation to theories of the functional significance of exercise play. muscle growth and helps develop general physical capacity. Brownlee (1954) did indeed propose that exercise play served as physical training, in the case of domestic cattle. However, the idea has been rather neglected until recently restated by Fagen (1976a). Fagen has argued that for young mammals, external needs or goals (for example, in food getting, or fighting) provide insufficient exercise practice, so that self-motivated exercise, or exercise play, is needed. Exercise in infancy is important for the future survival and evolutionary fitness of the animal; thus, although there are immediate fitness costs to exercise play, they may be outweighed by future benefits (Fagen 1976b). Fagen's review of exercise physiology supports the contention that regular exercise can improve both the strength and endurance of particular muscle groups, and more generally the functioning of the cardiopulmonary system; and that such exercise is particularly efficacious in the young. Most of this evidence is in fact drawn from work on humans. As stated by Fagen (1976a), this physical training theory explains some reasonably wellestablished facts about exercise play, notably that it is age-dependent (Fagen 1976b) and that it is only found in warm-blooded animals. Some predictions are also made from the theory, including an increase in play on release from confinement. Although not stated explicitly by Fagen, a corollary of this prediction is that such an increase in exercise play would decline with increased time from the end of the confinement period. Some anecdotal evidence does support these predictions. Cooper (1942) observed a lot of exercise play when lions were released from confinement, and Brownlee (1954) observed the same in domestic cattle. Krott & Krott (1963) described vigorous approach-withdrawal
Introduction Children often engage in vigorous physical activity. While this may sometimes be organized, as in gymnastics classes, it more usually occurs in a play context. During school break times, for example, many children engage in games or activities which involve running, chasing, climbing, swinging, hopping and other behaviours requiring vigorous muscle activity. This sometimes takes the form of rough-and-tumble play (Blurton Jones 1967) but more often there are no quasi-agonistic aspects and the activity may indeed be solitary. Vigorous exercise in an apparently nonfunctional context, either social or solitary, is described as 'exercise play' by Fagen (1976a) and 'general activity play' by Millar (1968). The former term will be used here. As these authors point out, exercise play is common in the young of other mammals. The historical explanation of exercise play is that of the surplus energy theory stated by Spencer (1878) and embedded in everyday descriptions of children 'letting off steam' or 'getting rid of their energy'. However, the surplus energy theory is now generally agreed to be inadequate. There is no independent criterion of what energy is 'surplus', the idea of a building up of energy which needs discharge is physiologically unsound, and no explanation is provided of why young mammals should have so much surplus energy to use up. Stemming from the alternative tradition of theorising by Groos (1898), a more satisfactory theory is obtained by inverting the logic of the surplus energy theory and stressing the functional importance of exercise play. Putting this in modern terms, young mammals who are intrinsically motivated to engage in exercise play do so because in life-history terms the benefits to inclusive fitness exceed the costs. The most likely benefit is that exercise play stimulates
922
SMITH & HAGAN: EXERCISE PLAY IN CHILDREN play in young brown bears after winter inactivity. However, data from more controlled experimental conditions is desirable, and here the evidence has seemed much more equivocal. The few previous experimental studies have all used non-human species. Mtiller-Schwarze (1968) deprived two black-tailed deer of leaping, running and kicking exercise by offering them milk each time they began such a play bout. The results were inconclusive. There was no increase in frequency of play behaviours after the deprivation period was over, though one of the deer only did show higher running speeds. The presence of milk as a possible reward for certain behaviours confounds the results of this study, which also had a very small sample size. MfillerSchwarze & Miiller-Schwarze (1969) did find less running in a play bout after deer had been walked for several hundred metres prior to that bout. Chepko (1971) deprived young goats of play by physical confinement and by interruption. After deprivation, there was an increase m total activity time, and number and duration of activity periods. However, Chepko reported 'too few observations and too little data at this point to compute meaningful statistics on the significance of the increase in activity following deprivation' (op. cit., page 524); and in a personal communication to Bekoff (1976) she reported failing to find a statistically significant effect in a follow-up study controlling for additional factors. Oakley & Reynolds (1976) deprived two species of monkeys of social play. Social play is distinct from exercise play but would overlap considerably in these species. Deprivation was achieved by throwing food at the monkeys to distract them from play, or by making them spend more time foraging by giving them seeds instead of monkey chow. Play was reduced by these methods, and a subsequent rebound observed, in a colony of Macaca mulatta. However, no such effects were obtained for a colony of Macaca fascicularis. These experimental studies are inconclusive (Bekoff 1976). Depriving play by means of offering food is essentially problematic, and even when confinement has been used the deprivation condition seems to have been novel for the animals concerned. One way to avoid such extraneous factors confounding the deprivation condition is to compare two such deprivation conditions, one of long and one of short duration. The study to be reported used this method,
923
with deprivation being achieved by naturally occurring physical confinement. The study was carried out on human children. This was felt to be particularly apposite, since much of Fagen's (1976a) supporting argument is based on human data. Nursery school age children were used since this is an age of high general physical activity (Routh et al. 1974), and the children are unselfconscious and readily observed with minimal disruption to ongoing behaviour (Connolly & Smith 1972). The study was designed to see if increased length of confinement led to increased occurrence of exercise play; if any such increase declined and over how long a time period; and whether any sex differences in activity level interacted with the deprivation rebound, if it existed.
Method Subjects The children were from a self-contained nursery class, taking separate groups for morning and afternoon sessions. The study was carried out independently on both groups, to provide a literal replication (Lykken 1968) and see if similar results were obtained. Each group had a maximum attendance of 20 children, but two children in each group were absent for most of the observations. This left the morning class with 18 children (9 boys, mean age 3 years 9 months; 9 girls, mean age 3 years 11 months) and the afternoon class with 18 children (9 boys, mean age 3 years 11 months; 9 girls, mean age 3 years 11 months). The age range overall was from 2 years 10 months to 4 years 9 months. All ages are from the time of commencement of the study. Mean attendance during observation periods was 14.7 children in the morning group and 17.3 children in the afternoon group.
