Is the appearance of an object solely determined by incoming sensory data? If not, to what extent is this sensation calibrated by what is memorized or know about the object? Under normal condition, do bananas, for example, appear more yellow because people know and or remember that bananas are yellow (most of the time), compared to other objects (all lighting and reflectance properties held constant)? Empirical research on this possibility has a long history, and it enjoys the reputation of perhaps the best example of an effect of cognition on perception. Here we review studies that are frequently cited as positive evidence, beginning in 1923 and continuing until present time. The intent is to provide a general sense of the methods that have been applied to the problem, and to conclude with a qualitative impression of the strength of extant evidence. Towards this end, we identify a number of pitfalls that persistently complicate the interpretation of results. And we highlight what we take to be the best evidence currently available, with suggestions for extending that work.