The Difference Between High-Functioning Autistic Disorder and the Other Pervasive Developmental Disorders in Mind-Reading Ability

Background: Many studies investigated the difference among the subgroups of Pervasive Developmental Disorders (PDD), defined by the Diagnostic and Statistical Manual, Forth Edition (DSM-IV) (APA, 1994), Text Revision (DSM-IV-TR) (APA, 2000) in the mind-reading ability, especially between high-functioning autistic disorder(HFA) and  Asperge’s disorder (AS).  But the results have been inconsistent (Dahlgren et al. 1996, Kaland et al. 2002, Ozonoff et al. 1991ab, 2000, Royers et al. 2001, Spek et al, 2009).   Regarding the predominant modality for the individual with AS in mind-reading, Golan et al. (2006) found that the male with AS had more difficulties recognizing emotions from faces than from voices.

Objectives: We aimed to examine the difference in the mind-reading ability between HFA and the other PDD which consist of AS and Pervasive Developmental Disorder Not Otherwise Specified (PDD-NOS) in both the visual and the auditory mind-reading tasks.

Methods: The participants consisted of 28 male adolescents and adults with PDD (mean age =24.5yrs, SD=7.7, range=16yrs-45yrs).  They were divided into two groups: HFA group(n=17, FIQ=103.2, VIQ=103.9, PIQ=100.3, AQ33.3) and the other PDD group(n=11, FIQ=108.2, VIQ=109.4, PIQ=106.5, AQ34.3). The control group consisted of 50 male students recruited from Chiba University (mean age 21.2 yrs).  The advanced mind-reading tasks that were consisted of 41 video clips (3 seconds~11seconds in length) from the TV drama “Shiroi Kyotou”, a story about malpractice in a famous Japanese medical school.  The tasks were designed to assess the mind-reading ability from either only the visual information (facial expression, gesture, posture) or only the auditory information (non-verbal aspects of speech: pitch/intonation/tone). One visual task and one auditor task were made for each corresponding clip.  A word or a phrase which expressed the mental state was shown along with each video and sound clip.  The participants were asked to judge if each word or phrase was appropriate or not for each scene.  

Results: In order to compare the correct response rates of the visual task and the auditory task among the HFA, the other PDD and the control groups, an ANOVA was performed with the correct response rates as depend variables, group (HFA/other PDD/control) and task(visual/auditory)as independent variables. Although there were significant differences between HFA (Visual=62.4%, Auditory=54.9%) and the other PDD (Visual=71.3%, Auditory=64.9%) in both the Visual and Auditory tasks, there are no differences between the other PDD and the control group (Visual=72.1%, Auditory=66.6%) in both.

Conclusions: The adequate difficult mind-reading tasks can distinguish the HFA from the other PDD.  Clinically, the individuals with HFA may have severer social problems than the individuals with AS or PDD-NOS.