Cognitive Biases in Everyday Decision-Making

Most people think they make decisions with careful reasoning. Take a job offer. Or a news article. The safety of a trip. Or how well they can do a task. Each seems to call for careful thought. Research says otherwise. People lean on mental shortcuts called heuristics. These turn hard questions into easier ones. Tversky and Kahneman (1974) noted that heuristics are usually helpful. But they can lead to serious and systematic errors. Those errors qualify as cognitive biases.

Although the two concepts are related, they are different. A heuristic is a shortcut. A bias is the predictable mistake that can follow. Some biases are not shortcuts at all. They describe how people search for information or judge themselves. A few examples can demonstrate the difference among these concepts: each of them influences the process of decision-making. In this case, the three instances are confirmation bias, availability heuristic, and the Dunning-Kruger effect. 

Confirmation Bias: Seeing What We Already Believe 

Gathering evidence is a first step in making a decision. This is where confirmation bias shows up. Nickerson (1998) described it as a tendency to seek or interpret information in ways that favour existing views. People don’t usually do this on purpose. So it often happens without them realising it. This bias can influence small choices like deciding which reviews to read before buying a product. Lord et al. (1979) showed how it affects interpretation. They gave 48 students two descriptions of studies on the death penalty.

Half the students supported it. Half opposed it. One study found that it deters murder. The other found that it does not. Both were equally well designed. Everyone read the same evidence. But each group saw the research that supported their point of view as more convincing. And each group also detected the shortcomings in the research done by the other group. After hearing both sides, each group grew more certain about their view. Those reactions are known as biased assimilation and attitude polarisation. The same phenomenon can happen in everyday decision-making, for instance, in the case of an article that presents both sides of an argument.

The information that supports a particular point of view can look more convincing than the one that goes against it. This link is an interpretation, since the study used one emotionally charged topic. Wason (1960) wanted to see how people check their own ideas. Wason gave 29 participants the sequence 2, 4, 6 and told them it followed a simple rule. Their job was to find it. They could test any three numbers, and the experimenter would say yes or no. A lot of them jumped to “add two each time” and tried 8, 10, 12. Each one got a yes, which seemed to prove them right. The actual rule was much broader, though: any three numbers in increasing order.

Only 6 of the 29 found it without first announcing a wrong rule. Everyday life offers a similar pattern. Someone who already likes a product may look only for positive reviews, and finding them feels like checking, even though the belief was never really tested. The same preference appears in what people choose to read. Hart et al. (2009) combined the results of many studies in which people could choose what to read or hear. People moderately preferred information that supported their views. The preference weakened when the issue mattered less. It reversed when challenging information helped with a goal. This suggests that in real decisions, the bias may begin before any evidence is weighed, in the choice of what to look at. 

The Availability Heuristic: What Comes to Mind Easily 

Whenever individuals are presented with new information, they set probabilities on the likelihood of the event that might occur. The availability heuristic plays a greater role here. Researchers point out that people’s judgment about an event and its frequency depends on how easily instances pop into their minds. In most of the cases it works well since things we encounter often are easier to recall (Tversky and Kahneman, 1973). 

Two of their experiments show this. In the first, people judged whether letters such as K and R appear more often as the first or the third letter of a word. Most said the first. In fact, all the letters tested appear more often in the third position. Words that start with a letter are much easier to bring to mind. So they seemed more common. In the second, people heard lists of names. The famous names were all of one sex. The less famous names were of the other sex. The famous names were easier to recall. People judged the group of famous names to be larger. It was not. This implies that even if an event is not the more frequent one, easily remembered details, such as a recent news story, can affect how likely it seems in daily life. 

Schwarz et al. (1991) pulled apart two things that usually go together. One is how many examples come to mind. The other is how easily they come. Participants listed either 6 or 12 times they had acted assertively. Then they rated how assertive they were. Listing 12 was hard. Those people rated themselves as less assertive than those who listed 6. They had produced more examples. But the difficulty itself acted as information. If examples were hard to find, they decided they were not very assertive. The effect changed when participants could blame the difficulty on something else, such as background music. This is important when making decisions about oneself, like determining one’s suitability for a position. Not just the examples themselves, but the effort to recall them can alter the conclusion. 

The heuristic also influences everyday risk decisions. After the events of 11 September 2001, Gigerenzer (2004) studied US traffic data. He concluded that more Americans died on the roads in the following three months, after many chose to drive instead of fly, than were killed on the four hijacked flights. A later analysis found even more additional road deaths (Sivak & Flannagan, 2004). This was described by Gigerenzer as a response to dread risk, or the fear of uncommon but disastrous occurrences. A memorable, vivid event is the kind the availability heuristic applies to. But that link is an interpretation. It is not a finding of those studies. It does show how a judgment about the safety of a trip can have real consequences. 

The Dunning-Kruger Effect: Not Knowing What We Don’t Know 

The final element is assessing one’s own ability. It is at this stage that the Dunning-Kruger phenomenon emerges. Kruger and Dunning (1999) argued that people who do not have much ability in a certain area would be unable to identify it. This was not because people lacked self-awareness in general. Rather, their argument was specific to the issue. The skills needed to judge a task are often the same ones needed to do it.

Thus, one who lacks knowledge of a grammar rule may also fail to see that a sentence violates this rule. They ran four studies on humour, logical reasoning, and grammar. Individuals in the lowest quarter significantly overestimated their performance. They received scores close to the 12th percentile in one study. They estimated their position to be close to the 62nd percentile. People in the top quarter frequently underestimated how they compared with others. In a later study, the reliability of self-assessment was improved with the help of various skills training courses.

