There are two ways to verify which anonymity settings were used for a particular survey.
1. On the 360 Surveys page, press Edit for the reviewee in question. Your anonymity settings will be indicated on this screen.
2. Turn on the Anonymity column on the main 360 Surveys page. This is a good option for checking anonymity on multiple surveys at one time.
Check out the article "Anonymity settings in 360 feedback surveys" for more information about anonymity settings.