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Written by Travis Ryan

June 2019

The Yes Bias

At a very basic level, are we predisposed to say yes rather than no?


Shades of Gray

Decisions aren’t always black and white, but studying movement can give us key insights into what is occurring at higher-levels of cognition...


If you’ve ever stood in front of a vending machine for an inexcusably long time, you know how difficult it can often be to make what is a fairly mundane decision. The more choices we have, the more powerless we seem to become. What’s going on in the brain that creates that sense of tension? What kind of biases are at work that influence the countless choices we make every day?


What Is Truth Anyway?

Life isn’t binary. Instead, our decisions are based on our own mental schemas and personal experiences. While we know certain semantic truths like “27 is more than 12” and “McDonalds make Big Macs”, more complex issues that rely on our differing points of view cause us enormous mental turmoil. All of the big ticket items we talk about today, from reproductive rights to immigration, are more divisive and require some deeper thinking.


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Measuring with Mouse Clicks

In one study, researchers tracked participants’ mouse cursors as they answered yes or no questions with varying truth values (McKinstry, 2008). Prompts ranged from completely true to not true at all, but participants only had two response options. The subjects began with a start box at the bottom of the screen and were instructed to click the “YES” box in one corner or the “NO” box in the other quickly and accurately, in accordance with their answers to the series of questions.


As you’ve probably guessed by now, the more straightforward propositions typically involved simple thought processes - people moved their cursors quickly and decisively when prompted with high truth-value questions, or those that swung heavily to the “true” side. In contrast they took the longest time to make decisions when faced with low truth-value propositions. Here are some of the findings to take away:



We’re more pulled toward “yes” when making a “no” decision than we are pulled toward “no” when making a “yes” decision.

The study suggests that people are typically more primed to say yes than no. We’re attracted to the affirmation even when we ultimately decide that we disagree, yet we don’t feel the same pull towards disagreement when we do in fact agree. These findings could shed new light on a range of concepts, such as peer pressure, whilst they could also drive new developments in marketing and sales approaches.


We’re quicker to make a decision when our answer is “yes” than when it’s “no”.

Subjects moved their cursors to the appropriate box quicker when they agreed with the prompt, and slower when they were posed low truth-value questions that they disagreed with. Basically, that means it takes less work for us to accept that something is true than it does to assure ourselves that it isn’t.


Not only are we less confident in our “no” decisions, we actually hesitate to make them.

When participants answered “no”, they did so slowly and, based on the movement of their cursors, they were attracted to the “yes” response despite choosing “no”. Our physical movements give us some insight as to how different types of processing happen in parallel as we decide whether or not we agree.

Now we know that the “pulling” sensation we feel is actually very real. So real, in fact, that it can be measured in our hand movements as we physically input a decision into a computer program. Those same movements imply that the decision-making process happens in different areas of the brain at the same time; participants “thought” through their hands as they started to move the cursor before making a concrete decision.


Despite how objectively we can measure the movements of a cursor, it’s important to think critically about what any of this actually means. Sure, it might take a second longer to decide something is false, but how big of an impact does that extra second have on our daily lives? Does it matter that we’re being “pulled” in one direction if we make the alternative choice anyway?


No study is perfect. Let's be candid for a moment - mouse clicks are an obscure kind of metric - there’s also always the possibility that other variables contributed to the results. At the very least, we can be reasonably sure that the brain doesn’t make a complete decision and then send the signal out to the body; we can see multiple systems at work simultaneously while we evaluate our choices.



Mckinstry, C., Dale, R., & Spivey, M. J. (2008). Action Dynamics Reveal Parallel Competition in Decision Making. Psychological Science,19(1), 22-24. doi:10.1111/j.1467-9280.2008.02041.x

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