Practical decisions based on self-assessment, for instance, whether to take a job or follow a suggestion, might be influenced by this as well. If someone is unable to see their own flaws, they have little reason to seek help from others. This is an implication rather than something that these studies tested. The effect is still debated. Gignac and Zajenkowski (2020) argued that much of the classic pattern is a statistical artefact. One cause is the above-average effect. This is the habit of rating oneself better than average.

Another is regression to the mean. Self-ratings and test scores are only loosely related. So the lowest scorers tend to rate themselves above their score. The highest scorers tend to rate themselves below it. Nobody needs a special blind spot for this to happen. In the study, 929 adults completed a reasoning test after rating their intelligence. The researchers could not confirm the typical pattern. Self-reports and scores were only weakly related. People generally overestimated their intelligence. So people do often overrate themselves. But how much this depends on skill is less certain than the popular version suggests. 

Putting the Three Together 

In real decisions, these steps often run together. Picture someone who hears several memorable stories about a home remedy for colds. The stories come easily to mind. So the remedy seems to work often. That is availability. The person then searches online and reads mostly pages that praise it. That is confirmation bias. The person has no medical training. So they may not know what a fair test of a remedy would involve.

The gaps in the evidence are hard to see. Confidence is high enough to skip the doctor. That is the Dunning-Kruger pattern. This is an illustration, not a study. Each step echoes an experiment above: the ease of recall in Tversky and Kahneman’s tasks, the preference for agreeing evidence in Hart et al.’s review, and the gap between skill and self-assessment in Kruger and Dunning’s studies. 

What Can Help 

Knowing about these biases does not make anyone immune to them. A few habits may still help, although none of them has been tested here. Looking for one piece of evidence against a belief may counter confirmation bias. Wason’s participants rarely tried sets that could break their guess. Asking how often something really happens, instead of how easily it comes to mind, may slow down the availability heuristic.

In Schwarz et al.’s study, the effect of ease of recall changed when people had another explanation for the ease. Training in a skill, or feedback from someone with more experience, may make a person’s sense of their own skill more accurate, and Kruger and Dunning’s training study points that way. In that study, the improvement followed training in the skill itself. 

Conclusion 

Each of these patterns affects a different step in a decision. One shapes what evidence is sought and trusted. Also, one shapes how probable an event seems. One shapes how skilled a person believes they are. Many classic findings come from laboratory tasks. So their strength in any one real decision will vary. The issue of the Dunning-Kruger effect is still controversial. Nevertheless, being aware of the particular stage gives a person a chance to slow down before acting.

References +

• Gignac, G. E., & Zajenkowski, M. (2020). The Dunning-Kruger effect is (mostly) a statistical artefact: Valid approaches to testing the hypothesis with individual differences data. Intelligence, 80, Article 101449. https://doi.org/10.1016/j.intell.2020.101449 
• Gigerenzer, G. (2004). Dread risk, September 11, and fatal traffic accidents. Psychological Science, 15(4), 286–287. https://doi.org/10.1111/j.0956-7976.2004.00668.x 
• Hart, W., Albarracín, D., Eagly, A. H., Brechan, I., Lindberg, M. J., & Merrill, L. (2009). Feeling validated versus being correct: A meta-analysis of selective exposure to information. Psychological Bulletin, 135(4), 555–588. https://doi.org/10.1037/a0015701 
• Kruger, J., & Dunning, D. (1999). Unskilled and unaware of it: How difficulties in recognising one’s own incompetence lead to inflated self-assessments. Journal of Personality and Social Psychology, 77(6), 1121–1134. https://doi.org/10.1037/0022-3514.77.6.1121 
• Lord, C. G., Ross, L., & Lepper, M. R. (1979). Biased assimilation and attitude polarisation: The effects of prior theories on subsequently considered evidence. Journal of Personality and Social Psychology, 37(11), 2098–2109. https://doi.org/10.1037/0022-3514.37.11.2098 
• Nickerson, R. S. (1998). Confirmation bias: A ubiquitous phenomenon in many guises. Review of General Psychology, 2(2), 175–220. https://doi.org/10.1037/1089-2680.2.2.175 
• Schwarz, N., Bless, H., Strack, F., Klumpp, G., Rittenauer-Schatka, H., & Simons, A. (1991). Ease of retrieval as information: Another look at the availability heuristic. Journal of Personality and Social Psychology, 61(2), 195–202. 
• Sivak, M., & Flannagan, M. J. (2004). Consequences for road traffic fatalities of the reduction in flying following September 11, 2001. Transportation Research Part F: Traffic Psychology and Behaviour, 7(4–5), 301–305. 
• Tversky, A., & Kahneman, D. (1973). Availability: A heuristic for judging frequency and probability. Cognitive Psychology, 5(2), 207–232. https://doi.org/10.1016/0010-0285(73)90033-9
• Tversky, A., & Kahneman, D. (1974). Judgment under uncertainty: Heuristics and biases. Science, 185(4157), 1124–1131. https://doi.org/10.1126/science.185.4157.1124 
• Wason, P. C. (1960). On the failure to eliminate hypotheses in a conceptual task. Quarterly Journal of Experimental Psychology, 12(3), 129–140. https://doi.org/10.1080/17470216008416717