Is Theory of Mind Understanding Impaired in Males with Fragile X Syndrome?

Abstract

Males with fragile X syndrome (FXS) have difficulties with social interaction and many show autistic features. This study examined whether the social deficits characteristic of FXS are associated with theory of mind difficulties. Two groups of boys with FXS participated: a group with few autistic features and a group with many autistic features. An intellectual disability control group also participated. In addition to using standard theory of mind tasks, new techniques were used that were able to separate out the various processing demands of the task (e.g., memory, inhibitory control). Overall, the findings indicate that both groups of boys with FXS have difficulty with theory of mind tasks compared to an intellectual disability control group. However, both groups with FXS also performed worse on comparison trials that required working memory but not theory of mind. Theory of mind difficulties are likely to be an important aspect of the FXS clinical profile, but are most likely the result from a more basic difficulty with working memory.

Appendix A

Standard location change false belief task. Based upon the Sally-Anne task (Baron-Cohen et al., 1985), the participant is introduced to two play-mobile figures and is invited to give them names (for example James and Carol). The experimenter then narrates the following story: “This is James and this is Carol. James has just come into the house from playing football outside. He takes his ball and puts in into his toy box and goes to play upstairs”. The participant sees the play-mobile figure put his ball into a box and exit the area. The narrative is then continued. “While James is playing upstairs, Carol decides to move the ball. Carol takes the ball out of the box and puts it in the cupboard”. The participant sees the second play-mobile figure remove the ball from the box and put it into the cupboard, where it is out of sight. This second figure then exits the area. The participant is then asked two control questions about the original and the current location of the ball: Memory Question: “Where did James put his ball in the beginning?” and the Reality Question “Where is the ball now?” The first play-mobile character is then brought back into the area, and the participant is told “James is going to play outside again now and he wants his ball”. Then the participant is asked the Test Question, “Where will James look for his ball?” The participant scores one for a correct response or zero for an incorrect response on the test question.

Standard Deceptive box false belief task. In this variant of the deceptive box task (Perner, Frith, Leslie, & Leekam, 1989), the participant is shown a sealed egg carton and asked, “What do you think is inside here?” The participant answers “eggs” or “those” (pointing to the picture of the eggs on the box). The box is then opened up and the participant is shown that the box actually contains a pen. The participant is asked to name the pen to check that they know what it is. The pen is put back in the box and the box is closed. The participant is then asked, “In a minute X is going to come and work with me. (S)he hasn’t seen this box yet, or what’s inside it. When (s)he comes in, I am going to show her/him this box, closed just like this (participant is shown box again). I am going to ask her/him “X, What’s in this box?” The participant is then asked the Test Question “What will (s)he say?” and a Reality Question, “What is really inside the box?” The participant scores one for a correct response or zero for an incorrect response on the test question.