There’s no place in the brain where it all comes together. —Daniel Dennett
You have a unified perception of the world. But inside your brain there is not unity but a division of labor: some parts process vision, some process hearing, others process smell. And within those divisions of labor are further divisions. In the case of vision, specialized cells detect color or light, lines or edges.
There’s lots of things going on at once. They’re not all that coherent. —Daniel Dennett
Cells in the secondary visual cortex are responsible for color constancy, which is why your turquoise mug always looks turquoise to you.
Color constancy is thought to occur because the secondary visual cortex can compare an object and the ambient illumination, and can subtract out the estimated illumination color; however, this process is strongly influenced by what color the viewer expects the object to be.
In fact, almost all higher order features of vision are influenced by expectations based on past experience. This characteristic extends to color and form perception, to face and object recognition, and to motion and spatial awareness. Although such influences occasionally allow the brain to be fooled into misperception, as is the case with optical illusions, they also give us with the ability to see and respond to the visual world very quickly. From the detection of light and dark in the retina, to the abstraction of lines and edges in the primary visual cortex, to the interpretation of objects and their spatial relationships in higher visual areas, each task in visual perception illustrates the efficiency and strength of the human visual system. —BrainHQ
With vision, as with all other sensory perceptions, you experience a unified picture. And the unified visual perception is combined with other sensory perceptions, such as sound or taste or touch. Your brain is constantly weighing and calculating (processing) multiple internal and external factors and inputs to arrive at its predictions—all within the context of what is normal for you—to determine what you perceive and to prepare your response.
Common sense tells you that seeing is believing, but really the brain is built for things to work the other way around: you see (and hear and smell and taste) what you believe. And believing is largely based on feeling. —Lisa Feldman Barrett
Somehow your brain is constantly creating coherent meaning from its network of distributed processes. How does it do that? This question is what’s known as the binding problem: how does the brain bind together the results of all these different processes to generate the unified whole you experience?
Not only is our perception of the world a construction that does not accurately represent the outside, but we additionally have the false impression of a full, rich picture when in fact we see only what we need to know, and no more. —David Eagleman, Incognito
Synesthesia is an example of abnormal binding, which is also referred to as “hyperbinding.” (The word synesthesia means joined perception.) Some synesthetes perceive letters and numbers to be certain colors. For those individuals, the color is a property of the letter or number. It always co-occurs with it. It is bound to it.
At the next MONTHLY MEETING OF THE MIND (& BRAIN), we’ll dig deeper into the predictive brain, the binding problem, and how the process your brain uses to make sense of the world actually gets in the way of behavior change. If you’re in the area and can join us, please do.