Thinking Too Much Impairs Decision-Making

Decision-making occurs on a continuum of thoughts with varying levels of consciousness. In most cases, people have no idea why they feel the way they do.

At one extreme, individuals may think very little—making decisions quickly and habitually—like pulling out already prepared foods for dinner.

In contrast, choosing where to dine out results in thinking too much—reading through reviews to weigh all of the pros and cons because their friend also asks for an explanation regarding the final selection.

Upon introspection—without knowing why—the individual honed in on irrelevant yet salient details that made sense, but in fact, did not lead to the best decision, at least by experts’ standards.

This example capitalizes on the unreliability of thinking consciously—also called the introspection illusion—where an attempt to understand one’s own perceptions and behaviors results in erroneous post-hoc explanations.

Based on the classic experiment by Wilson and Schooler, this video demonstrates whether asking participants to think about reasons for rating different jams interfered with their preferences compared to those who were simply asked to provide rankings.

In this experiment, two groups of participants—reasons-analysis and controls—are asked to taste test different jams that have been previously analyzed by experts, and then evaluate each one based on their preference.

During the tasting phase, those in the reasons-analysis group are asked to analyze the way they feel about each one by listing five reasons for liking or disliking it after tasting. This step allows participants to organize their thoughts and encourage better preparation for providing final ratings.

Each participant in the control group, on the other hand, is asked to complete a filler questionnaire and list reasons why they chose their college major. In either case, these first forms are discarded.

Subsequently, participants are given a second preference questionnaire by a different experimenter blinded to their condition. They are asked to anonymously evaluate each jam on a 9-point scale ranging from 1-disliked to 9-liked.

In this experiment, the dependent variable is the average preference rating of each jam as a function of group, reasons-analysis versus controls.

Participants who spend time deliberating about the reasons supporting their preferences are expected to show much less correspondence with an objective criterion of quality—the expert ratings—compared to controls. Such findings would support the illusion of introspection, where individuals change decisions because they aren’t truly aware of their attitudes.

Prior to the experiment, conduct a power analysis to recruit a sufficient number of individuals for a study entitled "Jam Taste Test". Call those enlisted and instruct them not to eat anything for 3 hrs prior to the study.

To continue preparation, acquire five brands of jam that vary in overall quality based on expert opinions, and randomly label them A through E. Now, set up the testing room.

Arrange the five brands on the table, and for each participant, record the order and what label each specific jam received.

Then, place a spoonful of each jar’s content directly in front.

To begin, escort a participant into the testing room, and have them sign the consent forms.

Explain that the purpose of the study is to evaluate different kinds of jams under different conditions and they have been randomly chosen to taste on spoons. Remind them to rate their liking preference for each one.

For participants randomly assigned to the reasons-analysis group, provide additional written instructions stating that they need to list their reasons behind liking or disliking each one to organize their thoughts prior to the final evaluations. Note, for control participants, do not provide any further instructions.

Have each participant sit at the table where the five jams were arranged, ask them to start their evaluation, and leave the room.

Following the tasting period, administer a questionnaire and remind them that the purpose of it is to simply organize their thoughts and that they do not need to hand it in. For the control participants, administer a filler questionnaire. Exit the room while the forms are being filled out.

Upon return, explain that this information will no longer be needed and throw it in the trash can. Now, introduce a second experimenter who is unaware of the participants’ assigned conditions.

To capture participants’ ratings, have this new researcher administer preference forms, in which they should place into a covered box on the table when they finish. Leave the room while they record their evaluations.

To end the experiment, fully debrief all participants and discuss the true purpose and procedures of the study.

To visualize the data, first plot the mean ratings across the five jams, in order of the experts’ ratings, and split by condition—controls versus reasons. Notice that control participants were more accurate compared to those in the reasons group, as their scores patterned the professional rankings.

To quantify the amount of agreement, compute correlation values between each participant’s and the expert’s ratings and plot the averages by condition. The average correlation in the control group was near 60%, whereas the mean value in the reasons condition was less than 20%, not significantly different from zero.

Thus, participants who spent time deliberating about reasons supporting their own evaluations showed less correspondence to an objective criterion, which supports the introspection illusion: Thinking too much does impair decision-making!

Now that you are familiar with how introspective thoughts affect decision making in an experimental setting, let’s look at other cases where deliberating between choices leads to suboptimal results.

When it comes to large purchases, like buying a car, many people take their time to weigh the options and consider the pros and cons at every angle, before committing to such an investment.

Although there may be economic advantages, psychologists have found that consumers who exhaustively deliberate these tough choices end up feeling less satisfied with their purchase—essentially showing buyer’s remorse.

Interestingly, older consumers tend to vacillate much less in the car buying process by sticking to brands that they have remained loyal to over the years.

In addition, relationships call for moments of intensive introspection, but all of this deep thought can cause people to make decisions that they also later regret. Researchers postulate that this happens because the introspective process causes them to lose touch with their feelings, leading them to act based on a false impression of their true emotions.

You’ve just watched JoVE’s video on how thinking too much impairs decision-making. Now you should have a good understanding of how to design, conduct, and analyze an experiment to study how our inner thoughts influence behavior, and how introspecting on one’s preferences can be applied to consumer behavior and interpersonal relationships.

Thanks for watching!