If people cannot sense a reward, she says,then they might have difficulty completing an activity.

VOA: special.2009.09.16

An example of a bottleneck is when people have difficulty detecting a second target if it appears on screen a few tenths of a second after an initial one.

ECONOMIST: Playing action games improves visual skills

If London were threatened, a British government would have little difficulty in persuading its taxpayers to spend heavily on a missile shield.

ECONOMIST: Rockets overhead

It might have been far easier to have overcome this difficulty if the original proposals for a Commonwealth civil service had been imaginatively carried out if the Commonwealth countries had been prepared to send more technicians and administrators of their own to serve the colonies in their transitional stages.

ECONOMIST: From the archive