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Although previous studies have suggested the involvement of dopamine (DA) and noradrenaline (NA) neurotransmissions in the autism spectrum disorder (ASD) pathophysiology, few studies have examined these neurotransmissions in individuals with ASD in vivo. Here, we investigated DA D1 receptor (D1R) and noradrenaline transporter (NAT) binding in adults with ASD (n = 18) and neurotypical controls (n = 20) by utilizing two different PET radioligands, [11C]SCH23390 and (S,S)-[18F]FMeNER-D2, respectively. We found no significant group differences in DA D1R (striatum, anterior cingulate cortex, temporal cortex) or NAT (thalamus, pons) binding. However, in the ASD group, there were significant negative correlations between DA D1R binding (striatum, anterior cingulate cortex, temporal cortex) and the “attention to detail” subscale score of the Autism Spectrum Quotient. Further, there was a significant positive correlation between DA D1R binding (temporal cortex) and emotion perception ability assessed by the neurocognitive battery. Associations of NAT binding with empathic abilities and executive function were found in controls, but were absent in the ASD group. While a lack of significant group differences in binding might be partly due to the heterogeneity of ASD, our results indicate that central DA and NA function might play certain roles in the clinical characteristics of ASD.

Intergroup bias, which is the tendency to behave more positively toward an in-group member than toward an out-group member, is pervasive in real life. In particular, intergroup bias in trust decisions substantially influences multiple areas of life and thus better understanding of this tendency can provide significant insights into human social behavior. Although previous functional magnetic resonance imaging studies showed the involvement of the right temporoparietal junction (TPJ) in intergroup trust bias, a causal relationship between the two has rarely been explored. By combining repetitive transcranial magnetic stimulation and a newly developed trust game task, we investigated the causal role of the right TPJ in intergroup bias in trust decisions. In the trust game task, the counterpart's group membership (in-group or out-group) and reciprocity were manipulated. We applied either neuronavigated inhibitory continuous theta burst stimulation (cTBS) or sham stimulation over the right TPJ before performing the trust game task in healthy volunteers. After the sham stimulation, the participants' degrees of investments with in-group members were significantly higher than those with out-group members. However, after cTBS to the right TPJ, this difference was not observed. The current results extend previous findings by showing that the causal roles of the right TPJ can be observed in intergroup bias in trust decisions. Our findings add to our understanding of the mechanisms of human social behavior.

People are often influenced by past costs in their current decision-making, thus succumbing to a well-known bias recognized as the sunk cost effect. A recent study showed that the sunk cost effect is attenuated in individuals with autism spectrum disorder (ASD). However, the study only addressed one situation of utilization decision by focusing on the choice between similar attractive alternatives with different levels of sunk costs. Thus, it remains unclear how individuals with ASD behave under sunk costs in different types of decision situations, particularly progress decisions, in which the decision-maker allocates additional resources to an initially chosen alternative. The sunk cost effect in progress decisions was estimated using an economic task designed to assess the effect of the past investments on current decision-making. Twenty-four individuals with ASD and 21 age-, sex-, smoking status-, education-, and intelligence quotient-level-matched typical development (TD) subjects were evaluated. The TD participants were more willing to make the second incremental investment if a previous investment was made, indicating that their decisions were influenced by sunk costs. However, unlike the TD group, the rates of investments were not significantly increased after prior investments in the ASD group. The results agree with the previous evidence of a reduced sensitivity to context stimuli in individuals with ASD and help us obtain a broader picture of the impact of sunk costs on their decision-making. Our findings will contribute to a better understanding of ASD and may be useful in addressing practical implications of their socioeconomic behavior.

Individuals with autism spectrum conditions (ASCs) often experience difficulty and confusion in acknowledging others' perspectives and arguably exhibit egocentricity. However, whether this egocentricity necessarily results in selfish behavior during social situations remains a matter of debate. To study this relationship, we used computerized visuospatial perspective-taking task (VPT) and social-discounting task (SDT), derived from cognitive psychology and behavioral economics, and examined egocentric and other-oriented judgments in participants with ASCs (mean age 29.0 ± 4.2 years) and a group of matched typically developing (TD) controls (30.8 ± 8.5). The response time in VPT showed altered perspective-taking in the ASCs group compared with the TD group that involved in enhanced self-other intrusion and condition-insensitive response. Regardless of self/other perspective judgments, responses were relatively slower and consistent in duration in the ASCs group compared with the TD group. Social discounting was attenuated rather than steep discounting in the ASCs group. Their discounting was comparatively more consistent, irrespective of the task condition (i.e., self-other closeness-level). In effect, ASCs group exhibited more generous decisions than the TD group in this task. Finally, those with more egocentric perspective intrusion in VPT paradoxically showed more generous behaviors in SDT in the ASCs group. Our findings suggest that having ASCs does not always exhibit selfish behavior during interpersonal communication. Reduced flexibility in distinguishing self/other perspective and shifting decision-rules might account for this unique relationship between egocentricity and apparently generous behaviors. These results extend the recent suggestion that more careful attention should be paid to the idea of egocentricity in individuals with ASCs. Autism Res 2019. © 2019 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: We aimed to examine whether seeing the world from another person's point of view and being generous toward other people are related in autistic and nonautistic people. We used a visual perspective-taking task and a social task in which individuals made decisions about how to divide a sum of money with others. Our results suggest that being autistic does not always make someone bad at seeing the world from another's viewpoint, and that autistic people may make fairer social decisions toward unfamiliar people because of lower bias.

The need for closure (NFC), a desire for a firm answer and less ambiguity, has a key role in cognitive flexibility in typical development (TD) populations. This study investigated this motivational construct and its relation to cognitive inflexibility in autism spectrum disorder (ASD). Compared with individuals with TD, those with ASD reported higher levels in preference for predictability and closed-mindedness and lower levels in decisiveness. These NFC facets were significantly associated with cognitive flexibility in ASD as well as TD groups. The study findings provide further insights into the motivational underpinnings of flexible behavior in ASD.

The sunk cost effect, an interesting and well-known decision bias, is pervasive in real life and has been studied in various disciplines. In this study, we modified a task exemplifying the sunk cost effect and used it to evaluate this behavior in individuals with autism spectrum disorder (ASD). The control group exhibited a typical sunk cost effect in our task. We found that the sunk cost effect was lower in the ASD group than in the control group. The results agree with previous evidence of reduced sensitivity to context stimuli in individuals with ASD and extend this finding to the context of the sunk cost effect. Our findings are useful in addressing the practical implications on their socioeconomic behavior.