Dimensions and Design of swimming pool fences and balcony - ANEC

the same bone. This small difference of 10 cm
corresponds to completely different anatomic
positions. At birth it is situated at the xiphoid
process while at an adult age it is located at the
level of the iliac crests or in the 2 nd or 3 rd sacral
vertebra. The high positioning of the gravity
centre explains the difficulty that children of
these ages have to get completely immobilized
after a run (Payne & Isaacs, 1995), and may
contribute to the steadiness and balance deficits
that can be easily observed.
Another aspect is that, as countries develop in
so many different ways, the growing rates in
different countries are also very variable. Secular
trend, for instance, are perhaps more
influential than traditional race differences. Secular
trend in China and Southeast Asia as well
as in other emergent countries, acts upon
children’s morphology in a striking way.
Normally, secular trend shifts toward a growing
dimension, but the trend can also be negative,
as demonstrated in countries with serious
developmental and economic negative growth.
2.3 Trends in motor development
2.3.1 Acquiring new skills
2.3.1.1 Perceptual development
Babies, infants and toddlers, share a common
feature: their perceptual systems are learning
to deal with huge amounts of information,
bringing pieces and details together, into unified
and unique representations of the world. This
developmental trend requires sensorial
maturation, environmental stimulation, and
opportunities to learn. The process of learning
how to interact with the environment is a
perceptual as well as a motor process.
Perceptual development requires maturation
support, but cannot be fully explained by
maturation. In fact, experience increases acuity
of perception, and experience requires action.
Vision plays a major role in this process. As a
matter of fact, all senses demand information
exchanges with the visual system in order to
calibrate all perceptual systems. That happens
with auditory, vestibular and tactile information,
in a process that origins the perception of a body
within an environment, and of a body that moves
in that environment. During the first years
of life some visual aspects develop very rapidly,
such as visual acuity, visual accommodation,
peripheral vision, fixation and tracking of
objects. For the purpose of this report it may
be interesting to focus on depth perception –
the ability to judge distances from objects and
surfaces (Williams, 1983). It has two basic and
distinct forms: the static depth perception that
informs about static features of the world, and
the dynamic depth perception, that concerns
moving objects, moving bodies or both. The visual
cliff experiment (Gibson & Walk, 1960)
demonstrated that crawling children can visually
perceive depth at an edge and behave
accordingly. But other studies (Svedja &
Dimensions and design of swimming pool fences and balcony and stairs barreirs to protect children from falling and from passing through, bellow or above
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