Sleep Motility as an Index of Motion-Picture Influence
Samuel Renshaw[1]
Inertia is a property of certain aspects of human con-duct just as it is a property of mass. Change of environment or occupation is often not enough to stop a process originating from some strong impression, particularly if that impression has been developed to a sort of climax, if it is colored by strong feelings, and if it has engaged the neuromuscular system for a duration that is greater than a certain minimum. It is a common observation that sleep frequently refuses to come after two hours or more spent in some intensive form of work or play which fits most or all of the above specifications. If it could be shown that the context of a motion-picture program is followed by an alteration of the normal dormition or characteristic motility pattern of a child, then sleep motility would afford one method of indicating the nature and ex-tent of the differential effect of various kinds of motion pictures.
It must be borne in mind that a suitable apparatus and technique must be developed so that we may be sure that
( 227) the effect is not an artifact from some other source. We must alter our method in the light of what experimental experience teaches until we are able to meet, with data capable of answering, all the objections which might fairly be aimed at whatever conclusions seem justifiable from the work. Concretely, we did not know in the beginning of the work what the normal sleep motility pattern was for children of various ages, for both sexes, whether the sexes differed sufficiently to take stock of it, whether diet, season of the year, diurnal activities, childish emotional upsets, etc., would alter the picture. We had to determine by experiment the facts that there are age, sex, and seasonal differences; that each child must serve as his own norm or control; and that to secure a sufficient sampling we must multiply experiments on relatively small groups and thus gain the advantages of checking long-section trends (as the season of the year, etc.). At the same time this procedure gave greater statistical reliability to the obtained figures.
No previous quantitative work had been done on children's sleep motility in the age range of six to eighteen years. No studies had previously sought to use measurements of sleep motility as an indirect method of determining the relative effects of different films upon different children. Those who are familiar with research will readily appreciate the many difficulties where one must shape his tools while he is using them. We had to make each separate experiment yield both cross and longitudinal section results.
Immediately the question arose: Where should we get children for our subjects? For our purposes it was necessary to have access to children where we could have control over diet, work and play activities, hours of retiring, etc. We needed also as complete medical; family, and scholastic histories as possible. It is at once clear that we could not use children at home, for several reasons. What we needed, it seemed, was some sort of an institution which yet was not an institution. This we found,
( 228) thanks to the very helpful interest and coöperation of the Ohio State Bureau of Juvenile Research and its staff. There we had at hand children of both sexes of all ages from six to eighteen; we had the needed medical, psycho-logical, and social resources, we had the children living in a regular routine of controlled diet, regular hours for eating, sleeping, bathing, play, study, small duties, etc., which was as nearly ideal as we could hope to have for the purposes of our studies. This distribution of the I.Q.'s of the 170 children who took part in our experiments was about that to be found in any average school population. The children knew they were resident at the Bureau for not more than 90 days—a period of observation and diagnosis preliminary to placement or being sent home. The Bureau is in no sense a custodial institution.
Our apparatus consisted of a polygraph, which is a paper tape recording device, driven by a synchronous motor and carrying 20 pens, each pen being moved magnetically through a circuit from a small device, called a hypnograph, mounted below the springs of each child's bed. The device was so arranged that any shift in the posture of the sleeper would interrupt the flow of current in the circuit and indite upon the tape a mark which indicated the number of breaker points which passed a fixed brush as a result of the movement. While separate movements could be differentiated with respect to magnitude, we found that it was sufficient to regard each minute of the night as an active minute if any movement occurred within that minute. A magnetic device printed a line across the tape each minute during the stay in bed. All these children retired at 9 and arose at 6.
We established the fact that under our conditions 15 successive nights were sufficient to give a stable norm for each child, particularly if the children were given the same bed each night and were permitted to sleep in the beds from three to five nights before any records were taken. They were told very little about the experiments except that they
( 229) were to go right to sleep as they would naturally, and that by good coöperation they would be rewarded by some visits to the movies. The novelty wore off in a. few days and no difference was noted by the assistant, in constant nightly attendance and observation, between the sleep patterns of those who knew they were sleeping in beds that recorded their movements from those children brought in new and unaware for the first few days of the experiment.
After the "normal" sleep series of 15 or more nights the children were taken to a neighborhood theater, two blocks from the Bureau, between the hours of 6.45 and 8.45 p. in. Ten different experimental groups of children, 10 to 20 in number, were taken to see from 1 to as many as 15 shows consisting of the usual newsreels, comedies, and feature pictures. These varied from the wild wests to the most sophisticated dramas. The children were back and made ready for bed at 9 p. m. Our aim was to keep the movie impression as nearly like the ordinary attendance of an ordinary child as possible.
Following the movie series, a second series of "normal" nights' records were taken. Thus each experimental group slept in the beds about 50 consecutive nights. About 170 different children were used in ten experiments, during which time various groups saw 58 different motion pictures.
From the data thus secured we were able to compare the "normal" sleep pattern with that on the nights movies were seen in the evening before retiring, and the first "normal" series could be checked against the post-movie series.
Each group of children was carefully selected so as to secure 10 boys and 10 girls distributed over the age range, and so selected that about all degrees of brightness would be represented.
Several additional experiments were made. Two groups of children participated in two experimental insomnia series, during which the customary sleep ration was reduced from nine hours to six, first by late retiring (midnight) and arising at 6, and again by early rising (starting the new
( 230) day at 3 a. m. and retiring at 9 p. m.) . Two groups were given coffee and a well-known decaffeinated coffee with the evening meal and again a half hour before retiring and in another part of the work at both times, and the effect noted. Another group was taken for an automobile ride through the city, permitting the children to window shop, etc., for two hours at the same time as the film attendance. In all cases effort was made to keep the daily activities, the health, the diet, etc., as uniform as possible. Special study was made of the records of all children who became ill and were forced to sleep in the hospital during the course of treatment. We used these records to find out if the sleep pattern would show a change before the child showed any overt symptoms of the oncoming illness, such as fever, headache, sore throat, etc. Special study was made by Dr. Miller of the limens of critical frequency for visual flicker in about a hundred cases. These measurements were made in order to ascertain what changes in the reactance of the eye were observable in varying stages of fatigue, and to determine whether pure visual flicker could possibly serve to produce nervousness or restlessness in the children. With all these data we were in position to differentiate the influence of the movie from other con-trolled variations. The analysis of the large amount of data collected in these experiments furnished us with a large number of new facts which could only be obtained because the methods we used made the intercomparisons from which they were derived possible.
Restful, recuperative sleep is a prime necessity for normal growth and development. The sleep pattern is a rather sensitive indicator of the effect of fatigue-inducing agents. Physiologically fatigue is a form of oxygen starvation, of intoxication. We. believe that the apparatus and the methods developed in the course of these studies have many possibilities for use on similar and related problems which have a definite social and hygienic bearing.[2]
