Survivor benefits vs. retirement benefits

You can receive widows/widowers benefits based on your age at any time between age 60 and your full retirement age as a survivor. However, if you start at an earlier age, your survivors benefits are reduced a fraction of a percent for each month before your full retirement age.

There are disadvantages and advantages to taking your survivors benefit before your full retirement age. The advantage is that you collect benefits for a longer period of time. The disadvantage is that your benefit may be permanently reduced.

This page may be helpful :
http://www.ssa.gov/survivorchartred.htm