It has been suggested that a number of Prime Ministers may have developed a personality disorder known as Hubris syndrome while in power.
Researchers at St George's, University of London have discovered that this personality change was reflected in both Blair's and Thatcher's use of language.
Hubris is commonly associated with a loss of contact with reality and an overestimation of one's own competence, accomplishments or capabilities.
It is characterised by a pattern of exuberant self-confidence, recklessness and contempt for others, and is most particularly recognised in subjects holding positions of significant power.
Fourteen clinical symptoms of Hubris syndrome have been described. Subjects demonstrating at least three of these could be diagnosed with the disorder.
Researchers at St George's, University of London searched for evidence of some of these clinical features in the language used by three British Prime Ministers - Margaret Thatcher, Tony Blair and John Major - by examining transcribed samples of spoken language taken from Prime Minister's Questions.
They thought that frequent use of certain words or phrases, such as 'sure', 'certain' and 'confident', the first person pronouns 'I' or 'me', references to God or history, might show up during 'hubristic' periods.
They found that 'I' and 'me' and the word 'sure' were among the strongest positive correlations over time in Tony Blair's speech. Blair's use of the word 'important' also increased with time.
Words and phrases that became more frequent with time in the speeches of Lady Thatcher and Tony Blair also included the phrase 'we shall', while phrases that included the word 'duties' diminished.
The authors also found that language became more complex and less predictable during hubristic periods.
For example, Lady Thatcher's language becomes more complex at the end of her term of office, when her decisions and judgements were opening deep divisions within her own party.
The same happened to Tony Blair's speech during the run-up to the invasion of Iraq.
These linguistic patterns were not reflected in the language of John Major. The relative frequency of the word 'we' compared to 'I' was in fact higher throughout the terms of office of both Thatcher and Blair than at any point of Major's premiership.
Additionally, the changes over time in words and phrases adopted by both Thatcher and Blair appeared to mirror the time course of hubristic behaviour.
Dr Peter Garrard, the lead researcher, from St George's, University of London, said: "Hubris syndrome represents a radical change in a person's outlook, style and attitude after they acquire positions of power or great influence.
"They become obsessed with their self-image, excessively confident in their own judgement and dismissive of others, often leading to rash, ill thought-out decisions. In other words, the acquisition of power can bring about a change in personality: it is as if power, almost literally 'goes to their head'."
"This work shows us that language can reflect this highly characteristic personality change. Spontaneous language production is an automatic process: to some extent we can influence how we come across in our choice of words, but most of the time we don't.
"The way we use language reflects the cultural and social environment, but biological factors, including personality, are also important," said Dr Garrard.
"Hubristic behaviour is widespread, and not confined to politics: hubristic overconfidence in the financial sector almost certainly contributed to the recent banking crisis.
"We need to refine these language based measures and apply them more widely using other sets of digital samples from the past, with a view to detecting hubris and preventing its potentially catastrophic consequences."
--IBNS (Posted on 30-09-2013)