Physical characteristics of eye movements are analysed in three expressions of cognition within this thesis. Thus methods for the analysis of the perception of human motion, images of real objects and text reading have been presented and compared here. Two video-based eye-trackers were used methods for the data acquisition and analysis were devised. Skilled and average Latvian readers contributed to estimation of key eye movement factors in reading. Methods have been developed for further usage in classification tasks by eye movements. Athletes are capable of using two visual strategies when assessing a novel sports scene and when watching it repeatedly.