I didn't have an imaginary friend growing up, but my older brother did. His mate was the little boy who lived in the doorknob – AKA his own reflection in the silver door handles on all the internal doors in our house.
He would chat to this little boy throughout the day, apparently, telling him what he was up to and offering to share his sandwiches (the little boy in the doorknob always politely declined).
Having an imaginary friend was once considered a sign of loneliness or social anxiety, but recent research has found children who have imaginary friends are actually less shy and have better perceptive skills.
Melbourne mum of two Mia says her elder daughter Millie has an imaginary dinosaur called Buster as a friend.
"Buster appeared around Mia's third birthday," Mia says. "We have no idea where the inspiration for Buster came from, but he stayed for a good couple of years.
"It started out all cute and fun, and [my husband and I] encouraged Millie's love for Buster, but once she started insisting on him having a meal served at dinner, and not wanting to go anywhere in the car because there was no seat for Buster, I started getting a bit over it."
Perth mum of one Nikki says her four-year-old son Billy's imaginary friend Chester never caused any trouble, and she was happy to have him around.
"Sometimes I feel guilty for making the choice to only have one child," Nikki says. "Chester seemed to fill the gap left by Billy's lack of siblings.
"Billy talks to Chester every day and plays games with him. Whereas he used to need me to do everything with him, Chester has made Billy more independent."
Having an imaginary friend is quite a common phenomenon clinical psychologist Lisa Miller told ABC Radio Hobart, and it can be incredibly beneficial.
"About two thirds of children will invent an imaginary friend at some point in their development," she says. "It's really safe to [practise social skills] with an imaginary play partner because they won't receive as many challenges back."
Clinical psychologist Sonia Wechsler agrees, and also notes the way children play with their imaginary friend can offer parents and carers an insight into what's going on with their child.
"An imaginary friend does give a child an opportunity to express something of themselves in an imaginary way," she says. "It would also provide their caregivers with some insight into the kinds of social difficulties their child might experience. For instance, an imaginary friend who the child reports to be often sad might suggest that this child is struggling with sad feelings."
Wechsler says there are warning signs to look out for, though, saying it's important to observe the way children interact with their imaginary friend.
"That is, do they often choose to play with their imaginary friend over their actual friends?" she says.
"Do they only have an imaginary friend? What might the imaginary friend be saying that the child feels they can't? Parents need to be mindful of the extent and details of their children's imaginary friend(s). There might be times of the day or in certain activities that the imaginary friend is called upon by the child."
But Wechsler also says the imaginary friend can be useful for the parent to engage with, in order to communicate more effectively with their child.
"Depending on the age of the child, it might be helpful for parents to engage imaginary friends in open and playful way," she says.
"It can be a way of testing the difference between the inside of their minds and their outside world. For instance, a parent might communicate with the imaginary friend about something that is difficult to discuss directly with the child. It can be a helpful parenting device, used in a mindful and creative way."
Wechsler says as with many childhood behaviours, it's ultimately important for parents to consider the imaginary friend within the context of their family and the specific child.
"Age and stage are very significant to assessing whether the existence of all childhood behaviours are problematic," she says. "But I would add that it is really the meaning for the child and how the child uses their imaginary friend."