Vicarious Effort-Based Decision-Making in Adults with Autism Spectrum Disorders

Background: There has been recent emphasis on examining motivational aspects of social deficits in ASD (Chevallier, Kohls, Troiani, Brodkin, & Schultz, 2012). The purpose of the present study was to evaluate vicarious effort-based decision-making to address one aspect of the social motivation hypothesis of ASD (i.e., the willingness to expend effort to win a reward for another person). Our research group recently reported that adolescents with ASD are characterized by impaired vicarious effort-based decision-making (Mosner, Kinard, Mcweeny, Shah, Damiano, Burchinal…& Dichter, 2016).

Objectives: As a follow-up to our prior study of adolescents with ASD, the present study explored vicarious effort-based decision-making in adults with ASD to examine potential developmental changes in vicarious effort-based decision-making in ASD between adolescence and adulthood.

Methods: Twenty-three typically developing controls (TDCs; age M= 21.32, IQ M=118) and 28 high-functioning adults with ASD (age M=20.00, IQ M=107) participated. Diagnoses of ASD were confirmed with the ADOS-2, and groups were matched on age and gender distribution (p’s<.05). A modified version of the Effort Expenditure for Rewards Task (EEfRT) was used as a behavioral measure of vicarious effort-based decision-making. In this task, participants are provided with the probability of receiving monetary rewards of various magnitudes on each trial and asked to choose between an “easy task” for a small, stable reward or a “hard task” for a variable but consistently larger reward (Treadway, Buckholtz, Schwartzman, Lambert, & Zald, 2009). Unlike the standard version of the task where participants work to earn money for themselves, in this version of the task, participants were working to win money for another person.

Results: There were no group differences (ASD vs. TDC) in the proportion of hard task choices across all levels of reward magnitudes and probabilities (p’s>.05, Cohen’s d<.27). There were also no significant Group x Magnitude or Group x Probability interactions (p’s>.05, Cohen’s d<.50). Effect sizes of this magnitude suggest results would remain non-significant with samples sizes as high as 67-270, depending on the effect examined.

Conclusions:  These findings suggest that adults with ASD did not differ in their willingness to expend effort for others across all levels of reward probabilities and magnitudes compared to TDC adults. Contrary to our previous findings with adolescents with ASD, adults with ASD did not differ in sensitivity to reward parameters when earning rewards for others. These findings also contrast with our previous findings with adults with ASD, in which we found greater effort expenditure across all reward parameters when earning rewards for themselves compared to TDC adults (Damiano, Aloi, Treadway, Bodfish, & Dichter, 2012). The difference in patterns of results between the present study with adults and our prior results from adolescents (Mosner et al., 2016) highlights the developmental differences in vicarious effort-based decision-making for others. Adolescence may be an especially vulnerable period of development for individuals with ASD during which deficits in social motivation differ compared to adults. Future studies in this area should include younger children with ASD to further explore the trajectory of vicarious effort-based decision-making across development.