This study examined the effect of differential block placement on the frequency of midline crossing during the Space Visualization test (SV) of the Southern California Sensory Integration Tests. The SV test was administered at distances of 0.75, 3.00, and 6.00 inches to a group of 71 normal right-handed boys (ages 5 and 7 years) to obtain the Space Visualization Contralateral Use score (SVCU) and the Space Visualization Contralateral Use Percentage score (SVCU percent). Space Visualization (SV) adjusted scores were also obtained to examine the effect of differential block placement on visual perception scores. The analyses for the SVCU and SVCU percent scores showed that age and distance were significant. Analysis of variance of the SV adjusted standard score indicated that trial, but not distance or age, was significant. There was a significant age-by-trial interaction. The need for a standard protocol for block placement during the administration of the SV test was shown. Future research needs were identified.