Partisan politics: Are Kiwi voters becoming more polarised?

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World politics are becoming increasingly polarised - but is blind partisanship also spilling into New Zealand's comparatively harmonious political life?

Researchers have pored over the views of nearly 20,000 Kiwis and found, over the past decade at least, we haven't drifted toward polarised politics. But that could yet change.

Over recent years, psychology researchers around the world have become observing what's called "affective polarisation" - or the tendency of people to feel positive about the party they support, while disliking and distrusting other parties.

Nicole Satherley, a doctoral candidate at the University of Auckland's School of Psychology, said this has been especially clear in the US, where data has shown Republicans and Democrats viewing each other with growing negativity.

Commentators have noted a massive gulf in recent job approval ratings for President Donald Trump, with a score of 91 per cent among Republicans, and just 2 per cent among Democrats.

Many of Trump's supporters have also taken to flouting public health measures designed to prevent Covid-19, with one US calling it the "partisan pandemic".

But Satherley explained affective polarisation was more than just plain political partisanship.

"This approach sees partisanship, or peoples long-term commitment to a political party, as reflecting a deep psychological attachment to the party, rather than a rational assessment of the party's policies," she said.

"So, people tend to act to maintain their positive identity with and image of the party."

What was driving this pattern still wasn't completely clear. In the US at least, one factor could be a rise in partisan news sources that skewed coverage around their political leanings.

"More generally, hostile behaviour between members of different political parties, or political party leaders, may normalise hostility toward the 'out-party' and its members."

But she added that affective polarisation might not always be a bad thing - particularly if it meant more people were engaging with politics, and turning out at polling stations.

"However, people should be conscious of whether they are acting in line with their own views about political matters, or whether they are simply siding with those of their party as an expression of support."

In her study, she wanted to put the issue in a New Zealand context, but also find out what drove some people to strongly oppose parties other than their own.

She and colleagues analysed around 19,000 survey responses from the longitudinal New Zealand Attitudes and Values Study, which has been canvassing Kiwis on various topics since 2009.

One survey within the programme asked people to rate their feelings of support - or opposition - toward the main political parties in New Zealand each year.

"So, we looked at a range of different factors that might increase or decrease the extent to which support for one party is associated with opposition toward another."

Among the different factors looked at, the researchers found "political identity centrality" - or the extent to which peoples' political preferences are central to how they see themselves - to be the biggest.

"Affective polarisation was higher among people who rated their political beliefs as being more important to their sense of self," Satherley said.

"In other words, when people's identities are strongly invested in politics, they tend to feel more strongly about the parties they support and oppose."

People whose own ideological orientation tended to align with that of their supported party also tended to be more affectively polarised.

"So, affective polarisation can also simply occur because we agree more ideologically with one party, but not with competing parties."

On the whole, however, the team didn't find anything to suggest there had been growing systematic polarisation going on amid Kiwi voters over the last 10 years.

Why the difference with the US?

Satherley said it could be a combination of factors, such as partisan news sources and New Zealand's very different media landscape, how political elites in each country behave, and even differences in the party systems more broadly.

"However, research on affective polarisation is still in its early years, and these are speculative possibilities," she said.

"Future research examining longer-term trends may shed more light on polarisation in New Zealand."

She's since followed up the study, published in the Journal of Research in Personality, with more research tracking the attitudes of voters of New Zealand's four main parties over the same 10-year period.

That found that, while the ratings of support voters gave for their own party versus others had been reasonably consistent since 2009, Labour and Green voters gradually came to express greater opposition toward National over the years.

"So, although the factors that lead people to have higher or lower levels of affective polarisation in New Zealand seem to match what we see overseas, changes in levels of affective polarisation between 2009 and 2018 were specific to certain voters," she said.

"Moreover, these findings may simply be linked to the National party's period in government, rather than longer term trends."

She added the results further suggested some polarisation in the ideological identification of voters.

"For example, Green and Labour voters tended to rate themselves as more liberal in 2018, compared to 2009, While National voters were slightly more conservative in 2018, compared to 2009."