Look Very Closely at a Study Claiming Thought Reading of Brains, and You'll Find the Shady Tricks Behind It

Certain web sites tend to fall "hook, line and sinker" for very dubious and poorly designed neuroscience papers (something that are extremely abundant these days). A recent example is a Gizmodo.com story with the very untrue headline "Brain-Reading Device Deciphers Internal Thoughts With Surprising Precision." We have an article hyping a new science paper with the groundless title "Representation of internal speech by single neurons in human supramarginal gyrus."

The EEG is a device attached to a head, a device that reads brain waves. EEG devices that measure brain waves are strongly influenced by muscle movements, and speech is a type of muscle movement. It does nothing to show that brains produce thinking if you have some EEG device that can detect different responses when different things of different length are spoken. That can be mainly picking up muscle movements, not thought. EEG devices are very sensitive to muscle movements, and if you have a medical EEG reading you will be told not to move during the reading.  

To try to back up unfounded boasts of being able to detect thoughts from brain activity, neuroscientists sometimes claim that they are picking up signals during "internal speech." What is the difference between "internal speech" and actual speech? Actual speech is when you say a word, and "internal speech" is when you only think of the word.  Unless a study is carefully designed, what will happen is that faint amounts of actual speech may occur when subjects were supposed to be using only internal speech. No such careful design has occurred in this study. Instead, we wonder whether the authors had chosen a design trying to get lots of traces of actual speech that could be called internal speech. 

Here is how a carefully designed study might be done, in a way that would minimize the chance of subjects producing a slight amount of actual speech (such as silently mouthing a word) when they were supposed to be only producing internal speech:

(1) A subject might first see a screen saying: "Please speak aloud this word: automobile."

(2) After the response was recorded, a device would then be put in the subject's mouth, to prevent any muscle movement in his mouth. 

(3) The next screen might say: "Now we want you to do something very different: to only think a word we give you, without moving your muscles at all. Be very careful not to move any muscle."

(4) Then the next screen might say: "Now please ONLY THINK this word: locomotive."

Nothing like this was done. We read this description of how the subjects or subject was instructed to act:

"During the cue phase, a speaker emitted the sound of one of the eight words (for example, python). Word duration varied between 842 and 1,130 ms. Then, after a delay period (grey circle on screen; 0.5 s), the participant was instructed to internally say the cued word (orange circle on screen; 1.5 s). After a second delay (grey circle on screen; 0.5 s), the participant vocalized the word (green circle on screen, 1.5 s)."

Get the picture? It was a super-hurried affair.  The "ms" in the quote above refers to milliseconds or thousands of a second, and the "s" in the instructions above stand for a second. Within a five-second period, the people tested were supposed to first speak a word, then only think the word, and then again speak the word. What can we expect would happen given so very hurried a situation, in which people were supposed to switch so quickly between speaking a word and only thinking a word, with two vocalizations of a word and one thinking of the word all occurring within five seconds? There would be a high chance of failing to follow the instructions properly. Given such instructions, the reported results are no compelling evidence for any detection of internal speech.  

Here's a test I want you to try right now, one with three easy, safe steps I want you to perform real fast, in under ten seconds:

(1) First give a big smile and say the word "rabbit" loud and clear.

(2) Next, give a big smile and again say the word "rabbit" loud and clear.

(3) Next, give a big smile and think the word "rabbit."

My guess is that at least 30% of my readers trying this test spoke or mouthed the word rabbit" when they came to the third line, even though that line said to merely think that word. Whenever instructions are given very rapidly, and there's a sudden change in the instructions, there's a large chance the instructions will not be followed exactly. 

So we can assume that given the instructions quoted in italics above (in which instructions are given to first speak a word, then think a word, and then speak the word again, all within five seconds), that in a large fraction of the cases some actual speech or mouth muscle movement occurred during the second part when the subjects were supposed to be only thinking the word.  So probably very much of the recorded "internal speech" was something more, including muscle movement. 

How many subjects were used? Only one subject for one of the tests, and two subjects for some other tests.  Were many trials used? No, not very many. Each subject was asked to think a total of only about 100 words. 

The subjects were given one of eight words to speak and then think of: battlefield, cowboy, python, spoon, swimming, telephone, bindip and nifzig.  Using only a time factor based on the length of activity, and the time of task engagement, a computer program could could probably predict with 50% accuracy which word was used. 

The reported results (about 50% prediction accuracy for some computer program) are results that can easily be explained without assuming any pure thoughts in the brain, by assuming:

(1) a significant fraction of the words that are claimed as "internal speech" actually involved traces of actual speech such as softly spoken words or mouthed words, which occurred because of the very rushed time frame in which participants were supposed to speak a word, then think the word, then speak the word all within five seconds (with a sudden change from instructions to speak a word to instructions to think a word). 

(2) the difference in word lengths was leveraged to help predict which word was mouthed or thought of;

(3) simple chance was leveraged,  easy to do in a situation where scientists are free to file away failing results in their file drawers. 

Because of the shady tricks used, we have here no evidence at all of picking up thoughts from some region of the brain.  A properly designed study of this type would have characteristics such as these:

(1) Instead of instructions given so rapidly or such a rapid-pace timescale (as if they were designed to produce a large amount of failure to follow the instructions), the instructions would be delivered slowly with a longer timescale, to maximize the chance that when subjects were supposed to be thinking (and not speaking), they really would be only thinking. 

(2) Additional measures would be taken to prevent mouth muscle movement when the subjects were supposed to be only thinking, measures such as putting something in the subject's mouth to prevent muscle movement. 

(3) All of the test words would be of an identical length, to prevent some computer program from predicting based merely on the length of the subject activity. 

For more on the misleading tricks used by studies claiming thought reading of brains, see my three posts below:

No One Is Actually Doing Thought-Reading by Scanning Brains or Reading Brain Signals

Misleading Tricks of the Latest Claim of Mind-Reading by Brain Scans

Suspect Shenanigans When You Hear Claims of "Mind Reading" Technology

Claims of mind-reading by brain scans or brain signal reading will continue, and they will typically be based on tricks such as these:

(1) Picking up signs of muscle movement, always possible for anyone who can talk, and wrongly passing that off as detection of "inner thought," aided by study designs which maximize the chance of "contrary to the instructions" muscle movement (or allow a possibility of some kind of muscle movement) when only "inner thought" is supposed to be occurring.

(2) Having tests with words of very different lengths, with a claimed detection of which word was thought of, the success being mostly based on longer time intervals corresponding to such longer words, not any real detection of what someone was thinking. 

(3) Various sneaky tricks in which data backdoors are leveraged, so that predictive success (claimed to be from reading brain data) is mostly coming from data grabbed from a source other than brain data (such as the study that showed people images, and that leveraged previously gathered descriptive data that existed for each of the images presented).