Behavioral Flexibility Impairments In Autism Spectrum Disorders Are Related to Symptoms of Insistence on Sameness

Background:

Individuals with ASD demonstrate impairments in flexibly shifting to newly adaptive response strategies when environmental contingencies change. This cognitive impairment may underlie aspects of behavioral rigidity and insistence on sameness in ASD, which are a major cause of functional disability in this disorder. 

Objectives:

To examine flexible choice behavior in ASD, and its relationship to clinical measures of behavioral rigidity.

Methods:  

Forty-seven individuals with ASD and 32 age- and IQ-matched controls performed a probabilistic reversal learning task. Participants were required to choose the correct stimulus from a pair of stimuli in order to obtain as many points as possible. After successfully choosing the correct stimulus over multiple trials during acquisition, the rewarded stimulus was switched unpredictably to the other stimulus choice. Thus at reversal, participants had to inhibit their response to the previously correct stimulus, and select the new correct stimulus to continue to accumulate points. Reinforcement, in the form of 10 point rewards, was presented immediately following participants’ response choices on an 80:20 probabilistic schedule, such that the “correct” choice was reinforced on 80% of trials and “incorrect” choice was reinforced on 20% of trials during both acquisition and reversal.

Results:  

Both the ASD and control group performed comparably in the initial acquisition phase of the task. However, following reversal of the response-outcome contingency, the ASD participants required significantly more trials to successfully shift their response choice to criterion than did controls. This was due to ASD participants making significantly more regressive errors post-reversal, such that after initially choosing the new correct choice, they more frequently reverted back to the previously correct choice than did controls.  Thus, in contrast to controls, ASD participants had difficulty maintaining the new choice pattern following reversal. This effect was driven by significantly more “lose-shift” responses post-reversal, such that the ASD group incorrectly shifted their choice to the other response after intermittent inaccurate feedback. In addition, the number of regressive errors, and lose-shift behavior was positively correlated with clinical measures of insistence on sameness, as measured by the RBS-R and repetitive behavior scores on the ADI-R.

Conclusions:  

These data suggest that individuals with ASD have difficulty shifting from a previously learned and rewarded response to a newly adaptive response choice, and have difficulty maintaining this newly learned choice in the face of intermittent non-reinforcement. Moreover, these reversal learning impairments are related to individuals’ clinical symptoms of insistence on sameness, suggesting that this clinical dimension is associated with a more general problem of cognitive and behavioral inflexibility. Distinct frontostriatal circuitry supports reinforcement learning and response inhibition processes necessary for successful reversal learning performance. Alterations in frontostriatal circuitry may thus underlie impaired flexible choice behavior in ASD, and contribute to insistence on sameness and other manifestations of behavioral rigidity.