Vividness of mental imagery reflects a broad range of internally generated visual experiences

This study demonstrates that simple vividness ratings serve as a robust, objective measure for a broad spectrum of internally generated visual experiences, suggesting that the definition of visual aphantasia should be refined to distinguish between those who faintly or unconsciously perceive mental images and those who completely lack pictorial representations.

The Gist

Imagine your mind is a private movie theater. For some people, this theater is a giant, IMAX screen where the movies play so clearly they feel like they are happening right in front of their eyes. For others, the "screen" is just a tiny, fuzzy sketch in the corner of their mind. And for some, there is no screen at all; they just know the plot of the movie without seeing a single frame.

This paper is a big investigation into how different people run their internal movie theaters. The researchers wanted to figure out if the way we describe our mental images is actually accurate, or if we are all just speaking different languages about the same thing.

Here is the breakdown of their findings, using simple analogies:

1. The Problem with "Vividness"

For years, scientists have asked people, "How vivid is your mental image?" and given them a score from 1 to 5.

• The Issue: Imagine asking two people to rate the "spiciness" of a soup. One person grew up eating mild food, so a little pepper feels like fire. The other person eats spicy food daily, so that same pepper feels like water. They are rating the same soup differently because their "reference point" is different.
• The Paper's Point: The researchers found that "vividness" is subjective. If you have never seen a mental image, you might rate a detailed thought as "low vividness" because you don't have a bright image to compare it to. If you do see images, you might rate a faint shadow as "low vividness" because it's not bright enough.

2. The Four Types of "Mind-Viewers"

The researchers asked people to imagine an apple and then choose a cartoon that best described how they saw it. They found four distinct groups:

• The Projectors (The "Hologram" Group): These people feel like they are projecting the apple onto a screen in front of their face. They can "see" it with their eyes open, floating in the air.
• The Insiders (The "Headphone" Group): They see the apple clearly, but it's locked inside their head. It's like watching a movie on a private screen behind their eyes.
• The Off-Screeners (The "Thought Bubble" Group): They know they are thinking about an apple, and they can picture it in a thought bubble behind their head, but they don't feel like they are "looking" at it. It's more like a mental sketch.
• The Verbalisers (The "List" Group): These people don't picture the apple at all. Instead, they get a list of facts: "Red, round, fruit, grows on trees." They have the concept of the apple, but no picture.

3. The Big Surprise: "Seeing" vs. "Vividness"

The most interesting discovery is that seeing an image and the vividness (clarity) of that image are two different things.

• The Analogy: Imagine two photographers.
  • Photographer A takes a picture that is slightly blurry but they hold it up right in front of their face. They see it clearly because it's right there.
  • Photographer B takes a crystal-clear, high-definition photo, but they keep it locked in a safe in their mind. They know it's perfect, but they don't "see" it floating in the air.
• The Finding: The study found that many people who score high on "vividness" (they have very detailed mental pictures) actually do not see them floating in front of their eyes. Conversely, some people who say they "see" images might only see faint, blurry shadows.

4. The "Banana Test"

To test if people really had pictures in their heads, the researchers asked a tricky question: "Is the banana in your mind yellow, or does it have black spots?"

• People with strong mental pictures could instantly answer: "It has black spots!"
• People with low vividness (the Verbalisers) often said, "That question makes no sense to me," or "I only know the shape."
• The Takeaway: If you can't answer a simple detail question about an object you are "imagining," you probably aren't picturing it at all; you are just thinking about the facts.

5. What is Aphantasia?

Aphantasia is the condition where people claim they have no mental imagery.

• The Old View: If you score low on a "vividness" test, you are aphantasic.
• The New View: The researchers argue we need to be more careful. There are two types of "no image" people:
  1. The True Aphantasic: They have no picture at all. They think in words or facts.
  2. The Faint-Imager: They have a picture, but it's so dim or "unseen" that they think they have nothing.
• Why it matters: If we lump these two groups together, we are mixing up people who think in pictures with people who think in words. This makes scientific studies messy.

6. The Solution: A Simpler Test

The standard test for mental imagery (the VVIQ) is long and boring—it asks 32 questions about imagining different scenes.

• The Paper's Idea: You don't need 32 questions. You can just ask one simple question with a picture: "Which of these five beach photos looks most like the beach in your mind?"
• The Result: This simple "cartoon test" worked just as well as the long questionnaire. It's faster, less confusing, and less likely to trick people into giving the same answer just because they are bored.

Summary

This paper tells us that our minds are much more diverse than we thought. Some people are like projectors, some are like internal viewers, and some are like librarians who only read the book summaries.

The researchers are calling for a new definition of Aphantasia: It shouldn't just be about "low scores" on a test. It should be about whether a person truly lacks a pictorial representation (a picture) in their mind, regardless of whether they "see" it with their eyes or just "know" it's there.

In short: Just because you can't "see" a mental movie doesn't mean you don't have a movie theater; you might just be watching it on a different kind of screen.

Technical Summary

1. Problem Statement

Research on mental visual imagery has historically relied on the Vividness of Mental Imagery Questionnaire (VVIQ/VVIQ-2) to quantify individual differences. However, the authors identify several critical flaws in this approach:

• Lack of Objective Reference: "Vividness" is a subjective construct with no objective standard. Participants with different phenomenological experiences (e.g., those who "see" images vs. those who only "know" them) may interpret the term "vivid" differently, leading to measurement noise.
• Conflation of Dimensions: Current studies often assume that all visualizers "see" their images projected into the external world. This ignores the possibility that imagery can be experienced as an internal, non-visual representation (metaphorical) or that "seeing" imagery and "vividness" (detail/clarity) are orthogonal dimensions.
• Methodological Redundancy: The VVIQ-2 requires 32 repetitive items, which may induce response biases (e.g., habituation to the lowest option for aphantasic individuals) and fails to distinguish between different types of imagery experiences (e.g., projectors vs. insiders).
• Ambiguity in Aphantasia Definitions: The binary definition of aphantasia (total lack of imagery) based solely on low vividness scores may be inaccurate, potentially misclassifying individuals who have faint or "unseen" pictorial representations.

