A lack of self-consciousness in Asperger's disorder but not in PDDNOS: Implication for the clinical importance of ASD subtypes

Self-consciousness plays an important role in a person's social life. Assuming that self-consciousness is a key to understanding social impairments in high-functioning autism spectrum disorder (ASD), we examined self-consciousness in individuals with Asperger's disorder, pervasive developmental disorder not otherwise specified (PDDNOS) and their controls using an episodic memory task. The PDDNOS group consisted of individuals in a milder subgroup of PDDNOS, with less autistic features than Asperger's disorder. In the learning phase, one of three types of questions (phonological, semantic, self-referential) was asked about each following target word. The target words were all personality trait adjectives. Next, a recognition test was conducted. The PDDNOS group, like the control, showed the most superior performance in self-referential processing (i.e. the self-reference effect) while the Asperger's group did not; however, both the ASD groups revealed an atypical pattern of relationship between memory performance and IQ. Individuals with PDDNOS, unlike those with Asperger's disorder, may be self-conscious to the same degree as typically developing individuals, but the cognitive process leading them to self-consciousness seems atypical, causing social impairments similar to those seen in individuals with Asperger's disorder who lack self-consciousness.