Two artists whose paintings have the power to provoke

Few contemporary artists have as distinctive a style as Victor Vasarely, and even fewer have garnered as wide a following as he has. His brilliantly colored -- or startlingly black and white -- paintings and prints, in which optical illusions have been transformed into art, are known throughout the world. And if that weren't enough, his reputation stands as high among his peers as it does with the public at large.

Dramatic proof of his art-world standing is the five-institution celebration of his 76th birthday now taking place here. New York University, the Guggenheim Museum, the New School for Social Research, Pace University, and the Vasarely Center have honored or are honoring him with various events. Of particular interest to the public is the fact that Pace University is sponsoring a retrospective of his prints and that the Vasarely Center has mounted a major exhibition of his paintings and three-dimensional works.

The latter consist of several very large canvases, a number of slightly smaller ones, and a handful of various-size sculptures. All represent the artist at his best and most vibrant, and they demonstrate beautifully his special knack at creating visual sensations that trigger insights into the nature of space, matter, and energy. They are truly impressive, but they require thoughtful attention. To see them primarily as optical illusions is to miss their poetic overtones - just as viewing them as merely handsome decorations negates their larger scientific, aesthetic, and philosophical implications.

Art such as Vasarely's springs from a very 20th-century attitude toward visual phenomena and reflects the probing, inquisitive approach of an artist who is almost as much scientist as painter. But while some of his work may resemble laboratory experiments, the vast majority do not. Indeed, they hold their own very nicely on the walls of those museums and collections that own them. Time will tell if what Vasarely has produced is significant and lasting. For the present, it is highly effective, and often quite beautiful.

At the Vasarely Center, 1015 Madison Avenue, through June 15.

Earl Staley

Art often does what's least expected, and when least expected. It can respond to an urge for novelty one minute, and become utterly serious the next. It can go from Rabelaisian earthiness to lacy elegance with ease. And it can, as has been proved recently, move from pure formalism to extravagant emotionalism in a very short period of time.

Not all art, of course, reflects such extremes. Most significant work springs from deeper and more responsible cultural soil, and it obeys a creative imperative only marginally concerned with the whims of the marketplace.

This imperative often bulldozes its way to the surface to find its appropriate form and expression. What results is not always great - or even good - but it is often extremely interesting and valuable in a blunt, uncompromising way.

Excellent examples of this kind of art can be seen in ''Earl Staley: 1973- 1983,'' a 10-year retrospective of this artist's work originally organized by the Contemporary Arts Museum in Houston and now on view at the New Museum of Contemporary Art here. Included are 90 paintings and works on paper with such varied subjects as wild-animal images and allegories; imaginary beings, including demons, mermaids, and dragons; Mexican themes and celebrations; large-scale landscapes; mythological creations; and highly subjective religious images.

With few exceptions, Staley's pictures are brassy, colorful, and profoundly idiosyncratic. They are also highly effective, and often quite moving.

Most important, they spring straight from the artist's imagination and almost totally ignore traditional standards of technique and good taste. Even when referring to real places and people, they crackle with a kind of Expressionist passion that makes even the most prosaic landscape appear charged with mythical dimensions.

That, of course, is crucial to the identity and impact of these canvases, in which no theme is too large (''The Temptation of St. Anthony''), too exotic (''A Flying Flaming House Appearing to a Praying Man''), or too dramatic (''The Last Day of Pompeii''). Since Staley's intention is to embody rather than to depict magical properties and mythological significances, nothing can be permitted to stand in the way of these paintings' maximum confrontational effectiveness. Everything must be as raw and direct, as unencumbered by neatness or polish, as the canvases of Nolde, Pollock, or Schnabel. This work may be representational and loaded with allegorical and metaphysical references; but it must nevertheless be as immediate as a painting by a child and as emotionally charged as any primitive or Expressionist work of art.

This does not mean that Staley's pictures are clumsy or inept, only that no attempt has been made to give them the academic veneer we've come to expect in paintings with ''large'' themes. In fact, many are technically impressive, with coloristic and compositional subtleties that become apparent only as one studies them. ''Boystown, Laredo, Mexico,'' for instance, is as original and effective a piece of color-handling as I've seen recently, and ''Leda and the Swan II'' has as superb a landscape image as one will find today.

Particularly effective is the three-panel work ''King, Shaman, Fool,'' which has a combined width of 39 feet, and which both celebrates and monumentalizes the great Southwest. I was also impressed by ''Turkey Buzzard,'' ''Storm Over Chisos,'' and ''Hercules and the Nemean Lion.'' In fact, I found the entire exhibition extremely worthwhile.

At the New Museum of Contemporary Art, 583 Broadway in SoHo, through May 20.