Perceptibility of body position in anteroposterior direction while standing with eyes closed

The perception of body position in the anteroposterior direction was invest igated by evaluating the reproducibility of the position from a quiet stand ing posture to forward or backward leaning posture with eyes closed. The su bjects mere 10 healthy male undergraduates, aged 20 to 28 years. The standi ng position was represented by the pressure center of the foot, which was s hown by the relative distance (%) from the heel to the length of the foot. The reference positions of the pressure center of the foot were Set at 10% increments from 20 to 80% of the length of the foot. The subjects attempted to reproduce each reference position 10 times, and the absolute and consta nt errors of the reproduced position were analyzed. The absolute errors at reference positions of 30 to 60% were distinctly larger than those at the o ther reference positions. This indicated that the perception of standing po sitions from 30 to 60% was less accurate. The constant errors at the refere nce positions of 40 to 60% mere significantly positive, which meant that th e reproduced position was located farther forward than the reference positi on.