The "black death", which plagued Europe most intensely during the middle part of 14th century and killed more than half of Italy, had a profound effect on subsequent artistic production and can reasonably be said to have contributed to what we now call "the renaissance". I think it almost seems fitting that such death would lead to such a rebirth.
Our textbook really doesn't mention much about the social and psychological impact of the plague, but I think it's the most important aspect to consider in order to understand the lasting changes brought on by the plague, including changes in art.
While researching the plague online, I noticed a particular assertion that was repeated several times-- Common people gained much more leisure time than they had previously known(something that modern Americans, as an example, take for granted) as a result of the plague. This was due to several reasons including the fact that many people were afraid to leave their houses for fear of contracting the disease from others. Also, the economy was in shambles and many jobs were lost, leaving people with no choice but to stay home. This gave the masses something they rarely had before, namely, time to reflect upon their lives, their mortality and, one could infer, the meaning of life. The plague had a profound, "in-your-face" effect on people in regard to acknowledging reality, albeit the darkest side of reality (which, by contrast, can also heighten the awareness of the ligter side of life as well). And consider the fact that the plague did not discriminate between poor and rich. The plague did not recognize any class system; People are just people, and the plague made this fact crystal clear.
I believe that the power of the church and the notion of the Christian God was naturally challenged by the plague as well. Where was God? Surely even the most ignorant sheeple of the time found this question creeping into their minds. Surely they noticed that priests and other clergy were not shown any special treatment by the plague nor the supposed God that supposedly favored them. Surely this made them wonder and take a good hard second look at reality, not for what they were told it was, but for what they could plainly see it was for themselves. They must have concluded that, for all intents and purposes, they were on their own as humans. Of course the masses didn't become atheistic but it seems that they did adopt more humanistic and naturalistic views on life.
The effect all of this had on art was that of a humanist and naturalistic influence which more accurately reflected reality both in regard to nature and to the sensitivities of the human condition. Human beings would now be portrayed,in art, not merely as props to display a message for the church but as human beings with interests and values that reflected the times. Of course the church survived the plague, as did its own self interest, so religious art didn't disappear. But now it had some stiff competition.