A melting pot of factors unique to driving can cause even the most placid person to loose their rag on the road, explains NZ anger expert Dr Ian Lambie.
In the most recent road rage incident in Auckland, an elderly couple were left stranded in CBD traffic after an irate cyclist took issue with their driving and snatched the keys from their car's ignition.
There have been at least five other key-snatching scenarios reported this year after locals lost their temper with tourists on the roads.
Dr Lambie, Associate Professor of Clinical Psychology at the University of Auckland, said drivers lose their cool so easily in a car because they're literally "behind closed doors".
Reactions aren't governed by the same social norms that apply when dealing with someone face-to-face, he explained.
"There's a separation between you and them," Dr Lambie said.
"You perceive them as being slightly removed... and this disinhibits someone to act in ways they would not usually."
We aren't able to communicate properly with other drivers, so we take minor things, such as changing lanes incorrectly, personally, when we shouldn't, Dr Lambie said.
"When someone does something to you it's 'an eye for an eye'... even though it might not be intentional it's like, 'If they'd been a bit more courteous to me this wouldn't have happened'."
This is compounded by the fact that fellow road-users are mostly strangers so there's less concern for the consequences of angry actions.
"We don't get angry at work colleagues... but here is a stranger who you don't have a relationship with."
Despite getting behind the wheel every day, driving is an inherently stressful task, Dr Lambie said, and under stress we behave differently. When another driver makes a mistake - minor or major - our thought processes are too quick to be rational, he said.
"(You think) 'Am I in danger? I have to react quickly, there's a threat and it's a stressful situation'.
The other driver is doing the same and, "as a result you impulsively react and that may be with your breaks ... or potentially with your mouth or your finger".
Five steps to keeping calm on the road
1. Catch yourself - recognise you're getting angry and tell yourself "stop" 2. Exhale 3. Count down from five 4. Tell yourself "it doesn't matter" - let it go 5. Deal with the situation rationally and move on