Couples that have been married for a long time communicate with each other like they would with a dog or baby.
Long-term married couples communicate in exaggerated ways
Husbands and wives use exaggerated facial expressions, simple language and a higher pitch to make sure they get their messages across.
The speech manner – often referred to as 'baby talk' and 'motherese' – is the same as that used to get the attention of toddlers and dogs, who are unable to understand what is being said.
Researchers in Hungary have theorised that couples communicate in this way to maintain emotional bonds and keep their partner's attention.
Edua Koos-Hutas, an expert from Eotvos Lorand University, said: "The way parents talk to babies and each other shares a lot of similarities in how their facial expressions are changed.
"This similarity could stem from the emotional closeness and bonding and help create a sincere and focused atmosphere when they talk."