Older children's brains respond differently to rewarding vs. negative experiences late in day

"When children transition into adolescence, they begin to chase rewards/pleasing experiences more and respond to losses/punishment less. How responsive someone is to rewards varies depending on time of day because of circadian rhythms," said Aliona Tsypes, a graduate student in psychology at Binghamton University. "So we wanted to see how time of day might affect reward responsiveness in children and how this might vary depending on their age. This is important to better understand (and prevent) teenage risk-taking, particularly because the rates of psychological problems increase dramatically during one's transition to adolescence. This is also important for us and other researchers who study reward to know, to make sure we consider the timing of our study sessions as a potentially influential factor."

Tsypes and Brandon Gibb, professor of psychology and director of the Mood Disorders Institute at Binghamton University, recruited 188 healthy children between the ages of 7 and 11 and had them complete a commonly used simple guessing task on a computer. In this task, they see two doors on the screen and guess which one has money behind it. Each time they guess correctly, they win 50 cents and each time they are incorrect, they lose 25 cents. During the task, the researchers measured children's brain activity using electroencephalography (EEG) to examine neural responses to wins and losses.

"One way to objectively assess someone's responsiveness to reward and loss is to measure their brain activity while they play a computer game during which they receive feedback about winning or losing money," said Gibb. "In our study, we were primarily interested in how these responses to gains versus losses may differ throughout the day in children."

The researchers found that older children had stronger neural responses to rewards/pleasing experiences than losses/punishments later in the day (after around 5:15 p.m.), whereas younger children showed the reverse pattern. These findings suggest that early adolescents might experience greater urges to engage in rewarding/pleasing experiences, even if such experiences are unhealthy or dangerous, later in the day.

"Heightened reward responsiveness in early adolescents later in the day may contribute to greater risk for making poor decisions in the evenings (e.g., choosing to engage in risky behaviors)," said Gibb. "This may help to explain why adolescence is a period of increased risk for developing psychopathology and substance use problems."

"If there are times during which children who approach adolescence are particularly responsive to rewards and particularly unresponsive to losses/punishment, these might be important times to particularly watch out for, to prevent dangerous behaviors," said Tsypes.

Tsypes continues to study reward-related processes, particularly as they relate to suicidal and self-harming thoughts and behaviors (STBs). She hopes to better understand the influences of circadian rhythms on reward and how this affects the risk for STBs.

"It is important to note that time-of-day effects are not strictly circadian, so future research should also examine additional relevant variables with a circadian rhythm (e.g., cortisol) to better distinguish reward-related processes from other cyclic processes within the human nervous system," said Tsypes.