Reasoning May Not Lead to Better Purchase Decisions. Here’s What to Do Instead.

Research suggests that unconscious thought can improve decisions

Riikka Iivanainen
11 min readApr 25, 2022


I was planning to write an article on how you can avoid bad purchases by carefully analyzing your decision. I had been crafting criteria against which you could rate each new purchase. For example, when buying a new jacket, you could rate it on a scale from 1–5 on four different attributes: style, quality, practicality and compatibility with your existing wardrobe. You could then calculate the total score and if it was above a certain threshold, say 15 points, you could confidently buy the jacket. Peak of human rationality, right?

But when I looked up some research to back up my article, I bumped into some papers saying that reasoning about a choice might lead to non-optimal outcomes. I was confused. My decision-making aid had initially been inspired by Thinking, Fast and Slow ¹, in which Daniel Kahneman talks about experts making better decisions when working together with an algorithm. I had gotten so excited about developing this tool that I had completely ignored the word “expert”.

The same rules didn’t seem to apply to novices. The papers I found indicated that to benefit from carefully analyzing a choice, you need to be experienced in the domain. And most of the time, you’re not that experienced in consumer choices, especially the ones you make more rarely like buying a hiking backpack or bouldering shoes.

Since I didn’t want to give bad advice, I decided to take a few weeks to dive into the research on preference formation, decision-making quality and post-choice satisfaction. In this article, I’m going to share what I’ve learned and hopefully make you reconsider how you make purchase decisions. At the end, I give my revised advice on how to become a more rational shopper.

This article is part of a series of articles on better buying. I call it the Timeless Wardrobe Project. You can check out the kick-off article here. It has a list of all the articles I’ve written on the topic at the end.

Reasoning about a choice might lead to non-optimal outcomes. Photo by Randy Fath on Unsplash.

Thinking too much about a decision

Let’s first take a look at two examples of decision-making processes. While you’re reading, consider which of the two persons you think has been more satisfied with their choice.

1. Last year, a friend of mine was considering whether he should switch jobs. He had received an interesting offer from a new company, but wasn’t quite sure whether he should leave or stay. To help with his decision, he listed all the pros and cons of each job. After making the list and contemplating for about a month, he decided to accept the offer.

2. Several years ago, my parents were looking for an apartment to invest in. They went to multiple open houses around the Helsinki area, but either they didn’t quite find what they were looking for or they reacted too slowly. One day, my parents went to yet another open house and as my mother walked around the apartment, she knew this was the one. My parents bid on the apartment and they’ve owned it ever since.

Based on these two stories, who do you think has been more satisfied with their choice later on?

Perhaps you voted for the more deliberate decision-making process my friend went through. He took his time and weighed the upsides and downsides of switching jobs, whereas my mother made the decision based on intuition. But in this case, both my friend and my parents have been happy with their choice. The outcome raises questions: Were my parents just lucky? Or should they also have made a list of pros and cons? The research implies the exact opposite: It was my friend who risked making a non-optimal choice.

However counterintuitive it may seem, research suggests that reasoning and introspection can reduce the quality of decisions.

However counterintuitive it may seem, research suggests that reasoning and introspection can reduce the quality of decisions ² ³ ⁴. For example, in one study college students were asked to evaluate jams ². Half of the research participants were told to analyze why they felt the way they did about each jam, whereas the other half wasn’t given any additional instructions. The preferences of the control group were more closely aligned with the preferences of an expert panel who had rated the jams in advance. In other words, the participants who made their decisions based on the samples alone (without reasoning about their preferences) made better decisions.

But wait a minute! The fact that the control group’s choices were more similar to those of the experts doesn’t mean that that was the right choice for them, or that the people who analyzed their preferences chose non-optimally. Perhaps introspection helped them align their evaluations with their unique preferences?

To find out, researchers have studied whether introspection affects how satisfied people are with their choice later on (they call it post-choice satisfaction). In another study inspired by the jam study ⁵, participants were asked to evaluate art posters either after thinking about the reasons for their preferences or after doing a fill-in task. At the end of the experiment, participants got to choose one of the posters to take home. After a few weeks, the researchers called the participants and asked them to rate their satisfaction with the poster they had picked. Were the participants who engaged in introspection equally satisfied as the ones who didn’t? They weren’t. The participants who had analyzed their preferences gave lower ratings.

