Conditionally set a boolean field in an InSight CSV import

[Greg Popp]

I'm trying to create an import attribute mapping for an object that contains a boolean field. If  the imported data field is set to the string "manifest" I want to set the boolean field in the object to true, and if it's set to anything else, I want it to be set to false. Is there a way to do this? Possibly with a regular expression?
I've tried using this simple regex:

manifest

But that results in the one record that has the field set to "manifest" to be set to false, and all the other objects have that field as "No Value". Then I tried to negate the regex:

.*(?<!manifest)$

But that always results in the field being set to false in every object, even when the imported data is the string "manifest".