CHANGE OF CONDITIONED ORIENTING REACTIONS IN 5 MONTH OLD INFANTS THROUGH PHASE SHIFT OF PARTIAL BIORHYTHMS

The aim of this study was to verify to which extent known synchronizing factors such as the rhythm of putting the child to bed and the rhythm of feeding will affect the rhythmical changes of the infant’s performance. In 10 five-month old infants a conditioned orienting head turning to a sound reinforced by the presentation of toys was estahfished. The conditioned responses were then elicited systematically in 15 min intervals during 2 h of the waking period. A 30 min shift of the feeding time was made each week so that results of experiments performed at different times in relation to the sleeping and feeding schedule were collected. On the basis of this bifactorial research design the influence of waking and digesting on latency of conditioned orienting responses was determined. The rhythm of the infant’s performance was influenced by two partial rhythms. (1) The waking process caused the latency of the reactions after awakening to become gradually shorter; the speed of the reactions attained in the 40th min its maximum and there- after decreased again. (2) The process of digestion caused the speed of the reactions to decrease slowly in the first 60 min after feeding, then to increase and after attaining the maximum in the 150th min to decrease again. By changing the relationship of feeding and sleeping time we combined the reciprocal phase position of both partial rhythms. It was found that children fed 30 min after falling asleep or immediately before sleep responded rapidly and were in a good mood during the waking period; in such a combination of sleep and feeding the peaks of both partial rhythms fill out the whole waking period. In children fed 30 or 60 min after awakening the peaks of both partial rhythms were apart; this desynchronization of the phases of both rhythms resulted in slow often erroneous reactions and in a bad mood. By mutual liming of feeding and sleep it is thus possible to shift the phases of partial rhythms, promote their synchronization or dcsynchronization, producing thus various qualitative changes in the tonus of the central nervous system and consequently various changes in the child’s performance. © 1968 S. Karger AG, Basel.