The correct answer to this open question is the following.
The most significant psychological barrier to critical thinking is mental effort.
The ability to analyze information being objective in order to make a judgment using the reason is what we understand for critical thinking. To do this, you have to evaluate data, sources, statistics, and numbers. Critical thinking is a way to make good decisions or solve complex problems. Mental effort can be a barrier of critical thinking in that it can derive in overthinking information or data, instead of trying to understand ideas or concepts that can be applied.