Wednesday, 30 November 2011

Change blindness and Plants Vs Zombies

For all you following my twitter feed (it's @GameUXTwit by the way) you may remember about 3 months ago I posted about an issue I found with the Plants vs Zombies tutorial:
Found a UX issue with the tutorial whilst showing it to the GF's Mum. Strangely pleased to find fault in a masterpiece.
The problem

Below is a screenshot from the iPad tutorial:

It's fairly clear what you're being asked to do. As it says, tap on the seed packet to pick it up. Then the below screen appears:

Quite a significant change yes? Once more, it's obvious what's needed... but is it? Only if you know where to look. Both sets of instructions are placed in the same position in the screen. Unless the player specifically looks to see if the instructions have changed they may not realise. This is what occurred when I showed the game. The player suffered from change blindness.

Change blindness is where people fail to spot large changes in their visual field simply because they are not paying attention to that area as the change occurs. Essentially if you're not looking directly at the area in a screen when it changes, it gets very hard to see these changes. You can see some change blindness examples here, but the most famous example is this exercise here. For all you who are passe with this, here's a more modern version.

This means that unless the player is aware the instructions have changed, or chooses to look/reread the instructions in the second screen there's a risk they may not notice the change, and so be unsure what to do next.

The solution

There's actually a fairly easy fix - remove the potential of change blindness occurring by deliberately moving the location of the text between each message/screen. See the mock ups below:

The text moves between screens, highlighting the change in instructions. Simple - but the issue should be resolved. Further testing would ideally be performed, to ensure the solution does fix the issue, and to ensure no further issues have been introduced by using this fix.

Additional - apparently as well as change blindness there's such a thing as change deafness. Game designers take note! In fact I'm sure you could take advantage of both in a horror game.

Thanks for reading! :)

No comments:

Post a Comment