Experimental Conditions The study was carried out in the autumn term. The usual nursery routine was for the children to spend some time at activities indoors, often table work, painting, or sand play, and then go outside into an adjoining play area. The indoor area was approximately 37 m 2, and the outdoor area approximately 204 m2; depending on attendance, space per child was 1.9 to 3.1 m2/child indoors, and 10.2 to 16:7 m2/child outdoors. Previous work on the effects of spatial density has shown that conditions as crowded as 1,9 to 3.1 m2/child severely restricts gross physical activity (Smith & Connolly 1977;
924
ANIMAL
BEHAVIOUR,
Connolly & Smith 1978; Smith & Connolly in press); in addition, the indoor area was full of equipment such as tables, chairs and worksurfaces. Exercise play or vigorous physical activity was rare in the indoors area, and tended to be discouraged by staff on the few occasions it did occur. When outdoors, however, there was abundant space, and exercise play was not only permitted but encouraged by the kinds of toys--tricycles, barrels, climbing-framemwhich were available. The two conditions of the study differed in the length of time spent indoors before outdoor play was allowed. For both morning and afternoon groups, the total session length was 2.5 h (0900 to 1130 hours, and 1300 to 1530 hours respectively). In condition 1 (short confinement) the children were indoors for half an hour, then went outdoors; after about three quarters of an hour the children went indoors again. In condition 2 (long confinement) the children were indoors for one and a half hours, then went outdoors for the remaining period (ostensibly one hour, but mothers began to arrive after three quarters of an hour). In previous terms the children had usually been indoors for about an hour before going outside if weather permitted, though the schedule had not been rigid. The two conditions chosen were therefore roughly equal departures from normal practice, as far as this could be defined. However, in the term in question a new nursery teacher had been appointed to the class, and she was willing to try out new schedules and varied the schedule for some weeks before formal observations began. Following the long summer break, the children therefore experienced a variable schedule and by the time the experiments started neither the long nor short confinement conditions would have seemed particularly unusual. Data Collection
After the initial acclimatization period for the children, and observational pilot work, the data collection period extended over six weeks in the middle of the autumn term. Data was recorded on most days, excluding bad weather or occurrences such as doctor's visits. The two conditions were counterbalanced for order effects, for each group. It had been intended to collect 10 observational sessions for each condition, for each group. However, increasingly bad weather towards the end of the term meant that eventually data were recorded
28,
3
for the morning group for eight sessions of condition 1 and ten of condition 2; while for the afternoon group nine sessions were obtained for each condition. For each session the attendance was recorded, and the outdoor temperature and weather conditions noted. The same outdoor play equipment was available on each occasion. For each outdoor session teachers ratings were obtained for the level of overall physical activity for the preceding indoors period. The ratings were on a seven point scale from 1 (very little physical activity) to 7 (a great deal of physical activity). Mean ratings were low, independent of condition: 1.9 and 1.9 for the two conditions for the morning class, and 1.9 and 2.0 for short and long confinement, in the afternoon class. This supports the previous research suggesting very little exercise play when spatially confined to the extent indicated. When let into the outdoor play area, pilot work had suggested that vigorous physical activity occurred but declined considerably over a half hour period; so a 30 min period was taken as the observation time for outdoor activity. Observational Procedure All observations were made by one observer, who stood at the side of the playground. Her presence during the acclimatization period meant that she was virtually ignored by the children (Connolly & Smith 1972). Observations were obtained by scan sampling (Altmann 1974) at 3-min intervals. Within each interval, children were observed in a predetermined order. At the moment of observation, the child was scored for occurrence or non-occurrence of exercise play. Exercise play was defined as any gross bodily or muscular activity; it principally consisted of running, hopping, jumping, throwing, chasing, fleeing, failing around, wrestling, hitting, climbing or rolling. Vigorous pedalling, or pushing of an object such as a pram or scooter, was included. Walking, or non-strenuous use of equipment, did not count as exercise play. Essentially, vigorous physical activity was being measured; the great majority of these occurrences would probably be described by most observers as playful, but this was not required in the scoring procedure. Accuracy of scoring was checked with independent observers before and after the main data collection. The mean percentage agreement for occurrence of exercise play was 91 70.
SMITH & HAGAN: EXERCISE PLAY IN CHILDREN
925
Table I. Results of Analyses of Variance for Morning and Afternoon Groups Morning group F value Condition Sex Condition x sex Time Condition • time Sex x time Condition x sex x time
F(1, 16) = F(1, 16) = F ( I , 16) = F(9,144) = F(9,144) = F(9,144) = F(9,144) =
Afternoon group
Sig. level 43.39 0.04 3.95 16.90 0.14 0.10 0.96
Results F o r each g r o u p in each condition, the p r o p o r tion o f scans in which exercise p l a y was observed was calculated for each child, over all sessions in which t h a t child was present. I n this w a y a c o m p a r a b l e score was o b t a i n e d for each child in each condition, despite variable attendance. U s i n g an arcsine t r a n s f o r m a t i o n ( W i n e r 1962, page 221) these d a t a were subjected to analysis o f variance. A four-factor r e p e a t e d measures design, c o n d i t i o n • subject x sex x time, was used. Results are shown in T a b l e I.
