What interests young autistic children? An exploratory study of object exploration and repetitive behavior

Jacques, C., Courchesne, V., Meilleur, A. S., Mineau, S., Ferguson, S. L., Cousineau, D., Labbe, A., Dawson, M., & Mottron, L. (2018). What interests young autistic children? An exploratory study of object exploration and repetitive behavior. PLOS ONE, 13(12), e0209251. https://doi.org/10.1371/journal.pone.0209251

Publication date: 31 Dec 2018 Added to AutiHub: 3 Jul 2026 Type: Article Article language: English

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9
Publication authors identified as autistic
1 / 9 (11.1%)

Abstract

Behaviors characterized as restricted and repetitive (RRBs) in autism manifest in diverse ways, from motor mannerisms to intense interests, and are diagnostically defined as interfering with functioning. A variety of early autism interventions target RRBs as preoccupying young autistic children to the detriment of exploration and learning opportunities. In an exploratory study, we developed a novel stimulating play situation including objects of potential interest to autistic children, then investigated repetitive behaviors and object explorations in 49 autistic and 43 age-matched typical young children (20-69 months). Autistic children displayed significantly increased overall frequency and duration of repetitive behaviors, as well as increased specific repetitive behaviors. However, groups did not significantly differ in frequency and duration of overall object explorations, in number of different objects explored, or in explorations of specific objects. Exploratory analyses found similar or greater exploration of literacy-related objects in autistic compared to typical children. Correlations between repetitive behaviors and object explorations (their frequency and duration) revealed positive, not negative, associations in both groups. Our findings, from a novel situation incorporating potential autistic interests, suggest that RRBs do not necessarily displace exploration and its possibilities for learning in autism.

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Cited references
73
Total cited references integrated for this publication.
Cited references with an identified autistic author
5 / 73 (6.8%)
Cited author occurrences identified as autistic
5 / 470 (1.1%)
Among occurrences linked to AutiHub author records: 5 / 106 (4.7%). Distinct cited authors identified as autistic: 2 / 410 (0.5%).
Cited author occurrences linked to AutiHub author records
106 / 470 (22.6%)
Distinct linked cited authors: 72 / 410 (17.6%)
Linked cited-author occurrences not identified as autistic
101 / 106 (95.3%)
Among linked cited-author occurrences only. Across all cited-author occurrences: 101 / 470 (21.5%). Distinct linked cited authors not identified as autistic: 70 / 72 (97.2%).
2 cited bibliography entries could not be fully enriched from DOI metadata.
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  1. Eva Troyb , Kelley Knoch , Lauren Herlihy , Michael C. Stevens , Chi-Ming Chen , Marianne Barton et al. (2016). Restricted and Repetitive Behaviors as Predictors of Outcome in Autism Spectrum Disorders . Journal of Autism and Developmental Disorders, 46(4), 1282-1296. Springer Science and Business Media LLC.
    Crossref OpenAlex OpenCitations
  2. Katherine Gotham , Susan Risi , Andrew Pickles , Catherine Lord (2007). The Autism Diagnostic Observation Schedule: Revised Algorithms for Improved Diagnostic Validity . Journal of Autism and Developmental Disorders, 37(4), 613-627. Springer Science and Business Media LLC.
    Crossref OpenAlex OpenCitations
  3. Noah J. Sasson , Jed T. Elison , Lauren M. Turner-Brown , Gabriel S. Dichter , James W. Bodfish (2011). Brief Report: Circumscribed Attention in Young Children with Autism . Journal of Autism and Developmental Disorders, 41(2), 242-247. Springer Science and Business Media LLC.
    Crossref OpenAlex OpenCitations
  4. John McEachin , Ron Leaf (1999). A Work in Progress: Behavior Management Strategies and a Curriculum for Intensive Behavioral Treatment of Autism .
    Type: Book OpenAlex: https://openalex.org/W567754130
    OpenAlex
  5. (2013). Diagnostic and statistical manual of mental disorders (DSM-5): American Psychiatric Association .
