A recent study found that the degree to which a person has autistic traits is related to how their brain processes social rewards compared to non-social rewards. The researchers found that poor connectivity between certain brain regions helps explain why people with more autistic traits often show no behavioral preference for social imagery. These findings show that personality neuroscience.
Daily life is full of rewards that shape human behavior. There are also purely physical or material rewards, such as a delicious cake or finding money on the street. Other rewards can be social, such as a warm smile from a friend or the joy of a family gathering. Research shows that people typically develop a strong preference for social rewards from an early age.
These social rewards remain important throughout life as they help people navigate relationships and build supportive communities. However, the degree to which people value social stimulation varies greatly from person to person. Clinical observations and behavioral tests often show that autistic people have a lower preference for social rewards than non-autistic people. However, the underlying brain structures that explain these differences remain poorly understood.
Most brain imaging experiments tend to examine social and non-social rewards separately rather than directly comparing them. The few studies that compare them often use artificial images that do not reflect real life, such as cartoon faces. Other studies have used real photographs, but the visual brightness and contrast between the two categories is not balanced. This makes it difficult to determine whether brain differences are caused by the social content itself or simply by bright images.
To fill this gap, Anthony Haffey, Chun-Ting Hsu, and Bhismadev Chakrabarti set out to investigate how the brain responds to these categories. Haffey and Hsu are current or former researchers at the University of Reading in the UK, and Chakrabarti holds positions at the University of Reading and institutions in India. They wanted to see whether brain regions that recognize social situations and those that process reward value communicate differently depending on a person’s level of autistic traits.
To test this, the research team designed an experiment using functional magnetic resonance imaging. This technology measures brain activity by detecting changes in blood flow. As areas of the brain become more active, they require more oxygen, which the scanner can observe in real time. The researchers recruited 37 adults from a local university to participate in an imaging session.
Instead of recruiting people who had been formally diagnosed with autism, the researchers measured autism traits across the general population. Autistic traits exist on a spectrum. This means that even people without a clinical diagnosis have varying degrees of traits associated with autism. These traits may include a preference for routine, intensely focused interests, or differences in social communication. Participants completed a standard 50-item questionnaire designed to measure these characteristics.
During the brain scanning session, participants lay in the machine and looked at a series of photographs. Half of the photos included social rewards, such as happy adults or children at a wedding or sporting event. The other half depicts non-social rewards such as tempting food, beautiful scenery, or money. The researchers edited the images to ensure they matched in brightness, contrast, and overall visual saliency.
Participants were instructed to simply press a button each time an image or a blank fixation cross appeared on the screen. This simple task kept me awake and alert throughout the scan session without having to make complex decisions. By matching visual characteristics, the researchers were able to be confident that the differences in brain activity were due to the content of the images.
Even outside the scanner, participants rated the joy and reward of finding each image on a scale of 1 to 9. This provided a behavioral measure of their preference for comparison with neurological data.
At a behavioral level, the study found that participants with higher scores on the Autism Trait Questionnaire rated their social images as less challenging. They did not show a similar decrease in enthusiasm when viewing non-social images. This pattern is consistent with previous behavioral research that has noted reduced preferences for social rewards among people on the autism spectrum. The brain scan data allowed us to take a deeper look into why this behavioral difference exists.
The researchers focused on how different brain regions communicate with each other during the task. This concept, known as functional connectivity, focuses on whether different parts of the brain are activated in synchrony. If two brain areas always light up at the same time, scientists assume they are sharing information. In particular, the research team looked at the relationship between the left fusiform gyrus and the anterior cingulate cortex.
The fusiform gyrus is an area of the lower visual system known for recognizing faces and the human body. The anterior cingulate cortex is a deep brain structure that helps you assign value to rewards. Typically, these two areas show synchronized activity when a person views a positive social image. However, the researchers found that participants with higher levels of autistic traits had weaker connections between these two areas.
In these people, visual processing centers and reward evaluation centers did not communicate as strongly. A similar pattern appeared in another pair of different brain regions. The left anterior insula is an area involved in processing internal body sensations and social norms. The medial orbitofrontal cortex is located near the front of the brain and is deeply involved in calculating the basic reward value of experiences.
The researchers observed that connections between the anterior insula and orbitofrontal cortex were also weaker in individuals with more autistic traits. A statistical evaluation called mediation analysis showed that these weak ties could fully explain behavioral differences in social preferences. The human brain relies on a vast network of connections, and the reduction of certain pathways can significantly change the way a person experiences the world.
The reduction in neural communication essentially mapped directly to the lower ratings participants gave to their social images. If visual and internal sensory areas cannot fully communicate with reward processing areas, smiling faces and happy crowds may not register as very positive experiences. The brain still sees faces and understands the context, but the internal signals that mark the event as rewarding are reduced.
Although the study provides observational insight into the brain mechanisms of social reward, the researchers noted several limitations. The images used in the study were still photographs of strangers taken from the internet. Although this setting is more realistic than using simple artificial figures, it still lacks the richness of true social interaction. Photos of smiling strangers are completely divorced from the participants’ real life situations.
The study also relied on self-report questionnaires to measure autistic traits in the general population. Self-reports can be influenced by cultural background and gender expectations, which can skew the data. A subjective view of one’s own personality may not fully capture one’s neurological reality. The researchers advocate using more objective behavioral tasks to measure these traits in the future.
The research team suggests that future experiments should use larger groups of participants to enable analysis of potential sex differences in reward processing. They also recommend looking at people with a formal clinical diagnosis of autism to see if similar neural patterns emerge at the higher end of the spectrum. Additionally, future tests may benefit from using more engaging and interactive scenarios rather than passive image displays. This could help capture the reality of how the human brain processes rewards in dynamic environments.
The study, “Autistic traits modulate neural and behavioral responses to social and non-social rewards,” was authored by Anthony Huffy, Chunting Hsu, and Bismadev Chakrabarti.