F value
P < 0.001 NS Ns P < 0.001 Ns Ns Ns
F(1, 16) = F(1, 16) = F(1, 16) = F(9,144) = F(9,144) = F(9,144) = F(9,144) =
Sig. level 71.80 0.30 0.00 24.35 5.54 1.95 2.06
P < 0.001 NS NS P < 0.001 P < 0.001 P < 0.05 P < 0.05
Fig. 1. T h e higher overall activity level o f the a f t e r n o o n g r o u p children m a y have helped m a k e this effect m o r e significant t h a n was the case for the children in the m o r n i n g group. The o t h e r two interaction effects only j u s t reach significance, for the afternoon group. The 50a
A,M, CLASS
40-
30
Effects of Short or Long Confinement The c o n d i t i o n effect is very highly significant, for b o t h m o r n i n g a n d a f t e r n o o n classes. I t is illustrated in Fig. 1. L o n g e r confinement leads very p r e d i c t a b l y to a c o n s i d e r a b l y higher level o f occurrence o f exercise p l a y when subsequently outdoors. Effects of Sex of Child F o r b o t h m o r n i n g a n d a f t e r n o o n classes, sex differences in the occurrence o f exercise p l a y were small a n d quite non-significant. T h e interactions o f sex with c o n d i t i o n were also n o n significant. Effects of Time Through Session W i t h successive scans t h r o u g h the 30-min session, the occurrence o f exercise p l a y declined very considerably, as shown in Fig. 1. This is highly significant for b o t h m o r n i n g a n d aftern o o n classes. F o r the a f t e r n o o n g r o u p only, there are significant interactions o f time t h r o u g h session with condition, sex, a n d c o n d i t i o n x sex. T h e m o s t significant interaction is t h a t with condition. Exercise p l a y declined m o r e r a p i d l y after long confinement t h a n after s h o r t confinem e n t in this group, the effect being a p p a r e n t in
~
20
.~,~
10
8 "~.j"\ ~] \"~"\ X u~
\
P.M. CLASS
.o~~~176....~~ 0"
~
6
9
~
12
MINUTES
n
- - u 90 MINS. IN.
~~ o~
~
18
21
24
27
30
OUTDOORS
u
--Q 30 MINS. IN.
Fig. 1. Percentage of scans in which exercise play occurred, after short (D - - o) or long (11 - - III) periods of confinement indoors.
926
ANIMAL
BEHAVIOUR,
incidence of exercise play fell off with time more rapidly with girls than boys, and especially in condition 2 (long confinement). Changes Over Sessions
For a given condition the incidence of exercise play on different sessions varied, though with no very consistent trends. Variations might be due to attendance, temperature, and weather conditions, as well as other reasons. Table II shows correlations over sessions of the incidence of exercise play with the above mentioned factors. There is some tendency for more exercise play when attendance is higher, and on sunny and moderately warm rather than rainy or cold days. It was of course impossible to control for these factors, and differences between the two conditions on these measures might conceivably confound the results. To examine this possibility, mean scores for the two conditions, for each group, were calculated and are shown in Table III. For the morning group, condition 2 (long confinement) sessions did have a slightly larger attendance, but slightly colder days and one more rainy day than condition 1. These small differences work against each other, and the likelihood of them substantially affecting the
28,
3
main results is slight. For the afternoon group, the two conditions are closely matched for attendance, and temperature. Condition 1 did have two more rainy days than condition 2, but these particular days did not produce lower scores for exercise play, as the positive correlation in Table II indicates. Discussion
Longer compared to shorter confinement leads very reliably to appreciably more exercise play in the three and four year old children who took part in this study. The effect was found independently in both groups of children, and is sufficiently large that alternative explanations are very unlikely. The two outdoor conditions did differ in actual time of day, since the long confinement meant outdoor play occurred one hour later. Time of day might in itself affect activity level. However, previous work suggests that activity level in morning and afternoon nursery sessions is similar (Smith & Connolly 1972); and anyway the use of separate morning and afternoon groups means that such an explanation of the condition effect is implausible. The afternoon group did have a higher overall activity level, but this could be explained by individual
Table H. Correlations of Proportion of Exercise Play with Attendance, Temperature, and Rainy/Sunny Weather, Over Sessions for Each Group in Each Condition
Morning group
Condition 1 Condition 2
Afternoon group
Condition 1 Condition 2
Attendance
Temperature
Rainy/sunny
0.32 0.03
0.28 0.27
-- 0.76* -- 0.17
0.20 0.43
0.00 0.01
0.23 -- 0.48
Note: rainy (1) or sunny (0) is treated as a dichotomous variable. *P < 0.05. Table HI. Mean Attendance and Temperature, and Number of Rainy/Sunny Days, for Each Group in Each Condition
Attendance Morning group
Condition 1 Condition 2
Afternoon group
Condition 1 Condition 2
Temperature (C) Rainy/Sunny
14.1 15.1
12.0 10.6
2/6 3/7
17.4 17.2
11.0 11.4
3/6 1/8
SMITH & HAGAN: EXERCISE PLAY IN CHILDREN differences in the children and by the higher average attendance (Tables II, III). The effects of attendance, temperature, and weather condition have been considered, and discounted as likely explanations of the condition effect. The observations were not done blind. This would have been difficult, as the conditions would have been obvious to any observer. Videofilming and subsequent scoring could circumvent this, but filming was felt to be less efficient and probably disruptive of the children's behaviour. The occurrence of exercise play was easy to score, and concordance with independent observers was high. The results are of sufficient magnitude that observer bias is an unlikely explanation. The effect of confinement was found to hold for both boys and g.irls, and the lack of a sex difference in exercise play may be noted. Generally, boys have been reported as being more physically active; but the difference for pre-school children seems to be small (Fales 1937; Pederson & Bell 1970; Smith & Connolly 1972). Also, part of the