The Cognitive Science of Moral Failure: The Stroop Effect

As mentioned a few posts ago, I'm reading the book Nudge by Richard Thaler and Cass Sunstein. (My post about the Amsterdam flies was also inspired by Nudge.) Reading Nudge has motivated me to devote a post or two to recent advances in cognitive science and the implications these might have for moral behavior.

The main insight I'd like to focus on is the growing consensus that the human brain has two distinct processing systems. The first system is fast, unconscious, automatic and heuristic. The second system is slower, conscious, effortful and deliberative. Many cognitive scientists speculate that the first system is older, evolutionarily speaking. It is a rapid response system that is tightly connected to our survival instinct and reward circuitry. If I throw a ball at you you instinctively catch it. That is System 1 at work. Fast and automatic. But the price you pay for speed is accuracy. This is what I meant by "heuristic." A heuristic is a rule of thumb that is generally effective. But not always. If I throw a porcupine at you you just might automatically catch it. Your automatic reaction is to catch anything coming at your head. Which is, generally speaking, a good rule of thumb. But it's error prone. Think about stereotypes. You find yourself making judgements about a person based on dress, race, or gender. Those judgments are heuristics that help you quickly size up social situations. Only in many cases the stereotypes are wrong or immoral. Reflective people know this and take the time to notice and shoo from consciousness any stereotype they feel to be in error or immoral. But more often than not, the stereotype, a social heuristic, goes unnoticed and affects the way you relate to the person in front of you, for good or ill.

By contrast, System 2 is believed to be a more recent evolutionary development and its logical/reasoning capabilities separate us from much of the animal kingdom. System 2 can do math problems, but there is nothing natural or easy about mastering the multiplication table or advanced algebra. These are deliberative and intentional skills. When Aristotle called man a "rational animal" he was talking about System 2.

However, given the late arrival on the evolutionary scene, our logical, analytical, and deliberative skills are bit removed from the reward systems of the brain. Where System 1 craves and acts impulsively, System 2 diets and counts calories.

The point I want to make today is that one of the root causes of moral failure, of not being the person we want to be, results from the fact that the human mind has these two distinct mental systems. More to the point, these systems often come into conflict. System 1 wants to eat and System 2 wants to lose weight. System 1 works with stereotypes and System 2 wants to treat people as individuals. System 1 is drawn to pornography and System 2 is seeking sexual purity. System 1 wants revenge and System 2 struggles to forgive. And so on.

In illustrating this conflict, the authors of Nudge point to a well known phenomenon in cognitive science: The Stroop Effect. The Stroop Effect is a wonderful example of how our two cognitive Systems come into conflict. Take the following stimulus card:

To experience the Stroop Effect read from left to right calling out the color of the ink for the first two rows. You'll note how easy that was. But now try to call out the color of the ink for the remaining words. Try to go as fast as you can. When you do this you'll feel the difference. You'll go slower and probably make a mistake or two. That slowing down and increase in error rate is called the Stroop Effect.

Obviously, the Stroop Effect is caused by the mixed signals. The color of the ink sends one signal to the brain ("blue") while the semantic content of the word sends a different signal ("green"). What is important for our purposes is that the brain is experiencing a conflict between the two Systems. System 1, processing the visual color in one part of the brain, is coming into conflict with System 2 which is processing language in a different part of the brain. You slow down in the Stroop Test because you have to take a second (or, rather, milliseconds) to figure out which System should trump. The two Systems have come into conflict and this hurts your performance.

The cognitive psychology behind the Stroop Effect is the same psychology frequently implicated in moral failure. System 1 wants to do A and System 2 wants to do B. Which one trumps? Which System wins?

Given all this, we might recast Paul's description of moral failure in the language of modern cognitive science:

Romans 7: 14-24a
We know that the law is controlled by System 2 but I am controlled by System 1, sold as a slave to System 1. I do not understand what I do. For what System 2 wants to do I do not do, but what I hate I do. And if I do what I do not want to do, I agree that the law is good. As it is, System 2 isn't doing it, but System 1. I know that System 1 controls me, that is, in my sinful nature. For System 2 has the desire to do what is good, but System 1 cannot carry it out. For what I do is not the good I want to do; no, the evil I do not want to do—this I keep on doing. Now if I do what System 2 does not want to do, it is not System 2 doing it, but it is System 1 that does it.

So I find this law at work: When System 2 wants to do good, System 1 is right there with me. For in System 2 I delight in God's law; but I see System 1 at work in the members of my body, waging war against System 2 and making me a prisoner of System 1 which is at work within my members. What a wretched man I am!

Post Script: An interesting and semi-related story.

A few years ago cognitive psychologists voted the Stroop Effect as the most influential finding in the history of cognitive psychology. So many ideas and laboratory techniques are based on the Stroop Test. Thousands and thousands of studies reference Dr. Stroop's pioneering work.

Here's the interesting part. Dr. Stroop, who died in 1973, was a member of my religious denomination, the Churches of Christ. Basically, the most famous and influential Church of Christ psychologist is Dr. John Ridley Stroop. Nothing I do as a psychologist will come remotely close to the impact of the Stroop Effect upon psychological research. Dr. Stroop is up there with Pavlov, Milgram and Skinner.

The interesting part is that soon after Stroop finished his pioneering doctoral work in 1933 he began his teaching career at David Lipscomb University, where I spent my first year of teaching. But Dr. Stroop didn't teach a lot of psychology at Lipscomb. He walked away from the discipline and became a bible professor, publishing books for bible classes and church audiences. His major work was a trilogy entitled God's Plan and Me. In short, the most famous Church of Christ psychologist walked away from psychology to teach bible classes. Which, if you know the Church of Christ, isn't remotely surprising. But it's a strange kind of story. A man writing books on the bible, toiling away on his bible classes when, all that time, his doctoral work in psychology is changing the face of the discipline.

And the funny thing is that I knew none of this. Dr. Stroop so thoroughly disappeared from psychology that the discipline effectively lost track of him. Of course I'd heard of the Stroop Effect. Every psychology student knows about it. But no one ever talked about Dr. Stroop's other research or heard him at conferences. The Stroop Effect was alive and well, but Dr. Stroop had vanished. So I didn't know Dr. Stroop was a member of my religious denomination or that he was a former professor at my university. I only found out about all this when the Chair of my department pulled some Stroop cards from his desk one day. Turns out he was cleaning out some closets in the department and found some of Dr. Stroop's old cards, the ones he used in his dissertation research. The original Stroop stimuli cards! I was stunned. I mean, these things should be in the Smithsonian or something. But there they were, in a dusty old closet. And my Chair sat back and told me the fascinating story of Dr. John Ridley Stroop, the discoverer of the Stroop Effect.