    Type: Other
    Crossref
  6. Ivy Y. K. Cho , Kristina Jelinkova , Manuela Schuetze , Sarah A. Vinette , Sarah Rahman , Adam W. McCrimmon et al. (2017). Circumscribed interests in adolescents with Autism Spectrum Disorder: A look beyond trains, planes, and clocks . PLOS ONE, 12(11), e0187414. Public Library of Science (PLoS).
    Crossref OpenAlex OpenCitations
  7. Donald F. Sandner , Lorna Selfe (1978). Nadia: A Case of Extraordinary Drawing Ability in an Autistic Child .
    Type: Book OpenAlex: https://openalex.org/W575207171
    OpenAlex
  8. Kristen S. L. Lam , Michael G. Aman (2007). The Repetitive Behavior Scale-Revised: Independent Validation in Individuals with Autism Spectrum Disorders . Journal of Autism and Developmental Disorders, 37(5), 855-866. Springer Science and Business Media LLC.
    Crossref OpenAlex OpenCitations
  9. Sally J. Rogers , Géraldine Dawson (2009). Early Start Denver Model for Young Children with Autism: Promoting Language, Learning, and Engagement .
    Type: Book OpenAlex: https://openalex.org/W1510017934
    Crossref OpenAlex
  10. Jennifer Richler , Marisela Huerta , Somer Bishop , Catherine Lord (2010). Developmental trajectories of restricted and repetitive behaviors and interests in children with autism spectrum disorders . Development and Psychopathology, 22(1), 55-69. Cambridge University Press (CUP).
    Crossref OpenAlex OpenCitations
  11. Andrea S. Mcduffie , Rebecca G. Lieberman , Paul J. Yoder (2012). Object interest in autism spectrum disorder: A treatment comparison . Autism, 16(4), 398-405. SAGE Publications.
    Crossref OpenAlex OpenCitations
  12. Emma Williams , Vasudevi Reddy , Alan Costall (2001). Taking a Closer Look at Functional Play in Children with Autism . Journal of Autism and Developmental Disorders, 31(1), 67-77. Springer Science and Business Media LLC.
    Crossref OpenAlex
  13. Anna R. Hodgson , Victoria Grahame , Deborah Garland , Fiona Gaultier , Jan Lecouturier , Ann Le Couteur (2018). Parents’ Opinions about an Intervention to Manage Repetitive Behaviours in Young Children with Autism Spectrum Disorder: A Qualitative Study . Journal of Applied Research in Intellectual Disabilities, 31(S2), 165-178. Wiley.
    Crossref OpenAlex OpenCitations
  14. Rebecca MacDonald , Gina Green , Renee Mansfield , Amy Geckeler , Nicole Gardenier , Jennifer Anderson et al. (2007). Stereotypy in young children with autism and typically developing children . Research in Developmental Disabilities, 28(3), 266-277. Elsevier BV.
    Crossref OpenAlex OpenCitations
  15. Eva Troyb , Alyssa Orinstein , Katherine Tyson , Inge‐Marie Eigsti , Letitia Naigles , Deborah Fein (2014). Restricted and Repetitive Behaviors in Individuals with a History of ASDs Who Have Achieved Optimal Outcomes . Journal of Autism and Developmental Disorders, 44(12), 3168-3184. Springer Science and Business Media LLC.
    Crossref OpenAlex OpenCitations
  16. Natacha Akshoomoff (2006). Use of the Mullen Scales of Early Learning for the Assessment of Young Children with Autism Spectrum Disorders . Child Neuropsychology, 12(4-5), 269-277. Informa UK Limited.
    Crossref OpenAlex OpenCitations
  17. So Hyun Kim , Catherine Lord (2010). Restricted and repetitive behaviors in toddlers and preschoolers with autism spectrum disorders based on the Autism Diagnostic Observation Schedule (ADOS) . Autism Research, 3(4), 162-173. Wiley.
    Type: Article DOI: 10.1002/aur.142 OpenAlex: https://openalex.org/W2083559833
    Crossref OpenAlex OpenCitations
  18. Clare Harrop , Clare Harrop , Helen McConachie , Kathy Leadbitter , Kathy Leadbitter , Jonathan Green (2014). Restricted and Repetitive Behaviors in Autism Spectrum Disorders and Typical Development: Cross-Sectional and Longitudinal Comparisons . Journal of Autism and Developmental Disorders, 44(5), 1207-1219. Springer Science and Business Media LLC.
