Abstract
This article reviews historically significant phenomenological studies of visual mental imagery (VMI), starting with Fechner in 1860 and continuing to the present. This synthesis of diverse VMI phenomenological studies in healthy adults serves as a unique resource for investigators of individual differences, cognitive development and clinical and neurological conditions. The review focuses on two kinds of VMI, “memory imagery” and “eidetic imagery”. Ten primary studies are drawn from three periods of the scholarly literature: early (1860–1929), middle (1930–1999) and recent (2000–2023). It is concluded that memory and eidetic imagery are two forms of constructive imagery, varying along a continuum of intensity or vividness. Vividness is a combination of clarity, colourfulness and liveliness, where clarity is defined by brightness and sharpness, colourfulness by image saturation and liveliness by vivacity, animation, feeling, solidity, projection and metamorphosis. The findings are integrated in a template that specifies, as a tree-like structure, the 16 properties of VMI vividness in healthy adult humans. The template takes into account the weight of evidence drawn from the accounts and reveals an extraordinary degree of consistency in reported VMI characteristics, revealed by specialized studies of healthy adult humans across time, space and culture.
What This Study Is About
This study looks at over 160 years of research to figure out what it actually feels like to "see" things in your mind. The researcher wanted to create a master list of all the different ingredients that make a mental image—the ability to picture things in your head—feel real or vivid.
How They Studied It
The researcher acted like a detective, reviewing 10 major studies from 1860 all the way to 2023. These studies included thousands of people from five continents, including famous scientists, college students, and people with intellectual disabilities. Participants didn't just answer "yes" or "no" to whether they could see images; they described their thoughts in detail, drew pictures of what they "saw," and took tests like the "Open Circle Test," where they tried to project a color into a blank shape.
What They Found
The study discovered that "vividness" isn't just one feeling—it’s a recipe with 16 different ingredients! These include:
- Clarity: How sharp or blurry the image is.
- Colorfulness: How bright or saturated the colors look.
- Liveliness: Whether the image moves, feels solid, or even has an emotional "vibe."
The most surprising finding? The researcher suggests that many people who think they have aphantasia—the inability to visualize—might actually have mental imagery that just doesn't show up on standard "vividness" quizzes. When asked to draw or describe specific details, some "aphantasics" might find they have more mental activity than they realized.
What This Might Mean
This suggests that imagining isn't like looking at a photo; it’s more like a "constructive process," where your brain builds a scene piece by piece. It also suggests that our current ways of "diagnosing" aphantasia might be too simple. However, because this was a review of older studies (some over 100 years old!), we have to be careful. Science "suggests" rather than "proves" here, and we need more modern tests with brain scans to confirm these ideas.
One Interesting Detail
The researcher compares studying the mind to the "Parable of the Blind Monks." In the story, several monks touch different parts of an elephant—one touches the trunk and thinks it's a snake, another touches the leg and thinks it's a tree. This study tries to look at the *whole* elephant of human imagination for the first time!