Asking staff about the qualities of a good leader is a surefire way to get them talking. Most would agree that having vision, people skills and integrity are important. And you would also expect intelligence to feature well up the list of desired attributes.

But new research suggests that having a very high IQ is not necessarily such a good thing when it comes to leadership – the brightest people are actually less effective leaders, according to new research.

The revelations come in a study by Switzerland’s University of Lausanne which is published in the Journal of Applied Psycsthology.

The researchers recruited 379 mid-level leaders at private companies in 30 mainly European countries, working in areas ranging from banking and telecoms to hospitality and retail.

The average IQ of the leaders was 111, compared to an average of 100 for the general population.

Each participant also completed a respected personality questionnaire known as the Wonderlic Personnel Test which measures ability to solve problems, understand instructions, learn efficiently and adapt to change.

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In addition, the researchers were given access to third-party assessments made by eight colleagues, who rated them by using the Multifactor Leadership Questionnaire. This revealed how the leader demonstrated various leadership styles such as transformational, instrumental or passive.

There were some variances caused by differences in age and sex – with women and older leaders tending towards better leadership styles overall. But the bulk of the variance was accounted for by personality and intelligence.

Intelligence showed a positive linear relationship with leadership effectiveness up to a certain point. But the association flattened out and then started to reverse at an IQ of about 120.

When the leaders’ IQ scores rose to 128 or above, the association with less effective leadership methods was clear and statistically significant, the British Psychological Society notes.

And these leaders demonstrated less transformational and instrumental leadership than leaders with a lower IQ.

The reasons behind the trend are harder to pinpoint. The highly intelligent leaders were not using harmful leadership styles, such as adopting a laissez-faire approach. But they did struggle to adopt the best leadership practices.

One of the reasons may be that very clever people sometimes fail to communicate clearly enough or explain complex tasks. They may also struggle to see what others find challenging. And if a manager comes across as too intellectual, it may make the leader appear aloof or unapproachable.

However, this study does not allow bosses to pinpoint the best possible IQ of an ideal leader, since it also depends on the intelligence of the staff.