This study was based on the following assumptions: (1) functioning of the brain's left hemisphere, because of its logical, verbal mode, facilitates conservation reasoning; (2) functioning of the brain's right hemisphere, because of its nonverbal, spatial mode, inhibits conservation reasoning; (3) visual input from the left eye will reach the left visual cortex before it reaches the right visual cortex, thereby giving the left hemisphere priority and vice versa; and (4) eye dominance is caused by hemisphere dominance. In order to test the validity of these assumptions, a series of conservation tasks (number, substance, continuous quantity and weight) were administered to a group of 82 children. The following predictions were made: A group of children who view the conservation materials with their left eye and are left eye dominant (LL) will demonstrate a greater frequency of conservation responses than a group of children who view the materials with their right eye and are right eye dominant (RR). A group of children who view with their left eye and are right eye dominant (LR) and a group of children who view with their right eye and are left eye dominant (RL), will demonstrate an intermediate frequency of conservation responses. The predicted sequence of LL.gt.LR approximately equal to RL>RR was found. LL and RR group differences were significant (z = 2.01, p = .02). (Author/MS)