The term Matthew effect was cooined by the Columbia University sociologist Robert K. Merton (1968a) to refer to the commonly observed tendency, noted above, for initial advantages to accumulate through time . . . In his pioneering studies of prestige systems in scientific communities, Merton demonstrated that prestigious scientists and institutions tend to attract inordinate attention and resources, leading to the further accumulation of prestige, which in turn attracts further resources (Daniel Rigney, The Matthew Effect: How Advantage Begets Further Advantage (New York: Columbia University Press, 2010), 4).The term has come to be used of occasions where a piece of research, an idea, a quotation, a story gets associated with a more famous, more prominent person. It is called the "Matthew effect" because of Matt. 13.12, "For to those who have, more will be given, and they will have an abundance; but from those who have nothing, even what they have will be taken away."
Now what I find delightful about this terminology is that it inadvertently contains within it an example of the very phenomenon it is describing. Matthew has been, since the early second century, the most popular Gospel, the Church's Gospel, and when people quote something that's in more than one Gospel, they invariably quote from Matthew.
So a saying that originates in Mark's Gospel (Mark 4.25),* which most scholars rightly take to have been written prior to Matthew, is actually remembered better as a saying in Matthew. It is not the Mark Effect but the Matthew Effect. The better known, more prominent Gospel lends its name to the feature that is thereby illustrated.
* See also Matt. 25.29, Luke 8.18, Luke 19.26.