Grouping positive & negative reviews and counting the words
Your code is actually really good.
But:


getWordListAndCounts should be get_word_list_and_counts.
This is as Python has a style guide called PEP8.
You use a ; but for no reason. It's best to never use it.
In get_texts you do [].append([...]). This can be: [[...]].
In get_texts you have r, it would be better to use review,
this makes it easier to read. Also all the ts in getWordListAndCounts.
You can make getWordListAndCounts a list/generator comprehension.
You seem to mix spaces and tabs. This leads to highly breakable code.
(Look at your question)
Don't have white space after code. It's really annoying, and violates PEP8.


Overall I would say your code is pretty decent.

I would re-write getWordListAndCounts to this for example:

def get_word_list_and_counts(text):
    # Rename the `t`'s I have no context on what they are.
    return Counter(
        str(ttt)
        for t in text
        for tt in t
        for ttt in (re.split("\s+", str(tt)))
    )


To remove the [].append, you can use the following if it has to be a list.

def get_texts(reviews, score):
    return [r[0].lower() for r in reviews if r[1] == str(score)]




As no-one has said it:

[[...]] in get_texts seems redundent, adds complexity, and makes the algorithm worse in memory, from \$O(1)\$ with generator comprehensions, to \$O(n)\$.

The way you call the code shows us also that there is potential to reduce the complexity.

getWordListAndCounts(get_texts(reviews, 1))


To show the change to get \$O(1)\$:

def get_texts(reviews, score):
    return (
        review[0].lower()
        for review in reviews
        if review[1] == str(score) # use ferada's change
    )

def get_word_list_and_counts(text):
    return Counter(
        word
        for line in text
        for word in (re.split("\s+", line))
    )


The above shows you can clearly see it's capable to be in a single function,
if you wish for it.
And remove one of the fors in the get_word_list_and_counts.

It as one function would look like this:

def get_word_list_and_counts(reviews, score):
    return Counter(
        word
        for review in reviews
        if review[1] == str(score)
        for word in re.split("\s+", review[0].lower())
    )


That with ferada's change is probably the smallest and most concise you'll get it.
Also the second for statement will only run if the if is true.