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To Forgive or Not to Forgive

The neuroscience behind grudges, and why toddlers don't seem to hold them.

The world might indeed be divided into two kinds of people—those who are able to forgive easily, and those envious of the ones able to do so. Grudges can be incredibly difficult to get rid of, and some scientists have even gone so far as to claim that these can be akin to a craving.

One of the nicest things about watching my toddler grow is observing how her anger or disappointment, while quite intense for the few minutes it lasts, just seems to roll off her like water off a duck’s back. What makes toddlers so resistant to holding long-term grudges, and what can we learn from them?

Anyone who has ever stewed over a feud knows that grudges can sometimes take a compulsive quality. Obsessing over how to mete out justice to someone who has wronged us seems to be a feature of long-term grudges. Given that the desire for revenge feels so unproductive and irrational, and that data shows that a significant percentage of violent acts are rooted in this desire, it might be tempting to think of the desire for revenge as some sort of disorder, and forgiveness as its cure. Indeed, for decades, the scientific consensus seemed to support such a hypothesis.

Grudges and forgiveness as part of an evolved cognitive system

More recent theories of revenge and forgiveness, however, claim that rather than being a defect of some kind, grudges might be part of a complex cognitive system that evolved in humans as a mechanism to deter harms. It might have been efficient for our ancestors—let’s call them the revenge-seekers—to impose some sort of harm or cost on an aggressor, so that the aggressor might weigh the costs the next time they wanted to exploit the revenge-seeker. Such retaliatory action, however, comes with its costs to interpersonal relationships. By this definition, forgiveness is merely a complementary system that helps maintain human relationships in the long run. The operation of the forgiveness system, according to this article by Micheal McCullough and colleagues, “depends on estimating the risk of future exploitation by the harm-doer and the expected future value of the relationship with them."

Brain regions involved in grudge-holding

Given that the rational response is to weigh the costs and benefits of holding a grudge, it should be no surprise that a wide range of brain regions have been found to be involved in the process. Neuroscientists use functional magnetic resonance imaging or fMRI to learn which parts of the brain are active when a person performs a particular task within the scanner. And yes, to learn about the neurobiology of anger and rumination, scientists provoked study participants while they were in the MRI scanner. Apart from interrupting them multiple times during an anagram task, the experimenter also insulted the participants in a rude and condescending manner. This served as the “anger induction” part of the experiment.

This study found that the dorsal anterior cingulate cortex or dACC, a region of the brain involved in responding to negative social situations, was related to the experience of anger. The dACC has also been proposed to be a “neural alarm system” that responds to incongruent or unexpected stimuli or goals. Humans, it has been found earlier, tend to generally have a positive bias towards new acquaintances. Given this tendency to believe people to be innocent until proven otherwise, it is no surprise that the neural alarm system went off in the participants of this study, as they had no reason to expect to be subject to rude treatment by the scientists.

The scientists performing this study sought to answer another interesting question—why do some people display aggression immediately following a slight, and others stay silent but take out their aggression on innocent individuals, such as their family members, later on? The latter kind of behavior, known as displaced aggression, is characterized by rumination rather than immediate aggression. The ruminators, in other words, are also the grudge-holders.

Neuroscience of rumination

To understand which brain regions were involved in angry rumination, the participants were asked questions such as, ‘‘Think about exactly what you have done from the start of the study until now." As was expected, “rumination increased activity in regions associated with emotion regulation, negative affect (or mood), and social cognition such as the cingulate cortex, the medial prefrontal cortex (mPFC), the lateral prefrontal cortex, and the insula." What was even more intriguing was that individuals who were “displaced aggressors” showed greater activation in the mPFC, a region known to be associated with the self-awareness of emotions and emotion regulation. The mPFC has also been found to be active when people are forming impressions, and trying to determine the mental state of other people. All in all, it is clear from this and other similar studies that maintaining a grudge is something that requires considerable mental effort.

All this leads me to wonder if one of the reasons that my toddler cannot stay angry for a long time is simply that she is too busy to be so! She does not have the time for angry rumination. Her mind is so active learning new things each minute that dwelling on her anger would be an immense waste of her time and mental resources.

