This is one of my favorite Google Talks. It features Barry Schwartz. Here he discusses how people make choices. Here is my very quick breakdown.
When people are confronted with a number of choices this is how they respond or feel:
- 1-2 choices does not feel like much of a choice
- 3 choices feels optimal and will generally go for the middle
- 4 choices or more are overwhelming and causes people to not make a choice
The general rule of thumb is create three choices with the middle choice being your main target.
There is way more detail in the video and I highly recommend watching it if you are in sales, marketing, or design.