In two of the studies, undergraduates were asked to take a modified version of what is called a Stroop task. The widely-used experiment is considered an effective psychological test of our mental vitality and flexibility and measures our ability to read words more quickly and automatically than we can name colours. In this instance, participants were shown a word stating a colour, such as blue, but presented on a background that was a different colour, like red or yellow. The researchers examined them on how quickly they could respond with the word, controlling for correctness.
In both studies, conservative candidates had as many correct answers as liberals, but performed the tasks faster. In the second case, the conservatives' results stemmed from their belief in their responsibility for their own outcomes.
In the third study, participants took part in an anagram self-control task. Importantly, they were told they could decide when they wanted to end the task.
The researchers found that the conservatives spent more time on the task than the liberals, but outperformed liberals only when they believed free will had a beneficial impact on self-control.
When participants believed free will could undermine self-control, liberals outperformed conservatives.
Study co-author Dr Joshua J Clarkson, of the University of Cincinnati, said self-control was often thought of as sticking to diets or not wandering off grocery lists, and all of these behaviours came down to exhibiting elements of attention regulation and persistence.
"Ultimately, however, it all comes down to believing whether or not you can control your own behaviour, and what we're finding is that conservatives are more likely to believe they can control their own behaviour."
Dr Danny Osborne, a political psychology lecturer at Auckland University, said the results, published in Proceedings of the National Academy of Sciences were "entirely applicable" to New Zealand and he would be surprised if they differed to tests done here.
Research done for the New Zealand Attitudes and Values Study had consistently shown a person's level of conscientiousness, including their self-discipline, was positively associated with conservatism.
Interestingly, another US study showed people who displayed high levels of conscientiousness as toddlers were more likely to be conservative when re-interviewed 20 years later. He said what the new US studies added was the nuance that people's free will beliefs partly explain why conservatism is positively associated with self-control.
"Indeed, the findings relevant to free will beliefs seemed to be the major contribution that this paper makes to the literature."
Taking the test
Take the test at onlinestrooptest.com
We asked six people involved in politics to take the online Stroop Test. The timed test presented them with 20 words stating different colours, but presented in colours that were sometimes mismatched. So the word 'black' could be red. Respondents were asked to select the colour of the word.
Each participant has two scores from the test. The first shows the answers out of five and response times for correctly coloured words. The second score is for the answers out of 15 and response times for miscoloured words (for instance, when the word 'black' is coloured blue in the test).
