(PS4-19) A Novel Progressive Ratio Task to Extend the Study of Effort to Infants and Improve Autism Interventions

Autism Spectrum Disorder (ASD) often involves diminished attention to social stimuli (e.g., reduced eye contact, response to social sounds). The social motivation hypothesis posits that these behaviors, which shape the diagnostic criteria of ASD, lead to less motivation for and response to social learning opportunities. Many early interventions for ASD rely on motivation for social and tangible rewards to shape behavior. However, many children with ASD show small gains after early intervention (Warren et al. 2011), perhaps due to individual differences in motivation. One particular aspect of motivation - willingness to work, or effort - has been extensively studied in both animals and human adults, and was included as a subconstruct of the NIMH RDoC (Research Domain Criteria) Positive Valence System with recommended tasks. To date, willingness to work is rarely studied in children or individuals with developmental disabilities, likely due to the high language and cognitive demands of the recommended tasks (i.e., gambling tasks: Bress et al., 2012; Knutson et al., 2000)). In this study, we developed a novel task with few linguistic or cognitive demands, pressMORE (pressing Measure Of Rewarded Effort), designed to assess willingness to work in children as young as six months. We tested feasibility in children 6-59 months old in order to extend our understanding of motivation to young children and individuals with developmental disabilities such as ASD. 

Historically, willingness to work has been studied using the progressive ratio task (PRT), a behavioral paradigm in which a reward (e.g., money, sucrose solution) is earned by an increasing amount of required effort (e.g., lever presses). PressMORE is a novel iteration of the PRT designed to measure willingness to work for rewarding stimuli in infants and children with developmental disabilities by pressing a large red button to activate bubbles or disco lights (Fig 1). Willingness to work for the reward is measured by the “breakpoint,” defined as the highest threshold (i.e., number of button presses) completed (and therefore reinforced by the reward) before the task is terminated (Hodos, 1961). During piloting, the reward was changed from disco lights to musical bubbles after caregiver feedback. 

In this pilot feasibility study, nine children (ages 6-59 months; Table 1) completed pressMORE. All participants across a wide age range successfully completed pressMORE, as indicated by 321 button presses reinforced by 19 disco light displays by the 59-month-old participant, and 67 button presses by the 6-month-old participant reinforced by 10 bubble releases. As expected, breakpoint increased with age (Fig 2). 

These pilot data demonstrate the feasibility of pressMORE to assess willingness to work in a broad range of children as young as six months. Data on pressMORE performance in autistic and non autistic preschool children will be available by November, 2024. This novel, developmentally appropriate task extends the study of motivation into a previously excluded demographic with implications for understanding the heterogeneous response to early intervention among autistic children.