Infant Crying Theoretical and Research Perspectives
The cries of infants and children are familiar to essentially all adults, and we all have our own common sense notions of the meanings of various cries at each age level. As is often the case, in the study of various aspects ofhuman behavior we often inve
- PDF / 40,237,128 Bytes
- 385 Pages / 439.32 x 666.12 pts Page_size
- 112 Downloads / 283 Views
Theoretical and Research Perspectives
\0 sARAi,} z. WtLlv YsU llwAvs. I
'-', II c. CI.. r- "'-- fa r- '1 -
l-
e;;
z 0.5
w 0
...J
~
a:
I(J
w
e, Cf)
0.0
u.. 0
s" -o.s
-1.0 40
10
2.5
PERIOD OF CYCLE (SECONDS)
Figure 1. Periodicities in the fundamental frequency of the cry of a healthy term newborn infant. The fast Fourier transform was applied to the fundamental frequency computed in successive 50 msec blocks of time. This plot shows the spectrum of the fundamental frequency with a major peak having an 8 to 10 second cycle.
THERE'S MORE TO CRYING THAN MEETS THE EAR
15
periodicities in Fo as shown in the figure. The major peak is in the middle of the spectrum showing an 8-10 second rhythm in the cry. Other investigators have reported similar rhythms in cardiac and respiratory activity that are thought to be controlled by the same supramedullary oscillator (DeHaan, Patrick, Chess, & [aco, 1977; Hathorn, 1979). It has been experimentally shown in dogs that the 8-10 second rhythm in cardiac activity is due to parasympathetic input. It may be that the homeostatic function of crying and cardiorespiratory activity is controlled by central neural oscillating mechanisms that control parasympathetic, particularly vagal, input. The functional significance of this 8-10 second rhythm may be to synchronize or coordinate crying and cardiorespiratory activity. Cardiorespiratory activitymust adapt itselfto crying as well as to other rhythmic activities such as sucking . Stratton (1982) has proposed that ontogenesis is marked by a shift from relaxation-type to pendulum-type oscillations. The pendulum oscillation is sinusoid in shape and is characterized by minimal energy exchange. Relaxation oscillations are sawtooth in shape, efficient, and more energy is transferred. They are more flexible, more easily entrained or synchronized by a forcing oscillation, and may be advantageous in early development. Neonatal functions such as respiration, heart beat, and crying fit the characteristics of relaxation oscillation. Bybeing responsive to fluctuating demands, there is a considerable biological advantage in early development as these systems have the ability to synchronize with a wider range of periodicities. There are grounds for proposing that endogenous oscillating or timing mechanisms are at the base of the development of behavioral control systems in infants. Control systems that oscillate around a mean as in relaxation oscillators, rather than trying to maintain a fixed level, as in pendulum oscillators, provide advantages for the integration of internal physiological processes and behavioral regulation through interaction with the caregiving environment (Stratton, 1982). The interplay of maturation and experience is suggested as biological rhythms synchronize internal homeostatic adjustments and provide the flexibility that enables the young infant to coordinate interrelated functions such as crying and cardiac and respiratory activity at a time when resources and functional capacities are more limited and ada
