Can Random Numbers Affect Our Relationship Judgements? Yes…If We Like What They Imply

What are the odds, from 0 to 100%, that someone will break your heart within the next five years?

How did you answer this question? Maybe you thought about your past relationship experiences, or the person you’re dating right now. Maybe you thought about relevant statistics, like the divorce rate, or the average rate of infidelity. But imagine that just before you read this question, you happened to be checking the weather and saw that the chance of rain tomorrow is 10%. Would that information influence your estimate? What if the chance of rain was 90%?

Arbitrary numbers—referred to by researchers as numerical anchors—can have a surprisingly large impact on people’s judgments.¹ We often lack the information we need for the judgments we are asked to make. You might be asked to estimate the length of the Nile river, for example, and find that you can only guess at the answer. To make that judgment, research shows that you are likely to grasp at whatever information you happen to have on hand, even if it’s completely irrelevant. If you’ve recently been looking at the prices of new cars, you might guess that the Nile is shorter than if you’ve recently been looking at the prices of new houses. This phenomenon, known as the anchoring effect, has been demonstrated in hundreds of studies on everything from general knowledge to legal sentencing decisions.²

Until recently however, anchoring had yet to be tested in the context of romantic relationships. Relationship judgments are different from many other judgments (e.g., the length of the Nile) in that people have a vested interest at arriving at a certain answer. We all want our romantic relationships to go well, and we deeply desire for them not to go poorly. Because of this, my colleagues and I thought that anchors might be used in a biased fashion in this context.³ People might be perfectly willing to use random numbers that support conclusions they prefer (e.g., that a new relationship will work out), but ignore any numbers that support threatening conclusions (e.g., that they will soon experience heartbreak).

Stephanie Spielmann, Geoff MacDonald, and I tested this idea across four studies that together involved over 3000 participants. Participants were asked to make judgments about positive or negative events that might happen to them in the future. Before making each judgment, participants were either given an optimistic anchor (which was consistent with their motivations), a pessimistic anchor (which was inconsistent), or no anchor (the control group).

Participants were told that the anchors were completely meaningless and should be ignored. Despite that warning, the anchors impacted participants’ judgments in every case but one. By first presenting people with seemingly random numbers, we could lead them to judge that a) good things were more likely to happen in their relationships, b) good things were less likely to happen in their relationships, and c) bad things were less likely to happen in their relationships.

But we consistently could not make people judge that bad things were more likely to happen in their relationships. For example, we could not make people think that they were more likely to eventually drift apart from their partner, come to regret their relationship, or find that their partner had fallen out of love with them.

In follow-up studies, we found that this limitation of the anchoring effect wasn’t unique to romantic relationships, but seemed to extend to any judgment involving the self. Just as we couldn’t use anchors to make people think that their partner might leave them broken-hearted, we similarly couldn’t use anchors to make people think that they might get fired from their job, have their car stolen, or get sued by someone.

Importantly, the anchors didn’t have to be entirely consistent with people’s preferred conclusions in order to be effective. Anchors were effective even when they suggested that positive events (e.g., living past the age of 80) were less likely to happen. But there seemed to be something particularly threatening about negative events, consistent with research suggesting that “bad is stronger than good”,⁴ and that “losses loom larger than gains”.⁵

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In one of my favorite classic relationship studies, researchers surveyed people who were in the process of applying for marriage licenses about the probability of divorce. Although the participants accurately pegged the national divorce rate at around 50%, their median estimate for their own odds of divorcing was 0%.⁶ This latest research uncovers a new way in which we manage to be biased when it comes to our own futures. Although we’re happy to use any information available—even utterly meaningless information—to reach the conclusions we want to reach, we will ignore the exact same kind of information if it sufficiently threatens those conclusions.

Want to learn more about how this research was conducted? You can download the original paper here.

1Tversky, A., & Kahneman, D. (1974). Judgment under uncertainty: Heuristics and biases. Science, 185, 1124-1131.

2Furnham, A., & Boo, H. C. (2011). A literature review of the anchoring effect. The Journal of Socio-Economics, 40, 35-42.

3Joel, S., Spielmann, S. S., & MacDonald, G. (in press). Motivated use of numerical anchors for judgments relevant to the self. Personality and Social Psychology Bulletin.

4Baumeister, R. F., Bratslavsky, E., Finkenauer, C., & Vohs, K. D. (2001). Bad is stronger than good. Review of General Psychology, 5, 323-370.

5Kahneman, D., & Tversky, A. (1979). Prospect theory: An analysis of decision under risk. Econometrica, 47, 263-291.

6Baker, L. A., & Emery, R. E. (1993). When every relationship is above average: Perceptions and expectations of divorce at the time of marriage. Law and Human Behavior, 17, 439-450.

Dr. Samantha Joel – Science of Relationships articles
Samantha’s research examines how people make decisions about their romantic relationships. For example, what sort of factors do people take into consideration when they try to decide whether to pursue a potential date, invest in a new relationship, or break up with a romantic partner?