The best examples are the use of radio by the Nazis in the early 1930s, and before the Rwandan genocide.

I would argue with deindividuation beeing facilitated in hate speeches. So if the speech makes the listners feel as a crowd beeing threatend or having to fight back, they will stop acting on their moral values. Thus they will be tempted to act more aggressively. Zimbardo didnt study hate speeches but deindividuation and you can argue the link.

Zimbardo, P. G. (1969). The human choice: Individuation, reason, and order versus deindividuation, impulse, and chaos. In Nebraska symposium on motivation. University of Nebraska Press.

I have a book coming out this year, where that's examined as an issue, with specific reference to indigenous peoples of what is now the United States - it's called 'Marginalisation and Aggression from Bullying to Genocide', and it's published by Sense (Rotterdam, Netherlands). There's an early version of one of the models I have since developed in this book on here as a conference paper - it's called 'Social cognition, genocide and the Sioux-Cheyenne campaign (1864 - 1890)'.

Hello Nicola

Vocalizing hate, thus hate speeches, influences the listeners feelings. Since a hate speech is usually directed toward a person or a group in the form of prejudice (or desire of revenge), and is often very critical or demeaning about the hater's target, most of the time his/her words are emotionally highly charged. People can react in different ways, but usually there will be a certain number of listeners who will adopt and agree with what the speaker said.

An example in case: say that we are listening to a presidential candidate rantings against emigrants and how dangerous those people are. His words can, and probably will, cause among his listeners fears about such outsider group.

What is the consequence? Could be that a sizable number of those listeners decide that it would be better for their country to evict ALL strangers. If the opportunity arises, those people could well be able to act violently towards a segment of them living in their close neighborhood. KKK comes in mind.

As Anthony mentioned, all dictators use hate speeches to promote their agendas, as they have to direct their audiences' feelings against the group of perceived enemies he is willing to exterminate. Alone, those tyrants cannot reach their goals, they need followers who congregate the same ideologies, prejudices, and xenophobic feelings.

So, answering your question, IMO, hate speeches can be precursors to physical violence, and history proves that many times they cause exactly that.

This paper may interest you:

Cobia, Debra C., and Jamie S. Carney. "Creating a culture of tolerance in schools: Everyday actions to prevent hate-motivated violent incidents." Journal of school violence 1.2 (2002): 87-103.

Be well

Tom

Many thanks to you all! Very helpful!

"As Anthony mentioned, all dictators use hate speeches to promote their agendas, as they have to direct their audiences' feelings against the group of perceived enemies he is willing to exterminate"

I think the problem is much wider than simply blaming dictators, and should be a current priority for social psychologists.  In Rwanda, the radio played upon existing tribal tensions, fears and conflict.  I don't recall there was a particular problem with dictatorship

In the early days of the Nazi party the radio exploited and amplified widespread popular disillusion with their current political parties. It was a bottom-up movement before the later top-down directives, ie dictatorship.   It is vital to clarify this, because Europe and the US now finds itself in a similar position of breakdown of trust in political institutions, and social media is far more immediate, powerful and divisive than the radio.

Everything starts from the words !

For theoretical understanding, you could look into sociological theories to get background. The labelling theory for instance looks into how in society people are stereotyped and labelled in certain ways (often negatively) and how it creates a self fulfilling prophecy. This may give a good insight on how social norms are challenged through hate speech and how it may help form a relationship to violence in different cultures! 

An E London schoolgirl who fled the country to fight for ISIS in Syria has just been killed, having tried unsuccessfully to return to the UK.   By all accounts she was a well-behaved A student from a good family, who was totally convinced by internet propaganda.  

With "hate speech" I mean the second option - that is "words designed and intended purely to promote division and hatred". In particular, I'm looking for research that investigated the use of web technologies to express hate speech against sexual minorities and women.

Many thanks!