A 10-year-old girl named Winter was shaken by her father as a baby. It left her unable to speak or eat solid food, and she is blind because of damage to her optic nerve. She needs oxygen to breathe at night and medication to sleep. Her father was convicted in 2000 of felony child neglect, fined $10,000, and given 5 years probation. “He made a horrible, tragic mistake,” says Winter’s mother, “and in the five seconds it took to shake Winter, he ruined her life.” He also irreparably changed his own: Both he and Winter’s mother are now tasked with looking after a seriously disabled daughter who needs constant care, and will for the rest of her life. (Newman, 2008)

In another case, Pablo Cano-Lopez told detectives that he was at “the breaking point” when he lifted his crying stepson, 4-month-old Elijah Llanos, and shook him four or five times. The baby stopped crying and whimpered before falling asleep. Six hours later, Elijah’s lips had turned blue. He was rushed to a hospital, but by the next day, Feb. 19, 2006, he was pronounced dead.

“He just kept on crying again, and that’s when I…I just got irritated, man,” Pablo is recorded as saying in police manuscripts. “That’s when I shook him.” The 23-year-old was found guilty of manslaughter and aggravated child abuse and sentenced to 20 years in prison. “It’s hard to understand,” says Robert Gershman, the man’s defense attorney. “He loved his children, and in a moment, shook the child out of not only frustration but irrational thinking. Not until it’s over does he realize it’s wrong, and he should have walked away.” (ibid)

Understanding why someone would shake a baby

It’s hard for many people to understand why anyone would shake a baby. After all, it certainly doesn’t help the situation or accomplish anything. (Then again, physical abuse is also counterproductive to a parent’s goals in the long run, yet to my knowledge, nobody has ever made the case that child abuse is a logical decision.) However, when you dig a little deeper and put yourself in the moment, it’s not so hard to see how it happens.

The first thing you need to understand is that shaking something or someone is somewhat of an instinctual frustration response. Just think of how you might jokingly shake your kids when they do something ornery or say things like “I’m going to shake you silly” when they give you grief. Think of all the cartoons and comics where frustration is typically expressed by shaking someone or motion lines to the side of one’s body. Or even how you just throw your hands in the air and shake your forearms when frustrated. Where and how we picked up this tendency or what purpose it serves is up for debate, but my guess is that is has something to do with our instinct for getting someone’s attention. We might be inclined to shake someone to rouse them from their sleep or otherwise get their attention. A child will tug your arm to get your attention, and you might grab a loved one’s shoulders and give them a quick shake when you think they aren’t listening to you. If you imagine this tendency in relation to our evolutionary past, when it might have been important to get one’s attention quickly or rouse someone from their slumber to escape a threat, shaking is probably hardwired into our brain as a means of getting attention.

The second factor is that movement serves as an outlet for stress. An infant’s cries trigger the release of stress hormones in an adult’s body. (All humans respond in this manner, not just the parents of an infant.) This is by design. Nature wants us to be stressed so that we’re motivated to soothe the baby and ease its distress. When a caretaker responds and the infant stops crying, all is well. Both baby and caretaker return to a non-agitated state and harmony is restored to the universe (or at least the home). But when an infant can’t be soothed, these stress hormones keep surging through the adult’s body. In addition to the stress hormone cortisol, this stress also releases adrenaline. Again, this is by design – a part of the ancient stress response system that prepares us for fight or flight. But a crying baby offers no prudent way to expend these hormones. So both the cortisol and the adrenaline build, making the adult not only agitated, but antsy – wanting to move or use their muscles.

When a frustrated caretaker is dealing with a crying infant, all of these factors can come together to produce tragedy. The frustration builds and the adrenaline surges, then wires somehow cross in a person’s brain that trigger this desire to shake as a means of getting attention. The result is a desperate gesture that is the culmination of both frustration and the need to expend physical energy mixed with the underlying desire to get the baby’s attention and ‘rouse’ them from this state of distress. None of this is conscious of course, but this, in a nutshell, is why it happens.