Category Archives: TDCS

Using TDCS to Zap Subconscious Bias

A hot topic in Quantified Self (QS) circles is transcranial direct current stimulation (TDCS) and its ability to nudge the brain toward different types of growth. I wanted to see if I could start using TDCS to zap subconscious bias. The QS community has a love/hate relationship with TDCS. There are people who embrace it or those who slap a big warning label on it.  I decided to do my own tests to see what results I could get.

Paraphrasing Wikipdia: “TDCS uses a constant, low current delivered to the brain area of interest via electrodes on the scalp. TDCS can increase cognitive performance on a variety of tasks, depending on the area of the brain being stimulated. It has been utilized to enhance language and mathematical ability, attention span, problem solving, memory, and coordination.” This is not a photo of me, but when I do a TDCS session the application of direct current to my brain it looks like this:

Using TDCS to Zap Subconscious Bias

My Question

Could I use TDCS to change a subconscious bias?

What I Did

I took 21 subconscious bias tests while running TDCS (or not) based on a random schedule. The bias test was from a web instrument offered by Project Implicit of Harvard. You can take fourteen different tests to determine if you have a subconscious bias.

These tests can measure your bias with respect to weapons, skin tone, religion, sexual orientation, etc. I am purposely not going to report on which bias I measured so the topic of this study remains altering the subconscious vs which biases I might have. If you are curious about your own biases I recommend you try a test.

How I Did It

I generated a “0” or “1” randomly in a spreadsheet for each day I was going to do the tests. On the days that a “0” was generated I took the bias test without modification by TDCS. On the days a “1” was generated I took the test while applying TDCS.

When applying TDCS I used a commercial TDCS device to apply 2 milliamps of current to my prefrontal cortex. There are over 50,000 “montages” (placements) for TDCS electrodes so I chose a common and straightforwad one that reportedly improves learning rates. Here are the placements for the montage:

Using TDCS to Zap Subconscious BiasAfter taking the test, I translated the result of “strong, moderate, slight or no” bias into numbers (1 – 5) that would allow me to run the math on whether there was a statistically significant change to my bias when applyint TDCS.

What I Learned

Direct application of current to the learning area of the prefrontal cortex did not immediately alter my subconscious bias during that session. Over time, either due to TDCS stimulus or my getting “better” at taking the test, my subconscious bias was reduced.

When I compared those sessions where I was either using TDCS or not, I ran a Student’s T-Test on the two groups of results. The result showed the groups were not statistically different with a p-value of .38. If the p-value was under .05 the results would have been significant. This means the use of TDCS in a session did not change the bias in that session.

When I looked at the scores over time, a trend emerged. It appeared that over time my bias decreased. Here are my scores over the 21 sessions:

Using TDCS to Zap Subconscious Bias

The trend goes down. So either I learned how to take the test more efficiently or the TDCS had an effect. The tests are designed to not be modified by conscious effort so any learning is likely to have been at a subconscious level.

There is more work to do. The theory is that the TDCS current nudges the brain toward more plasticity while learning. I was not learning other than taking the test multiple times. An alternate test would be to apply TDCS while learning something new about the bias. This first study provided the basis for future views, but did not deliver a complete result. So goes science and so goes Quantified Self.

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