Date of Graduation

Spring 2024


Master of Science in Psychology



Committee Chair

Dana Paliliunas


Studies have documented floor effects and low intelligence quotient (IQ) scores for individuals with autism spectrum disorder (ASD). Conventional IQ tests may be inadequate in assessing cognitive ability for this population given the associated differences in language and communication in autism. Utilizing nonverbal IQ tests may address these concerns and provide a more accurate representation of ability. Studies have shown utility in using nonverbal IQ tests for this group. This study examined the relationship between measures of cognitive ability in children with autism. The Primary Test of Nonverbal Intelligence (PTONI; Ehrler & McGhee, 2008) was used as a measure of cognitive ability, nonverbally, and the Promoting the Emergence of Advanced Knowledge (PEAK) Comprehensive Assessment (PCA; Dixon, 2019) was used to measure cognitive and language ability linked to participants’ applied behavior analysis (ABA) curriculum. Participants were between the ages of 3 and 16, diagnosed with ASD, and received services as participating ABA clinics. Primary findings demonstrate a strong positive correlation between PTONI raw scores and PCA total raw scores, r(16)=.95, pr(16)=.48, p=.06. This study contributes to gaps in literature by comparing a nonverbal IQ test to PEAK, using the PTONI as a primary measure, and general psychometric research examining cognitive ability for this group. Additional implications suggest the utility of nonverbal IQ tests to measure ability and treatment progress for individuals with autism. Future research may attend to project limitations and expand the scope of the present study.


nonverbal intelligence, cognitive ability, autism, PTONI, PCA, PEAK

Subject Categories

Applied Behavior Analysis | Clinical Psychology | Cognitive Psychology


© Paige Hemming

Available for download on Saturday, May 01, 2027

Open Access