usability - Heuristic approaches for users' evaluation of UX

A heuristic evaluation typically employs three main approaches;

1. Provide evaluators with a set of tasks to be carried out


2. Provide system goal’s and let evaluators develop their own tasks


3. Let evaluators assess dialogue elements

I understand that choosing the right approach depends on time constraints and the maturity of the system. So for instance if the system is a functioning product then the first approach shall be used, the second approach is for early stages, alpha, beta... But i don't understand the third approach can somebody please explain?

Answer

As the SitePoint article, from which I believe this question is derived states:

Ask evaluators to go through the interface a number of times and examine and assess the efficacy of those elements of your Website that contribute to a dialogue with your site visitors.

If you're looking for when this approach would be used over the other two, I'd say probably when the design and copy is thought to be complete but maybe the functionality isn't quite there.

Edit: For example, UX.SE's intended is for users to ask and answer questions about UX. If you look at the top navigation, the sidebar at the right, the main content area or the footer, all the visible items (read, elements) contribute to that and help get questions answered.