difference usually observed may be attributable to a preference in boys to go outdoors when a choice is available (Harper & Sanders 1975). In the present study, all the children went outdoors after the indoor period. Sex differences might of course be greater in older children. The enhancement of exercise play by confinement, and the decline to near zero of the differential effects of short and long confinement (after about 30 min in the present study), are in conformity with Fagen's (1976a) theory. However, such results would also be consistent with any functional theory of exercise play which postulated a self-motivated need to engage in such activity. Such a need might be fairly directly tied to physiological factors, or more indirectly mediated by some requirement of external stimulus change. Indeed, the present results would be compatible with the surplus energy theory, although drawbacks to this theory were mentioned in the introduction. Future work might consider in more detail the variety of muscle groups exercised and the kinds of exercise involved. Fagen (1976a) would predict systematic exercise of a variety of muscle groups for both force and stamina, with corresponding specific rebound effects of deprivation which would not be predicted on a surplus energy theory. Examination of the confinement effect in relation to exercise play of
927
older children would also provide a test of Fagen's theory, which should predict that effects of confinement may, at first, increase with age, but should subsequently decrease. The reasoning would be analogous to that of Fagen (1976b). In humans, in contrast to non-human species, the young ma.y be required to engage in physical exercise, as m gymnastics classes or dance routines; these may provide much of the exercise necessary for physical training. However, it seems likely that children will also be selfmotivated to engage in physical exercise, and the more so, the longer since the last exercise period. The present study has demonstrated the existence of this phenomenon, but its practical as well as theoretical implications deserve more extended study. For example, much academic schooling is largely sedentary, and short playground breaks are allowed, partly to afford opportunity for physical exercise. The length and scheduling of such school breaks, and the relationship to children's age and to their educational and physical development, could profitably be examined in the light of further research in this area. Acknowledgments We are grateful to the staff and children of the Mushroom Lane Nursery School, Sheffield, for their participation in the study, and to Dr Sean Neill for comments on an earlier draft of the paper. REFERENCES Altmann, J. 1974. Observational study of behavior: sampling methods. Behaviour, 49, 227-265. Bekoff, M. 1976. Animal play: problems and perspectives. In: Perspectives in Ethology, Vol. 2 (Ed. by P. P. G. Bateson & P. H. Klopfer), pp. 165-188. New York and London: Plenum Press. Blurton Jones, N. G. 1967. An ethological study of some aspects of social behaviour of children in nursery school. In: Primate Ethology (Ed. by D. Morris), pp. 347-368. London: Weidenfeld and Nicolson. Brownlee, A. 1954. Play in domestic cattle: an analysis of its nature. Br. Vet. J., 110, 48-68. Chepko, B. D. 1971. A preliminary study of the effects of play deprivation on young goats. Z. Tierpsychol., 28, 517-526. Connolly, K. & Smith, P. K. 1972. Reactions of preschool children to a strange observer. In: Ethological Studies of Child Behaviour (Ed. by N. Blurton Jones), pp. 157-172. Cambridge: Cambridge University Press. Connolly, K. & Smith, P. 1978. Experimental studies of the pre-school environment. Int. J. Early Childhood, 10, 86--95. Cooper, J. B. 1942. An exploratory study on African lions. Comp. PsychoL Monogr., 17, 1--48.
928
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BEHAVIOUR,
Fagen, R. M. 1976a. Exercise, play, and physical training in animals. In: Perspectives in Ethology, Vol. 2 (Ed. by P. P. G. Bateson & P. H. Klopfer), pp. 189-219. New York & London: Plenum Press. Fagen, R. M. 1976b. Selection for optimal age-dependent schedules of play behavior. Am. Nat., 111, 395-414. Fales, E. 1937. A comparison of the vigorousness of play activities of preschool boys and girls. Child Dev., 8, 144-158. Groos, K. 1898. The Play of Animals. New York: Appleton. Harper, L. V. & Sanders, K. M. 1975. Preschool children's use of space: sex differences in outdoor play. Dev. Psychol., 11, 119. Krott, P. & Krott, G. 1963. Zum Verhalten des Braunb~iren in den Alpen. Z. Tierpsychol., 20, 160-206. Lykken, D. T. 1968. Statistical significance in psychological research. PsychoL Bull., 70, 151-159. Millar, S. 1968. The Psychology of Play. Harmondsworth: Penguin. Miiller-Schwarze, D. 1968. Play deprivation in deer. Behaviour, 31, 144-162. Miiller-Schwarze, D. & Miiller-Schwarze, C. 1969. Spielverhalten und allgemeine Aktivit~it bei Schwarzwedelhirschen. Bonner Zool. Beitrage, 10, 282-289. Oakley, F. B. & Reynolds, P. C. 1976. Differing responses to social play deprivation in two species of
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macaque. In: The Anthropological Study of Play: Problems and Prospects (Ed. by D. F. Lancy & B. A. Tindall), pp. 179-188. Cornwall, N.Y.: Leisure Press. Pedersen, F. A. & Bell, R. Q. 1970. Sex differences in preschool children without histories of complications of pregnancy and delivery. Dev. PsychoL, 3, 10-15. Routh, D. K., Schroeder, C. S. & O'Tuoma, L. A. 1974. Development of activity level in children. Dev. PsychoL, 10, 163-168. Smith, P. K. & Connolly, K. 1972. Patterns of play and social interaction in preschool children. In: Ethological Studies of Child Behaviour (Ed. by N. Blurton Jones), pp. 65-95. Cambridge: Cambridge University Press. Smith, P. K. & Connolly, K. 1977. Social and aggressive behaviour in preschool children as a function of crowding. Soc. Sci. Inform., 16, 601-620. Smith, P. K. & Connolly, K. In press. The Ecology of Preschool Behaviour. Cambridge: Cambridge University Press. Spencer, H. 1878. The Principles of Psychology, Vol. 2. New York: Appleton. Winer, B. J. 1962. Statistical Principles in Experimental Design. New York: McGraw-Hill.
