Interpretation of compound nouns by adolescents with specific language impairment and autism spectrum disorders: An investigation of phenotypic overlap

Abstract

The study aimed to investigate (i) whether adolescents with Specific Language Impairment (SLI) and Autism plus Language Impairment (ALI) experience word-formation difficulties, and (ii) whether these two groups present with a similar language phenotype. The study investigated four groups using a 2 (language status) ×2 (autism status) design; adolescents with SLI (n = 14), ALI (n = 16), Autism Language-Typical (ALT; n = 14), and language matched controls (n = 17), with all groups presenting with typical non-verbal skills. Mean age was 14;10. Comprehension of conventional Noun–Noun lexical compounds (e.g., snowman), synthetic compounds (SCs, e.g., cat chaser), and novel root compounds (RCs, e.g., sheep socks), was assessed using a forced-choice picture selection task. The SLI and ALI participants frequently mis-parsed the SCs, interpreting the first noun as the agent. Those with poorer vocabularies and non-word repetition had greater difficulties. Reaction time (RT) profiles were flatter in the ASD groups, with similar RTs across different compounds. Language difficulties in the SLI and ALI groups extend to word-formation processes; for example, comprehension of SCs. This may reflect difficulties making analogies with stored lexical items. Overall the results support the hypothesis of a phenotypic overlap between SLI and ALI.

Keywords::

• Autism spectrum disorders (ASD)
• developmental language impairment
• adolescents

Acknowledgements

The authors wish to thank Autism Speaks/The National Alliance for Autism Research for their generous funding; the parents/guardians and individuals who participated; and Susie Chandler, Abigail Davison-Jenkins, Ann Ozsivadjian, and Vicky Slonims for their help with assessment. Thanks also to the editor and two anonymous reviewers for their insightful comments.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

Appendix I: Stimuli

• Lexical compounds: sunglasses, raincoat, ice-cream, fruit bowl, sweet jar, flower pot, dog collar, snow man, dog house, apple tree, biscuit tin, butter knife, tea towel, wedding ring, seat belt, picture book, football pitch, tennis court.

• Root compounds: seal man = man–seal hybrid, snail woman = snail–woman hybrid, donkey man = man selling donkey rides, bird woman = woman feeding birds, bull man = man riding bull, aeroplane truck = aeroplane–truck hybrid, cat balloon = balloon shaped like a cat, water lorry = lorry for carrying water, granny lift = stair lift, sand boat = boat which goes on sand, tree woman = woman who lives in tree, pool man = man who fills pools, rubbish woman = female rubbish collector, dog shirt = shirt for dogs, sheep socks = socks for sheep, mouse slippers = mouse-shaped slippers, penguin jumper = jumper with penguin on it, monkey magazine = magazine about monkeys.

• Synthetic compounds: cat chaser, spider eater, crocodile killer, dog hitter, donkey kicker, dog watcher, bear hugger, cat rider, dog lifter, elephant squasher, car puller, robot shooter, truck lifter, bus crusher, granny pusher, police catcher, doctor robber, nurse rescuer.

Appendix II: Examples of the picture stimuli with target pictures on the right

It's a dog house (Lexical compound)

Look at the donkey kicker (Synthetic compound)

He's a seal man (Root compound)