Psychological and neurological studies often run into the same problem over and over again: Many thought patterns and behaviours can be elicited on demand, yet the underlying mechanism in the brain that causes the thought may be altered from what may happen if the thought occurs naturally. In the article referenced, researchers were interested in the cause of "self talk", or inner speech occurring in the mind. Almost everyone experiences this, be it psyching oneself up for a sports match, or going over an argument and wondering what could have been said differently after the fact. The researchers in the referenced study used fMRI to monitor subject's brains while they were first prompted to start an internal monologue, and then start an internal conversation. The brains behaved as predicted; the monologue caused the areas affiliated with speech to light up, whereas the dialogue caused the areas affiliated with both speech and monitoring the speech of others activated. However, the experimenters designed an alteration to the study, where the subjects were not prompted to have any sort of inner speech and instead were monitored constantly in the machine, and prompted by random beeps to transcribe what they were thinking. This resulted in discovering a completely different area of the brain associated with inner speech.
This study demonstrates one of the key failings of studying human psychological experience. While fMRI provides useful information, it doesn't always capture the whole picture of how we think, since lying very still inside of a large and very loud metal tube is not the most natural setting. Yet there doesn't seem to be much alternative. Survey studies about mental experience are indeed possible, but often people are not inclined to share their deepest thoughts with a strange researcher. We also do not have the technology to monitor brain function at the level of an fMRI while people are just walking around. Morally, would that even be something we would want to do? In order to map natural brain function, necessity demands that some sort of portable monitor be developed, yet is that too much of an invasion into what is usually considered the most private of places, the mind?
I apologize for the formatting, the original article was from Scientific American and was only accessible in a paid format online, so I scanned my print copy.
In a way, the topic of inner speech makes me feel uncomfortable, because as you had mentioned, the mind is considered one of the most private places. I personally have quite a large difference between my inner speech and my overt speech. I wonder exactly what the correlation between inner and overt speech is. After doing some research, I came across an interesting Article titled Discrepancy between inner and overt speech: Implications for post-stroke aphasia and normal language processing. In this study, they were trying to understand the relationship between inner and overt speech. They found that patients with chronic post-stoke aphasia were distributed across a wide spectrum with some having poor abilities in both inner and overt speech, while some had better performance in inner speech than overt speech. This just makes me wonder what the difference is in between these patients; possibly the area of the brain where the stroke occurred? I also wonder if inner speech is markedly different for people who suffer from mental health disorders such as anxiety or depression. Very entertaining post and it now has my inner speech going!
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