    Crossref OpenAlex OpenCitations
  19. Karen Pierce , Eric Courchesne (2001). Evidence for a cerebellar role in reduced exploration and stereotyped behavior in autism . Biological Psychiatry, 49(8), 655-664. Elsevier BV.
    Crossref OpenAlex OpenCitations
  20. Laurent Mottron , Michelle Dawson *Autistic author. Learn more… , Isabelle Soulières (2009). Enhanced perception in savant syndrome: patterns, structure and creativity . Philosophical Transactions of the Royal Society B: Biological Sciences, 364(1522), 1385-1391. The Royal Society.
    AutiHub · Autistic Scholars Crossref OpenAlex OpenCitations
  21. Michelle Turner (1999). Annotation: Repetitive Behaviour in Autism: A Review of Psychological Research . Journal of Child Psychology and Psychiatry, 40(6), 839-849. Wiley.
    Crossref OpenAlex OpenCitations
  22. Tony Charman , Eva Loth , Julian Tillmann , Daisy Crawley , Caroline Wooldridge , David Goyard et al. (2017). The EU-AIMS Longitudinal European Autism Project (LEAP): clinical characterisation . Molecular Autism, 8(1), 27. Springer Science and Business Media LLC.
    Crossref OpenAlex OpenCitations
  23. Judy S. DeLoache , Gabrielle Simcock , Suzanne Macari (2007). Planes, trains, automobiles--and tea sets: Extremely intense interests in very young children. Developmental Psychology, 43(6), 1579-1586. American Psychological Association (APA).
    Crossref OpenAlex OpenCitations
  24. Kyle M. Frost , Natalie Hong , Catherine Lord (2017). Correlates of Adaptive Functioning in Minimally Verbal Children With Autism Spectrum Disorder . American Journal on Intellectual and Developmental Disabilities, 122(1), 1-10. Informa UK Limited.
    Crossref OpenAlex OpenCitations
  25. Grace T. Baranek , Brian A. Boyd , Michele D. Poe , Fabian J. David , Linda R. Watson (2007). Hyperresponsive Sensory Patterns in Young Children With Autism, Developmental Delay, and Typical Development . American Journal on Mental Retardation, 112(4), 233. Informa UK Limited.
    Crossref OpenAlex OpenCitations
  26. Jonathan Green , Tony Charman , Helen McConachie , Catherine Aldred , Vicky Slonims , Patricia Howlin et al. (2010). Parent-mediated communication-focused treatment in children with autism (PACT): a randomised controlled trial . The Lancet, 375(9732), 2152-2160. Elsevier BV.
    Crossref OpenAlex OpenCitations
  27. Somer Bishop , Jennifer Richler , Catherine Lord (2006). Association Between Restricted and Repetitive Behaviors and Nonverbal IQ in Children with Autism Spectrum Disorders . Child Neuropsychology, 12(4-5), 247-267. Informa UK Limited.
    Crossref OpenAlex OpenCitations
  28. Victoria Grahame , Denise Brett , Linda Dixon , Helen McConachie , Jessica Lowry , Jacqui Rodgers et al. (2015). Managing Repetitive Behaviours in Young Children with Autism Spectrum Disorder (ASD): Pilot Randomised Controlled Trial of a New Parent Group Intervention . Journal of Autism and Developmental Disorders, 45(10), 3168-3182. Springer Science and Business Media LLC.
    Crossref OpenAlex OpenCitations
  29. Somer Bishop , Vanessa Hus , Amie Duncan , Marisela Huerta , Katherine Gotham , Andrew Pickles et al. (2013). Subcategories of Restricted and Repetitive Behaviors in Children with Autism Spectrum Disorders . Journal of Autism and Developmental Disorders, 43(6), 1287-1297. Springer Science and Business Media LLC.
    Crossref OpenAlex OpenCitations
  30. Cornelia Taylor Bruckner , Paul Yoder (2007). Restricted object use in young children with autism . Autism, 11(2), 161-171. SAGE Publications.
    Crossref OpenAlex OpenCitations
  31. Ericka L. Wodka , Pamela Mathy , Luther Kalb (2013). Predictors of Phrase and Fluent Speech in Children With Autism and Severe Language Delay . Pediatrics, 131(4), e1128-e1134. American Academy of Pediatrics (AAP).
