I AM not sure how I have managed to exist in this world for five decades and not know what a polygraph is. Maybe I was too busy watching Pollyanna-style films and not enough James Bond movies as a kid. But there you have it. The truth will out eventually.

Thanks to art and the Internet, I now know what a polygraph is, even though the introduction panel to Polygraphs at Glasgow's Gallery of Modern Art (GoMA) doesn't tell you. For those in the dark, a polygraph is a lie detector. One of these gadgets you see being used in spy films which measures and records blood pressure, pulse, respiration, and other physical reactions as the subject is asked and answers a series of questions.

If ever there was an appropriate moment to interrogate The Truth through art, then it is now. Our daily news channels bandy terms around such as Post-Truth and Fake News expecting us all to be au fait with these contemporary cliches while Donald Trump sneers at respected journalists in White House press conferences for being purveyors of fake news.

Polygraphs is a group exhibition centred around a work by Hito Steyerl called Abstract. This two-channel seven and a half minute long video work by the Berlin-based filmmaker and writer was gifted to Glasgow Museums by the Contemporary Art Society through the Collections Fund 2015. This 2012 video work commemorates Steyerl’s childhood friend Andrea Wolf, who became an activist and revolutionary and was eventually killed in the Kurdish region of Turkey in 1998 when fighting for the PKK.

It's a powerful watch. You never see Steyerl’s full face but she is in the video. In several scenes, she is holding an iPhone up with her eyes obscured by the phone, or we see her viewed from the back. In one scene, she is standing in front of the Brandenburg Gate, a potent symbol of European unity and peace, while on the other screen we see a close-up of the arid site where her friend was killed in Turkey. In another, she is viewed from behind holding the iPhone up to an office building. The other screen tells us: "This is the company Lochheed Martin that produces the missiles." [which killed her friend].

Through Abstract, Steyerl (currently number seven on Art Review’s Power 100), brings home our connectivity to the arms trade, global economics and a seemingly distant battlefield. Placing Steyerl's video at the heart of this exhibition doesn't overpower the other art on display. If anything if serves to shed light on the through processes behind them.

There's work on show by leading contemporary artists, including Barbara Kruger, Graham Fagen and kennardphillips. There are also older pieces on show by artists such as Muirhead Bone, Alasdair Gray, Ian Hamilton Finlay and David Hockney.

Bone's photogravure, Tanks (1918), is the oldest work on display. Bone, who was educated at the Glasgow School of Art, was the first official war artist to be sent to the Front by the War Propaganda Bureau during the First World War. The Bureau used print, the primary means of mass distribution available at that time, to tell people about "our boys" progress at the Front.

The Hockney etching will surprise as it's not instantly recognisable as A Hockney. My Bonnie Lies Over The Ocean, which includes a collaged postage stamp (of George Washington), is sketchy and – save for a large American flag – rendered in monochrome. It was made, and exhibited, by a 24-year-old Hockney during his first visit to New York in 1961 when he found himself separated from his male lover at a time when homosexual acts were still considered illegal.

Even in comparatively recent works on show here, such as kennardphillips' photomontage Know your Enemy (2005), there is an historic feeling of a time before photo-manipulation was the preserve of the masses thanks to apps which can instantly alter truth. Know your Enemy places former British Prime Minister, Tony Blair, and ex-US President George W. Bush chummily entering Number 10 Downing Street. On the ground behind their backs, a man in a foetal position has been bound by ropes and is being subjected to a seemingly violent assault.

Graham Fagen, who represented Scotland at the Venice Biennale in 2015, has work here which illustrates the three ships Robert Burns was booked on to sail to Jamaica in 1786. They are displayed alongside Plans and Records and Portrait of Alvera Coke (AKA Mama Tosh) and were originally commissioned by GoMA to mark the 200th anniversary of the Abolition of the Slave Trade Act.

“At this tumultuous time of potentially huge change I think this is an important show," Fagen says. "As an artist, part of my role is to capture the changing environment and create new ways of understanding that viewers can explore. It’s essential society continues to question the stories, accounts and explanations we’re presented with.

“In creating these works I was trying to offer something positive and to contribute another voice in the debate about Scotland's role in the Atlantic slave trade. I’m making an attempt to understand the history and how the past continues to impact on the present. All of the other pieces invite the audience to do the same, across a range of subjects.”

Polygraphs, Gallery of Modern Art, Glasgow until September 17, 2017