Duncan MacMillan: Cain's good – but I don't think she's the best of this talented Scottish bunch

THE Aspect Prize, now in its seventh year, is given exclusively for painting and it is limited to Scots or artists established in Scotland.

As a painting prize, it is not unique – the Jerwood Prize is also a well-established and valuable painting prize. Nor is it unique as a painting prize limited to Scotland: the Jolomo Prize for landscape painting set up by John Lowrie Morrison is also a Scottish prize for painters, though it is restricted to landscape.

But the Aspect Prize has no such limitation, nor does it have an age limit, which is welcome when everything seems to be aimed at the young. So much contemporary art also seems to be focused on anything but painting (think of the Turner Prize – or preferably don't). So it is great that the Aspect Prize exists to encourage Scottish artists of all ages to paint and in whatever way they like.

Human beings have expressed themselves in paint since they started decorating the walls of caves and I don't think they will ever stop. It is an instinctive thing to try to record your observations and feelings through colour and in the tactile nature of paint.

The four shortlisted artists each take away 5,000, while the winner also takes another 10,000.

Scot Sinclair paints vivid Op-art – or at least his work uses dazzling colours as the Op-artists do, but with softer edges so that it is also somewhat reminiscent of Impressionism.

Alec Galloway is a professional stained glass artist and his painting with strong black drawing and luminous glowing colours is reminiscent of stained glass. Prize-winner Patricia Cain turned to painting after having trained and worked as a solicitor. Her entry, Inscape 3, is a view of scaffolding and what seems to be the inside of an unfinished building.

At 27, Paul Kennedy is the youngest on the list – the other three are in their forties. His painting, Springburn Hopes, is to me the most impressive of the four.

It is a portrait, but with a very strong sense not only of the presence of the sitter – a young boy – but also of the place. It was the place that inspired the picture, the artist says. He was working at the Red Road flats in Springburn, when he found himself looking at the ruins of the once-grand Winter Gardens.

The sense of nostalgia and sadness that he felt inspired this portrait. That's how painting works and to my mind this one is a winner.