Grudges have also been found to have other negative effects on people, including an increase in the stress hormone cortisol. Curiously enough, all it seems to take to reverse this increase in cortisol is for the aggressor to show reconciliatory behavior such as apologies or self-abasing behavior. When the injured party perceives the aggressor as agreeable due to such reconciliatory attempts, they trust them more and are in turn more ready to forgive them for their affront.

Brain regions involved in forgiveness

When it comes to forgiveness, it appears that the anterior superior temporal sulcus or the aSTS, a region that is part of the ‘theory of mind’ network, has a role to play. A 2017 study published in Nature magazine found the gray matter volume of the left aSTS to be associated with the degree to which people were willing to forgive other people.

If you are confused about how the size of a brain region would affect traits such as forgiveness, you are not alone. In the paper, the authors say “It is still unclear how and why individual differences in brain morphometry are found to be correlated with personality traits and task performance, but it is often assumed that greater gray matter volume is associated with better computational efficiency of that region, which in turn leads to enhanced task performance."

In order to forgive someone, the brain needs to generate a mental representation of the aggressor as having innocent intentions. This positive feeling would have to compete against the negative emotions generated by the harms done by the perpetrators in order for forgiveness to take place. The authors of the study propose that greater gray matter volume in the aSTS could be enhancing an individual’s ability to generate and process information about innocent intentions, leading to more ready forgiveness.

For all my insistence that my toddler doesn’t hold grudges, I know that it is only a matter of time before she begins to do so. While toddlers might not have much of a tendency to hold grudges, studies have shown that older children and adolescents are in fact way more likely than adults to do so.

Emergence of forgiveness in toddlers

A series of studies by Oestenbrook et al designed to understand the emergence of forgiveness in 4- and 5-year-olds showed some fascinating findings. While 4-year olds required someone to explicitly apologize after harming them, 5-year olds were ready to forgive the transgressor if they simply showed signs of remorse. For instance, after accidentally tearing a picture that the toddlers had been working on, the remorseful person would say “Oh, I've torn your picture. I didn't want that to happen. It's my fault.” Given that no superficial cues of apology were relied on in this part of the study (the transgressor did not explicitly say sorry), the authors suggest that “5‐year‐olds have begun to perceive the true meaning behind apologizing, namely, to convey remorse and to demonstrate a desire to make amends.” This was not true of the 4-year-olds, however.

In the second part of the study, the authors set out to understand if an explicit apology would make 4-year-olds more ready to forgive the transgressor. So in this part of the study, the remorseful transgressor would say something more direct—“Oh, I've torn your picture. I'm sorry. I apologize.” It was found that in the presence of an explicit apology, 4-year-olds behave very similarly to the 5-year-olds in study 1, that is, they are more ready to forgive. This indicates, perhaps, that younger children need a clear apology to forgive a person, given that they are not as emotionally capable as the 5-year-olds to pick up on subtle or superficial cues of remorse.

Theory of Mind in Children

Theory of mind, or the ability to make inferences about the psychological states of other people, does not develop until age 4 in most children. This ability is what enables a 4-year-old to understand that just because they know something, it does not mean others do so as well. If a 3-year-old, for instance, discovers that a candy box is filled with pencils instead of candy, they will assume that another child, who has not opened the box yet, will also know that there are pencils inside. This usually changes when the child turns 4, when theory of mind is developed enough for them to realize that just because they themselves know that the box doesn’t contain candy, it does not imply that another child will know that fact as well.

Finally, in the second part of the Oestenbrook et al study, the authors found that the 4-year-olds did not form broader negative evaluations about the transgressor as readily as the 5-year-olds did. For example, when an unremorseful transgressor tore a picture of theirs, the 4-year-olds reported that they would not expect the transgressors to be more likely to push them off a swing (They did report, however, that the transgressors would be more likely to tear up another piece of paper of theirs). The authors suggest that preschool-age children might need more behavioral examples to make negative trait attributions about other children. Studies have also shown that preschool-age children have difficulty grasping that people’s traits remain stable and can predict their future behavior across different situations.

Well, I, for one, am going to enjoy this stage of my daughter’s toddlerhood, where people are instantly forgiven when they apologize, their negative traits not generalized too much, and where there is absolutely no time for rumination. I also think we can all learn a little something from these munchkins before they grow up to become grudge-holders and revenge-seekers like the rest of us.