Based on a few videos I have seen around how the brain works, it seems that it has a sort of “gut instinct” mode and a “critical thinking” mode that it can work in. But, interestingly, you can switch it from one mode to the other if you do something simple like making it hard to read a question. The gut instinct can’t figure it out well enough to even make an attempt to answer the question, so the critical thinker wakes up, reads the problem, and then sticks around long enough to work on the actual contents of the problem. End result: The person performs better on a test that is harder to read.
My question: What is the neurochemical or other means that the brain would use for the one part of the brain to signal to the other part of the brain to take over?
I have no answer as to the electro/chemical process involved here. However I do take issue with your premise: “The person performs better on a test that is harder to read.”
Which part do you doubt? I have seen a variety of sources discuss the deliberate vs. gut rift of thinking and I’m reasonably satisfied that this is a widely proven model for understanding the human mind. The specific experiment that I used as an example, where different quality fonts are used on a test, was apparently tested across 3,400 people in 35 studies and the 35% to 90% difference in results seems like a sufficient rift to make it seem unlikely that we’re looking at a statistical anomaly. It seems to fit the definition of substantiated pretty well. (Granted, I don’t know if the 35 studies were all performed by the same person or a variety of people, so it could be questionable if there was just one guy running all of the experiments each time.)
But, even ignoring the specific experiment, if we accept that there are the two modes of thinking, then it seems likely that there would be a signalling mechanism for the brain to switch from one mode of cognition to the other.
It could be handled through switching in neurons and back-propagation, but I think that’s less likely because it would imply a learned methodology for solving problems, that each of us would have to have developed independently. A structural difference seems more likely, and thus some signalling mechanism for switching around which structures to use.
This is one of those annoying situations where the answer is that part of your question is wrong. These two parts aren’t communicating with each other, but with the part of your brain asking the question. When presented with a problem, we first check our memory to see if we’ve encountered this problem (or a similar one) before and how to solve it. If memory doesn’t have the answer, we query analysis which is MUCH slower to produce answers.
So, it’s not instinct calling in reinforcements from critical-thinking, it’s instinct saying “I don’t know” and controller calling in critical-thinking, if you (the one trying to solve the problem) consider it worth the effort.
As for the specifics, it’s just chemical messages passing between and along nerve cells.
Sodium and potassium (and calcium) ions in neurons manage the action potential (depolarization and hyperpolarization) but they are not themselves chemical massagers. Actual messagers (neurtransmitters and neuropeptides) are tranferred between cells and though referred to as “messagers”, they should really be thought of as more conditioners which influence how different cognitive structures in the brain respond to inputs. The neurotransmitter most clearly identified with alertness and focus of thought is acetylcholine, which is produced for the neocortex by the nucleus basalis. (Acetylcholine is also used to activate motor neurons and a variety of other functions outside ofhte brain in the autonomic and enteric nervous systems.) The neocortex is the area primarily responsible for both visual processing and many aspects of higher cognitive function, so it is not suprising (though hardly a definitive conclusion) that encountering a complicated font would sharpen cognitive alertness. The same is true in general for moving images and sharp contrast in colors and shapes.
However, to address a fundamental assumption of the o.p. and the linked video, any time someone talks about using or not using “different parts of the brain” without reference to specific aspects of cognition, they are at best speaking metaphorically and more than likely talking out of their ass. The entire brain is involved in higher cognition, and it is constantly engaged, albeit at differing levels of potentiation and activity depending on mood and environment. The notion that there are specific parts of the brain that control specific behaviors is, while not entirely wrong, so simplistic as to be not very useful at addressing how the brain makes decisions and produces the qualia of experience. One thing that should be understood is that many of the actions and decisions you appear to ‘make’ throughout the day are virtually autonomic and are then rationalized by the cognitive mind post hoc. Being faced with a focused challenge will activiate and dedicate more of the brain’s cognition to a specific problem which may improve performance but it isn’t as if sections of the brain lay completely idle until a novel problem comes up.
As for the study mentioned in the video, no reference is given to population sizes or other controls, and like many studies in cognitive psychology is of dubious merit without extensive replication. Did the same subjects take both tests, and so the first test prepped them for better performance on the second? Or did they use separate populations of subjects, and what effort was made to evaluate and control for differences in the populations. Did they try using other fonts or other means to stimulate awareness? Although the hypothesis of making the font more challenging to read activated more cognitive alertness and attention is plausible, it is not clear that this is the primary driver, nor that the attentional effort could be sustained for an extended duration of time. And the sprawling explanation that the narrator of the video espouses about the success of “difficult” advertizing is at best tenuously supported by any fact.
May I add that even if some chemical (and there are lots of them involved!) has some specific function in neural transmission, there is no need to postulate that the shift from “idleness” to “alertness” in the brain must be related to the levels of said chemical. After all, you don’t have to re-dope the silicon in the processor of your computer every time you shift between Word and Excel, or between Chrome and Firefox…!