So does this mean that we should just trust our gut and make a decision the minute we are confronted with one?

Why “sleep on it” may not be such bad advice

There is a difference between choosing based on the first impulse and trusting your gut. When researchers have put three different kinds of decision-making processes to the test — decisions made immediately, after careful deliberation and after being distracted by an unrelated task — the ones made after some distraction have been the best. This is the case both when the “best” is measured objectively ² (alignment with experts’ ratings) and subjectively ⁶ (post-choice satisfaction). Leaving some time for unconscious processing appears to be the key. So the next time your friend or your mum tells you to “sleep on it” when facing a tough choice, consider following their advice.

However, introspection doesn’t always produce non-optimal outcomes. If you are an expert on the topic ² or the choice you are facing is very simple ⁴, you may benefit from carefully weighing the options. But why does the unconscious appear to play a valuable role, especially when making more complex choices?

The power of the unconscious mind is its lack of limitations. It can process and integrate lots of information, whereas the conscious mind can have a hard time dealing with complexity ³. If you ask the conscious mind for advice on which hiking backpack to choose (and you’re not a seasoned hiker) it’s likely to resort to what’s most familiar and salient. It may focus on the most prominent attributes (e.g., the volume of a backpack) or the ones that you have language for (“I love this petrol blue”). The problem is that the most prominent attributes or the ones you can describe might not be the ones that actually determine how much you enjoy hiking with the backpack. Perhaps the key is how easily you can pack and unpack the bag and what it feels like to walk 10 km with 20 kg in it. And if these criteria aren’t met, the beautiful petrol blue won’t save the trip.

Due to the limits of the conscious mind, reasoning about a choice might lead us to weigh different aspects of a choice, which according to research often results in non-optimal outcomes.

Due to the limits of the conscious mind, reasoning about a choice might lead us to weigh different aspects of a choice, which according to research often results in non-optimal outcomes. As Dilip Soman put it in his book The Last Mile ⁷, “we know what we like but not why we like it”. And if we don’t really know why we like something, trying to rationalize our choice is bound to lead us astray.

So considering all of this, is there anything you can do to make better choices? Or do you just need to rely on the unconscious?

3 tips on becoming a more rational shopper

The science-backed recipe for making choices you can also later be happy with, goes like this: consider the options, leave time for some unconscious thought (go for a walk or a coffee) and then make the decision. But luckily, there are also a few other things you can do.

1. Test it out (or make a low-impact choice)

If you’re unfamiliar with a product category, you probably don’t know which attributes you should weigh the most when making a decision. In these cases, the research indicates that you can benefit from gaining more experience in the “domain” ⁸. Uhmm, isn’t being inexperienced the whole problem? Yes, it is. But whenever possible, try to test out the item you’re interested in buying before making a final purchase decision. Borrow the item from a friend or make a shout-out on social media. Some stores also let you rent clothing or free time gear for a reasonable price.

I used this method to buy twerk shorts. Instead of buying new shorts for the first choreography that we filmed in my beginner’s twerk class, I borrowed a pair from a friend who’s about the same size as me. After wearing them for one class, I knew the size was slightly off and while the pink color was cute, I didn’t feel comfortable in it. I ended up ordering the same pair, but a size smaller and in black.

Another way to approach the same advice is making what I call a low-impact choice. The idea is to buy a cheap version of the item before investing lots of money. My sister’s partner tends to buy new sports clothing and equipment at Decathlon which is an affordable sports store in Europe. After learning which attributes matter the most in, for example, a pair of winter running pants, he upgrades to a higher-quality version. If you want to do the more environmentally friendly version of this technique, you can try to find the item at the thrift store first.

But what if you can’t find anyone who already owns what you’re planning to buy or can’t or don’t want to get a more affordable version of it?

2. Ask for advice from someone who has experience in the domain

Another great approach to improving your decision-making quality is asking the experts for help. An expert can be anyone who has experience in the category of goods you’re planning to buy. Because of their experience, they are better able to identify the most important attributes.

For example, when considering what kind of hiking backpack to buy for overnight trips and weekend getaways, I decided to ask my cousin for advice. I know she has several hiking backpacks of different sizes and has been backpacking around Europe. She recommended I get a backpack from a brand that’s known for comfort and to go for the higher end of the volume spectrum. Apparently, she had upgraded to a bigger backpack quite quickly after buying her first one. So when I went to an outdoor store, I had already ruled out several options and was able to have a better conversation with the salesperson.

