Extreme-scale cooperation provokes more intense positive emotions.

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We scale back extreme movements in either direction because they are unlikely to be repeated.

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At the extreme end of the scale, the consequences of head injury are death, persistent vegetative state or severe physical and mental disablement.

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Control Risks ranks countries across four categories, including political and terrorist risk, and rates each country on a five-point scale, from Insignificant through Extreme.

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To see the scale, compare a city like Miami (at one extreme, with just one district covering almost all the metropolitan area) and Boston (at the other, with 70 districts within a 30-minute commute of downtown): that big an increase in choice is associated with an improvement in attainment of 1.4 grades and an increase in young adult earnings of 15%.

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Extreme no-growth zoning and building policies have made all but small-scale development impossible, particularly on the coasts.

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Now banks all over the eurozone, in Greece, Cyprus, Portugal, Ireland, Spain and Italy (as the most extreme examples), are only alive at the moment thanks to the sheer scale of the money they've been able to borrow from the ECB and from their respective national central banks.

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For younger people, it provides extreme action by offering a reason to visit exotic climes, explore abandoned mines or scale difficult peaks.

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