Children Respond Differently to Different Learning Rewards

Children with Angelman syndrome respond to different types of rewards to promote learning, and the preferred type may vary based on the genetic cause, a new study indicates.

The study, “Refining the Behavioral Phenotype of Angelman Syndrome: Examining Differences in Motivation for Social Contact Between Genetic Subgroups,” was published in Frontiers in Behavioral Neuroscience.

The symptoms of Angelman include cognitive, social, and behavioral abnormalities. Specifically, the disorder is typically characterized by intellectual impairment and learning difficulties, coupled with heightened desire for social engagement and frequent laughing and smiling. Sensory-seeking behaviors also are common.

In the new study, a team of researchers from the U.K. and Australia examined the effects of different types of rewards on learning in 21 children with Angelman. In the experiments, children were prompted to do something (e.g., touch an object), and if they did so they received a reward.

Two types of rewards were used: a sensory reward (a favored toy) and a social reward (interaction with the person running the experiment). The type of social reward also varied. For example, in some cases, the person running the experiment would avoid eye contact or physical contact. In total, five different types of social reward were used.

The team calculated the percentage of times that the desired behavior was executed in the presence of different kinds of rewards. They found no significant differences based on whether sensory or social rewards were used in the overall group.

However, there were differences among genetic groups. Angelman is caused by genetic defects on the copy of chromosome 15 inherited from a person’s biological mother. In about 70% of cases, a part of this chromosome is erroneously deleted.

The team found that, among 14 children with deletions in the study, only four (28.6%) responded to social rewards. In contrast, among the remaining seven children with other types of genetic abnormalities, all but one (85.7%) responded to social rewards.

Among those without a deletion, all five children with an imprinting center defect (ICD) responded to social rewards. ICD is a type of genetic anomaly in which there is a problem with imprinting, a process by which one copy of a gene (inherited from either biological parent) is preferentially silenced.

“Children without a deletion were more likely to be reinforced by social stimuli than children with a deletion. Most notably, all children with AS caused by an ICD were reinforced by social stimuli,” the researchers concluded.

The results suggest “that genetic subtype may be an important consideration when developing guidelines or advice regarding behavior,” they added.

Comparisons across different types of social rewards generally did not reveal statistically significant differences.

“This may suggest that whilst social interaction functions as a reinforcer in [Angelman syndrome], this may not be specific to any one component of interaction,” the team wrote. “These findings contradict the research suggesting that eye contact may be an important component of social interaction … .”

However, the researchers noted that the majority of children (60%) only responded to one of the five types of social reward tested — and only one child responded to all five.

“Whilst no consistent social reinforcer was identified across participants, the results indicated that type [sic] of social interaction was still important for individual children. … This has implications for future interventions conducted with children with AS, suggesting that the type of social interaction needs to be established in order for it to function as a reinforcer most effectively,” the researchers wrote.

More generally, the researchers stressed that individual children in this study responded differently to different types of rewards — some responded more to sensory, others to social. As such, they noted a need to establish an individual child’s preferences, when trying to reinforce behavior in the context of learning.

“Whilst no consistent reinforcer was found across children, the results suggest careful selection of reinforcers may be important; some children showed almost zero levels of target behaviors in some sensory and/or social interaction conditions,” the team wrote.

The results show, “that the assumption of a strong drive for social contact in [Angelman] is not ubiquitous,” they added.

Limitations of this study include its small sample size, particularly for genetic analyses, as well as the fact that the learning experiments were fairly short in duration, according to the researchers.