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This and That: The Conjunction Fallacy in Practice

Convincing the consumer that dual benefits can be derived from a product using the conjunction fallacy. It starts with understanding the associations your consumer holds and crafting your message so that they perceive benefits in conjunction with each other.

Editor’s Intro: Behavioral science approaches to marketing and research have rapidly grown to take account of the kinds of cognitive phenomena Lindsay Cannon discusses in her article. As other authors have noted, there are a great many “biases” of the sort that Lindsay presents – maybe we shouldn’t be thinking of them as “biases” as much as what simply makes us human.


In 1983, two psychologists, Daniel Kahneman & Amos Tversky, outlined a cognitive error called the conjunction fallacy. Kahneman & Tversky described a phenomenon whereby individuals ignore the conjunction rule, which states that the probability of two joint events co-occurring cannot exceed the probability of the events happening separately. This means that the probability that two distinct things are true of one person or situation is always much lower than the probability that only one of those things is true.

Let’s try out an example: John is a 23-year-old graduate student. He is heading down the street walking a dog and carrying a bag containing a pint of mint chocolate chip ice cream. Which is more likely?

  1. John loves dogs.
  2. John loves dogs and he loves mint chocolate chip ice cream.

Because you are given information that describes John as having both a dog and mint chocolate chip ice cream, it is likely that you picked option 2. And, if you picked option 2, you are in the majority, as 85% of people also chose the option that includes the conjunction, or the “and” statement. However, the probability that someone only loves dogs or only loves mint chocolate chip ice cream is much higher than the probability that they love both dogs AND mint chocolate chip ice cream.

Simply stated, the human brain tricks us into thinking that the statement that includes more information, or is more representative of what we are expecting, is more likely to be true than the simpler option. This thinking process relies on a key concept called the representativeness heuristic. This heuristic is a mental short-cut which we utilize in our day-to-day lives, which helps us to recognize familiar concepts and to make decisions about new situations based on our ability to frame new information in the context of what we have seen before. This explains our tendency to overestimate the likelihood of co-occurring events, as these events activate multiple internal stereotypes, causing us to believe that they are true in tandem.

When it comes to your business, how can you leverage the tendency of consumers to identify with scenarios that are information rich than those that are simpler? Is less really more?

Many times, businesses want consumers to believe that two concepts that are related, but not the same, both apply to the same product. By activating two different stereotypes, one may be able to persuade consumers that the product being marketed is the solution to multiple needs. But how can this be done subtly?

Take Neutrogena, for example. This skincare brand has built a platform that equates health with beauty by striving to show consumers that these concepts are one in the same and that their products can deliver both outcomes. However, health and beauty are not always synonymous, as beautiful skin can be unhealthy, and healthy skin can lack beauty. Yet, Neutrogena has built their brand on homogenizing these two concepts. How?

Imagine yourself, a teenager who has been struggling with frequent breakouts, searching for a solution to alleviate the acne that has been plaguing you for months. You long to have clear skin, and, when browsing through your favorite magazine, you stumble on a possible solution. A full-page Neutrogena ad shows the glowing face of your favorite celebrity, under the tagline “#1 Dermatologist Recommended.” Not only does the dermatologist recommendation make you believe that this product will help make your skin healthy, but you see the clear, beautiful skin of your favorite actress and assume that she must have healthy skin too. You get in your car and drive to the store, in search of this product to help you get the beautiful, healthy skin you so desperately desire.

With their simple ad, Neutrogena has successfully activated two stereotypes using the conjunction fallacy. By using a tagline that is intrinsically related to health, they have activated a representation of healthy skin. By pairing this tagline with the image of a beautiful celebrity, the consumer is additionally prompted to think of beauty, such that the two concepts become paired in the mind of the consumer. This marketing strategy has convinced the consumer that they will derive these dual benefits from Neutrogena’s products, merely by utilizing the pairing of a statement and image that invoke strong stereotypes representing the consumer’s expectations and needs.

It is possible to move your consumer from an “or” to an “and” mentality for your brand. It starts with understanding the associations your consumer holds today and crafting your message such that they perceive benefits in conjunction with each other.

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2 responses to “This and That: The Conjunction Fallacy in Practice

  1. This would be pretty interesting if it weren’t for the fact that many researchers, including Kahneman and Tversky themselves aren’t quite sure of the reality or the stability of the conjunction fallacy (see Thinking Fast and Slow pp. 163-165). You don’t need to rely on a cognitive bias to claim more than one benefit for a product – it’s that the two benefits need to be (a) not in conflict with each other and (b) plausible in their own right. Those of us of a certain age remember Certs (two mints in one) and Miller Lite (tastes great, less filling).

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Lindsay Cannon

Lindsay Cannon

Project Catalyzer, Ability to Engage