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RESEARCH BLOG #9: “The Left-Digit Effect…” More Psychology at use in game design

“The Left digit Effect” demonstrates one of the ways psychological manipulation is used in video game design. Madigan explains the “left digit effect” in pricing, noting how $2.99 for example seems like less than $3.00: “The left digit disproportionately affects our perception of price.” In a 2005 study, subjects were asked to estimate how many items they could buy from a catalog with $73.00. They were first presented with prices ending in .00, then with prices ending with .99—“Across all conditions, subjects estimated they could afford to buy more when prices ended in .99” (Madigan). The left-to-right reading process makes the first number the most significant.

“$59.99 is seemingly less than $60.00 because the leftmost 5 is coded as meaningfully less than the 6. The relatively slow moving, rational part of one’s brain catches up an instant later and recognizes that a penny’s difference means nothing; but the snap judgment has already been made and perceptions of price are now subtly biased”(Madigan).

Madigan goes on to say that “as with most cognitive biases, we’re especially susceptible to the left digit effect when the rational part of our minds is busy or tired.” The left digit effect can be applied to more than just prices, however, and can happen regarding any number or measurement—including elements in video game worlds (“average scores, weapon stats, gigabytes of space,”—anything represented numerically.) For game designers trying to maximize player’s reward-satisfaction, without compromising the balance of ease and fun, the left digit effect can be a highly effective technique to adopt. It is also likely to be most effective “when player’s mental [or virtual] resources are depleted or directed elsewhere (combat, challenge, character creation process, or player and item stats).

If you’re designing an axe for your RPG that does 3.02 damage per second, it’s going to be seen as disproportionately better than a sword with a 2.99 DPs. Adding a skill point to reduce the cool-down timer on an ability from 5 seconds to 4.5 seconds is going to seem like a better use of the skill point than the previous time it was reduced from 5.5 to 5. And 3,000 experience points for a quest reward is going to be a lot better than 2,950 –more so than math alone would lead you to believe (Madigan).

The use of psychology in video game design is highly underestimated and underutilized. There are so many psychological facets, like the left brain effect, that can be applied to game play. It’s all about learning and reinforcement. It’s all about perception.


Madigan, Jaime. “The Left Digit Effect: Why Game Prices end in .99.” The Psychology of Video Games: Examining the Intersection of Psychology and Video Games. 3 June 2013. Web. 26 June 2013. <http://www.psychologyofgames.com/&gt;



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