Do you have a short temper? Uh, so, don't hit us, but… you may not actually be as smart as you think you are. That's according to a new study by researchers in Poland and Australia.

And it's because anger is strongly related to traits such as optimism and narcissism, which tend to lead a person to overestimation of their own abilities.

"In a recent project I examined the relationship between anger and various cognitive functions," psychologist Marcin Zajenkowski of the University of Warsaw told Psypost.

"I noticed from the literature review that anger differs significantly from other negative emotions, such as sadness, anxiety or depression. Anger is more approach oriented and associated with optimistic risk perception and generally optimistic bias."

He wanted to see if anger had any relationship with a bias in favour of the person's own abilities, so, together with psychologist Gilles Gignac of the University of Western Australia, designed an experiment to test it.

They recruited 528 people and had them fill out questionnaires. These questionnaires quizzed them on their temper, and asked them to also rate their own intelligence on a 25-point scale. Then they had to take an intelligence test.

There was no relationship found between the participants' temper and their actual intelligence levels. So you could, in fact, be a smart angry person.

However, those with a high temper were found, overall, to overestimate how intelligent they actually were. This facet of anger - overconfident optimism - was found to be related to narcissism. And it could be causing damage interpersonal relationships, too.

"Individuals with high Narcissism do not establish deep, intimate bonds with others, but rather surpass and dominate others. Correspondingly, Trait Anger is associated with problems in relationships," the researchers wrote in their paper.

"We speculate that these difficulties may be related to the thoughts of superiority to others, especially in the ability domain. Often, experiences of anger might result in thoughts such as, 'I am smart' and 'You are stupid', which may, in turn, cause problems in creating positive relations with others."

The study did have limitations. All the participants were Polish university undergraduates, which may subject it to the WEIRD problem. The researchers' measure of self-assessed intelligence was also a somewhat simple one, and there may be more reliable ways of assessing overconfidence.

Lastly, it was based on self-report surveys, rather than an experiment. In these cases, it's possible that the participants' assessment of their own behaviour is inaccurate.

So a causal link between the correlation of anger and intelligence overestimation cannot be established at this point - further research would need to take place.

The team noted that they only assessed those with a disposition towards anger. Future research, they said, could also look at transient, fleeting anger to determine if a similar effect can be observed.

The team's research has been published in the journal Intelligence.