Millions visit museums and seek pleasurable “aesthetic” experiences (AE). But what is the peculiarity of the AE? Though philosophers, psychologists and many others have worked on this question we still miss a theory that is generally accepted. Our innovative hypothesis is that the extension in time–as an elongated perceptual experience with a pleasurable duration–is a constitutive indicator for the difference between the AE and the common visual experience: We like to behold artworks longer and repeatedly, whereas in common perception longer times on stimuli lead to fast saturation, habituation and boredom. The project verifies this theory and determines 1. subjective and psychophysical measures of AE, 2. the main dimensions that influence the time course and thereby 3. the nature of AE. This pioneering cognitive science project combines approaches from psychology and art history to develop a new theory with practical implications for museum design and educational issues.