What would you do if you woke up one morning and could not recognize faces? This might seem like a stupid question, however, a few people around the world have had to deal with such a situation.. We can all agree that diseases contribute a net negative to humanity. however; most do not consider the path which different diseases create. In the field of neuroscience, neural illnesses are detrimental to decrypting mental mechanisms.
Almost everything we do in the modern world relies on vision. To read this article, you are currently integrating billions of bits of information, all to create a percept. This mental concept will then be translated into meaning. On the other side of vision lies a percept that we do not usually think of; faces. What does it take to recognize your mother's face? What if all faces looked like blurred lines to you? These questions might seem abstract or philosophical, but people with prosopagnosia struggle with these questions every day. Prosopagnosia is a disease that leads to the inability to perceive faces and only faces.
Moreover, this disease is caused by damage to a specific area of the brain called FFA. In other words, these people are not blind; they can read, play sports and use technology. Prosopagnosia shows us 2 things about the mind. 1: that facial recognition is different than object recognition. 2: that face recognition is housed in a specific part of the brain.
Imagine waking up one day and half of your world did not exist; you eat only half of the food given to you; you shave only half of your face; you don't realize you have two arms. However, the worst part is that you are unaware this is happening. That might sound like a horror film. Nevertheless, some people deal with a disease that does just that. Hemispatial neglect, where one cannot pay attention to the left side of their world. For instance, when asked to draw a clock, a patient will draw only half a clock. Moreover, when we do not pay attention to something, we are unaware it exists; as an example, you might not have noticed that I put 2 periods after "situation" in the second sentence of this article.
To you, that second period did not exist. In the same manner, patients are not aware that there is a whole side of their world that they are not seeing. Like prosopagnosia, hemispatial neglect is housed in a specific brain area (parietal lobe). From this disease we found that humans use frames of references to determine handedness; since we can neglect with our head as a reference frame (the left of the head vs the right of the head) and be okay with an object centered frame of reference.
Do we have 2 minds up there?
The brain has two hemispheres connected by wires called the corpus callosum. Each of these hemispheres has distinct features. For example, language is on the left side. Now let's imagine, what would happen if we cut those wires, and the left and right side could no longer communicate. Would they compete? Fortunately for neuroscientist (unfortunate for the patients), neurosurgeons treat some seizures by doing just that. They find that indeed the left and right-side house different aspect of our consciousness. This paradigm manifests starts to manifest itself after studying these patients more and more.
For instance, when asked to read a word (key) presented to their left, they could not do so. But they could draw it. In brief, these patients could draw a key, but they could draw a key but could saw out loud that they saw the word "key". It's as if the left and right side of the brain were operating independently of each other.