Excitement, desperation, and boredom - these are some of the motivations for those who commit an armed robbery, says Canterbury University criminologist Greg Newbold.
Although there are a range of motivations behind a person's decision to rob a location with a weapon, Mr Newbold said there were four main types.
"Some may be to reclaim a debt, some robberies are done as just for the excitement ... some of them are to get money, and some are just acts of desperation," he said.
The venues targeted in recent Hawke's Bay robberies are now the most common type, as the "professional robber" - those who targeted banks, financial agencies, and jewellers - was a thing of the past.
Most robberies now occurred in alcohol stores and dairies, where there was a higher level of security, and lower profit.
"People who risk years in prison for a few bottles of whisky, or a couple of hundred cigarettes, are young amateurs. They're normally stupid and uneducated, normally very young, and normally with very little experience."
Younger perpetrators were often "living their own fantasy", and copying what they had seen on television.
"They're acting as stars in their own movie," he said, "and then they're the stars in their own court case, and the stars in their own prison cells."
When asked if the age of a perpetrator revealed their motivation, Mr Newbold said they were all in the same category.
"If someone who's older robs a gas station ... they're old and stupid, instead of being young and stupid."
Most armed robberies involved the use of a knife, or bat, and statistically people who robbed with these weapons were more likely to use them on those they were stealing from.
"You're better off to be robbed by someone with a firearm," he said. "With a bat you can get bashed over the head to intimidate you, but no one's going to fire a shotgun at you. They might fire a shot at the roof, but you're less likely to be injured."
Commonly, most armed robberies involved more than one perpetrator, as "it gives them courage". Those who committed robberies alone were more likely to get caught, as they might not have a "getaway driver".
Mr Newbold said he could not think why such robberies were increasing in Hawke's Bay, but said it could be a "fad". When robberies got high publicity in the media, this often spawned copy cats and made committing robberies become a "trendy thing to do".