Our minds play all kinds of tricks on us. We’ve got all kinds of cognitive biases that influence what we do with our thoughts, and our brains do interesting things with the what it picks up through our senses.
There’s a philosophical argument as to whether or not there is a truly objective reality, but for our purposes, let’s say there is. Information about that objective reality arrives at our senses, but that’s where the objectivity ends.
What our brains do
Sensory organs determine what we’re able to detect from the outside world, but from there, it’s our brain that puts the information together into a neat little package that it thinks will be most useful to us (i.e. our conscious awareness).
The seamless field of vision that we see is a construction of our brains. The brain puts together the offset views from each of our eyes into a continuous whole. I wonder what vision is like for my guinea pigs and other prey animals with eyes on the sides of their head.
My eyes see things quite differently from one another. I had LASIK surgery on both, but 10 years later I needed revision surgery, as my vision had gotten worse. The surgeon wanted to only redo one eye for strategic reasons. Now, that eye sees well at a distance, and my other eye is good for close-up. It took about a year for my brain to figure it out, but now it automatically serves up the most in-focus image.
Then there are all kinds of fun visual illusions. The young lady/old lady one below is a classic. I can see both, but I see the young lady first.
Then there was the white & gold vs. blue & black dress that went viral online a few years ago. The actual photo that was being circulated was the one in the middle. The ones on either side of it are colour-adjusted to give an idea of what different people are seeing. I see white and gold, and no matter how hard I try to see blue and black (which is what the dress actually is), I just can’t.
Our brains do the same kind of thing with sounds. Yanny vs. Laurel went viral a while back. I hear Yanny, and am not getting Laurel at all. In this video, they adjust the pitch, and only then can I hear Laurel (which was, in fact, the original sound).
Philosophy and other fields have assorted ideas about what reality is, but there is no one universally agreed upon true way. From a sociological standpoint, social constructionists would say that reality as we experience it is socially constructed, and whatever objective element there may be, it’s inexplicable intertwined with our social understanding of it.
Realism is the idea that there is a single, immutable version of reality. However, that doesn’t necessarily mean we’re all perceiving it in the same way. For example, my guinea pigs aren’t experiencing sensory inputs in the same way that I am.
Then there’s epistemological dualism, the view that our conscious experience is not, in fact, a direct representation of reality. So, reality is out there, but it’s not the same thing as the reality that we come up with in our heads.
Where mental illness comes in
Hallucinations can involve any of the senses, although auditory hallucinations are the most common.
If what any of us perceives is determined by our brains rather than solely by some form of objective reality, who’s to say that hallucinations are “real”?
A key thing that distinguishes hallucinations from “reality” is where the input comes from. When you and I are listening to the Yanny/Laurel recording, we’re interpreting it differently, but for both of us, our ears are receiving sound waves from the same external source. With hallucinations, there’s an internal (i.e. within the brain) rather than an external stimulus.
Regardless of the source of the stimulus, though, the brain is still putting it into a neat little package for you to receive, and what it’s serving up based on internal stimuli isn’t necessarily going to be much different from what the brain puts together based on external stimuli.
So what is reality?
Who knows. But our brains will always stand between our conscious awareness and what’s going on out in the world. So reality may be one way, but what you and I perceive may be very different things.