According to my understanding of Bion, the mechanism of projective identification functions in terms of our need to have others process emotional material into a digestible (and communicable) form for us.
“I cannot tolerate this state of mind — you have it,” is the preconscious motive governing projective identification. Actually it is only a part of our mind that we require the other to have, the part that arouses anxiety. To complicate matters further, the specific (and often idiosyncratic) nature of our anxiety is itself a product of the way we have been nurtured — our social conditioning.
So, we require that others use their minds, or sometimes their bodies, to process that which we fear we cannot. We require them to use their minds in such cases as when we are leaning upon them for support — then they become the processing “container” for our undigested thoughts (or Beta elements, to use Bion’s term). We require them to use their bodies to remove our anxieties from us when we treat them as a scapegoat, and label them with the negative qualities that are in us, actually or potentially, which we do not wish to face.
Projective identification needn’t take an extremely severe or pathological form. Rather, it is incredibly common in milder formulations, where people engage in deeper conversations than talking about the weather. Whenever we look to another to corroborate a feeling or perspective, we are requiring them to process more thoroughly our thoughts for us — ie. turn Beta elements (unexpressed intuitions) into Alpha elements (ideas that make sense.) This involves projective identification of the other as one who can take on the burden of our intuitions for us, and make sense out of them.
In the exact same way, whenever we are in need of processing our Beta elements into Alpha elements, we are in the process of moving material from its undigested form in the Paranoid-schizoid to the Depressive field (the comparably less exciting state of mind that accepts that others have their own sensibilities, that may differ in many ways from yours).
Artists are the same as everyone else, in that they follow this pattern whereby the pendulum of their awareness swings between Ps D. The only difference is the swing of the pendulum, for artistically aware types is more extreme than is statistically normal. Also, rather than using others for their projective identification, the artist uses his or her art as “container” — a means to give public form to his or her privately held questions about existence.