New method measures how vividly we picture things in our minds

Imagine an apple. How clearly does it appear in your mind? Do you see a bright red, clearly defined apple, almost as though it were right in front of you, or is the image vague and colourless? Perhaps you do not see anything at all? Or maybe the apple is green? People vary considerably in how vividly they can generate such mental images. In a new study, researchers at the University of Iceland and the University of Akureyri introduce a new method designed to shed clearer light on these individual differences.

People vary considerably in their ability to form mental images. “Some people seem to be able to generate mental images that are so vivid they could almost be real, while others do not see anything at all; they simply know that they are thinking about what is being described. People in the first group are said to have hyperphantasia, while those in the latter group are considered to have aphantasia. Many people, however, seem to fall somewhere in between; visual imagery most likely exists along a broad spectrum,” says Heiða María Sigurðardóttir, PhD in neuroscience and Professor at the University of Iceland’s Faculty of Psychology.

She is one of the authors of the study, The Visual Imagery Visually Anchored Scale (VIVAS) reveals dissociable perceptual dimensions and category-specific structure, recently published in the scientific journal Cortex. The other authors are Árni Gunnar Ásgeirsson, Associate Professor at the University of Akureyri’s Department of Psychology; Vaka Vésteinsdóttir, Associate Professor at the University of Iceland’s Faculty of Psychology; Dagur Árnason, a master’s student in clinical psychology at the University of Iceland; and Marelle Mäekalle, who holds an MSc in psychology from the University of Iceland.

But why is it important to study visual imagery? Our ability to visualise may play a role in various cognitive processes, including learning and memory. Mental imagery can also influence emotions and may play a role in mental health difficulties. Intrusive thoughts associated with a range of mental disorders, for example, are often experienced as mental images, and such imagery can have a greater emotional impact than verbal thoughts. “This raises the question of whether therapeutic techniques based on visual imagery are equally effective for individuals who differ in their capacity to generate mental imagery,” the researchers write. They point to recent research suggesting that people with aphantasia are more likely than those with vivid imagery to perceive imagery-based therapy as less helpful.

A new test for assessing visual imagery

Until now, individual differences in visual imagery have primarily been studied using questionnaires in which people rate the vividness of their own mental imagery. The best known of these is the Vividness of Visual Imagery Questionnaire (VVIQ), in which people are asked to imagine particular objects or scenes and rate, on a scale from 1 to 5, how vividly they appear in their mind’s eye. The researchers behind the Cortex study point out, however, that one limitation of this approach is that what one person rates as a 2 on the scale might be rated as a 4 by someone else.

“Researchers encounter the same problem whenever they try to compare people’s subjective experiences more generally: Is my experience of the colour red the same as yours? Could it be that you experience red in the way that I experience green? Is there any way to compare the experiences of two individuals when those experiences are, by their very nature, entirely subjective and locked inside each person’s mind?” asks Heiða.

The researchers note that no measurement tool can give us direct access to another person’s mental imagery. The question, therefore, is not whether it is possible to develop a tool that precisely captures each individual’s experience, but rather whether such a tool can measure that experience in a reliable and interpretable way and complement other methods.

In their Cortex article, Heiða María and her colleagues describe a new test they have developed called the Visual Imagery Visually Anchored Scale (VIVAS). Rather than relying solely on verbal descriptions, VIVAS allows people to rate their mental imagery using visual examples. The aim is to capture aspects of mental imagery that may not be adequately captured by conventional questionnaires.

How vividly can you imagine a piece of sushi?

In the study, participants were asked to generate mental images of objects belonging to specific categories. For example, participants were shown an image of a piece of sushi on a screen for three seconds, after which the image disappeared. They were then asked to generate a mental image of the sushi.

Next, participants rated their mental image according to three visual properties: transparency, sharpness and colour saturation, using visual examples presented on the screen in front of them. In total, participants were asked to generate mental images of objects from six different categories: animals, buildings, faces, food, man-made objects, and novel objects that they had not seen before.
Around 1,500 people randomly selected from the Icelandic National Registry were invited to participate in the study and asked to complete both the VVIQ questionnaire and the VIVAS test. A total of 205 participants completed the study.

The results showed that the three visual properties of mental imagery, transparency, sharpness and colour, were strongly related, but nevertheless represented distinct dimensions. In particular, people’s ability to imagine colours could differ from their ability to generate a sharp and clearly defined mental image. The researchers thus suggest that mental imagery may depend partly on dissociable components, with some relating to the clarity and structure of an image and others to its colour.

In other words, being able to generate a clear mental image does not necessarily mean that all of its visual properties are equally vivid. Some people, for example, may find it particularly easy to imagine colours while finding it more difficult to generate a sharp or clearly defined mental image, or vice versa.

Familiar objects are easier to visualise

What people were asked to imagine also mattered. Mental imagery for novel and unfamiliar objects was weakest across all three measures. This suggests that familiarity plays an important role in determining how vividly we are able to generate mental images. In other words, it appears easier for the mind to visually reconstruct things we already know.

Of all the object categories participants imagined, food was the exception. Participants generated particularly vivid mental imagery for food colours, whereas the clarity and form of mental images varied relatively little across categories of familiar objects. The researchers point out that colour is particularly important when evaluating food, for example, in determining whether something appears edible.

Two tests can paint different pictures

When participants’ VIVAS results were compared with their VVIQ scores, the researchers found a moderate association between the two measures. In some cases, however, individual participants showed substantial discrepancies. Some people who ranked in the lowest 10% on one measure ranked in the highest 25% on the other.

The researchers argue that this is important because such tests can help identify people at either end of the visual imagery spectrum, including those with aphantasia and hyperphantasia. If a test and a questionnaire yield markedly different results for the same individual, identifying people with unusually weak or vivid mental imagery may be more complex than previously assumed.

VIVAS adds a new, visually anchored measurement approach to the self-report questionnaires already in use and may help researchers develop a more precise and multifaceted understanding of how people experience their internal visual world.
The full research article is available here: Read the study in Cortex.