My PhD research was concerned with the effects of adaptation on our perception of speed. The main finding, extending previous research was that adapting to movement not only generates a movement aftereffect - in which stationary patterns appear to move in the opposite direction to the adaptation motion - , but the perceived speed of moving patterns can be radically changed. Most often the perceived velocity of patterns moving at the adaptation speed or slower, have their apparent velocity greatly reduced. An additional finding that emerged during this work was that reducing the luminance contrast of moving gratings can also affect their perceived velocity. This latter finding has proved particularly valuable when assessing the plausibility of models of speed and and motion perception.