Mental Rotation: A High-Level Perceptual Strength of Young ASD Children

Background: Some individuals with autism spectrum disorder (ASD) perform more proficiently in particular low- (e.g. discrimination) and mid-level (e.g. visual search) visual tasks than may be predicted by their general cognitive performance. How these low- and mid-level visual abilities relate to performance in high-level tasks such as pattern manipulation is poorly understood.  

Objectives: We sought to determine whether young ASD children of typical intelligence perform better in a pattern manipulation task, mental rotation, than typically developing children.  

Methods: Mental rotation was measured with the first 10 questions of the “Rotations” part of the modified Purdue Spatial Visualization Test (PSVT:R; Guay, 1977). This test measures an individual’s ability to determine by mental rotation whether three-dimensional shapes, rotated around a particular axis, are identical or different representations of the same object. All participants were recruited from public nursery schools in Kanazawacity (Japan), Kanazawa University Hospital and prefectural hospitals in Toyama (Japan). Eighteen ASD children were included (age: 83.9 months [59 – 111], mean IQ 105 [77 – 145]).They were diagnosed with childhood autism (n = 13), atypical autism (n = 4) or Asperger's syndrome (n = 1) according to the Diagnostic Interview for Social and Communication (DISCO) criteria. Cognitive skills were assessed with the Japanese adaptation of the Kaufman Assessment Battery for Children (K-ABC). Exclusion criteria were an IQ below 70 (i.e., two standard deviations below the mean), hearing loss, or an identified neurological condition other than autism. Eighteen typically developing children (TD; age: 85.9 months [54 - 122], mean IQ 103 [69 - 134]) matched in age, gender and general cognitive ability were included as controls.Written informed consent was obtained prior to enrolment in the study. The Ethics Committee of Kanazawa University Hospital approved themethods and procedures, all of which were in accordance with the Declaration of Helsinki.  

Results: ASD children performed the task with a meanspeed of 11.4 s (4.9 – 18.0) whereas TD children of equivalent intelligence performed the task with a mean speed of 14.8 s (9.0 – 30.3). ASD children performed the task significantly faster than TD children (t = 2.11 P = 0.042). The number of correct responses was similar between the two groups  (mean proportion of correct answers: 0.26 [0 - 0.60] in ASD children and 0.27 [0.1 – 0.7] in TD children).  

Conclusions: These findings replicate and extend those of Soulières et al (2011). ASD children perform mental rotation tasks faster than may be predicted by their general cognitive performances, showing that enhanced perceptual functionning extends beyond pattern detection, to the manipulation of visual patterns.