making me very uncomfortable

[azz]

a. John was talking incessantly and Bob was drinking shot after shot of vodka making me feel very uncomfortable.

b. John was talking incessantly and Bob was drinking shot after shot of vodka, making me feel very uncomfortable.

The two sentences are the same except for the comma after the word vodka.

What does 'making me feel very uncomfortable' modify in each case? In which case is the phrase preceding 'and' modified as well as the one following it?

In other words, can we tell if John's talking and Bob's drinking are both making me feel uncomfortable or only Bob's drinking?

Does the comma change anything?


Many thanks

[Alan]

The comma is necessary.

The referent (implicit subject) of 'making' could be construed - depending on sense/context - as either 'Bob' himself or the action(s) being referred to (i.e. whereby 'making' would be considered a summative modifier - the participial equivalent of a sentential relative clause).