(Received 7 August 1979; revised 2 October 1979; MS. number: 1921)
EFFECTS OF DEPRIVATION ON EXERCISE PLAY IN NURSERY SCHOOL CHILDREN BY PETER K. SMITH & TERESA H A G A N
Department of Psychology, University of Sheffield, Sheffield S10 2TN Abstract. The incidence of exercise play outdoors was observed in nursery school children aged three to four years, after a short or long period of confinement indoors. For both boys and girls there was a greater incidence of exercise play after the long period of confinement, the levels of exercise play decreasing with time. No sex differences were obtained. The results are considered in relation to theories of the functional significance of exercise play. muscle growth and helps develop general physical capacity. Brownlee (1954) did indeed propose that exercise play served as physical training, in the case of domestic cattle. However, the idea has been rather neglected until recently restated by Fagen (1976a). Fagen has argued that for young mammals, external needs or goals (for example, in food getting, or fighting) provide insufficient exercise practice, so that self-motivated exercise, or exercise play, is needed. Exercise in infancy is important for the future survival and evolutionary fitness of the animal; thus, although there are immediate fitness costs to exercise play, they may be outweighed by future benefits (Fagen 1976b). Fagen's review of exercise physiology supports the contention that regular exercise can improve both the strength and endurance of particular muscle groups, and more generally the functioning of the cardiopulmonary system; and that such exercise is particularly efficacious in the young. Most of this evidence is in fact drawn from work on humans. As stated by Fagen (1976a), this physical training theory explains some reasonably wellestablished facts about exercise play, notably that it is age-dependent (Fagen 1976b) and that it is only found in warm-blooded animals. Some predictions are also made from the theory, including an increase in play on release from confinement. Although not stated explicitly by Fagen, a corollary of this prediction is that such an increase in exercise play would decline with increased time from the end of the confinement period. Some anecdotal evidence does support these predictions. Cooper (1942) observed a lot of exercise play when lions were released from confinement, and Brownlee (1954) observed the same in domestic cattle. Krott & Krott (1963) described vigorous approach-withdrawal
Introduction Children often engage in vigorous physical activity. While this may sometimes be organized, as in gymnastics classes, it more usually occurs in a play context. During school break times, for example, many children engage in games or activities which involve running, chasing, climbing, swinging, hopping and other behaviours requiring vigorous muscle activity. This sometimes takes the form of rough-and-tumble play (Blurton Jones 1967) but more often there are no quasi-agonistic aspects and the activity may indeed be solitary. Vigorous exercise in an apparently nonfunctional context, either social or solitary, is described as 'exercise play' by Fagen (1976a) and 'general activity play' by Millar (1968). The former term will be used here. As these authors point out, exercise play is common in the young of other mammals. The historical explanation of exercise play is that of the surplus energy theory stated by Spencer (1878) and embedded in everyday descriptions of children 'letting off steam' or 'getting rid of their energy'. However, the surplus energy theory is now generally agreed to be inadequate. There is no independent criterion of what energy is 'surplus', the idea of a building up of energy which needs discharge is physiologically unsound, and no explanation is provided of why young mammals should have so much surplus energy to use up. Stemming from the alternative tradition of theorising by Groos (1898), a more satisfactory theory is obtained by inverting the logic of the surplus energy theory and stressing the functional importance of exercise play. Putting this in modern terms, young mammals who are intrinsically motivated to engage in exercise play do so because in life-history terms the benefits to inclusive fitness exceed the costs. The most likely benefit is that exercise play stimulates
922
SMITH & HAGAN: EXERCISE PLAY IN CHILDREN play in young brown bears after winter inactivity. However, data from more controlled experimental conditions is desirable, and here the evidence has seemed much more equivocal. The few previous experimental studies have all used non-human species. Mtiller-Schwarze (1968) deprived two black-tailed deer of leaping, running and kicking exercise by offering them milk each time they began such a play bout. The results were inconclusive. There was no increase in frequency of play behaviours after the deprivation period was over, though one of the deer only did show higher running speeds. The presence of milk as a possible reward for certain behaviours confounds the results of this study, which also had a very small sample size. MfillerSchwarze & Miiller-Schwarze (1969) did find less running in a play bout after deer had been walked for several hundred metres prior to that bout. Chepko (1971) deprived young goats of play by physical confinement and by interruption. After deprivation, there was an increase m total activity time, and number and duration of activity periods. However, Chepko reported 'too few observations and too little data at this point to compute meaningful statistics on the significance of the increase in activity following deprivation' (op. cit., page 524); and in a personal communication to Bekoff (1976) she reported failing to find a statistically significant effect in a follow-up study controlling for additional factors. Oakley & Reynolds (1976) deprived two species of monkeys of social play. Social play is distinct from exercise play but would overlap considerably in these species. Deprivation was achieved by throwing food at the monkeys to distract them from play, or by making them spend more time foraging by giving them seeds instead of monkey chow. Play was reduced by these methods, and a subsequent rebound observed, in a colony of Macaca mulatta. However, no such effects were obtained for a colony of Macaca fascicularis. These experimental studies are inconclusive (Bekoff 1976). Depriving play by means of offering food is essentially problematic, and even when confinement has been used the deprivation condition seems to have been novel for the animals concerned. One way to avoid such extraneous factors confounding the deprivation condition is to compare two such deprivation conditions, one of long and one of short duration. The study to be reported used this method,
923
with deprivation being achieved by naturally occurring physical confinement. The study was carried out on human children. This was felt to be particularly apposite, since much of Fagen's (1976a) supporting argument is based on human data. Nursery school age children were used since this is an age of high general physical activity (Routh et al. 1974), and the children are unselfconscious and readily observed with minimal disruption to ongoing behaviour (Connolly & Smith 1972). The study was designed to see if increased length of confinement led to increased occurrence of exercise play; if any such increase declined and over how long a time period; and whether any sex differences in activity level interacted with the deprivation rebound, if it existed.
