Angry Birds: A Visual Field Case Study

Earlier this month I came upon Charles Mauro’s lovely and entertaining cognitive study of Angry Birds. As a player of the game and UX practitioner with an interest in the design of games, the article had great appeal. So this past week when we, the UX team, started a monthly design workshop for our company and visual field was chosen as our first topic, Angry Birds immediately came to mind. Our manager went along with the idea – it was a nice balance to the more dire examples of the Challenger explosion and Cholera epidemic of 1854 – so I read up on Mauro’s findings and turned them along with my own playing experiences to the idea of visual fields.

Here is the handout that my co-workers received on the subject:

In the Angry Birds game experience the designers used visual field not to solve a puzzle but to increase the complexity of one. The gamescape is designed to be wider than the actual screen on which the game is played, so one side of the screen is always out of the visual field.

The constraints of the visual field make players engage their short-term memory by panning across the gamescape at the beginning of each level to show them the structure that they are seeking to take out then bouncing back leaving that structure beyond the visual field. Since short-term memory is both finite and volatile, the visual and auditory engagement of the birds bouncing and chirping in the visual field distracts from remembering the structure that was just seen. This taxing of the player’s short-term memory ups the complexity of the game and therefore makes it even more rewarding when a level is completed.

While this combination of limited visual field and reliance upon short-term memory has the potential to be frustrating, the game is designed to easily adjust the view of the gamescape thus refreshing the player’s short-term memory. It also follows the flight of the bird across the gamescape to its destructive end, hopefully changing the actual structure being aimed at and so refreshing the player’s short-term memory with a new version of the target.

Another tool that the game uses to help the player adjust to the limited visual field is the bird’s flight path. When a bird is shot, it leaves behind a trail of clouds which will remain on the screen for the next shot giving the player visual clues for their launching angle while still keeping the end goal out of the visual field. Only the immediately previous bird’s flight path is visible so the player must set their short-term memory of the structure against the previous bird’s flight to decide their next move.

On the iPad, players can pinch in the zoom to bring the entire gamescape into the player’s view, which prevents short-term memory loss thus decreasing the complexity of the game. This decrease allows the game to be completed more quickly and proficiently but the decrease in challenge makes it less interesting to play and therefore less fun over time. From this we see that what is hidden from the visual field can be just as important was what we include in it.

Drawn in part from Charles L Mauro’s article ‘Why Angry Birds is so successful’

If you’d like a PDF version of the handout for your personal use, grab it here.


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