Positron lifetime studies have been per-formed during the heating cycles of the samples prepared either by quenching or slow cooling from the liquid crystalline phase of the compound MIS. The o-Ps pick-off lifetime in the quenched sample, unlike the slow cooled sample, exhibits peaks at various temperatures before it finally undergoes a glass transition. These peaks have been ascribed to various segmental motions executed by the molecule. Studies performed in another liquid crystal forming material, EBBA have also yielded similar results.