Offered otherwise similar rewards, people prefer the one that will arrive sooner. This makes sense, but some research has shown that people discount the value of future rewards hyperbolically rather than exponentially (which would be the mathematically correct approach).
For example, people seem to be much more likely to choose $1 today over $2 in a week, relative to $1 in a year or $2 in a year and a week, despite these being essentially the same choice.