Mittwoch, 25. Januar 2012

Task 5: Heuristic Prototype Evaluation

The following blog post will show our heuristic evaluation result of our first software prototype. As the basic set of the evaluation we used the ten usability heuristics by Jakob Nielsen. Due to the fact the project time is very limited we focused on the gallery part for creating the heuristic evaluation.

Error prevention:

In the gallery mode we had to implement some error preventing arrangements, because the pictures stop sliding right- or backwards if the user is close to the kinect. We implement this feature in the previously prototype to provide the ability to watch a picture in a fix mode. But the problem was that it is not so easy for the user to control the gallery very accurate, which leads to the inconvenience that the user was in the fixed mode between two pictures.


To solve this error state, we improved the fixed modus. The application now detects the picture which fits best for showing in the fixed mode. This is the closed picture to the center of the public display screen. After detecting it, it slides to the horizontal center, so that the user got a perfect view on the selected picture.


We also implemented an error prevention to have a minimum size of the pictures in the gallery. In the old prototype the problem occurs that the user can be very far away from the kinect, which leads to an state that the pictures were very small.

Recognition rather than recall:

In our previous prototype it was not possible to switch between pictures if you are in the fixed gallery modus. The user had to go backward for leaving the fixed mode, go right- or leftwards to switch to another picture and go forward to get again in the fixed mode. We thought about different kind of interactions to switch pictures in the fixed mode, like a special gesture by hand. But we solved the problem by using the go right- or leftward interaction, which we also used to start the gallery slide. The reason for that is, that user already knows this kind of interaction. The issue that user usually do not have any experience with an interactive public display system leads to the point that the user always need a lot of time to understand how to control/interact with the system, which affected the usability because people have to spend a lot of time to understand how to interact. To avoid this effect, it is good to use consistently interaction techniques.

Severity Ratings for Usability Problems:

  • The severity of a usability problem is a combination of three factors (Jakob Nielsen):
  • The frequency with which the problem occurs: Is it common or rare?
  • The impact of the problem if it occurs: Will it be easy or difficult for the users to overcome?

The persistence of the problem: Is it a one-time problem that users can overcome once they know about it or will users repeatedly be bothered by the problem?

Both problems which are described previously occur very often because they are part of the main navigation through the gallery. So it got a four on the frequency rating scale, which can be found here, and needed to be fixed quickly.

The impacts of both problems are huge, because they impact the navigation through the gallery. The user can overcome these problems by performing special interactions, like going backward; focus on a new picture and go forward to select a new picture. But these overcomes are not really user friendly and lead to a huge loss of usability. Due to these facts the problem got a three on the impact scale.

The persistence of the problems is also high and got a four on the persistence scale, because the user will be repeatedly be bothered by both problems.

Keine Kommentare:

Kommentar veröffentlichen