That is, she would receive $500 in retirement benefits plus a spousal supplement of $578, bringing her total benefit up to $1,078. Now if you die first, she simply switches to your benefit of $2,155. Or, if she dies first, you do not switch; you continue receiving your larger amount of $2,155.
About me
I hold a doctorate in economics from the University of Wisconsin and taught economics at the University of Delaware for many years.