Interaction Dynamics and Persuasion Strategies

I recently read Chenhao Tan et al’s 2016 WWW paper Winning Arguments: Interaction Dynamics and Persuasion Strategies in Good-faith Online Discussions, which presents an interesting study of the linguistic features of persuasion.

Coming from a deliberative background, the word ‘persuasion’ has negative connotations. Indeed, Habermas and others strongly argue that deliberation must be free from persuasion – defined roughly as an act of power that causes an artificial opinion change.

In its more colloquial sense, however, persuasion needn’t be so negatively defined. Within the computer science literature on argument mining and detection, persuasion is generally more benignly considered as any catalyst causing opinion change. If I “persuade” you to take a different route because the road you were planning to take is closed, that persuasion is not problematic in the Habermasian sense as long as I’m not distorting the truth in order to persuade you.

Furthermore, Tan et al gather a very promising data set for this investigation – a corpus of “good faith online discussions” as the title says. Those discussions come from Reddit’s Change My Mind forum, a moderated platform with explicit and enforced norms for sharing reasoned arguments.

Each thread starts with a user who explicit states they want to have their opinion changed. That user then shares said opinion and outlines their reasoning behind the opinion. Other users then present arguments to the contrary. The original poster then has the opportunity to award a “delta” to a response if it succeeded in changing their opinion.

So there’s a lot to like about the structure of the dataset.

I have a lot of questions, though, about the kinds of opinion which are being shared and changed. Looking through the site today, posts cover a mix of serious political discussion, existential crises, and humorous conundrums.

The all time most highly rated post on the site begins with the opinion, “Strange women lying in ponds distributing swords is no basis for a system of government.” So it’s unclear just how much we can infer about debate more broadly from these users.

However, Tan et al, intentionally restrict their analysis to linguistic features, carefully comparing posts which ultimately win a “delta” to the most similar non-delta post responding to the same opinion. In this way, they aim to “de-emphasize what is being said in favor of how it is expressed.” 

There’s a lot we lose, of course, by not considering content, but this paper makes valuable contributions in disambiguating the effects of content from the effects of syntactic style.

Interestingly, they find that persuasive posts – those which earn a delta from the original poster – are more dissimilar for the originating post in content words, while being more similar in stop words (common words such as “a”, “the”, etc). The authors are careful not to make causal claims, but I can’t help but wonder what the causal mechanism behind that might be. The similarity of content words matched by the dissimilarity of stop words seems to imply that users are talking about different things, but in similar ways.

There’s a lot of debate, though, about exactly, what should count as a “stop word” – and whether stop word lists should be specially calibrated for the content. Furthermore, I’m not familiar with any deep theory on the use of stop words, so I’m not sure this content word/stop word disjunction really tells us much at all.

The authors also investigate usage of different word categories – finding, for example, that posts tend to begin and end with tangible arguments while become more abstract in the middle.

Finally, they investigate the features of users who award deltas – e.g., users who do change their mind. In this setting, they find that people who use more first person singular pronouns are more likely to change, while those using more first person plurals are less likely to change. They posit that the first person plural indicates a sort of diffuse sense of responsibility for a view, indicating that the person feels less ownership and is therefore less likely to change.

I’d love to see an extension of this work which dives into the content and examines, for example, what sorts of opinions people are likely to change – but this paper presents a thought-provoking look the persuasive effects of linguistic features themselves.


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