I think youll find that it may be the opposite.
The human psyche is a strange thing, a human will do everything in its power to remain alive, however under certain situations the brain will make the decision that its not going to survive, once that happens it goes through a logical process of events to ensure the further survival of the species, or to ensure that unharmed organisms have a greater chance of survival.
In the case of the young girl and her mother you will probably find that other than possibly the odd nightmare and a bit of tears at first she will have already accepted it. If the woman was alive the first 2 - 3 days she would have used that ensure that her 5 year old daughter was fully aware of the situation and well prepared for a few days of survival both mentally and physically, also preparing her daughter for the inevitable.
Children are a lot tougher and durable as well as amazingly adaptable than many think. in situations like that instinct will take over, the need for food, water and warmth will take over. It amazes me that children learn to walk, communicate and interact with their surroundings in 2 years, many older people take 2 - 3 years to learn a new language.
Thats why when my children are very young I shall have them learning German, French, Afrikkans and any other language of friends I have. That way when they grow up although they wont be fluent they will be able to communicate in other countries.
also I will teach them reading, writing, using a PC and any other skill from a very young age. twill allow them to have an easier life later