Why can't pgAdmin3 connect to Postgres?

I added a new user to posgresql (amanda) which is the same as my linux system user. At the console, I can open psql just fine -- I don't need a password because I'm already authenticated as amanda. But when I try to set up pgAdmin III without a password, I get an error: An error has occurred: 01:18:47 PM: Error: Error connecting to the server: fe_sendauth: no password supplied And if I provide my system password, I get a password error: An error has occurred: 01:15:30 PM: Error: Error connecting to the server: FATAL: password authentication failed for user "amanda" FATAL: password authentication failed for user "amanda" How do I get pgAdmin3 talking to postgres as amanda? This is all @ localhost. I read this: https://dba.stackexchange.com/questions/8111/pgadmin-iii-how-to-connect-to-database-when-password-is-empty but the answer there discusses trust authentication. My read of the [auth methods](https://www.postgresql.org/docs/9.1/static/auth-methods.html#AUTH-TRUST) section of the manual suggests that what I want is for pgAdmin3 to use Ident Auth.