    Crossref OpenAlex OpenCitations
  32. Owen E. Parsons , Andrew P. Bayliss , Anna Remington (2017). A few of my favorite things: circumscribed interests in autism are not accompanied by increased attentional salience on a personalized selective attention task . Molecular Autism, 8(1), 20. Springer Science and Business Media LLC.
    Crossref OpenAlex OpenCitations
  33. Patricia Howlin (2011). Early Start Denver Model for Young Children with Autism: Promoting Language, Learning, and Engagement . Child and Adolescent Mental Health, 16(2), 128-128. Wiley.
    OpenAlex
  34. Amy M. Wetherby , Whitney Guthrie , Juliann Woods , Christopher Schatschneider , Renee D. Holland , Lindee Morgan et al. (2014). Parent-Implemented Social Intervention for Toddlers With Autism: An RCT . Pediatrics, 134(6), 1084-1093. American Academy of Pediatrics (AAP).
    Crossref OpenAlex OpenCitations
  35. Juhi R. Kaboski , Joshua John Diehl , Jane Beriont , Charles R. Crowell , Michael Villano , Kristin Wier et al. (2015). Brief Report: A Pilot Summer Robotics Camp to Reduce Social Anxiety and Improve Social/Vocational Skills in Adolescents with ASD . Journal of Autism and Developmental Disorders, 45(12), 3862-3869. Springer Science and Business Media LLC.
    Crossref OpenAlex OpenCitations
  36. Clare Harrop , Amanda Gulsrud , Wendy Shih , Lilit Hovsepyan , Connie Kasari (2017). The impact of caregiver‐mediated JASPER on child restricted and repetitive behaviors and caregiver responses . Autism Research, 10(5), 983-992. Wiley.
    Type: Article DOI: 10.1002/aur.1732 OpenAlex: https://openalex.org/W2559402744
    Crossref OpenAlex OpenCitations
  37. Grace T. Baranek , Linda R. Watson , Brian A. Boyd , Michele D. Poe , Fabian J. David , Lorin McGuire (2013). Hyporesponsiveness to social and nonsocial sensory stimuli in children with autism, children with developmental delays, and typically developing children . Development and Psychopathology, 25(2), 307-320. Cambridge University Press (CUP).
    Crossref OpenAlex OpenCitations
  38. Zoe Vinen , Megan Clark , Jessica Paynter , Cheryl Dissanayake (2018). School Age Outcomes of Children with Autism Spectrum Disorder Who Received Community-Based Early Interventions . Journal of Autism and Developmental Disorders, 48(5), 1673-1683. Springer Science and Business Media LLC.
    Crossref OpenAlex OpenCitations
  39. Susan Leekam , Margot R. Prior , Mirko Uljarević (2011). Restricted and repetitive behaviors in autism spectrum disorders: A review of research in the last decade. Psychological Bulletin, 137(4), 562-593. American Psychological Association (APA).
    Type: Article DOI: 10.1037/a0023341 OpenAlex: https://openalex.org/W2009973636
    Crossref OpenAlex OpenCitations
  40. Noah J. Sasson , Emily W. Touchstone (2014). Visual Attention to Competing Social and Object Images by Preschool Children with Autism Spectrum Disorder . Journal of Autism and Developmental Disorders, 44(3), 584-592. Springer Science and Business Media LLC.
    Crossref OpenAlex OpenCitations
  41. Noah J. Sasson , Lauren M. Turner‐Brown , Tia N. Holtzclaw , Kristen S.L. Lam , James W. Bodfish (2008). Children with autism demonstrate circumscribed attention during passive viewing of complex social and nonsocial picture arrays . Autism Research, 1(1), 31-42. Wiley.
    Type: Article DOI: 10.1002/aur.4 OpenAlex: https://openalex.org/W2010392115
    Crossref OpenAlex OpenCitations
  42. Ami Klin , Judith H. Danovitch , Amanda B. Merz , Fred R. Volkmar (2007). Circumscribed Interests in Higher Functioning Individuals with Autism Spectrum Disorders: An Exploratory Study . Research and Practice for Persons with Severe Disabilities, 32(2), 89-100. SAGE Publications.
