Mental Imagery: Philosophy, Psychology, Neuroscience. Not really a Precis.
Bence Nanay
Let’s assume you’re reading this piece on your phone – a reasonable assumption these days. And let’s assume you’re reading it while standing in line at the checkout of your grocery store – a good time to read a short fluff piece like this one…
Reading a blog post about mental imagery is a perceptual activity that also involves language processing. Given the subject matter, it also involve at least some abstract thinking, maybe. But what is much less obvious is that at this very moment you exercise your mental imagery in a wide variety of different ways.
Here are some examples:
What’s behind your phone? Probably the back of the shopper in front of you in the line or maybe the stand with the trashy magazines. How do you represent those parts of the coat of the shopper in front of you that are occluded by your phone? I argue that you do so by means of mental imagery.
Something smells weird. Sweet, but also acidy. Maybe someone has spilt something in the aisle behind you? What you have here is olfactorily induced multimodal visual imagery.
Maybe you have met me before or heard me talk. And when reading this, you ‘hear’, in your mind’s ear, my voice, accent, etc. That would be visually induced multimodal auditory imagery.
You’re looking at your groceries and try to establish how many bags you will need: you’re performing a mental action of imaginatively fitting all these groceries to only three bags. Again, mental imagery.
You’re having a flashback to an especially good-looking papaya that you ended up deciding against. That is also mental imagery.
Without making any effort and without wanting to visualize anything at all, by reading these passages, the image of a different supermarket comes into focus – maybe one where you used to go to as a child. That is also mental imagery.
I could go on. My book Mental Imagery: Philosophy, Psychology, Neuroscience (Oxford: Oxford University Press, 2023) has many goals, but the most basic one is to make a case for just how important mental imagery is for a wide variety of different mental processes and for our life in general.
But all these forms of mental imagery are quite different – from amodal completion in the first example to various forms of multimodal mental imagery and beyond. Another aim of the book is to try to find a common denominator in these divergent mental phenomena.
And the common denominator is that all these mental phenomena amount to perceptual representations that are not directly triggered by sensory input. The amodal completion of parts of the shopper’s coat in front of you is a perceptual representation that is not directly triggered by sensory input because your visual system does not receive sensory input from that particular part of the shopper’s coat. When you feel the weird smell, you form a visual perceptual representation that is not directly triggered by visual input, but by olfactory input – by smell. When you hear my voice in your mind’s ear, your auditory perceptual representation is not triggered directly by auditory input, but by the visual input of reading these words. And so on.
Some of these examples of mental imagery are voluntary (for example, imagining how many bags I’ll need), some are involuntary (for example, the flashback to the juicy papaya). Some are visual, some are auditory, some are tactile, and so on. And – a more controversial claim – some of them may be conscious, whereas others unconscious.
I introduced the concept of mental imagery here on the basis of these hopefully vivid examples, but there will be some readers (according to some estimates, about 5-8% of the population) who find it difficult to relate to any of this. They do not ‘see’ the supermarket in their mind’s eye.
More generally, there is enormous interpersonal variation in the vividness of people’s mental imagery. People who lack conscious mental imagery are called aphantasics. People whose mental imagery is so vivid it is close to what perception is like are called hyperphantasics. Most of us are somewhere in between. The vividness of imagery in different sense modalities is not created equal either: visual imagery tends to be much more vivid than olfactory one, for example.
This interpersonal variation of mental imagery is itself a good reason to come up with a way of talking about mental imagery that does not rely on introspection – on how mental imagery feels –, as mental imagery feels different for different people. And understanding mental imagery as perceptual representation that is not triggered directly by the sensory input does not rely on introspection. It is also the way most – not all – empirical scientists think about mental imagery.
And bringing together philosophical arguments and the empirical data on mental imagery was one of my most important goals. The subtitle of the book is Philosophy, Psychology, Neuroscience and while these three disciplines are not represented equally (philosophy still dominates), the aim was to write for all these three very different audiences. As a result, I tried to use as little jargon (philosophical, psychological or neuroscientific) as possible and I also did my best not to take any prior knowledge in any of these three disciplines for granted. So the reader would not feel out of depth regardless of what background they come from.
I argue that mental imagery plays a crucial role in perception (Part II and Part III), cognition (Part IV) and action (Part V), including a variety of mental phenomena, including various forms of memory, emotions, dreams, desires, implicit bias, hallucination, cognitive dissonance, synethesia, sensory substitution, and many more.
If you want to read more about mental imagery, my book is fully open access, you can freely download the pdf from the OUP website. And make sure to check out the three excellent commentaries on this site later this week!