Morpholexical Processes in Children with Autism Spectrum Disorder: Evidence from Artificial Word Learning

Objectives: This study aims to investigate the ability of high-functioning children with autism spectrum disorder and normal language (ALN) to learn artificial words, and to investigate their ability to use their knowledge of morphophonological patterns for this learning. Methods: Children with ALN and typically developing (TD) children, matched for cognitive and language measures, learned 8 artificial Hebrew words during two daily practice sessions by means of identification and naming tasks. Half the words were constructed from existing morphophonological patterns, and the other half were constructed from pseudo-morphophonological patterns. The two types of words allowed the investigation of the participants' ability to use their knowledge of morphophonological patterns (morpholexical processes) for word learning. Both accuracy and speed were measured. Results: The ALN group improved incrementally at a rate (slope) similar to that of the TD group in identifying and naming the artificial words, in both accuracy and speed. However, the ALN group were slower than their TD peers in learning to identify the artificial words. Both groups demonstrated higher accuracy and faster speed in both tasks in learning the artificial words with existing morphophonological patterns than those with pseudo-patterns. However, this gap was smaller in the ALN group in the accuracy of naming and marginal in speed of identification. Conclusions: Children with ALN possess a lexical learning mechanism that is qualitatively not atypical but may be less efficient than that of their TD peers, including exploiting knowledge of morphophonological patterns - where such patterns exist - for word learning.