Crowded visual search in children with normal vision and children with visual impairment.
This study investigates the influence of oculomotor control, crowding, and attentional factors on visual search in children with normal vision ([NV], n=11), children with visual impairment without nystagmus ([VI-nys], n=11), and children with VI with accompanying nystagmus ([VI+nys], n=26). Exclusion criteria for children with VI were: multiple impairments and visual acuity poorer than 20/400 or better than 20/50. Three search conditions were presented: a row with homogeneous distractors, a matrix with homogeneous distractors, and a matrix with heterogeneous distractors. Element spacing was manipulated in 5 steps from 2 to 32 minutes of arc. Symbols were sized 2 times the threshold acuity to guarantee visibility for the VI groups. During simple row and matrix search with homogeneous distractors children in the VI+nys group were less accurate than children with NV at smaller spacings. Group differences were even more pronounced during matrix search with heterogeneous distractors. Search times were longer in children with VI compared to children with NV. The more extended impairments during serial search reveal greater dependence on oculomotor control during serial compared to parallel search.
Bartiméus, Institute for the Visually Impaired, Zeist, The Netherlands; Behavioural Science Institute, Radboud University Nijmegen, Nijmegen, The Netherlands. Electronic address: b.huurneman@psych.ru.nl.
Bianca
B
Huurneman
Bartiméus, Institute for the Visually Impaired, Zeist, The Netherlands; Department of Developmental Psychology, University of Groningen, Groningen, The Netherlands.
Ralf F A
RF
Cox
Department Brain, Body & Behavior, Philips Research, Eindhoven, The Netherlands.
Björn N S
BN
Vlaskamp
Bartiméus, Institute for the Visually Impaired, Zeist, The Netherlands; Behavioural Science Institute, Radboud University Nijmegen, Nijmegen, The Netherlands; Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
F Nienke
FN
Boonstra
D000704:Analysis of Variance; D001288:Attention / Q000502:physiology*; D016022:Case-Control Studies; D002648:Child; D005133:Eye Movements / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D020417:Nystagmus, Congenital / Q000503:physiopathology*; D010775:Photic Stimulation / Q000379:methods; D012684:Sensory Thresholds / Q000502:physiology; D014786:Vision Disorders / Q000503:physiopathology*; D014792:Visual Acuity / Q000502:physiology
Children; Crowding; Development; Visual impairment; Visual search