Physically abused kids struggle to learn about rewards | Science News for Students

Physically abused kids struggle to learn about rewards

Challenges adjusting from an unpredictable home life can lead to misbehavior
Mar 6, 2017 — 7:10 am EST
upset child

Lab experiments show that physically abused kids have trouble learning to make choices that consistently lead to a reward. Later on, this difficulty can contribute to behavior problems, researchers say.


Abused kids may be hit, choked and otherwise physically attacked by their parents. This leads them to see the world as a place where hugs and other positive responses to good behavior happen inconsistently, if at all. And this physical abuse doesn’t just leave kids black and blue. It also bruises their ability to learn how to act at school and elsewhere. This can lead to the problem behaviors often seen in abused children.

That’s the finding of a new study. And it is the first time researchers have linked trouble learning a basic form of social skills in children to their misbehavior years later.

Jamie Hanson is a psychologist at the University of Pittsburgh in Pennsylvania. He and his colleagues focused on decision-making in abused kids. Their experiments showed that physically abused kids lag behind others in learning to make choices that lead to a reward. This was true even after many trials.

These children stick to what they learned early in life — that rewards are rare and unpredictable, but punishment is always imminent. In situations outside their families, “Physically abused kids fail to adjust flexibly to new behavioral rules,” explains coauthor Seth Pollak. He’s a psychologist at the University of Wisconsin at Madison. Such kids never learn rules for good behavior with teachers and other children. So they end up fighting peers on the playground and acting out in class.

The researchers published their findings February 3 in the Journal of Child Psychology and Psychiatry.

What they found

Hanson’s team studied 41 physically abused and 40 nonabused kids. All were between the ages of 12 and 17. The kids were different races and lived with their parents in poor or lower-middle-class neighborhoods. All were similarly bright and successful in school.

In one experiment, kids saw a picture of a bell or a bottle. Researchers told them to choose one of those objects to earn points they could exchange for toys. Kids who got enough points could choose from several cool toys in the lab. These included a chemistry set and a glow-in-the-dark model of the solar system. Kids with fewer points would choose from plainer toys, such as a Frisbee or colored pencils.

During 100 trials, one of these pictures earned points for the kids 80 percent of the time it was selected. The other picture got them points only 20 percent of the time. (At the start of the experiment, researchers randomly chose whether the valuable picture would be the bell or the bottle.) In a second round of 100 trials, kids saw pictures of a bolt and a button. This time, one randomly chosen image resulted in points 70 percent of the time, versus 30 percent for the other image.

Both groups of kids chose higher-point images more often as the experiment went on. This showed that they all gradually learned the values of the images. But physically abused kids lagged behind. They chose the more-rewarding image in 131 out of 200 trials, on average. Nonabused kids picked that image in 154 out of 200 trials. Pollak thinks the abused kids were held back by the expectations they had picked up at home.

More than 117,000 U.S. children were victims of documented physical abuse in 2015. That’s the latest year for which data are available. If the new finding holds up, it could lead to new ways to help such kids.

For example, Pollak says, these kids might get training in how to tell apart safe frpm dangerous settings. They might also get lessons on how to control their impulses. Treatments currently focus on helping abused children feel safe and less anxious.

If abused kids have trouble learning new rules about rewards, it indeed could lead to behavior problems later on, says Kathryn Humphreys. She’s a psychologist at Stanford University in California who did not work on the new study. There are, however, other possible reasons that abused kids might act disruptively, she points out. They might be especially sensitive to social stress, for example. Or, she adds, they might be convinced that others always have bad intentions.

Power Words

(more about Power Words)

behavior     The way a person or other organism acts towards others, or conducts itself.

chemistry     The field of science that deals with the composition, structure and properties of substances and how they interact with one another. Chemists use this knowledge to study unfamiliar substances, to reproduce large quantities of useful substances or to design and create new and useful substances. (about compounds) The term is used to refer to the recipe of a compound, the way it’s produced or some of its properties. People who work in this field are known as chemists.

coauthor     One of a group (two or more people) who together had prepared a written work, such as a book, report or research paper. Not all coauthors may have contributed equally.

colleague     Someone who works with another; a co-worker or team member.

journal     (in science) A publication in which scientists share their research findings with the public. Some journals publish papers from all fields of science, technology, engineering and math, while others are specific to a single subject. The best journals are peer-reviewed: They send out all submitted articles to outside experts to be read and critiqued. The goal, here, is to prevent the publication of mistakes, fraud or sloppy work.

model     A simulation of a real-world event (usually using a computer) that has been developed to predict one or more likely outcomes.

peer     (noun) Someone who is an equal, based on age, education, status, training or some other features. (verb) To look into something, searching for details.

physical     (adj.) A term for things that exist in the real world, as opposed to in memories or the imagination. It can also refer to properties of materials that are due to their size and non-chemical interactions (such as when one block slams with force into another).

psychiatry     (adj. psychiatric) A field of medicine where doctors study and treat diseases of the human mind. Treatments may consist of talking therapies, prescription drugs or both. People who work in this field are known as psychiatrists.

psychologist     A scientist or mental-health professional who studies the human mind, especially in relation to actions and behavior. 

psychology     (adj. psychological ) The study of the human mind, especially in relation to actions and behavior. To do this, some perform research using animals. Scientists and mental-health professionals who work in this field are known as psychologists.

reward     (In animal behavior) A stimulus, such as a tasty food pellet, that is offered to an animal or person to get them to change their behavior or learn a task.

social     (adj.) Relating to gatherings of people; a term for animals (or people) that prefer to exist in groups. (noun) A gathering of people, for instance those who belong to a club or other organization, for the purpose of enjoying each other’s company.

solar system     The eight major planets and their moons in orbit around the sun, together with smaller bodies in the form of dwarf planets, asteroids, meteoroids and comets.

stress     (in biology) A factor, such as unusual temperatures, moisture or pollution, that affects the health of a species or ecosystem. (in psychology) A mental, physical, emotional, or behavioral reaction to an event or circumstance, or stressor, that disturbs a person or animal’s usual state of being or places increased demands on a person or animal; psychological stress can be either positive or negative.


Journal: J. Hanson et al. Early adversity and learning: Implications for typical and atypical behavioral development. Journal of Child Psychology and Psychiatry. Published online February 3, 2017. doi:10.1111/jcpp.12694.

Report: Department of Health & Human Services Administration for Children and Families. Child Maltreatment 2015. Published online January 19, 2017.