Verbal Fluency in Individuals with Autism Spectrum Disorder

Background:

Previous studies  of lexical organization (Boucher 1988; Turner, 1999;  Dunn, Gomes & Sebastian, 1996; Toichi & Kamio, 2003)  in individuals with Autism Spectrum Disorder (ASD)  using verbal fluency   (i.e., Tell me as animals as you can in a minute), indicate that they are markedly less prototypical than their typical counterparts (e.g., animal → ocelot (autism), versus animal → dog (typical)).

Objectives:

An investigation of verbal fluency, providing participants with a subordinate target (i.e., TREE) will provide information regarding how individuals with ASD organize the lexicon.  We therefore propose the following question.  Do individuals with ASD exhibit different lexical organization as that of their typically developing peers? 

Methods:

Fifteen individuals with ASD (aged 14;0 to 19;2) were compared to the performance of children in two control groups:  16 children with typical language development, including children matched for chronological age (CAM) (aged 15;0 to 19;7), and 16 children with typical language development matched for raw score (VM) on the Peabody Picture Vocabulary Test 4^th Ed (aged 8;1 to 21;10) (Dunn & Dunn, 2007).  Thirty-seven single syllable nouns were presented auditorily to participants.  Participants were instructed to name as many words as possible within a 60 second time frame. Reaction time and response data were collected.

Results:

No significant difference in mean reaction time for the first fluency response was found across all three groups (p > .05). Furthermore, no significant differences were found between the ASD group and two control groups for mean number of responses produced (p > .05). There was a significant main effect, however, for categorization of response type (ASSOCIATED, PERSEVERATION, PROPER NOUN, PHRASE, OTHER) across groups (p < .05). The prototypicality of appropriate responses will be discussed.

Conclusions:

Individuals with ASD produced responses that were generally comparable to their CAM and VM control groups.  They responded to fluency targets with similar reaction times, as well as comparable numbers of responses.  However, individuals with ASD have substantially different word associations (i.e., fewer ASSOCIATED, and increased number of PROPER NOUNS, PHRASES, PERSEVERATIONS, and OTHER responses).   Results support aforementioned work (Boucher 1988; Turner, 1999;   Dunn, Gomes & Sebastian, 1996; Toichi & Kamio, 2003), and have expanded understanding of how the lexicon is organized in individuals with ASD.  These findings support the Executive Functioning Hypothesis for individuals with Autism Spectrum Disorder (Ozonoff, South, & Provencal, 2007).