Often, we intuitively assume that there are common factors in life. For example, we test people with a visual acuity test to determine whether they are allowed to drive a car or not- with the implicit assumption that the acuity test is representative of vision. Likewise, we make considerable efforts to exactly understand certain visual paradigms because we assume that they measure core functions of the human visual system. Contrary to many fields of psychology, researchers have paid very little attention to common factors in vision. In a series of studies, we tested batteries of standard visual paradigms in a variety of populations including the “normal” healthy population, video gamers, the older population, and schizophrenia patients. Even though test-retest reliability was generally good, all our studies indicate that most visual tests only weakly correlate with each other. Factor analysis supported this conclusion. Hence, we need to rethink to what extent common visual paradigms test what we implicitly assume they do. [Swiss National Science Foundation, NCCR Synapsy, Velux Foundation.]