Method Subjects The children were from a self-contained nursery class, taking separate groups for morning and afternoon sessions. The study was carried out independently on both groups, to provide a literal replication (Lykken 1968) and see if similar results were obtained. Each group had a maximum attendance of 20 children, but two children in each group were absent for most of the observations. This left the morning class with 18 children (9 boys, mean age 3 years 9 months; 9 girls, mean age 3 years 11 months) and the afternoon class with 18 children (9 boys, mean age 3 years 11 months; 9 girls, mean age 3 years 11 months). The age range overall was from 2 years 10 months to 4 years 9 months. All ages are from the time of commencement of the study. Mean attendance during observation periods was 14.7 children in the morning group and 17.3 children in the afternoon group.
Experimental Conditions The study was carried out in the autumn term. The usual nursery routine was for the children to spend some time at activities indoors, often table work, painting, or sand play, and then go outside into an adjoining play area. The indoor area was approximately 37 m 2, and the outdoor area approximately 204 m2; depending on attendance, space per child was 1.9 to 3.1 m2/child indoors, and 10.2 to 16:7 m2/child outdoors. Previous work on the effects of spatial density has shown that conditions as crowded as 1,9 to 3.1 m2/child severely restricts gross physical activity (Smith & Connolly 1977;
924
ANIMAL
BEHAVIOUR,
Connolly & Smith 1978; Smith & Connolly in press); in addition, the indoor area was full of equipment such as tables, chairs and worksurfaces. Exercise play or vigorous physical activity was rare in the indoors area, and tended to be discouraged by staff on the few occasions it did occur. When outdoors, however, there was abundant space, and exercise play was not only permitted but encouraged by the kinds of toys--tricycles, barrels, climbing-framemwhich were available. The two conditions of the study differed in the length of time spent indoors before outdoor play was allowed. For both morning and afternoon groups, the total session length was 2.5 h (0900 to 1130 hours, and 1300 to 1530 hours respectively). In condition 1 (short confinement) the children were indoors for half an hour, then went outdoors; after about three quarters of an hour the children went indoors again. In condition 2 (long confinement) the children were indoors for one and a half hours, then went outdoors for the remaining period (ostensibly one hour, but mothers began to arrive after three quarters of an hour). In previous terms the children had usually been indoors for about an hour before going outside if weather permitted, though the schedule had not been rigid. The two conditions chosen were therefore roughly equal departures from normal practice, as far as this could be defined. However, in the term in question a new nursery teacher had been appointed to the class, and she was willing to try out new schedules and varied the schedule for some weeks before formal observations began. Following the long summer break, the children therefore experienced a variable schedule and by the time the experiments started neither the long nor short confinement conditions would have seemed particularly unusual. Data Collection
After the initial acclimatization period for the children, and observational pilot work, the data collection period extended over six weeks in the middle of the autumn term. Data was recorded on most days, excluding bad weather or occurrences such as doctor's visits. The two conditions were counterbalanced for order effects, for each group. It had been intended to collect 10 observational sessions for each condition, for each group. However, increasingly bad weather towards the end of the term meant that eventually data were recorded
28,
3
for the morning group for eight sessions of condition 1 and ten of condition 2; while for the afternoon group nine sessions were obtained for each condition. For each session the attendance was recorded, and the outdoor temperature and weather conditions noted. The same outdoor play equipment was available on each occasion. For each outdoor session teachers ratings were obtained for the level of overall physical activity for the preceding indoors period. The ratings were on a seven point scale from 1 (very little physical activity) to 7 (a great deal of physical activity). Mean ratings were low, independent of condition: 1.9 and 1.9 for the two conditions for the morning class, and 1.9 and 2.0 for short and long confinement, in the afternoon class. This supports the previous research suggesting very little exercise play when spatially confined to the extent indicated. When let into the outdoor play area, pilot work had suggested that vigorous physical activity occurred but declined considerably over a half hour period; so a 30 min period was taken as the observation time for outdoor activity. Observational Procedure All observations were made by one observer, who stood at the side of the playground. Her presence during the acclimatization period meant that she was virtually ignored by the children (Connolly & Smith 1972). Observations were obtained by scan sampling (Altmann 1974) at 3-min intervals. Within each interval, children were observed in a predetermined order. At the moment of observation, the child was scored for occurrence or non-occurrence of exercise play. Exercise play was defined as any gross bodily or muscular activity; it principally consisted of running, hopping, jumping, throwing, chasing, fleeing, failing around, wrestling, hitting, climbing or rolling. Vigorous pedalling, or pushing of an object such as a pram or scooter, was included. Walking, or non-strenuous use of equipment, did not count as exercise play. Essentially, vigorous physical activity was being measured; the great majority of these occurrences would probably be described by most observers as playful, but this was not required in the scoring procedure. Accuracy of scoring was checked with independent observers before and after the main data collection. The mean percentage agreement for occurrence of exercise play was 91 70.
SMITH & HAGAN: EXERCISE PLAY IN CHILDREN
925
Table I. Results of Analyses of Variance for Morning and Afternoon Groups Morning group F value Condition Sex Condition x sex Time Condition • time Sex x time Condition x sex x time
F(1, 16) = F(1, 16) = F ( I , 16) = F(9,144) = F(9,144) = F(9,144) = F(9,144) =
Afternoon group
Sig. level 43.39 0.04 3.95 16.90 0.14 0.10 0.96
Results F o r each g r o u p in each condition, the p r o p o r tion o f scans in which exercise p l a y was observed was calculated for each child, over all sessions in which t h a t child was present. I n this w a y a c o m p a r a b l e score was o b t a i n e d for each child in each condition, despite variable attendance. U s i n g an arcsine t r a n s f o r m a t i o n ( W i n e r 1962, page 221) these d a t a were subjected to analysis o f variance. A four-factor r e p e a t e d measures design, c o n d i t i o n • subject x sex x time, was used. Results are shown in T a b l e I.
