SAY "cheese". Say "sausages". Say "sex". All these tricks of the photographer's armoury seek to induce or entrap a smile, and yet why is such pressure always applied in those time-capsule moments, frozen by flashlight?

Distance lends reflection, and never more so than in Dublin photographer and video artist Trish Morrissey's Seven Years, a study of family portraiture and family relationships newly commissioned by Impressions Gallery (which will be launching an accompanying book at Sunday's fifth annual summer party).

Morrissey's starting point is her contention that one of the functions of the family album is to reinforce the myth of the happy family, a vision of happiness that often runs contrary to the true tensions behind the scene. That assertion will strike a chord with anyone who ever hacked a face out of a photo with a pair of angry scissors.

Over a two-year period from 2002 to 2004, Trish worked with her elder sister, Anne - seven years her senior, hence the exhibition title - to produce a series of elaborately-staged colour portraits. The siblings are depicted impersonating family members and associates (both real and imagined) as they re-enact memories from all our yesterdays: childhood birthday parties, holidays by the sea, driving lessons.

Filming the images in and around her pebble-dashed former family home in Dublin, Morrissey is part fashion historian, part forensic expert, as she uses old clothes found in her parents' attic and props from second-hand shops to recreate the atmosphere of the 1970s and 1980s.

Her works are serious yet witty, nostalgic but unnerving, drawing your imagination beneath the surface. The underlying darkness drives home hardest and yet humour is gently applied too. The blurred fingers of the photographer in the portrait of a young girl in her swimsuit (uncomfortable, but aware of her nascent sexuality) will bring back memories of so many botched holiday snaps.

Immediately striking is how smiles are all but absent or they look forced. Morrissey's portraits strip away that protective, dazzling sheen, changing the focus to gestures and body language.

Look at the girl keeping her hands to herself in September 4th 1972 (see picture, right): is she truly in love, or is she merely taking advantage of the young man in the tank top and big-collared shirt, using him to teach her how to drive?

Seven Years is accompanied by two new video works.

In the bittersweet Eighteen And Forty Five, daughter and mother dance in the same wedding dress in the harsh surroundings of a back yard, their faces never revealed, but their movements revealing age and thought.

In Eleven And Three Quarters a small boy chases an elusive rabbit around a garden, evoking a feeling of not quite being able to grasp dreams. In all her work, Trish Morrissey grasps the nettle, and it stings.

Updated: 11:04 Wednesday, July 14, 2004