But what about those regular clothing purchases? Tip number one might work in some cases, but asking a friend for recommendations on which dress to buy might go terribly wrong. Shouldn’t you be the expert on your own style?

3. Develop a better vocabulary for your preferences

It appears that developing a more nuanced vocabulary for your preferences is beneficial for developing stable preferences (which is what building a timeless wardrobe means in practice). In one study ⁹, participants who were provided with a leaflet which described quilt designs developed more consistent preferences for quilts than the control group who only read about the history of quilts. Their preferences also grew increasingly consistent over time, indicating that reading about quilt designs enhanced learning. According to the authors, this kind of consumption vocabulary can help people better identify different attributes and weigh these attributes against their personal preferences.

So how can you develop your own style vocabulary?

You can start by analyzing your favorite pieces of clothing. And by favorite I mean clothes that you not only love, but also regularly wear (even if only once a year for Christmas). These should be your go-to pieces. Take them out of your wardrobe and describe what makes each of them so special. Try to be as specific as possible: think about style, quality, practicality and how well it matches the rest of your clothes. You can do a similar exercise with unsuccessful purchases (decluttering is an excellent learning opportunity!). Try and identify what made you not want to wear a certain piece of clothing.

Another thing you can do is create a mood board for your style. This is more of an aspirational method and is crucial for the ones who feel like they own very few clothes that they love. Collect images of outfits that you love on Pinterest or cut them out from magazines. But make sure you focus on outfits that you could imagine wearing for years (we’re trying to build a timeless wardrobe, remember?). You can also do this at a thrift store or even a regular store, but be careful that it doesn’t turn into a shopping haul.

Most importantly, be patient. Becoming an expert on your style can take years (and lots of trial and error).

Most importantly, be patient. Becoming an expert on your style can take years (and lots of trial and error). But if you keep practicing, I’m confident that the work will pay off.


I’ve noticed that my gut feeling towards a new piece of clothing is a pretty good predictor of how much I end up wearing it. The feeling is often quite ambiguous: it either feels right or it doesn’t. Now I know that I should listen to this feeling (as well as distract myself for a moment) before making a final purchase decision. And whenever I’m making a choice I have experience in, I might reason a little more.


1. Kahneman, D. (2011). Thinking, Fast and Slow. Penguin Books.

2. Wilson, T. D., & Schooler, J. W. (1991). Thinking Too Much: Introspection Can Reduce the Quality of Preferences and Decisions. Journal of Personality and Social Psychology, 60(2), 181.

3. Dijksterhuis, A. (2004). Think Different: The Merits of Unconscious Thought in Preference Development and Decision Making. Journal of Personality and Social Psychology, 87(5), 586.

4. Dijksterhuis, A., Bos, M. W., Nordgren, L. F., & Van Baaren, R. B. (2006). On Making the Right Choice: The Deliberation-Without-Attention Effect. Science, 311(5763), 1005–1007.

5. Wilson, T. D., Lisle, D. J., Schooler, J. W., Hodges, S. D., Klaaren, K. J., & Lafleur, S. J. (1993). Introspecting About Reasons Can Reduce Post-Choice Satisfaction. Personality and Social Psychology Bulletin, 19(3), 331–339.

6. Dijksterhuis, A., & Van Olden, Z. (2006). On the Benefits of Thinking Unconsciously: Unconscious Thought Can Increase Post-Choice Satisfaction. Journal of Experimental Social Psychology, 42(5), 627–631.

7. Soman, D. (2015). The Last Mile: Creating Social and Economic Value from Behavioral Insights. University of Toronto Press.

8. Hoeffler, S., & Ariely, D. (1999). Constructing Stable Preferences: A Look Into Dimensions of Experience and Their Impact on Preference Stability. Journal of Consumer Psychology, 8(2), 113–139.

9. West, P. M., Brown, C. L., & Hoch, S. J. (1996). Consumption Vocabulary and Preference Formation. Journal of Consumer Research, 23(2), 120–135.



Riikka Iivanainen

Fascinated by all things design and human behavior. Especially curious about how and why we make the decisions we do.