Cases of shared mental breaks have been recorded globally since 1955

A paranoid Australian family who sparked an interstate man hunt after fleeing their home to hide from an unfounded threat against their lives are one of many groups from around the world who have been affected by 'shared delusions'.

The Tromps - including father Mark, mother Jacoba, son Mitchell and daughter's Riana and Ella - were unable to explain what exactly caused the bizarre 'off grid' road trip that left two of them receiving psychiatric help in a mental health facility.

Mark, 59, was found in a confused state wandering a highway five days after he urged his family to leave their phones, credit cards and passports at their Silvan home, east of Melbourne, and jump in the car so they could evade a mystery threat.

Many speculated the family had been under the influence of psychoactive drugs, others suggested they were in financial trouble, mentally disturbed or caught in the grips of a sinister cult, but experts believe they experienced a shared mental break.

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The Tromps were unable to explain what exactly caused the bizarre 'off grid' road trip that left two of them receiving psychiatric help in a mental health facility (Pictured from left to right: Riana, Mark, Jacoba, Mitchell and Ella)

Similar to unsubstantiated tales of long eared 'goblins' terrorising a family in Kentucky, or accounts of a UFO attacking a car in Perth - medical sociologist Robert Bartholomew claims the Tromps were victims of 'small group panics'.

'Most episodes involve normal, healthy people who, as a result of a series of unusual events, grow paranoid and literally scare themselves after growing convinced that their lives are in imminent danger,' he told Psychology Today.

He said fatigue and fear causes members - who are often influenced by a prominent member in the group - to become emotionally unstable, which makes them more suggestible and further limits their power to critically assess the situation.

'Within this atmosphere of fear, members begin to redefine everyday objects and events in a new light,' he said.

'It is within this context that a car backfiring, may be perceived as a gunshot, or rustling in the bushes is mistaken for a monster or hostile gang member.'

Professor Bartholomew said those affected by shared delusions are often influenced by a prominent member in the group - in the Tromp's case father Mark

A timeline of events before Mark was found wandering a highway near Wangaratta Airport

THE TROMP FAMILY'S OFF-GRID VACATION Monday, August 29 The Tromp family abandon their redcurrant farm in Victoria and flee the town in their family station wagon without any bank cards or mobile phones. Son Mitchell, 25, is found to have a mobile phone and it is thrown from the vehicle east of Melbourne. Tuesday, August 30 Mitchell becomes concerned with his parent's 'delusional' behaviour and leaves the family trip at Bathurst before boarding public transport home. Mark, 51, his wife Jacoba, 53, and their two daughters Ella, 22, and Riana, 29, continue travelling to the Jenolan Caves. Ella and Riana allegedly steal a utility truck and leave their parents in Goulburn. The sisters become separated in the regional town and Riana is found in a catatonic state hiding in the back of a local man's utility truck. The 29-year-old was taken to hospital and treated for a stress-related illness. Ella started travelling back to the family home in the stolen vehicle. Police visit the family farm after the couple are reported missing. Wednesday, August 31 Ella and Mitchell arrive home separately and are met by police. Officers spot the family station wagon in Victoria's north-east and a man, believed to be Mark, flees the vehicle and runs into a nearby park but is not found. Thursday, September 1 Jacoba is found 'dazed and confused' in Yass after separating from her husband. She was taken to a local hospital to be treated for a stress-related illness. Mitchell reveals his parents were paranoid and afraid when he abandoned the trip. Friday, September 2 Jacoba was transferred to Goulburn hospital where Riana is undergoing treatment. Saturday, September 3 Mark was found wandering the streets near the Wangaratta airport in 'good health' and was taken into police custody. Advertisement

Professor Bartholomew said the Sutton family from Kentucky, in America's mid-west, left their home riddled with bullet holes in 1955 after fooling themselves into thinking there were creatures with huge heads, glowing eyes and pointed ears coming for them.

The various members of the family - made up of seven adults and three children - reported spotting the creatures near the house or peering through the window over a period of three hours, resulting in the family opening fire on the perceived threat.

