contingent upon their ability to perform a conservation of liquid substance test, two groups of ss were selected for experimental treatment: 20 natural conservers (ntc), and 40 non-conservers (n-c). the n-c were randomly divided into two equal groups -an experimental group and a control group. the experimental group was taught conservation of liquid by a learning program based upon halford's learning theory model of liquid conservation. at intervals of 24 and 6 days after training of the n-c, all the ss were given a conservation of liquid test. the ss were also asked their reasons for thinking that the amounts of water were equal or different after each change of shape was performed. in order to determine their resistance to extinction, both natural conservers and those non-conservers who had learned to conserve were given 6 extinction trials.