Researcher in Profile: Rodolfo Cortes on Reciprocity

By Chia-wa Yeh, Head Teacher and Research Coordinator

An adult accidentally drops a pen on the floor near a child. The adult tries to retrieve it unsuccessfully due to a table blocking the way. Watching this happening, how likely is it that the child will help the adult pick up the pen?

How children learn what behavior is expected of them is at the core of an ongoing investigation by Rodolfo Cortes, a fourth-year graduate student in developmental psychology at Stanford University, who is interested in how children acquire culture.

Cortes was born in Uruapan in Michoacán, Mexico, a city known for its monarch butterfly sanctuary and vast avocado farming. He immigrated to the United States with his parents when he was 9 years old. A keen observer, Cortes noticed minute details in people and his surroundings from a very young age. His acute ability to take in cues, both verbal and non-verbal, was further heightened when his family moved from Mexico to Los Angeles—a highly diverse metropolis ethnically and linguistically—as he had to adapt to a different way of being and learn a new language. Growing up, he loved learning about ancient history and mythology and wanted to be an archeologist, Indiana Jones style. He was also attracted to psychologist Carl Jung’s idea of archetypes and that all of the world’s cultures may show similar mythologies.

Cortes’s interest in how children acquire culture can be attributed to his own experience of moving to the United States. “It’s important to be able to navigate different cultural contexts. In some cultures, some ways of being are more emphasized, more rewarded than others. Children have to learn how to be attuned to [different situations] and learn how they can thrive in one context and how they can thrive in another context. When children are constantly entering into new groups, they need to be able to figure out how people expect them to behave and they need to have some sense of their goal,” said Cortes.

Cortes studied social sciences at the University of California in Berkeley as an undergraduate and volunteered to conduct research with infants. As an undergraduate, he participated in the Leadership Alliance’s Summer Research-Early Identification Program at Stanford and conducted research at Bing Nursery School under the guidance of Stanford psychologist Carol Dweck, PhD. His summer research experience solidified his interest in pursuing advanced training in research in developmental psychology, and one year later he enrolled as a doctoral student with Dweck as his advisor.

One aspect of culture involves helping others and being generous. Cortes and Dweck have examined what experiences can promote these outcomes. They hypothesize that children who experience reciprocal interactions—interactions characterized by give-and-take with others—are more likely to help and be generous towards others than those without such experiences.

Some of the research questions Cortes and Dweck have investigated together:

Reciprocity and helping

To test their hypothesis, the researchers set up two play conditions: one reciprocal and the other parallel. In the reciprocal condition, the researcher and the child took turns rolling a ball, pushing buttons on a musical toy and handing large plastic rings to each other. Identical toys were used in the parallel play condition but the researcher had his own set of toys and played a few feet away from the child.

In both conditions the researcher played a few feet away from the child, looked toward the child’s face, smiled and made friendly statements regarding the situation (e.g., “Toys are fun!”) After six minutes, the researcher “accidentally” dropped a few objects such as a pen from a table to the child’s side, making it out of reach for the researcher. The results showed that children in the reciprocal condition helped more.

Reciprocity and generosity

To examine the extent of the effect of reciprocity, children took part in one of the two conditions as in the previous study. The researcher left the room after the first phase and someone else entered the room and invited the children to give one or two stickers to the person they’d just played with. The results showed that children in the reciprocal play condition were significantly more likely to give two stickers, rather than just one.

Why might this occur? The researchers hypothesize that reciprocity builds a “benevolent social contract”—an abstract representation of culture where the proper course of action is to maximize another’s welfare. They tested this in follow-up studies.

Expectations of generosity

Children interacted with two researchers. With one adult, they played in parallel while with another researcher they played reciprocally. Next, another person showed children pictures of the two individuals and asked “who would share this play-dough with you?” The results showed that children expected the reciprocal interaction partner to act generously.

Learning from video

To learn whether children learn these patterns by simply observing others interact, the researchers showed children videos of an adult interacting reciprocally with another adult (adult A) or acting in parallel with a second adult (adult B). The researchers asked the children: “Of these two people (adult A and B), who do you think would share play-dough with you?” In another version of the study, children were asked to donate stickers to one of the two people. The results showed that children are generous toward people who engage reciprocally with other people and expect those people to be generous to them as well.


In this study, the researchers examined why children may have expected people they had seen engage in reciprocal activities to act prosocially, and why the children acted prosocially toward them as well. They postulated that it’s because children trust those people more. In the study, children watched videos of two people interacting, and then the two people claimed that a novel object was called either, for example, a “toma” or a “dax.” Children were asked whether they thought the object was really a toma or a dax. The results showed that, regardless of the label, children trusted the information provided by the person who interacted reciprocally.

Does the benevolent social contract support the emergence of culture?

Two of the most important aspects of culture involve learning language and learning how to use tools. Cortes pondered: If children are more trusting of people who interact reciprocally, does that mean that they will prefer to learn from these people? The results showed that children chose information from the person who engaged reciprocally.

In another version of the study, children were given the information about a machine and the name for an previously unknown object beforehand and the task was reversed. To whom did children choose to provide useful information? They chose those who interacted reciprocally.

Cortes argues that these studies in a constructed microcosm demonstrate that reciprocity not only induces altruism (i.e., being helpful to others) but also helps children to acquire culture, and it triggers their own transmission of the valuable information that they have learned.

These studies begin to suggest that children are extremely sensitive to social rules—they can understand how they are expected to behave, Cortes said. Some social contexts, such as reciprocal interactions, seem to facilitate learning and teaching. The implications for improving young children’s development are that in order to thrive and help others thrive, children may need to experience reciprocity.

Cortes recently received Stanford’s DARE (Diversifying Academia, Recruiting Excellence) Fellowship for two more years of doctoral training. He greatly enjoys research and hopes to be a professor at a university.

“A little bit of reciprocity goes a long way,” Cortes pointed out that the process that researchers engage in with children to establish rapport validates his research approach. Researchers first interact with children positively in the classroom, for example, reading books, to acquaint themselves with the children, who in turn participate in the researchers’ studies, which are often presented as a game. His hope is that as children develop, the experience of reciprocal interactions will build their self-esteem, which may allow children to develop into parents who maximize their own children’s chances for success in life.