show hide multiple fields

Hi, I want to have a checkbox, that if selected hides several fields. By default the fields are visible.

I have a small script that does not work. I renamed all the fields I want hidden with a pec. prefix. (pec.Firstname, pec.Address)

var Hidepec = (event.value == "No");

this getField("pec").hidden = HideUserInfo;

Any ideas?