South African artist William Kentridge appears on video in his studio, twice. On the right he sits scribbling, waiting for an idea to surface. Meanwhile his alter ego stands impatiently by, trying to peek at his other half’s notes and, desperate for enlightenment, even reads a recipe out loud. The artist, it seems, doesn’t have a clue; he is as much in the dark as everyone else. A Lesson in Lethargy, 2010 offers a brief moment of humour in this relentlessly dark exhibition.

This rather disappointing documentary about the great American painter Edward Hopper (1882-1967) has such a dry parade of experts and such a slow linear narrative that it leaves plenty of time to be frustrated by all that’s been left out.

There stands Lucian Freud in Reflection with Two Children (Self-portrait), 1965 (main picture) towering over you, peering mercilessly down. Is that a look of scorn on his face or merely one of detachment? His two kids seem to be squirming and giggling beneath their father’s unblinking stare. Who wouldn’t be, especially when the huge lamps hanging overhead are reminiscent of an interrogation chamber? All the better to see you with, my dear.

Remember Gangnam Style, the music video that went viral in 2012? PSY’s cheeky lyrics and daft moves attracted 1.6 billion hits on YouTube, sparked dozens of parodies and turned the world on to K-pop. And that was just the beginning; K-pop has since mushroomed into a global phenomenon characterised by catchy tunes and fast-paced dance routines performed by beautiful young people in snappy outfits.

I have powerful memories of performances by Marina Abramović. Back in 1977 at Documenta in Kassel, Germany, she and her then partner Ulay stood either side of a doorway, facing one another. There was only enough room to squeeze through sideways and, since both were naked, choosing whom to face was an interesting challenge.

Across the pond Winslow Homer is a household name; in his day, he was regarded as the greatest living American painter. He was renowned especially for his seascapes and his most famous painting, The Gulf Stream, 1899/1906 (main picture) features in the National Gallery’s retrospective.

Life is messy and so is Carolee Schneeman’s work. She wanted it that way. Breaking down the barriers between art and life, between inhabiting a woman’s body and using it as primal material, was a key objective.

The businessman in Heinrich Maria Davringhausen’s Der Schieber (The Profiteer), 1920-1921 sits several floors above the city streets, pencil in hand; the high-rise buildings pressing at the windows around him. Not in Germany. In France.

In later life Gustav Metzger appeared a marginal, eccentric figure. The diminutive, white-bearded artist, was often to be seen round London’s galleries in the early to mid-2010s, dropping off piles of hand-produced fliers urging his fellow artists to “remember nature”.

I’ve always been bemused by the American painter, Milton Avery. Not having seen enough of his paintings together, I couldn’t gauge if they are quirkily naive – lodged in a cul de sac aside from the mainstream – or hyper-sophisticated harbingers of things to come.