Comments

Grounding:

Wow, you definitely got some really interesting results. I think the fact that the participants thought they influenced their partner more over AIM than FtF is explainable - there are fewer visual cues that might suggest otherwise (they can't see their partners shake their heads, etc). But the fact that they were more successful in guessing each other's knowledge over aim is quite unintuitive. You'll have to closely analyze the transcripts to see why the conversations were so different. Maybe there was a lot of superfluous material in FtF that distracted from the utterances about the poem. Great job overall!

Emotion:

It's great that your participants were not suspicious of the setup of the experiment and that mood induction worked as planned. They fact that emotion could not be detected by the participants' partners, even though there were clear language differences, is very intriguing but not necessarily surprising given the content of your transcripts. Indeed, for example, most people would probably not associate the use of past tense with being in a sad state. Also, I'm sure that the fact that the two were strangers had an impact - I find it fairly easy to detect the mood of someone I know well over AIM. Nice presentation and good luck on the rest of your analysis!