    Crossref OpenAlex OpenCitations
  43. Amy M. Wetherby , Juliann Woods , Lori Allen , Julie Cleary , Holly Dickinson , Catherine Lord (2004). Early Indicators of Autism Spectrum Disorders in the Second Year of Life . Journal of Autism and Developmental Disorders, 34(5), 473-493. Springer Science and Business Media LLC.
    Crossref OpenAlex OpenCitations
  44. Shulamite A. Green , Leanna Hernandez , Susan Y. Bookheimer , Mirella Dapretto (2016). Salience Network Connectivity in Autism Is Related to Brain and Behavioral Markers of Sensory Overresponsivity . Journal of the American Academy of Child & Adolescent Psychiatry, 55(7), 618-626.e1. Elsevier BV.
    Crossref OpenAlex OpenCitations
  45. Keith Atkin , Marjorie Perlman Lorch (2006). Hyperlexia in a 4-year-old boy with Autistic Spectrum Disorder . Journal of Neurolinguistics, 19(4), 253-269. Elsevier BV.
    Crossref OpenAlex OpenCitations
  46. Sharon Bradley‐Johnson (1997). Mullen Scales of Early Learning . Psychology in the Schools, 34(4), 379-382.
    Type: Article DOI: 10.1002/(sici)1520-6807(199710)34:4 OpenAlex: https://openalex.org/W2037716870 Crossref: not found DataCite: not found
    OpenAlex
  47. Nadim Nachar (2008). The Mann-Whitney U: A Test for Assessing Whether Two Independent Samples Come from the Same Distribution . Tutorials in Quantitative Methods for Psychology, 4(1), 13-20. The Quantitative Methods for Psychology.
    Crossref OpenAlex OpenCitations
  48. Alvin Loh , Teesta Soman , Jessica Brian , Susan E. Bryson , Wendy Roberts , Péter Szatmári et al. (2007). Stereotyped Motor Behaviors Associated with Autism in High-risk Infants: A Pilot Videotape Analysis of a Sibling Sample . Journal of Autism and Developmental Disorders, 37(1), 25-36. Springer Science and Business Media LLC.
    Crossref OpenAlex OpenCitations
  49. Elizabeth C. Bacon , Eric Courchesne , Cynthia Carter Barnes , Debra Cha , Sunny Pence , Laura Schreibman et al. (2018). Rethinking the idea of late autism spectrum disorder onset . Development and Psychopathology, 30(2), 553-569. Cambridge University Press (CUP).
    Crossref OpenAlex OpenCitations
  50. Richard A. Armstrong (2014). When to use the B onferroni correction . Ophthalmic and Physiological Optics, 34(5), 502-508. Springer Science and Business Media LLC.
    Crossref OpenAlex OpenCitations
  51. Lauren M. Turner-Brown , Kristen S.L. Lam , Tia N. Holtzclaw , Gabriel S. Dichter , James W. Bodfish (2011). Phenomenology and measurement of circumscribed interests in autism spectrum disorders . Autism, 15(4), 437-456. SAGE Publications.
    Crossref OpenAlex OpenCitations
  52. Sylvie Goldman , CUILING WANG , MIRAN W SALGADO , PAUL E GREENE , MIMI KIM , ISABELLE RAPIN (2009). Motor stereotypies in children with autism and other developmental disorders . Developmental Medicine & Child Neurology, 51(1), 30-38. Wiley.
    Crossref OpenAlex OpenCitations
  53. EM Mullen (1995). Mullen scales of early learning . Mullen scales of early learning.
    Type: Other
    Crossref
  54. Zsuzsa Kaldy , Catherine Kraper , Alice S. Carter , Erik Blaser (2011). Toddlers with Autism Spectrum Disorder are more successful at visual search than typically developing toddlers . Developmental Science, 14(5), 980-988. Wiley.
    Crossref OpenAlex OpenCitations
  55. Kyle Sterrett , Maira Tafolla Magaña , Amanda Gulsrud , Tanya Paparella , Connie Kasari (2023). Predictors of Attrition in a Randomized Trial of a Social Communication Intervention for Infant-Toddlers at Risk for Autism . Journal of Autism and Developmental Disorders, 53(8), 3023-3033. Springer Science and Business Media LLC.
