Top Brain, Bottom Brain

There are a ton of books out there exploring left/right brain dichotomy. Among them one finds decent science based books, as well as books filled with pseudo-scientific mumbo jumbo. With this book I get the sense that the authors have observed that people like to be able to categorize people according to which part of the brain they appear to use the most, and then tried to come up with a novel divide. To their credit the authors do provide arguments for why the top/bottom brain perspective is better than the left/right brain perspective, but I am not convinced. Indeed I was a bit disappointed because when I bought the book I thought that the bottom brain referred to sub-cortical brain regions, such as the limbic system, brain stem, cerebellum etc, but no. One could read this book and not even realize that the brain consists of more than the cerebral cortex (full disclosure: I am a scientist studying the cerebellum).

The story that Stephen Kosslyn is trying to sell is that the dorsal (top) and ventral (bottom) part of the cerebral cortex (the top brain), are to some extent discrete systems performing different tasks, although he is also quick to point out that they constantly work together. There is definitely some truth to the top brain, bottom brain dichotomy. For instance, when we see something we typically use the dorsal stream to analyze movement whereas the ventral stream is used for identification. Still, this book goes way way beyond the evidence.

For example, the authors claim that people rely more heavily on one or both of these systems and depending on which parts of the brain someone uses, he or she is categorized as a mover (top+bottom), stimulator (top), perceiver (bottom), or adapter (context dependent use). It is said that movers are good, both at making plans and observing and adapting to the consequences. Stimulators meanwhile make plans and execute them but are insensitive to the consequences of their plans. Perceivers don’t make much happen but are good at observing what happens around them. To be logically consistent I guess that adapters should be terrible at making plans and terrible at observing what happens around them, but instead it is argued that their top and bottom brain activity is contextually dependent, as if that is not true for all people. I do not know of any evidence to support this idea except that people are different which is hardly a revolutionary observation.

I do not know of any evidence to support this idea except that people are different which is hardly a revolutionary observation. Readers of this book will almost certainly read about the different categories and think that they resemble one category more than the others, but this does not mean that the theory is accurate. People are experts when it comes to confirmation bias. Give people a general astrological description (e.g. in general you like being with people but sometimes you feel shy), and a high percentage will think that it is a good description of their personality. People generally do not seek to falsify such statements.

In sum then, I think that there is a possibility that this book has hit upon an interesting brain dichotomy which we may want to explore further. However, the claims made in this book are very far distanced from the scientific foundation. For the reader who wants a good introduction to the brain I recommend going for Incognito instead.

Bet you didn't know that your cerebral cortex has two parts. Well sort of. A kind of upper, frontish part and lower rearward part. Well, not exactly. I mean, some parts that you'd think were part of the upper part are really in the lower part, and like it's not always clear what's part of what, but the point is, they're different. They do different things, or differentish anyway; it's all a bit hazy- you know how the brain is. Now your upper brain part does space, like 'where' and shape and things of that sort, so it handles planning- I mean because really maybe it's better to say it does 'how' more than just 'where', according to the author. But the mostly lower brain part does something different- it does 'what'. Like such as, identifying and perhaps classifying and other related things, so it brings in a lot of emotion too. The book's not super clear on that.

Now I can already hear you thinking, how could the lower part identify what something is without analyzing it's spatial structure and relations, which is what the upper part does? And that would be an interesting and possibly profound question. So this book doesn't address that.

But guess what? It turns out that the the two parts of the brain interact. They're connected! It's true. It's all scientifically summarized by a line drawing of the brain lobes. See those swooping arrows? Dynamic, real time connectivity! (And you just know that's got to include some feedback.) I've rarely seen so much neurobiology packed so economically into to such a compact, childlike illustration. Take that, people who say the brain is constituted from functionally homogeneous disconnected domains!

So now you're thinking: distinct yet connected functional regions, upper and lower brain parts, I get that. But that has me thinking about the inevitability of cognitive modes. Well this book has got your cognitive modes right here. And not your grandpa's right and left hemisphere cognitive modes, either. No, this is much subtler and more vertical than that. Because it turns out that- and mind you this is not one thing more than pure rote speculation by the authors- some people emphasize the use of their upper brain part, and others rely more on their lower(ish) brain part, while still others- oh when will it stop?- emphasize both parts equally, and finally some people don't emphasize either part, which seems sad. If the force of the pristine combinatorial logic of this scheme doesn't convince you then... well I guess you won't be convinced, because the book provides exactly no other evidence for the existence of these cognitive modes.

Now, these cognitive modes break down into a quadripartite psychological typology consisting of Mover mode, Perceiver mode, Stimulator mode and zzzzzzzzz...

Really, it is all just so trite and totally made up. By the time I reached the last third of the book- the cognitive modes part- I felt as though I was being repeatedly hit with a new model of Taser, powered by banality rather than electricity. Remember when you and your friends would watch lousy movies just to crack up at how unbelievably bad they were? Well it got to that point for me.

In fact, I actually returned this audiobook for a refund of my credit (you knew Audible has a return policy, didn't you?) But then I un-returned it so I could write a review. So you see it is something of a sacred mission with me to prevent you from wasting your credit and your time on this book. Because I love brains, and can't bear to see this book happen to them.