The instruction that stopped me
I was reading a study about imagination when a simple instruction started to seem less simple: picture a shape. It sounds like something everyone understands, until you ask what actually happens when someone tries.
One person may experience an image. Another may know exactly what the shape is without seeing anything in the mind at all.
That difference is the starting point of aphantasia, the absence of voluntary visual imagery. It is not the same as being unable to see the world in front of you, and calling it a lack of imagination can make the finding sound much broader than it is.
The study I was reading did not ask people to tell a moving story about that difference. It asked them to look at bright and dark shapes, then try to imagine them while researchers watched their pupils.
At first, the surprising part seemed obvious: the eyes could respond to something that was not actually there. But further into the paper, a smaller detail changed the way I read the whole experiment.
It concerned what happened when the task became harder. That detail matters because it speaks to an assumption people can make about someone else’s experience: perhaps they simply are not trying.
When a private experience becomes a research problem
There is a practical difficulty in studying a mental picture. A researcher cannot borrow someone’s inner experience for a moment and compare it directly with another person’s.
Words help, but they can also conceal differences. Two people may both say they are imagining a triangle while describing quite different experiences when asked more carefully.
In the 2022 study published in eLife, Lachlan Kay, Rebecca Keogh, Thomas Andrillon and Joel Pearson used pupil measurements to investigate those differences. The analysis included 42 people who reported visual imagery and 18 people with aphantasia.
The researchers first presented bright or dark triangles. As expected, pupils became smaller in response to brightness and larger in response to darkness.
That response helps regulate the amount of light entering the eye. It also gave the team a useful starting point: before examining imagined brightness, they could observe how participants responded to actual brightness.
After viewing the shapes, participants had a pause to let afterimages fade. They were then cued to imagine the shapes while their eyes remained open, allowing the tracking equipment to continue measuring their pupils.
Those details matter. This was not someone glancing into a mirror and deciding whether a thought had made their eyes look different.
It was a controlled task, with repeated measurements and checks intended to separate an imagined image from the lingering effect of one the person had just seen. The researchers were trying to give a private report an additional, measurable point of reference.
The difference appeared after the shapes disappeared
Among participants who experienced visual imagery, imagined brightness and darkness produced different pupil responses. Imagining bright shapes was associated with more constriction than imagining dark ones.
Within individuals, trials rated as more vivid also showed stronger imagery-related pupil differences. The researchers compared their pupil findings with another laboratory measure of imagery strength, rather than relying only on a person’s choice of descriptive words.
Then came the participants with aphantasia. Their pupils responded to the shapes when those shapes were actually visible.
But when they attempted to imagine bright and dark shapes, the researchers did not find the same significant brightness-related difference. The distinction appeared in the imagery task, not as a general failure of the eyes to respond to light.
Reading that, I wanted to keep the wording precise. The result was not that their pupils never changed, or that their minds were doing nothing.
It was that a particular response associated with imagined brightness was absent in this group under these experimental conditions. A finding can be remarkable without being inflated into a complete account of someone’s inner life.
There were also limits. The aphantasia group was small, and these were people who had contacted the laboratory about their lack of visual imagery, not a random sample of everyone who might have it.
The research offers physiological evidence supporting a real difference in imagery. It does not turn a casual conversation about picturing an apple into a definitive home diagnosis.
The harder task revealed something else
The team had included another comparison: sometimes participants were asked to imagine one shape, and sometimes four. Holding more objects in mind makes the task more demanding.
Pupil size can respond to mental effort as well as light. That gave the researchers another way to examine what was happening when people with aphantasia attempted the task.
In that group, pupils were larger during the four-shape condition than during the one-shape condition, averaged across brightness conditions. The brightness-related imagery response was missing, but the response associated with increased mental demand was still there.
As UNSW’s account of the research explains, this supported the interpretation that participants were engaging with the task rather than simply declining to attempt it. They could be trying without producing the visual experience someone else expected.
That is the detail I find most worth carrying out of the paper. Not a claim that an eye tracker can reveal every thought, but evidence against an easy and unfair explanation.
From outside, an absent result can look like absent effort. This experiment made room for another possibility: the person is doing the work, but the process does not resemble yours.
The researchers did not need to invent a dramatic life story to make that distinction meaningful. The contrast between one shape and four was enough to raise a better question.
A better question than asking someone to try harder
I do not read this study as a ranking of minds. It did not measure whose life was richer, whose ideas were better, or who cared more deeply about the people they remembered.
It examined a specific feature of visual imagination. Turning that feature into a judgment about an entire person would repeat the mistake the research helps us notice.
There is a gentler conversation available instead. When someone says they do not picture things, we can ask what thinking about an object is like for them, without insisting that the answer must resemble our own.
We can also describe an instruction more flexibly. Thinking about a place, listing its details, or considering its layout need not be treated as failed attempts simply because no mental picture appears.
Those are suggestions for listening, not treatments established by this experiment. The paper did not test a classroom method, a therapy, or a technique for changing aphantasia.
What it did offer was a reason to be more careful with a familiar sentence: just picture it. For some people, that instruction asks for something quite different from what the speaker assumes.
The part that stays with me is not only that imaginary light can affect the eyes. It is that, when one expected response was missing, the researchers looked for evidence of effort before deciding what the absence meant.
That seems like a useful habit beyond any laboratory. Ask what is happening before deciding that nothing is.
