Wandering behaviors in dementia and developmental disability often cause the stumbling or slipping accident. Purpose of this study is to prevent persons with dementia and developmental disability from these accidents by evaluating on the basis of the experimental data using eye reflection camera how they find barriers. The data were compared with normal group. The results were summarized as follows: Bigger barriers attract more eye fixations in three groups. Time to find smaller barrier in the dementia and developmental disability group is slower than in the normal group. The dementia and developmental disability groups tend to fail discovering the goal in order to concentrate more eye fixations on barriers.