"[It's] more than ever before.
"While there is no concrete evidence that smartphone use does lead to mental health issues, there's certainly a lot of corresponding evidence."
Just two weeks after taking effect, the cellphone contract was making a difference.
"We've got banter all the time.
"It's quite interesting."
Although the pair initially said the rules were not fair, they were "really accepting" when the reason was explained.
"It's been fantastic, a really interesting learning experience for us all."
The rules included no cellphone use in bedrooms, or before getting ready for school.
Previously, the pair watched videos on their phones during breakfast.
They were more aware now of their surroundings.
"We'd be frustrated because they weren't listening, whereas now, I guess they're more present," Hou said.
Ella said her first reaction had been negative, but using her phone less made it "easier to focus".
Most of her friends had no restrictions on smartphone use.
"I think one of my friends do, but everybody else can go on it whenever."
Hou said his son had needed a Facebook account because he had been missing basketball practice, which was a reflection on how schools were communicating with pupils. As the children were young, phones were not a big part of their social life yet. Hou intended to keep the rules throughout their teenage years.
"I think it's really important that parents are involved and follow what [their children] post."
