It is said that personal adjustments make the environment more comfortable, but there are some reports which deny this statement. To make sure this, authors made subjects adjust lighting in working room. As expected, subjects who had decisional control reported significantly higher subjective rating scores than those who had not. However under bad lighting condition, the subjects who had no perceived control reported that there was significantly less need for adjusting lighting than those who had. It can be said that decisional control has positive effect and perceived control sometimes has negative effect on subjective rating.