Do your dreams have smells? New study on ‘blind minds’ reveals vast differences in imagination

It’s common to think we all have similar experiences of life. But the more we learn about other people’s hidden thoughts, the more evidence there is that this is untrue. For instance, not everyone has the same ability to have imagined sensations. Most people can visualize—they can have imagined experiences of seeing people and scenes that aren’t there. But not everyone can.

We are both visual aphantasics, which means we can’t voluntarily imagine seeing things in our minds’ eyes. When we read a book, neither of us can imagine seeing the characters.

Yet other types of our waking imagined experiences are quite different. Derek can imagine hearing snippets of music at will, but Loren has a silent mind. She can’t even imagine hearing herself talk. Loren can have vivid imagined feelings of touch, taste and smell, but Derek doesn’t have any of these.

So, when we’re awake, our imaginations are quite different. But what about our dreams? In our new study published in Scientific Reports, we delved into the dreams of aphantasics to see how they overlap—or don’t—with their imaginations when they’re awake.

Dreams in blind minds

While neither of us can visualize during the day, like many aphantasics, Derek has vivid visual dreams. But Loren doesn’t have visual or audio dreams. Her dreams are always lucid: experienced as an unfolding awareness of a storyline she can control, accompanied by a succession of different feelings of texture and movement.

Derek’s dreams, by contrast, are filled with sights, sounds and sensations of movement—but they don’t involve imagined feelings of touch, taste or smell.

So Loren has a silent mind whether she’s awake or dreaming, whereas Derek can’t have imagined feelings of touch, taste or smell while awake or dreaming.

This made us think that the imagined experiences aphantasics have while awake might correspond in some way to the content of their dreams. So, we conducted a study to find out.

We recruited 84 visual aphantasics and a comparison group of 121 non-aphantasics and asked them all to report on their dreams and their waking imagined experiences.

We used standard measures of people’s imagined experiences and devised new measures to check for consistency, including a measure of everyday imagined experiences.

We found that aphantasics tended to report having similar imagined experiences while dreaming and when awake. But there were also differences. Some aphantasics reliably reported that there was no correspondence at all.

What is the brain doing?

Scientists are interested in the overlap of aphantasics’ dreams and their waking imagined experiences because it could give us insight into the differences between aphantasics and people who can visualize.

Since many aphantasics report having visual dreams, some argue that their brains can generate imagined experiences, but some neural process necessary for awareness of imagined sensations must fail when they’re awake. They might visualize without knowing it.

Our research suggests another possibility. Some aphantasics might have brains that can generate a full range of different types of dreamed sensations.

But other aphantasics might have brains that simply can’t create some types of imagined sensation, regardless of whether they’re awake or dreaming.

Further research is needed to tease apart these possibilities.

Dreams vary in non-aphantasics, too

While our study focused on aphantasics, we also asked about the dreams of other people. Here, too, there were differences. For instance, 37% of non-aphantasics reported that they never have sensations of smell in their dreams, and 33% reported that they never have dreamed sensations of touch.

People also often reported being unsure about the content of their dreams. So if you ask family and friends, they’ll likely say they have different combinations of dreamed sensations.

In our study, we also found evidence for a relationship between the content of dreams and people’s imagined experiences in their daily lives. For instance, if people often have dreamed sensations of smell, they’ll more likely report imagining the smell of cooking when they think about dinner while awake.

Why do we care?

We’ve found it’s relatively common for people to report having a different collection of imagined sensations, both when they dream and when they’re awake.

Some readers will have strong imagined experiences of smell, and others will report that they never have these imagined experiences. Our ongoing research aims to understand these differences and relate them to the structure, functioning and connectivity of people’s brains.

Understanding imagined experiences might give us insight into how human brains create a type of conscious experience—one of the great mysteries of science.

From a practical perspective, visualizations are among the world’s most popular psychological treatments, and it’s unclear if aphantasics can benefit from attempts at imagery.

There are also issues for education. Teachers often encourage children to visualize, and it’s unclear what proportion of children can’t do that.

One day soon, we hope to be able to explain why some people can, and others cannot, imagine smelling their dinner before they turn on the stove.

Who’s behind this story?

Lisa Lock

BA art history, MA material culture. Former museum editor, paramedic, and transplant coordinator. Editing for Science X since 2021.

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Andrew Zinin

Master’s in physics with research experience. Long-time science news enthusiast. Plays key role in Science X’s editorial success.

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This article is republished from The Conversation under a Creative Commons license. Read the original article.