We tend to think of ourselves as being able to make rational decisions based on the information we have available to us. If we're missing some information but we're able to conclude that this information would have no influence on our decision then we should be able to press ahead and make a decision in the absence of this information. But that's not how we work. The very presence of uncertainty (regardless of it's relevance to the decision we're trying to make) paralyses our ability to make a decision at all. We'd rather wait until we have all the information at hand even if this delay incurs a minor cost.

1. Decision paralysis
How uncertainty affects decisions

2. Participants in this study were students who had just
taken an important exam two weeks before the Christmas
holidays
The students had to wait two days to get their results and
in the meantime they discovered a discounted holiday to
Hawaii they could book for the vacation

4. Wow – what
a great price for a
holiday to
Hawaii!

5. Students were given three options:
A) Buy the holiday today
B) Pass on the holiday today
C) Pay $5 to lock in the price for two days
However two of three groups were told they had either
passed or failed the exam thus removing option C

6. I want to
know my exam
result before deciding
whether to go to
Hawaii

7. I’ve passed!
Well wouldn’t a
holiday to Hawaii be a
great way to
celebrate!

8. I’ve failed. I
need a holiday to
Hawaii to take my
mind off things!

9. 57% of students who were told they had passed their
exam chose to go on the holiday (option A)
54% of students who were told they had failed their
exam chose to go on the holiday (option A)
However 61% of those who didn’t know whether they
had passed or failed, chose to pay $5 to wait two days
to get their exam results before deciding (option C)

10. So if students pass, they want to go on holiday
If they fail, they also want to go on holiday
But if they don’t know whether they’ve passed or failed,
they… wait and see before deciding

11. Conclusion
1. Uncertainty paralyses our ability to make decisions
even when the outcome of the uncertainty is irrelevant
to the decision we make

12. Reference
The Disjunction Effect in Choice Under Uncertainty
Psychological Science 3 (1992) 305-9
Amos Tversky and Eldar Shafir