Visual Arts:Aidan Dunne reviews Saphir, Zineb SediraTemple Bar Gallery, 5-9 Temple Bar Tues-Sat 11am-6pm, Thurs 11am-7pm Until July 7 and other stories

Weight of Pass, Wesley Triggs. Paul Kane Gallery, 6 Merrion Sq Until June 16 087-6478423

New paintings and gouaches, Bridget Riley.Green on Red Gallery, 26-28 Lombard St East Until June 30 01-6727117

Hansel's House, Tom Climent. Kevin Kavanagh Gallery, 66 Great Strand St Until Sept 6 01-8740064

A suspiciously minded viewer might be inclined to ask if an artist opts for a two-screen video installation because what's happening on one screen isn't interesting enough in itself. Certainly the mere multiplication of screens gives our eyes and minds more to do and creates the impression that there is more going on, even if there isn't. So what of Zineb Sedira's Saphir at the Temple Bar Gallery? Sedira was born in Paris to Algerian immigrant parents who later returned to Algeria. Although she went to study in London, she too has spent more and more time in Algeria, and much of her work to date has elucidated and explored the colonial and postcolonial experience of Algerians, drawing directly on her family background.

Saphir boasts high production values. It is set in the port of Algiers, which looks absolutely terrific: dazzling white buildings and blue Mediterranean sea and sky. Hence the title Saphir, or sapphire. The video involves two actors who ascend and descend staircases and spend most of their time looking out to sea. They inhabit the same narrative space but never meet. Sedira says she had in mind an amalgamation of "true facts and a fictional space". So the man we see is an Algerian actor who has no particular desire, unlike many of his compatriots, to go to France, and the woman is the daughter of pied-noir parents, French people forced out of Algeria with independence. She is having a look, so to speak, at the country her parents had to quit. The harbour is the focus of coming and goings.

Perhaps it is Sedira's conscious ambiguity, her desire to keep one foot in a factual and one in a fictional world that stymies the work, but whatever the reason, it is oddly thwarted and hesitant. There is an awkwardness about the physical presence and movement of the actors that may be intentional, a kind of Brechtian alienation, but comes across as a lack of fluency in the language of film. This impression is reinforced by the way the elements of dramatic film narrative, including the close-up and a 360-degree pan, are used arbitrarily. It's worth noting that the information about the people we see comes from the interview with Sedira printed in the catalogue.

In other words, the catalogue fills us in on the biographical details of the actors and their relationship to the characters they depict, but precious little in the work itself does. We don't get any sense of internal life or psychology, and they remain ciphers, neutral elements in the composition of each frame.

Saphir was a large undertaking involving the co-operation of several bodies, including the Photographers' Gallery in London, Kamel Mennour and Paris Musées. It is accompanied by a substantial publication that is usefully informative on Sedira's work to date but doesn't make a convincing case for Saphir itself, which for much of its length looks as if it might be a travel advertisement. On the face of it, the idea of generating a work in which characters muse about memory and change, their status and identity, and ponder the difference between here and an aspirational there, is worthy and promising, but, despite its incidental pleasure, Saphir doesn't deliver.

There are just two large paintings in Bridget Riley's exhibition at Green on Red, as well as a series of small gouaches, but make the effort of climbing the stairs in Lombard St East, emerge into the gallery space, and your response is likely to be: wow. Riley has from the first been attuned to the physicality of optical effects and the paintings positively dance off the walls. The one facing you as you enter the gallery, Green Painting, is particularly vibrant, utilising a palette of roughly equivalent tones, so that the colours continually vie for our attention.

This presents us with a conundrum. Our eyes are continually drawn back to the bright, attractive colours, but we can never possess the painting, so to speak, with our gaze. We can't grasp it as a coherent unit even though it is palpably that, and we can't really settle down into a contemplation of its surface because the rhythms of pattern and colour keep us moving. All of which might sound vaguely unpleasant, a form of optical irritation, but that's not the case either. The painting is visually engaging and engrossing, but dynamically, movement and restlessness are fundamental to it.

Given that Riley established her reputation with black-and-white works in the 1960s that were, you could say, much more visually aggressive, tougher on the eye, all of this is hardly surprising. The smaller gouaches are on one level the proving ground for the eventual large compositions, but they are much more than that as well. Her large paintings on linen are generally executed by her assistants. The configuration of colour and pattern are the decisive parts of the process, and there is no subjective leeway in the application of paint. Flat areas of colour abut each other and that's that. But she paints the gouaches herself and they are entirely satisfying as works in their own right.

Tom Climent makes architectonic paintings, often on a large scale. They evoke classical tradition, specifically though not necessarily consciously Spanish painting, with its sombre palette, warm earth hues, and deep shadows enlivened by flashes of light. But his work is not a restatement or straightforward extrapolation of historical sources. There is a sense in what he does of an art haunted by its own past, and an awareness of not being able to return to that past. Hence the spaces in Climent's paintings are fractured and contradictory, and human presence is implied and uneasy rather than representationally conventional.

Wesley Triggs, whose show Weight of Pass is at the Paul Kane Gallery, is a not dissimilar painter in several ways. He too makes bold, architectonic compositions that emerge from the sweep of energies across the surface. He cites the influence of the city, the experience of living in and moving through the city, with its constantly changing, myriad visual juxtapositions, its fragmentary, overlapping spaces and textures. And he does manage to convey the pace and energy of the experience, often with great bravura and the feeling of capturing momentary glimpses of balance and harmony against a background of flux.