A three-point scoring system was then
applied to each item. A four- or fivepoint
system was rejected because we
believed it would result in more subtle
differences in the performance choices
and produce greater scoring indecision
than a three-point scale. A three-point
system simplified the assessment process
and allowed the examiner to choose between
more obvious differences in the
observed performance of each item. The
longitudinal data of Thomas et al9
demonstrated
that distinct changes in active
tone, passive tone, and primitive reflexes
occur at about 32 weeks gestational
age and again at about 36 weeks
gestational age. The resting posture of
an infant, for example, shows absence
of extremity flexion before 32 weeks
gestational age, leg flexion between 32
and 36 weeks gestational age, and flexion
of all extremities after 36 weeks
gestational age. Similarly, grasp is weak
before 32 weeks gestational age, reasonably
strong between 32 and 36 weeks,
and strong enough to lift the infant off
the bed (traction response) after 36
weeks gestational age. The natural evolution
of tone and primitive reflexes,
therefore, coincides nicely with a threepoint
scoring system.