Reduced effects of social feedback on learning in Turner syndrome

Abstract

Turner syndrome is a genetic condition caused by a complete or partial loss of one of the X chromosomes. Previous studies indicate that Turner syndrome is associated with challenges in social skills, but the underlying mechanisms remain largely unexplored. A possible mechanism is a reduced social influence on learning. The current study examined the impact of social and non-social feedback on learning in women with Turner syndrome (n = 35) and a sex- and age-matched control group (n = 37). Participants were instructed to earn points by repeatedly choosing between two stimuli with unequal probabilities of resulting in a reward. Mastering the task therefore required participants to learn through feedback which of the two stimuli was more likely to be rewarded. Data were analyzed using computational modeling and analyses of choice behavior. Social feedback led to a more explorative choice behavior in the control group, resulting in reduced learning compared to non-social feedback. No effects of social feedback on learning were found in Turner syndrome. The current study thus indicates that women with Turner syndrome may be less sensitive to social influences on reinforcement learning, than the general population.

Figure 1

Experimental design. In counterbalanced order, participants completed 75 trials in each condition rounds. Choosing the correct option was followed by receiving (A) social feedback (animation of a smiling face, social condition) or(B) non-social feedback (animation of a stack of gold coins, non-social feedback). Incorrect choices, in both condition rounds (A and B), were followed by an animation of the letter “X” moving towards the participant, (C). In both conditions, the reward probabilities of the stimuli were 2/3 and 1/3 respectively. Stimulus color and position of the better stimulus (left/right) were counterbalanced between participants and conditions.

Figure 2

Exploitation-exploration balance. Effects of different values of the reinforcement learning parameter β (exploitation-exploration balance). Higher values of β leads to more deterministic choices, so that a stimulus with higher expected value is chosen with higher probability. Lower levels of β leads to a higher probability of explorative choices.

Figure 3

%Correct choices over the course of the experiment in participants with Turner syndrome and controls. The dashed line indicates chance level performance (50% correct choices). Trials were grouped into five blocks of 15 trials.

Figure 4

%Correct choices by group and condition. Pairwise follow-up tests: %correct choices by group and condition. Crossbars show estimated marginal means and 95% confidence intervals. Note ** p < .05 Bonferroni corrected.

Figure 5

Bonferroni-corrected follow up comparisons. β in the control group and Turner syndrome group as a function of condition. Crossbars show estimated marginal means and 95% confidence intervals. Note ** p < .05 Bonferroni corrected.