Multi-sensory systems, including the visual, somatosensory, and vestibular ones, are involved in maintaining standing balance. The organization of these sensory systems is as important as the efficiency of each individual system in maintaining optimal balance. The purpose of the present experiment was to investigate the developmental changes in static standing balance and sensory organization under altered sensory conditions. This study involved 64 children (from 4 to 15 years of age) and 17 young adults. The children were divided into four age groups: 4~6, 7~9, 10~12, and 13~15 years. Static standing balance was assessed with the one-leg standing test under four different sensory conditions: the children stood on a firm surface with (1) eyes open or (2) closed, and they stood on a foam surface with eyes (3) open or (4) closed. In balancing ability, the age groups exhibited significant differences. The function of sensory organization for balance control was poorer for the children than for the young adults. The functional efficiency of the somatosensory system of the children aged 7~9 years was at the young adults' level, and the visual function of the children aged 10~12 years had also reached the young adults' level. However, the functional efficiency of the vestibular system of children was significantly lower than that of the young adults, even at the age of 15 years. This may indicate that sensory organization and standing balance are still developing after the age of 15 years.

The ability to maintain an upright position during quiet standing is a useful motor skill. The Sensory Organization Test (SOT) is a timed balance test that evaluates somatosensory, visual, and vestibular function for maintenance of upright posture. The Fugl-Meyer Sensorimotor Assessment (FMSA) balance subscale is the functional status assessment that indicates amount of assistance needed during various balance tasks. Functional Independence Measure (FIM) is the functional status assessment tool and FIM can be used clinically as an outcome measure. The purpose of this study was to see if the SOT can be used as a evaluation tool to measure hemiplegic patients' balance ability. Thirty-six patients with hemiplegia participated in this study. SOT scores were significantly correlated with FMSA balance scores and FIM scores(p<0.05). However correlation coefficients were not so high (r=0.60, and r=0.51, respectively). Therefore, further study is needed to verify the SOT's usefulness when physical therapists are evaluating for hemiplegic patients' balance ability.