Earliest models of time were correlated to change. Later models expanded interactions with environment and cognitive changes (Fraisse, 1963; Block & Reed, 1978). Poynter (1983), Wood, Quinn & Kashy (2002) and Omstein (1969) showed demands on cognitive processes were linked to perceived duration. This experiment examines the relationship between levels of cognitive activity and perceptions of duration in participants (N= 57) suggesting dynamic interaction. Under retrospective or prospective judgmental conditions, levels of cognition were altered by exposure to visual stimuli in three 2 minute presentations with participants recording the passing of 8-second durations. HypoFinal Year Project states cognitive activity is a primary factor in perceived duration. A 2x3 ANOVA analysed data, significance being found across presentations and recorded clicks. Implications for information processing and influences of semantics on cognitive activity are discussed.