2. Methodology

The authors conducted two online surveys to investigate the relationship between vividness, the sensation of "seeing" imagery, and the location of imagery (internal vs. external).

Experiment 1:

• Participants: 95 valid participants (recruited via social media and the Aphantasia Network, leading to a sample enriched with individuals interested in imagery extremes).
• Measures:
  • VVIQ-2: The standard 32-item vividness questionnaire.
  • Novel Cartoon Likert Scales: Participants rated the clarity of a "beach" scene and an "apple" (eyes open/closed) using images ranging from photorealistic to text-only descriptions.
  • Self-Classification: Participants chose a cartoon depicting their imagery experience:
    • Projector: Image seen in front of the head.
    • Insider: Image seen inside the head.
    • Off-screener: Image in a thought bubble (off-screen).
    • Verbaliser: No image, only a list of adjectives/facts.
  • Additional Probes: Questions on reading fiction, daydreams, dreams, the "Tetris effect," and free-text descriptions of a "pink elephant" and "triangle."
• Analysis: Kruskal-Wallis tests for group differences and Spearman's $\rho$ correlations for relationships between variables.

Experiment 2:

• Participants: 230 valid participants (recruited more broadly to reduce sampling bias).
• Modifications: Removed the VVIQ-2 to test the efficacy of a single proxy measure.
• Measures: Used the "beach clarity" cartoon question as a proxy for vividness. Added questions on thought modality (visual vs. verbal) and specific definitions of aphantasia.
• Goal: To replicate findings and determine if a simplified questionnaire could replace the VVIQ-2.

3. Key Contributions

• Decoupling "Seeing" from "Vividness": The study demonstrates that the ability to "see" an image (project it externally or see it against closed eyelids) is not perfectly correlated with the self-reported vividness (detail/clarity) of that image.
• Identification of Imagery Subtypes: The authors validate a four-group classification system (Projectors, Insiders, Off-screeners, Verbalisers) that captures distinct phenomenological experiences beyond simple high/low vividness.
• Validation of Simplified Metrics: The study shows that a single cartoon-based question (beach clarity) correlates strongly with the full VVIQ-2 and other imagery measures, suggesting the VVIQ-2 is redundant and prone to response bias.
• Redefinition of Aphantasia: The authors argue for a stricter definition of aphantasia that distinguishes between those with faint/unseen images and those with no pictorial representation at all.

4. Key Results

• Vividness Correlations: VVIQ-2 scores (and the beach clarity proxy) strongly correlated with:
  • The propensity to visualize while reading fiction.
  • The frequency and clarity of visual dreams and daydreams.
  • The "Tetris effect" and hallucinations after repetitive tasks.
  • Free-text descriptions of imagined objects (higher vividness = richer detail).
• The "Seeing" Paradox:
  • There is a strong correlation between vividness and the tendency to "see" imagery (Projectors/Insiders).
  • Crucially, many individuals with high vividness scores reported not seeing images (scoring low on "apple eyes-shut" or "apple-in-frame" questions). Conversely, some with low vividness scores reported seeing faint images.
  • This suggests that "seeing" and "vividness" are related but distinct dimensions; a person may have a highly detailed internal image that they do not literally "see" projected externally.
• Group Differences:
  • Verbalisers (18.9% in Exp 1, 5.2% in Exp 2) consistently scored lowest on all vividness and "seeing" measures and often found imagery questions "made no sense."
  • Projectors and Insiders generally had higher vividness scores, but a significant subset of Projectors had very low VVIQ-2 scores (some scoring the minimum of 32), challenging the idea that Projectors are always "hyperphantasic."
  • Off-screeners occupied a middle ground, often reporting imagery that was pictorial but not "seen" in the external world.
• Methodological Efficiency: The single "beach clarity" question correlated more strongly with the overall VVIQ-2 score ($\rho=0.86$) than most individual items within the VVIQ-2 correlated with each other, confirming the redundancy of the 32-item scale.

5. Significance

• Theoretical Impact: The paper challenges the assumption that mental imagery is a monolithic experience. It proposes that "aphantasia" is not a binary state but a spectrum involving different modalities (visual vs. verbal) and phenomenological qualities (seen vs. unseen, internal vs. external).
• Clinical & Research Implications:
  • Redefining Aphantasia: The authors propose redefining aphantasia to exclude individuals who have faint or "unseen" pictorial representations, focusing instead on the total absence of pictorial content.
  • Improved Measurement: Researchers are encouraged to move away from the lengthy VVIQ-2 toward concise, cartoon-based Likert scales that reduce response bias and better capture the nuance of imagery location and clarity.
  • Neural Mechanisms: The distinction between "Projectors" (who see images externally) and "Associators" (who know images internally) parallels distinctions in synesthesia and may have distinct neural correlates, warranting future investigation.
• Broader Context: The findings suggest that the neural mechanisms for generating phantom images (prophantasia) exist in healthy populations and are distinct from pathological hallucinations, likely involving reality monitoring failures rather than a complete breakdown of sensory processing.

In conclusion, the study establishes that while vividness is a robust measure of the quality of mental imagery, it must be interpreted alongside the location and modality of the experience to fully understand the diversity of human visual imagination.