F value
P < 0.001 NS Ns P < 0.001 Ns Ns Ns
F(1, 16) = F(1, 16) = F(1, 16) = F(9,144) = F(9,144) = F(9,144) = F(9,144) =
Sig. level 71.80 0.30 0.00 24.35 5.54 1.95 2.06
P < 0.001 NS NS P < 0.001 P < 0.001 P < 0.05 P < 0.05
Fig. 1. T h e higher overall activity level o f the a f t e r n o o n g r o u p children m a y have helped m a k e this effect m o r e significant t h a n was the case for the children in the m o r n i n g group. The o t h e r two interaction effects only j u s t reach significance, for the afternoon group. The 50a
A,M, CLASS
40-
30
Effects of Short or Long Confinement The c o n d i t i o n effect is very highly significant, for b o t h m o r n i n g a n d a f t e r n o o n classes. I t is illustrated in Fig. 1. L o n g e r confinement leads very p r e d i c t a b l y to a c o n s i d e r a b l y higher level o f occurrence o f exercise p l a y when subsequently outdoors. Effects of Sex of Child F o r b o t h m o r n i n g a n d a f t e r n o o n classes, sex differences in the occurrence o f exercise p l a y were small a n d quite non-significant. T h e interactions o f sex with c o n d i t i o n were also n o n significant. Effects of Time Through Session W i t h successive scans t h r o u g h the 30-min session, the occurrence o f exercise p l a y declined very considerably, as shown in Fig. 1. This is highly significant for b o t h m o r n i n g a n d aftern o o n classes. F o r the a f t e r n o o n g r o u p only, there are significant interactions o f time t h r o u g h session with condition, sex, a n d c o n d i t i o n x sex. T h e m o s t significant interaction is t h a t with condition. Exercise p l a y declined m o r e r a p i d l y after long confinement t h a n after s h o r t confinem e n t in this group, the effect being a p p a r e n t in
~
20
.~,~
10
8 "~.j"\ ~] \"~"\ X u~
\
P.M. CLASS
.o~~~176....~~ 0"
~
6
9
~
12
MINUTES
n
- - u 90 MINS. IN.
~~ o~
~
18
21
24
27
30
OUTDOORS
u
--Q 30 MINS. IN.
Fig. 1. Percentage of scans in which exercise play occurred, after short (D - - o) or long (11 - - III) periods of confinement indoors.
926
ANIMAL
BEHAVIOUR,
incidence of exercise play fell off with time more rapidly with girls than boys, and especially in condition 2 (long confinement). Changes Over Sessions
For a given condition the incidence of exercise play on different sessions varied, though with no very consistent trends. Variations might be due to attendance, temperature, and weather conditions, as well as other reasons. Table II shows correlations over sessions of the incidence of exercise play with the above mentioned factors. There is some tendency for more exercise play when attendance is higher, and on sunny and moderately warm rather than rainy or cold days. It was of course impossible to control for these factors, and differences between the two conditions on these measures might conceivably confound the results. To examine this possibility, mean scores for the two conditions, for each group, were calculated and are shown in Table III. For the morning group, condition 2 (long confinement) sessions did have a slightly larger attendance, but slightly colder days and one more rainy day than condition 1. These small differences work against each other, and the likelihood of them substantially affecting the
28,
3
main results is slight. For the afternoon group, the two conditions are closely matched for attendance, and temperature. Condition 1 did have two more rainy days than condition 2, but these particular days did not produce lower scores for exercise play, as the positive correlation in Table II indicates. Discussion
Longer compared to shorter confinement leads very reliably to appreciably more exercise play in the three and four year old children who took part in this study. The effect was found independently in both groups of children, and is sufficiently large that alternative explanations are very unlikely. The two outdoor conditions did differ in actual time of day, since the long confinement meant outdoor play occurred one hour later. Time of day might in itself affect activity level. However, previous work suggests that activity level in morning and afternoon nursery sessions is similar (Smith & Connolly 1972); and anyway the use of separate morning and afternoon groups means that such an explanation of the condition effect is implausible. The afternoon group did have a higher overall activity level, but this could be explained by individual
Table H. Correlations of Proportion of Exercise Play with Attendance, Temperature, and Rainy/Sunny Weather, Over Sessions for Each Group in Each Condition
Morning group
Condition 1 Condition 2
Afternoon group
Condition 1 Condition 2
Attendance
Temperature
Rainy/sunny
0.32 0.03
0.28 0.27
-- 0.76* -- 0.17
0.20 0.43
0.00 0.01
0.23 -- 0.48
Note: rainy (1) or sunny (0) is treated as a dichotomous variable. *P < 0.05. Table HI. Mean Attendance and Temperature, and Number of Rainy/Sunny Days, for Each Group in Each Condition
Attendance Morning group
Condition 1 Condition 2
Afternoon group
Condition 1 Condition 2
Temperature (C) Rainy/Sunny
14.1 15.1
12.0 10.6
2/6 3/7
17.4 17.2
11.0 11.4
3/6 1/8
SMITH & HAGAN: EXERCISE PLAY IN CHILDREN differences in the children and by the higher average attendance (Tables II, III). The effects of attendance, temperature, and weather condition have been considered, and discounted as likely explanations of the condition effect. The observations were not done blind. This would have been difficult, as the conditions would have been obvious to any observer. Videofilming and subsequent scoring could circumvent this, but filming was felt to be less efficient and probably disruptive of the children's behaviour. The occurrence of exercise play was easy to score, and concordance with independent observers was high. The results are of sufficient magnitude that observer bias is an unlikely explanation. The effect of confinement was found to hold for both boys and g.irls, and the lack of a sex difference in exercise play may be noted. Generally, boys have been reported as being more physically active; but the difference for pre-school children seems to be small (Fales 1937; Pederson & Bell 1970; Smith & Connolly 1972). Also, part of the difference usually observed