Police became involved in the incident - referred to as the Hopkinsville goblin encounter or the Kentucky space goblins - at about 11pm after the family made a break for it and drove to the nearest police station for back up.

But upon returning to the rural farmhouse, police found no evidence of the three-foot-tall intruders and left just after 2am.

The various members of the family - made up of seven adults and three children - reported spotting the creatures near the house or peering through the window over a period of three hours, resulting in the family opening fire on the perceived threat

A police officer who interviewed the family concluded they had seen a flock of Great Horned Owls which have similar physical descriptions and aggressive defend their nests after dusk

The ordeal did not end there, with police being called back to the scene after the mother claimed to have seen one of the creatures lurking near the window.

A police officer who interviewed the family concluded they had seen a flock of Great Horned Owls which have similar physical descriptions and aggressive defend their nests after dusk.

'After the owls were scared off by the gunfire, fatigue and imagination appears to have taken over and the terrified occupants were soon firing at shadows and rustling in the bushes,' Professor Bartholomew said.

Another incident believed to be spurred on by a shared delusion dates back to 1978 when two suspected drug dealers became paranoid their house was being watched, resulting in another one-sided gun battle.

A man known as Masters and his friend Cordell noticed half of a discarded gum wrapper on the roof, while the other was strewn near a pile of wood - further fueling their suspicions they were being watched through the widows.

Another incident believed to be spurred on by a shared delusion involve two suspected drug dealers who became paranoid their house was being watched like Mark Tromp (pictured)

Instead of fleeing their home like the Tromps, Cordell and Masters took a stockpile of weapons and attempted to defend their property from the perceived threat (Pictured: Tromp home)

After spotting a 'kid' in camouflage clothing, Cordell gave chase and yelled a threat to the other people he believed were hiding nearby that he was armed and willing to shoot.

The pair ended up recruiting another friend, Hamby, after concluding they were under siege. The duo continued reporting noises and claimed to see shadowy figures throughout the night, and as their exhaustion grew so did their delusion.

Cordell told police he had shot and killed a man he saw hanging from a window of the house, explaining in details the gurgling noises his victim made as he died.

But there was no blood spatter, body or witnesses that could corroborate his story - only destruction and empty shell cartridges scattered throughout the empty house.

Another Australian family captivated the nation with claims they survived an extra terrestrial encounter in January 1988.

Another Australian family - the Knowles - captivated the nation with claims they survived an extra terrestrial encounter in January 1988 (Pictured: Patrick, Faye, Sean and Wayne)

The family claim a UFO picked their car (pictured) up as they were driving across the Nullarbor

Faye Knowles had been driving for around thirteen hours from Perth to Melbourne with her three sons - Wayne, Sean and Patrick - when Sean became convinced he spotted a UFO floating in the sky above the Nullarbor Desert.

He notified the rest of his sleeping family before growing increasingly fearful that the spaceship was following his family causing him to speed off down the highway.

The family then claimed a sponge-like object lowered down and lifted the car off the road as a grey mist slowly seeped into the vehicle.

'I wind down the window and it was on top of the roof ... it all come inside the car like smoke - we thought we were dead,' Faye Knowles said.

'I wind down the window and it was on top of the roof ... it all come inside the car like smoke - we thought we were dead,' Faye Knowles (pictured) said

'I swear to God I am not lying... the car started going out of control and it was like smoke... and gasses started coming in,' Patrick added

'I swear to God I am not lying... the car started going out of control and it was like smoke... and gasses started coming in,' Patrick added.

Me and my brother started to go crazy. I thought it was going in my head. It felt like My brain was getting sucked out.'

Two truck drivers came upon the family in a distressed state after they claimed to have changed a tyre that was busted when the UFO dropped them.

The car was covered in a thick layer of ash and there was a dent on the roof, but it was found to be clay and salt from the road.

'Given the lack of corroborating physical evidence, and the frightened state of the occupants, it appears that family members, fatigued from a long trip, under the cover of darkness while traveling on an unfamiliar road, mistook an anomalous light for an extraterrestrial space craft that they believed was pursuing them,' Professor Bartholomew said.