Dr Reddy said: "Fake crying is one of the earliest forms of deception to emerge, and infants use it to get attention even though nothing is wrong. You can tell, as they will then pause while they wait to hear if their mother is responding, before crying again.
"It demonstrates they're clearly able to distinguish that what they are doing will have an effect. This is essentially all adults do when they tell lies, except in adults it becomes more morally loaded."
She added: "Later it becomes more sophisticated by saying, 'I don't care' when threatened with a punishment - when they clearly do."
Dr Reddy thinks children use early fibs to discover what kinds of lie work in certain situations, and also learn the negative consequences of lying too much.
In a way, yes, fake crying by babies is an early attempt at manipulation. So is the 'bluffing' by toddlers. Is this essentially the same as what adults do when lying? I would say that adults are obviously more morally culpable because they should know better. With children, it's our jobs as parents to make sure we call them on their bluffs as much as we can to demonstrate that lying does not change the reality of what they've done (the consequences). With babies, they need to know that we'll be there when they need us and that they can affect the world around them (including their parents). When babies have no other means of communication, I don't really believe that using the few tools they have in alternate ways can be called lying.