may be attributable to a preference in boys to go outdoors when a choice is available (Harper & Sanders 1975). In the present study, all the children went outdoors after the indoor period. Sex differences might of course be greater in older children. The enhancement of exercise play by confinement, and the decline to near zero of the differential effects of short and long confinement (after about 30 min in the present study), are in conformity with Fagen's (1976a) theory. However, such results would also be consistent with any functional theory of exercise play which postulated a self-motivated need to engage in such activity. Such a need might be fairly directly tied to physiological factors, or more indirectly mediated by some requirement of external stimulus change. Indeed, the present results would be compatible with the surplus energy theory, although drawbacks to this theory were mentioned in the introduction. Future work might consider in more detail the variety of muscle groups exercised and the kinds of exercise involved. Fagen (1976a) would predict systematic exercise of a variety of muscle groups for both force and stamina, with corresponding specific rebound effects of deprivation which would not be predicted on a surplus energy theory. Examination of the confinement effect in relation to exercise play of
927
older children would also provide a test of Fagen's theory, which should predict that effects of confinement may, at first, increase with age, but should subsequently decrease. The reasoning would be analogous to that of Fagen (1976b). In humans, in contrast to non-human species, the young ma.y be required to engage in physical exercise, as m gymnastics classes or dance routines; these may provide much of the exercise necessary for physical training. However, it seems likely that children will also be selfmotivated to engage in physical exercise, and the more so, the longer since the last exercise period. The present study has demonstrated the existence of this phenomenon, but its practical as well as theoretical implications deserve more extended study. For example, much academic schooling is largely sedentary, and short playground breaks are allowed, partly to afford opportunity for physical exercise. The length and scheduling of such school breaks, and the relationship to children's age and to their educational and physical development, could profitably be examined in the light of further research in this area. Acknowledgments We are grateful to the staff and children of the Mushroom Lane Nursery School, Sheffield, for their participation in the study, and to Dr Sean Neill for comments on an earlier draft of the paper. REFERENCES Altmann, J. 1974. Observational study of behavior: sampling methods. Behaviour, 49, 227-265. Bekoff, M. 1976. Animal play: problems and perspectives. In: Perspectives in Ethology, Vol. 2 (Ed. by P. P. G. Bateson & P. H. Klopfer), pp. 165-188. New York and London: Plenum Press. Blurton Jones, N. G. 1967. An ethological study of some aspects of social behaviour of children in nursery school. In: Primate Ethology (Ed. by D. Morris), pp. 347-368. London: Weidenfeld and Nicolson. Brownlee, A. 1954. Play in domestic cattle: an analysis of its nature. Br. Vet. J., 110, 48-68. Chepko, B. D. 1971. A preliminary study of the effects of play deprivation on young goats. Z. Tierpsychol., 28, 517-526. Connolly, K. & Smith, P. K. 1972. Reactions of preschool children to a strange observer. In: Ethological Studies of Child Behaviour (Ed. by N. Blurton Jones), pp. 157-172. Cambridge: Cambridge University Press. Connolly, K. & Smith, P. 1978. Experimental studies of the pre-school environment. Int. J. Early Childhood, 10, 86--95. Cooper, J. B. 1942. An exploratory study on African lions. Comp. PsychoL Monogr., 17, 1--48.
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Fagen, R. M. 1976a. Exercise, play, and physical training in animals. In: Perspectives in Ethology, Vol. 2 (Ed. by P. P. G. Bateson & P. H. Klopfer), pp. 189-219. New York & London: Plenum Press. Fagen, R. M. 1976b. Selection for optimal age-dependent schedules of play behavior. Am. Nat., 111, 395-414. Fales, E. 1937. A comparison of the vigorousness of play activities of preschool boys and girls. Child Dev., 8, 144-158. Groos, K. 1898. The Play of Animals. New York: Appleton. Harper, L. V. & Sanders, K. M. 1975. Preschool children's use of space: sex differences in outdoor play. Dev. Psychol., 11, 119. Krott, P. & Krott, G. 1963. Zum Verhalten des Braunb~iren in den Alpen. Z. Tierpsychol., 20, 160-206. Lykken, D. T. 1968. Statistical significance in psychological research. PsychoL Bull., 70, 151-159. Millar, S. 1968. The Psychology of Play. Harmondsworth: Penguin. Miiller-Schwarze, D. 1968. Play deprivation in deer. Behaviour, 31, 144-162. Miiller-Schwarze, D. & Miiller-Schwarze, C. 1969. Spielverhalten und allgemeine Aktivit~it bei Schwarzwedelhirschen. Bonner Zool. Beitrage, 10, 282-289. Oakley, F. B. & Reynolds, P. C. 1976. Differing responses to social play deprivation in two species of
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macaque. In: The Anthropological Study of Play: Problems and Prospects (Ed. by D. F. Lancy & B. A. Tindall), pp. 179-188. Cornwall, N.Y.: Leisure Press. Pedersen, F. A. & Bell, R. Q. 1970. Sex differences in preschool children without histories of complications of pregnancy and delivery. Dev. PsychoL, 3, 10-15. Routh, D. K., Schroeder, C. S. & O'Tuoma, L. A. 1974. Development of activity level in children. Dev. PsychoL, 10, 163-168. Smith, P. K. & Connolly, K. 1972. Patterns of play and social interaction in preschool children. In: Ethological Studies of Child Behaviour (Ed. by N. Blurton Jones), pp. 65-95. Cambridge: Cambridge University Press. Smith, P. K. & Connolly, K. 1977. Social and aggressive behaviour in preschool children as a function of crowding. Soc. Sci. Inform., 16, 601-620. Smith, P. K. & Connolly, K. In press. The Ecology of Preschool Behaviour. Cambridge: Cambridge University Press. Spencer, H. 1878. The Principles of Psychology, Vol. 2. New York: Appleton. Winer, B. J. 1962. Statistical Principles in Experimental Design. New York: McGraw-Hill.
(Received 7 August 1979; revised 2 October 1979; MS. number: 1921)