They were the 90 minutes of television that set America on fire. As Donald Trump and Hillary Clinton stepped up to the podium for the first presidential debate of the 2016 election, the battle was already raging on Twitter.

But not all of those users joining in the discussion were human.

Then Democratic presidential candidate Hillary Clinton and President Donald Trump, who faced off in the first presidential debate in September 2016. Credit:Matt Rourke

An army of so-called Twitter bots, or automated accounts, were also at work, firing off hashtags and worming into feeds, in a wave of "information warfare" that has since come under investigation by a US probe into Russian interference in the presidential race.

Now, on the other side of the world, Canberra computer scientists have written an algorithm to track the influence of these bots on the election - and the results have surprised even them.