Impairment in social interaction is a core symptom of autism spectrum disorders (ASD), and reported weak processing of nonverbal affect may play a critical role. Children with developmental language disorders (DLD) are considered to have intact processing of social-affective information.
At IMFAR 2009 we reported weaker performances of children with ASD vs. typically developing (TD) children on vocal affect, situational affect, and facial affect. Here, we report for the first time results for children with DLD.
To compare children with ASD and DLD on processing social-affective information conveyed in face, voice, and situational contexts.
Classification into the ASD group (N=29) utilized the Social Communication Questionnaire (SCQ); the revised algorithm of the ADOS; and DSM-IV-TR-based clinical diagnosis of ASD, via independent ratings and consensus agreement by a team of licensed psychologists and language pathologists. Classification into the DLD group (N=19) following an equally rigorous process, utilized Tomblin’s Epi-Sli criteria (Tomblin et al., 1997) or a CELF index score at -1 s.d. plus a spontaneous language measure at -1 s.d.; and DSM-IV-TR-based clinical consensus diagnosis. ADOS scores were not used to make or rule out a diagnosis of DLD.
The DLD and ASD groups were well-matched on nonverbal IQ and age.
Affect measures included computerized tasks where participants touched an “affect button” that matched the emotion on a person’s face (Facial Affect; Fein, et al., 1985; 1992), a person’s feeling in a conventional social situation (e.g., birthday party; ibid) (Situational Affect), or the emotion of a recorded voice (Vocal Affect).
The DLD group performed significantly better than the ASD group on Situational Affect, marginally better on Vocal Affect, and similarly on Facial Affect.
The lack of significant differences between groups on Vocal and Facial Affect, and the significant differences between ASD and TD groups found on all affect measures (IMFAR 2009), suggest that the DLD and ASD groups are both impaired in the ability to process affect in faces and vocal prosody.
Given these striking findings suggestive of a possible overlap between ASD and DLD, an analysis was conducted in which we removed a DLD subgroup with ADOS algorithm scores at criterion for ASD (this did not affect IQ and age matching). Results then showed significant differences on Situational Affect and Vocal Affect, but not Facial Affect.
Results indicate that children with DLD understand the affective import of conventional social situations better than children with ASD; however, this may be less, if at all, the case for vocal and facial affect. When children with DLD, who on the ASD-DLD continuum (e.g., Bishop, 2000) are maybe closer to the ASD “border,” were removed, significant differences between groups emerged in vocal affect. These findings indicate the importance of further exploring areas of overlap between the disorders in social cognition and competencies, as Leyfer et al. (2008) have discussed. Perhaps these are some of the characteristics of the broader range of DLD children that may be responsible for recently discussed diagnostic substitution of ASD for DLD (Bishop, et al., 2008).