Any attitude or behavior, if sufficiently rehearsed, becomes a habit. Once formed, habits automate attitude or behavior, producing mental “knee-jerk” responses to the events of life. So, the key to honorable behavior, for example, is to think carefully about the attitudes and behaviors one is repeating. If it contributes to personal integrity, habit is a good thing. If repeated attitudes and behaviors are teaching you to be dishonest, you will have done it to yourself—and made it lasting.
A clear example of teaching oneself to be dishonorable comes from a British university study showing that people become desensitized to lying. The experiment involved creating scenarios whereby people could lie. In the experiment with 80 people, pairs in separate rooms viewed a photograph of a jar filled with pennies. The photo was clear only for one person, whose task it was to advise the other person how many pennies were in the jar. The person making the estimate was told that the reward would vary on each trial, without knowing critical details about the built-in incentive structure. No feedback was provided. The more the advice was deliberately exaggerated, the more financial reward was to be given. Conditions were manipulated so that lying could benefit both partners, benefit the advising partner at the expense of the other partner, or benefit the advising partner only. (There were features of the design that I think could have been improved, that is beyond the scope of this post.)
The greatest lying occurred when it benefited only the lying person. Dishonesty persisted at lower levels if the partner also benefited. There was zero lying under conditions were lying was punished by lower reward while the partner benefited.
People's lies grew bolder the more they lied. Brain scans revealed that activity in a key emotional center of the brain, the amygdala, became less active and desensitized as the dishonesty grew. In essence, the brain was being trained to lie. Thus, a little bit of dishonesty might be viewed as a slippery slope that can lead one to grow more dishonest.
Emotions are at the core of the issue. Normally, we tend to feel guilty when doing something we know is wrong, like lying. But as we get in the habit of lying, the associated shame or guilt habituates. We get used to it and our conscience doesn't bother us so much. So, we are less constrained in our future behavior. We can't always be brutally honest, but it is now clear that each little lie or dishonest act can escalate and negatively change the person we are.
Another possibility is that positive reinforcement of behavior is involved. A well-known principle of behavior is that one tends to repeat behavior that is rewarded. Thus, if a person benefits from lying, he will likely do more of it. However, the brain area most associated with positive reinforcement, the nucleus accumbens, did not show any change in activity. The authors still asserted that lying was motivated by self-interest because the greatest lying occurred when only the adviser benefited. However, the experiment was designed so that subjects could not know when their advice was being rewarded. Thus, the likely remaining explanation is that they just adapted to lying and it didn't bother them so much to exaggerate their estimates.
The absence of feedback was a crucial part of the design. But the authors point out that in the real world, the extent of dishonesty is greatly affected by feedback in terms of whether the deceiving person thinks there will be benefit or punishment.