How transitivity works
Any full sentence contains a proposition, which describes a process. At its most basic, this could consist of a subject — someone or something that is 'doing', which is represented by a noun phrase — and a predicate — a verb phrase representing the thing that is being 'done', e.g. 'the conservatives won', 'the rebellion continues', 'power corrupts'. Transitivity looks in detail at the way processes are described, taking as its object of study the predicate, and the way in which this element allows a speaker/writer to present a process in different ways.
When analysing transitivity, and its possible significance, the first thing to do is to work out which 'category' of verb, or process, is being used. Each of the four main categories is described below, with examples to illustrate how they work.
Material action processes
Material action processes are perhaps the most straightforward and easy to recognise. These processes describe something being done. For example, a journalist might comment on how 'The chancellor cut public spending': here, we can discern an 'actor' who acts out the process (the chancellor), the action that the actor performs (cutting) and a goal, i.e. the person or thing that is acted upon (public spending, which has been cut).
In the chancellor example, we imagine that the chancellor performed this action intentionally: we would call this a material action intention process. However, if we subsequently read that 'The chancellor angered the public', we would probably imagine that the chancellor (unless especially masochistic!) had not performed this action intentionally. This second example, then, represents another possibility: a material action supervention process, whereby the actor does not intentionally act out the process.
One final type of material action process is the material action event process, in which the actor is inanimate. An example might be 'Public spending shrunk', where it is hard to attribute either intention or lack of intention to the actor.
Verbalisation processes are very similar to material action processes, only differing in the fact that they describe a verbal action. We could change the chancellor example above from a material action to a verbalisation process like so: 'The chancellor explained that public spending would be cut'. As with material actions, verbalisation processes are divided into three parts: the sayer (the chancellor), the process (the explaining) and the verbiage, or what was said (that public spending would be cut).
While material action and verbalisation processes tend to refer to things that can be seen or heard in the world around us, mental processes refer to internal processes in our minds. Again, processes divide into three parts, in this case describing a sensor, a process, and the phenomenon that is being sensed. There are also three types of mental processes: cognition processes ('The chancellor realised what he had done wrong'), reaction processes ('The chancellor disliked having to perform a U-turn') and perception processes ('The chancellor heard the public's criticisms').
While in each of the other types of process there is the sense of an action being performed, relational processes simply report the relationship between a carrier and an attribute. Once more, there are three different types of process: intensive processes ('The chancellor is mad'), possessive processes ('The chancellor has big problems') and circumstantial processes, which tend to refer to placing and timing ('The chancellor's budget is at one o'clock').
Newspaper coverage of important events can be an interesting subject for the study of transitivity. The limited amount of space that is available, and the need to communicate what has happened in an attention-grabbing way, can make for telling transitivity choices. One notable example from recent British history is the way newspapers covered the English riots of August 2011. We might expect that many headlines would use material action intention processes to describe rioters rioting, as the Times did: "Mobs rule as police surrender streets" (note that the adverbial clause contains a second material action intention process, with the police forced into an action by the 'mobs'). However, many headlines used noun phrases to clearly define what was happening in a concrete way: "Flaming morons" (The Daily Express), "The battle for London" (The Guardian), "Anarchy" (The Sun). Others used material action event processes, which created the frightening idea of something inhuman, something beyond control, causing chaos: "The anarchy spreads" (The Daily Mail), "The madness spreads" (Metro). Material action intention processes were used more frequently in subheadings, featuring 'thugs' and 'gangs' as actors: "Gangs run riot from east to west" (The Daily Telegraph), "Thugs and thieves terrorise Britain's streets" (The Daily Express), "Gangs of masked youths attack shops in Birmingham" (Metro). Politicians (but notably not the police) were also portrayed as actors, in processes detailing the response to the riots, creating the comforting idea of someone taking action: "PM dashes back as riot terror spreads" (The Daily Star), "Cameron ends holiday early" (The Daily Telegraph), "Politicians fly home to deal with crisis" (Metro). Relational processes were less common, although The Daily Mail notably used a pair of relational intensive processes to spell out 'the way things are': "To blame the cuts is immoral and cynical. This is criminality pure and simple."
Transitivity and ideology
A speaker or writer's choice of verb has an inevitable effect on the way a proposition is portrayed, and can have significant ideological implications. A single event can be described in different ways using different processes, each showing the same event in a different light. Returning to the chancellor example, we can think of different ways in which people might react to the news of the budget being cut, and how the choice of process might help to shape that reaction. It is important to note that particular processes don't inherently portray things in a positive or negative light — rather, the way certain people or things are put into particular types of processes can allow speakers and writers to portray (consciously or not) events in a way that suits their beliefs and purposes.
Commentators angered by the chancellor's decision might use material action intention processes to place clear responsibility for the decision at the chancellor's door. For example, a headline might read 'Chancellor slashes public spending', or a columnist might opine that 'The chancellor damaged many people's opportunities', clearly labelling the chancellor as the culpable party. They may also use mental processes to try to ascribe certain thoughts or feelings to the chancellor, even though, of course, it is not possible for someone to have access to another's thoughts: 'The chancellor thinks he can get away with taking money from the poorest', 'The chancellor believes that the public will put up with years of austerity'.
A more objective tone might be achieved by using a verbalisation process to report what the chancellor actually said. For example, a report might note how 'The chancellor said the cuts were tough, but necessary', or 'The chancellor regretted the impact the cuts would have'. Alternatively, passivisation — the removal of the subject/actor from a clause — might be used to remove culpability altogether, as in 'Public spending has been cut'. Finally, the chancellor themselves might defend their decision by using relational processes to allude to how things actually are in the world, perhaps by claiming that 'Cuts are the only way to deal with our economic problems', or 'I have little choice but to tighten the nation's belt'. These uses of relational processes suggest that the chancellor's actions were forced upon him by circumstances, rather than being a deliberate, planned policy choice.
As noted in the example above, the way transitivity is used in newspaper headlines is often interesting, and can be indicative of the ideological viewpoint of the writer/publication. When reading headlines, consider who is being described as doing what (and to whom): what impression does this quick snapshot give you of the events that the article goes on to describe?
The 'Representing Actions/Events/States' section in Jeffries' textbook outlines the significance of transitivity:
Jeffries, Lesley. 2010. Critical Stylistics: The Power of English. Hampshire: Palgrave, 37-50.
For a summary of 'Sentence construction: syntax and transitivity', see Richardson's study of British newspapers:
Richardson, John E. 2007. Analysing Newspapers: An Approach from Critical Discourse Analysis. Hampshire: Palgrave Macmillan, 54-59.
Simpson and Mayr's introductory guide to studying language and power includes a section demonstrating the significance of transitivity on the way gender issues are discussed in texts ('Gender and power: using the transitivity model'):
Simpson, Paul and Andrea Mayr. 2010. Language and Power: A Resource Book for Students. London: Routledge, 65-70.