Does Skinners theory back up Rachaels first words?
Rachaels first words support Skinners theory because the majority of Racheals words are words that would often be repeated in her daily routine by her parents/careers, meaning that she would be able to imitate them and learn them for rewards. Eg her parents would probably often say to her 'more?' as in if she wants more food etc. and she would repeat it learning that when she says it, she would be rewarded by getting more.
Words such as 'mummy' and 'daddy' also support Skinners theory, when she repeats the words she would be rewarded by the parents going to her etc. They are words that would most likely be the most often heard in her daily routine too.
But also; one of Rachaels first words is 'wassat' which shows she is trying to repeat words she has heard, the missing sounds are the least stressed words which shows that she is listening and trying to repeat the words by listening to the sounds made. Skinners theory said that children learn through language by repeating words and then receiving rewards (positive reinforcement), and this supports it as she is clearly trying to repeat words that she has heard before.

Child language acquisition:
What does this say about how a child learns language?
The words in the categories tell us that children learn nouns quicker than any other category. This may be due to these words being used more often. Nouns are probably more incorporated within the child's daily routine, meaning they hear them more and can more easily put the word and object together. For example. two of the child's first words are 'sock' and 'shoe' this could be explained by every time a parent and the child leave the house, the parent could say 'now we must put on your shoes' and then carrying out the action of putting on the child's shoes places the object and the word together for the child. Being able to have a physical meaning behind the word that the child can associate together is probably more easily remembered/learnt than a word that is more of a concept, eg something being too hot.

The lack of adjectives could be down to the idea that before the child can communicate their satisfaction/dissatisfaction or preferences they first must learn the words that get them what they need. Satisfaction/dissatisfaction can also be shown be sounds or body language, not necessarily words, for example crying if they're too hot or hungry. But words such as 'poo', 'toast', 'cup', 'spoon' etc can not be communicated by a sound easily, or at all. If the child wants toast or a cup etc it must learn to ask for one, by saying the one word of what it is wanting it can convey their meaning. This could be another reason why nouns are by far the biggest category of learnt words.

However; there are also a lot of personal words such as 'hello', 'hiya', 'no', 'yes', 'ta' and 'please'. This is probably due to the parents trying to teach their child basic politeness. When giving the child something, the parents might now allow the child to take the object until they say 'ta'. This makes the word important to the child, as they will soon learn to get what they want they must say 'ta'. The same for 'please'. They are also very common words to be heard in everyday language, again repeating the idea that repetition is an important factor for children when learning new words.

'Ta' is obviously short for 'thank you' this shows us that children may learn their language is smaller sounds and then build them up to make the full word. At the age the child is when they say 'ta' they may not have developed the sounds needed to say the full 'thank you'. Later on as they hear the words 'thank you' more, they may start to learn how to make the necessary sounds needed. The child also says 'wassat' as in 'whats that' put together, again repeating the idea that children need to learn the sounds to make the words they are trying to communicate. Over time as the child hears the words more often they may become more familiar with the sounds and be able to say the two words separately.