Put out more flags
What does a flag do, exactly?
Once upon a time the answer was fairly straightforward: a flag served as a rallying point on a battlefield.
These days they can be expressions of identity or threat. Or they can just hang around looking pretty.
Now, thanks to research at Strathclyde University's school of government and public policy, we know they also have a hitherto hidden power: to change the way we think about things.
With the help of the BBC, Prof Laura Cram and her colleagues asked people about issues like national pride and the economy.
More than 10,000 people took part in the online survey. It was billed as an attempt to test the mood of the nation.
First, people were asked where they lived. Then they were asked to answer a quick quiz.
But although they answered similar questions, not everyone saw the same thing. That's because the survey randomly assigned each person pages of a subtly different design.
The top of each question page carried a small flag - but people saw one of three different types.
Some saw a neutrally-coloured flag. They were the control group.
The second group were randomly assigned pages carrying the Union flag.
The third option depended on where people said they lived. Those who said Scotland might have seen the saltire, those in England the St George's Cross.
The point of it all? Not just to find out how people felt about the nation, but to discover how seeing different flags might alter people's attitudes.
The findings? Flags do make a difference to how people feel about things - and in intriguing ways.
One example is an issue traditionally thought to be emotion-led: national pride.
For those who said they lived in Scotland, neither the Saltire nor the Union flag had a significant effect on Scottish national pride.
For those who identified themselves as English and said they lived in England, though, the group that was shown the Union flag felt more proud of being English. The St George's Cross did not have the same effect.
What does that English response tell us? Perhaps something about the intermingling of English and British identities. Or that the Union flag is the national flag for people who identify themselves as English.
And what about more material issues like the economy?
These are supposedly the issues where our rational selves take over - matters of the head rather than the heart.
On both sides of the border, 42 % of people who saw the neutral or the Union flag felt positive about the current economic situation.
But if they saw either of the national flags this had a negative effect, with only 37% reporting confidence in the current economic situation in their country.
And the Saltire had a stronger negative effect on people's feelings about the current economic situation in Scotland.
Anti-independence campaigners are likely to seize on it as a sign of an unconscious fear among Scots of "going it alone" in an independent economy.
But not necessarily. It could be that by reminding people of being English or Scottish, rather than British, it makes them feel less in control of their economies within the UK. Or more hard done by.
So what does all this tell us? That different flags make people feel differently about things. They seem to trigger unconscious "gut responses" which bypass our conscious thought processes.
And that applies to allegedly emotional issues like national pride - and supposedly rational ones like the economy.
We need to attach plenty of caveats to this - not least that the respondents were self-selecting and - given that thousands of them watch Sunday Politics Scotland, they can be expected to be more politically savvy than most.
People in Northern Ireland and Wales also filled in the quiz, but sadly not in large enough numbers to allow the researchers to draw any conclusions.
The quiz closed before the Jubilee, with its surfeit of Union flags, so we don't know how that may have affected things. And indeed the European football championships, where the St George's Cross will be hard to avoid.
And with an independence referendum campaign under way, it'll be the saltire's turn.
The message to politicians appears to be: if you want to change how people feel, put out more flags. But which ones?