Perceptual diversity: do you see what I see?

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Publication Date
01/12/2022
Knowledge in sound, audio wave, overlapping circles gradually increasing in size and decreasing in opacity against a blue/purple background
Knowledge in sound
Perceptual diversity: do you see what I see?
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Professor Fiona Macpherson on the meaning of perceptual diversity: What’s in your mind when you imagine the colour red? Is your blue the same as my blue? 

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Fiona Macpherson FRSE MAE, Professor of Philosophy, Director of the Centre for the Study of Perceptual Experience, University of Glasgow

People perceive the world differently. Some of these differences are well-known. I am short-sighted. Aunt Mabel is tone-deaf. Uncle Monty has a rather discerning palate for wine. But beyond these familiar differences, philosophers and scientists are starting to uncover other – often rather surprising – differences.

This “perceptual diversity” occurs for different reasons: we have different bodies, brains, sensory acuities, and past experiences.

Some people experience “synaesthesia” – a mixing of the senses. For example, some people experience colours when they hear music. Some people have “aphantasia” and lack sensory imagination. They may lack visual imagination and be unable to form mental images in their mind’s eye, or they may not be able to hear a tune silently in their head. They may lack an inner voice. Some people tend to focus more on the details of certain scenes, while others tend to see the bigger picture.

This “perceptual diversity” occurs for different reasons: we have different bodies, brains, sensory acuities, and past experiences. There is no doubt that your past experiences can shape how you perceive the world today, although the mechanisms by which this can occur are still disputed. For example, whether your beliefs and desires can affect your perceptual experience – whether there is “cognitive penetration” – is a question of intense debate in philosophy and psychology.

Perhaps no one is perceiving a shared objective reality, rather each of us is getting a glimpse of the creations of our own minds.

I have examined perceptual diversity for almost all my career. Today, I am excited to share with you my latest project, The Perception Census, and to ask you for your help with it.

The Perception Census consists of a series of online fun interactive games, illusions, and brain teasers that explore how you perceive the world, including colour, sound, time, and dreams. By completing it, you’ll learn about your own powers of perception and how people differ. My fellow researchers (neuroscientists at the University of Sussex, Anil Seth, David Schwartzman, Reny Baykova, and Trevor Hewitt) and I are conducting this study as major citizen science project to reach a broad spectrum of people – more than we could in any lab-based study. With your help, we hope to gather information about perceptual diversity on a scale not achieved before.

We want to investigate types of diversity, their prevalence, and whether some types are correlated with others. The data may also help us reflect on what happens when differences in perception leads to apparent disagreement between people. In some instances, disagreement might mean some people are seeing the world correctly, and some incorrectly. But that does not automatically follow. One person might be accurately detecting one feature of the world, a second person another. Or perhaps no one is perceiving a shared objective reality, rather each of us is getting a glimpse of the creations of our own minds. This last possibility has led many philosophers to contemplate whether the mind is something over and above the physical. We even have a section of The Perception Census asking you to tell us about your philosophical views about the mind.

We would be delighted if you completed The Perception Census and shared it with your friends and family too.

The PerceptionCensus has been developed as part of the Dreamachine Project (https://dreamachine.world), produced by Collective Act.


Professor Fiona Macpherson FRSE MAE is a Professor of Philosophy and Director of the Centre for the Study of Perceptual Experience at the University of Glasgow, and a Fellow of the Royal Society of Edinburgh.

The RSE’s blog series offers personal views on a variety of issues. These views are not those of the RSE and are intended to offer different perspectives on a range of current issues.