Dieter is drawing a little man in the corner of his sheet of paper as his wife surrounds it with colourful, abstract shapes.
Meanwhile, a woman takes her mother Erna's hand in her own to get it moving, and when she releases it the elderly lady continues on her own to paint orange circles on the paper.
Dieter, 76, Erna, 93, and Ingrid, 79, all dementia sufferers, are getting creative in a Frankfurt studio and at the same time making a contribution to a greater understanding of their condition.
The geriatrics department at the city's university hospital aims to find out with the aid of 60 patients and their care workers whether art therapy and viewing art can further dementia treatment.
"One thing that can improve is that communication and the relationship between patient and care worker can improve along with subjective wellbeing," says Arthur Schall, the head of the project.
There is also a positive impact on the symptoms associated with dementia. "Apathetic patients begin to move and restless or aggressive patients become calmer," he says, while cautioning that alleviating the effects of dementia is not on the cards.
The patients attend the museum sessions in small groups once a week for a guided tour and a workshop, each lasting an hour.
The themes vary - the city of Frankfurt, family and children, still life, faces, the colour blue and abstract art.
This group - Dieter, Erna, Ingrid and Hanne - have arrived at the end of the tour - at abstract art. Seated in front of paintings from the museum's Modern Art collection, they are discussing the pictures with their care workers.
"What do you see?" Dagmar Marth, an art therapist, asks. She is one of seven specially trained carers specialising in the pedagogic use of art.
Hanne sees "hair" on a photograph by the artist Wolfgang Tillmans. "But it's green," Dieter says. "But these days people colour their hair the craziest colours," says Roswitha, whose 93-year-old mother is sitting silent but smiling in her wheelchair.
Hanne is not impressed with the bright circles in yellow and orange, by contrast with Ingrid, who finds them cheerful.
"They are too confused for me, especially as I am very agitated myself at the moment," says the lively grey-haired woman, who has only recently being diagnosed with the condition.
By contrast Erna at 93 is barely able to speak. "My mother tends to communicate by mime and signs," her daughter says. This is the biggest challenge facing Marth.
"At times we have a lot of fun," the art therapist says, pointing to a key theme running through the groups. "These people are in a way very free - freer than healthy people."
The participants are unrestrained in their comments. "It's deliberately provocative," Hanne says on being confronted with a garish piece of modern art.
Today the pairs of patients and their care workers are drawing autumn and winter with pastels to the strains of Vivaldi's Four Seasons. At the end the pictures are hung on the wall and discussed.
"It wasn't easy. You want to get it right after all," says Ingrid.
Hanne doesn't like her picture at all. "It's too precise. I've been precise all my life, and that was wrong," she says, even though the others like her picture.
Dieter and his wife have tried without success to create a harmonious whole from his little figure and her abstract shapes of colour. "What's that at the bottom?" Marth asks.
"That's me," Dieter says, while his wife says drily: "That's the opposition."
While it is clear that art cannot cure dementia, patients and care workers all say they have benefited from the experience. Erna's daughter reports that her mother is certainly tired after the day, but is awake and has a clear head the next day.
Dieter and his wife have decided to visit museums more often. What they particularly enjoyed was the group experience. "We've seen that it also affects other people," she says.
The idea originates with a similar project at New York's Museum of Modern Art (MoMA). "When memory starts to break down, non-verbal communication can help people with mild to moderate dementia," says Johannes Pantel, director of geriatrics at Frankfurt's Goethe University.
"We expect communicative abilities to be stimulated and enhanced, wellbeing and quality of life to be maintained and relations within the family stabilised," the professor says.
Several studies have shown that music therapy can help with dementia, but the contribution that art may be able to make has been little studied.