    OpenCitations
  56. Géraldine Dawson (2008). Early behavioral intervention, brain plasticity, and the prevention of autism spectrum disorder . Development and Psychopathology, 20(3), 775-803. Cambridge University Press (CUP).
    Crossref OpenAlex OpenCitations
  57. Mary Hanley , Mariam Khairat , Korey Taylor , Rachel Wilson , Rachel Cole-Fletcher , Deborah M. Riby (2017). Classroom displays—Attraction or distraction? Evidence of impact on attention and learning from children with and without autism. Developmental Psychology, 53(7), 1265-1275. American Psychological Association (APA).
    Crossref OpenAlex OpenCitations
  58. Sally Ozonoff , Suzanne Macari , Gregory S. Young , Stacy Goldring , Meagan Thompson , Sally J. Rogers (2008). Atypical object exploration at 12 months of age is associated with autism in a prospective sample . Autism, 12(5), 457-472. SAGE Publications.
    Crossref OpenAlex OpenCitations
  59. Lauren Bishop-Fitzpatrick , Nancy J. Minshew , Carla A. Mazefsky , Shaun M. Eack (2017). Perception of Life as Stressful, Not Biological Response to Stress, is Associated with Greater Social Disability in Adults with Autism Spectrum Disorder . Journal of Autism and Developmental Disorders, 47(1), 1-16. Springer Science and Business Media LLC.
    OpenAlex OpenCitations
  60. R Leaf (1999). ref41
    Type: Other
    Crossref
  61. Diane C. Chugani , Harry T. Chugani , Max Wiznitzer , Sumit Parikh , Patricia A. Evans , Robin L. Hansen et al. (2016). Efficacy of Low-Dose Buspirone for Restricted and Repetitive Behavior in Young Children with Autism Spectrum Disorder: A Randomized Trial . The Journal of Pediatrics, 170, 45-53.e4. Elsevier BV.
    Crossref OpenAlex OpenCitations
  62. Frederick T. L. Leong (2008). Diagnostic and Statistical Manual of Mental Disorders(DSM) . Encyclopedia of Counseling. SAGE Publications, Inc..
    OpenAlex
  63. Alexia Ostrolenk , Baudouin Forgeot d’Arc , Patricia Jelenic , Fabienne Samson , Laurent Mottron (2017). Hyperlexia: Systematic review, neurocognitive modelling, and outcome . Neuroscience & Biobehavioral Reviews, 79, 134-149. Elsevier BV.
    Crossref OpenAlex OpenCitations
  64. Dolores Elaine Battle (2013). [NO TITLE AVAILABLE] . CoDAS, 25(2), 190-191. FapUNIFESP (SciELO).
    OpenAlex
  65. Michelle Dawson *Autistic author. Learn more… , Laurent Mottron , Morton Ann Gernsbacher (2008). Learning in Autism . In Learning and memory: A comprehensive reference (pp. 759-772). Elsevier.
  66. (n.d.). O'Brien S, Hanley M, Riby DM, Swettenham J, Remington A. Enhanced Perceptual Capacity in the Classroom: Harnessing Cognitive Strengths to Promote Learning. International Meeting for Autism Research; San Francisco, USA2017.
    Type: Other
    Crossref
  67. LK Miller (1989). Musical savants: Exceptional skill and mental retardation .
    Type: Other
    Crossref
  68. L Selfe (1978). Nadia: A Case of Extraordinary Drawing Ability in an Autistic Child .
    Type: Other
    Crossref
  69. (n.d.). Jacques C, Courchesne V, Mineau S, Cimon Paquet C, Degré-Pelletier J, Pelletier S, et al. Positive, Negative, and Other Emotions in Young Autistic Children: the Importance of Context. International Meeting for Autism Research; San Francisco, USA2017.
    Type: Other
    Crossref
  70. Michelle Dawson *Autistic author. Learn more… (2008). Learning and Memory: A Comprehensive Reference. 2 Cognitive Psychology of Memory .
    Type: Other
    Crossref
  71. (2012). Mullen Scales of Early Learning . SpringerReference. Springer-Verlag.
    OpenAlex