gun deaths in america

February 11: CNN reports breaking News: “Man accused of killing 3 Muslim students”. It follows with “Was it a dispute over a parking space or something more sinister that prompted the shooting death of three students in an apartment near the University of North Carolina, Chapel Hill campus? My intuitive brain had no doubt: An ugly hate crime! Muslim students, a white killer, the South…it all fits. The initial police report about a parking dispute brought on a wry smile: yeah…and he probably felt threatened and shot the three of them in self defense. The picture of a paunchy, balding man didn’t do him any favor either.

Craig Stephen Hicks, who was said to have obsessed over parties, patterns and parking near his home, has confessed to killing three neighbors, the police say. Source: the NYT.Credit Chuck Liddy/The News & Observer, via Associated Press
Craig Stephen Hicks confessed to killing three neighbors, police say.
Source: the NYT Credit Chuck Liddy/The News & Observer, via Associated Press

March 3: A headline in the NYT: “In Chapel Hill, Suspect’s Rage Went Beyond a Parking Dispute.” Of course, I thought, I knew it the moment it was reported. But reading the article put a different and much more interesting light on the case.

Here is a quote:

“Mr. Hicks was unemployed, taking night classes at a community college in hopes of becoming a paralegal. He spent long hours in his apartment with a collection of at least a dozen guns, including four pistols and a Bushmaster AR-15. Mrs. Hicks told her lawyer that Mr. Hicks would stare out the second-floor window, obsessing over neighbors’ parties, patterns and parking…According to a police search warrant, he kept ‘pictures and detailed notes on parking activity’ on his computer.”

Another detail: Mr. Hicks was a rabid atheist (I didn’t know such a species existed), fulminating about all religions, especially Christianity on his Facebook page. Surely doesn’t fit the profile of a southern racist.

What caught my attention was his obsessiveness, his endless rumination over such a trivial matter.



Rumination is intrusive perseverative cognition. In clinical psychology, perseveration is the uncontrollable repetition of a previously appropriate or correct response, even though the repeated response has since become inappropriate or incorrect. In our case, the rumination is not focused on a word or a response to a question; it is a meme, or an idea, in his cognition that was caught up in an infinite loop, much like the needle of a record player stuck in a groove. Once an idea got into his head, it kept preying on his mind. He was unable to expunge it. In plain English, he couldn’t let go.

The capacity to forget is adaptive. Can you imagine if we remembered forever the thousands of trivial events that occur to us daily? When the occurrence is traumatic, the consequences may be severe.

PTSD is probably the most devastating manifestation of the failure to forget. A soldier experiencing the horrors of war, a women being raped or subjected to domestic violence, a child being continuously harassed at school—all these emotional experiences leave an indelible memory trace that keeps returning to haunt the victims years after the event. Are some people more susceptible to PTSD than others? Not all soldiers who saw combat return home psychologically and neurologically damaged. This suggests that there may be a genetic influence on the susceptibility to developing PTSD.


It all happens in the ventral striatum


Mammals have a brain structure called the ventral striatum. It forms an arc of neuronal bundles that sits between the amygdala (the emotional center), and the hippocampus (involved in memory formation and storage) on the one end, and the prefrontal cortex (the executive, decision-making center, which regulates and tamps down the emotional inputs from the amygdala). It gets inputs from both ends. Thus, the ventral striatum is functionally strongly associated with both emotional and motivational aspects of behavior. So it is not surprising that structural and functional disturbances of ventral striatum have been shown to be correlated with various forms of psychopathology, such as schizophrenia, addictive behavior, and most importantly for our understanding of dysfunction of “forgetting”: obsessive-compulsive disorder (OCD) and PTSD.

Our memories are constantly being edited between remembering and forgetting. Some are consolidated into long-term memories, most are erased without a trace. This yin/yang process is generated by dopamine and two dopamine receptors—one mediating memory, the other forgetting. And the whole process is genetically controlled. The gene PRKCA, is associated with the formation of strong memories. A variant of this gene generates an excessively strong memory capacity which alters the delicate balance between memory and forgetting and increases the risk of PTSD and OCD.


What does it feel like?

We can’t get into Mr. Hicks’s head, but we can imagine that what he felt wasn’t good; rumination is either about angry or guilty emotions. Why is that? Why don’t we ruminate obsessively about happy events? Neurobiology hasn’t provided the answer, yet. But we do know that psychologically people have a tendency to attach much higher weight, or “valence” in psychological lingo, to bad than to good.

A review of the literature by Roy Baumeister and his colleagues at Case Western University (Baumeister is currently at Florida State University) and at Free University of Amsterdam, found that negative experiences carry more weight (valence) than positive ones. In fact, one can even quantify how much more “bad” is worth than “good”—the ratio is about 5:1. Thus, five good events are needed to counteract a single bad one.

As the authors put it in their summary: “Bad emotions, bad parents and bad feedback have more impact than good ones. Bad impressions and bad stereotypes are quicker to form and more resistant to disconfirmation than good ones.” Maybe that’s why rumination is associated with negative emotions.

A recent study (Negative Emotional Events that People Ruminate about Feel Closer in Time) suggests that one psychological consequence of ruminating about negative emotional events is that the events feel as though they happened metaphorically “just yesterday.” Based on their experiments the authors conclude that “these findings have implications for understanding the role of emotional rumination on memory processes in clinical populations and people prone to rumination. This research suggests that rumination may be a critical mechanism that keeps negative events close in the heart, mind, and time.”

As Daniel Gilbert put it, we are the only animal that can peer into the future. Thinking and planning about the future is pleasurable, which is why humans daydream. So imagine how awful it must feel being held captive by recurring angry thoughts about the past.

Most ruminators don’t end up murdering the objects of their obsessions. But when the infinite loop they are caught in is also a positive feedback loop, or self-reinforcing, the consequences can be tragic.

Hicks is an extreme example. We can’t excuse his awful deed; he needs to be held fully accountable. But it would be helpful if we could understand what drove him to the breaking point.

Dov Michaeli, MD, PhD
Dov Michaeli, MD, PhD loves to write about the brain and human behavior as well as translate complicated basic science concepts into entertainment for the rest of us. He was a professor at the University of California San Francisco before leaving to enter the world of biotech. He served as the Chief Medical Officer of biotech companies, including Aphton Corporation. He also founded and served as the CEO of Madah Medica, an early stage biotech company developing products to improve post-surgical pain control. He is now retired and enjoys working out, following the stock market, travelling the world, and, of course, writing for TDWI.


  1. Thank you Dr Michaeli, today understood what was happend in my mind, for long time those ideas for the day bad experience took my mind in the midle of the night, many times awake with the thoughs loop over and over.

    But now i know the therapy to work in that !
    Thanks alot

    • Glad you got the problem under control. It can be very debilitating and many times requires professional help. Cognitive Behavioral Therapy (CBT) has been shown to be effective.

  2. A very interesting topic. It helps me to understand what could take people to such incomprehensible, tragic actions. Greetings from Colombia.

    • Thank you Anna, and greetings to Colombia. We spent a delightful time around this time of the year in Medellin (minus Escobar, of course).
      Rumination may also explain how isolated young people fall prey to Muslim extremists’promises of comradeship, social recognition and hopes of self-fulfilment. These young people are ripe for murderous actions after years of resentful ruminations.


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