 Not just the similarities, but the differences between mental imagery and perception also need to be explained. And the difference between perceptual content and the content of mental imagery also plays an important role in the debate about a phenomenologically salient and historically influential difference between the vividness of perception and the vividness of mental imagery. The historically influential view, championed most memorably by the British empiricists, is that mental imagery is paler and less vivid than perception. Even if we set aside hyperphantasics, who report very similar vividness for mental imagery and perception, this distinction does not seem to hold across the board. The properties that constitute the content of mental imagery can be very determinate indeed – and most of the properties that constitute perceptual content are not particularly determinate (see Dennett 1996 for a classic argument). Nonetheless, determinacy plays a role in yet another major difference between perceptual content and the content of mental imagery.