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Assessment of Performance Fields in Children

May 2003. Results. Adults (17-27 yrs.). H:V = 1.3 H:V = 1.4 H:V = 1.3. Visual performance fields (% accuracy) along meridians. 3 Stimulus Conditions. Shapes. N. Letters. E. W. Numbers. Trial sequence. 100%. 100%. 100%. 100%. References. Target. Fixation 500 ms. x. Goal. ISI

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Assessment of Performance Fields in Children

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  1. May 2003 Results Adults (17-27 yrs.) H:V = 1.3H:V = 1.4H:V = 1.3 Visual performance fields (% accuracy) along meridians 3 Stimulus Conditions Shapes N Letters E W Numbers Trial sequence 100% 100% 100% 100% References Target Fixation 500 ms x Goal ISI 500 ms B Display 20-100 ms* Response Introduction Method Assessment of Performance Fields in Children ▪ Our ability to perceive objects is not evenly distributed across our visual field. ▪ Performance field: ▪ 0.5 deg (adults) and 0.8-1.0 deg (children) ShapesLettersNumbers 5 ecc (4-13 deg) 8 meridians Horizontal-vertical anisotropy (HVA) Superior discrimination, detection, and localization along the horizontal than vertical axis Rijsdik et al. 80, Rovamo & Virsu 79 Vertical meridian asymmetry (VMA) Impairment in performance at locations directly above fixation. Children (5-11 yrs.) ▪ 160 (adults) and 80 (children) trials/condition ▪ 4 AFC identification task ▪ 23 adult and 60 children Yun-Xian Ho, Kate S. Mahon & Marisa Carrasco - New York University H:V = 1.2H:V = 1.1H:V = 1.2 ▪ HVA is present in childhood. ▪ HVA becomes more pronounced with age. ▪ There was no impairment in the North locations for either adults and children in this object identification task. Heterogeneities more pronounced with increasing spatial frequency (shown), set size and eccentricity. Carrasco, Talgar & Cameron (2001); Cameron, Tai & Carrasco (2002) HVA and VMA are also present in spatial resolution tasks (e.g. Landolt square, texture) Talgar & Carrasco (2002); Carrasco, Williams & Yeshurun (2002) Future Research… ▪ Would children exhibit any impairment in the North locations with stimulus displays containing higher spatial frequencies, larger set sizes, or lower contrast? ▪ Children’s ability to perceive form: School children aged 4-7 years, exhibit psychophysical form coherence thresholds close to adult values. Braddick et al (2000) • Braddick, OL, Atkinson, J, Curran, W, Wattam-Bell, J, O’Brien J, Anker, S, Newman, C, and Hua, M (2000). ISIS Symposium. • Carrasco, M, Talgar, C, and Cameron, EL (2001). Spatial Vision15(1), 61-75. • Carrasco, M, Williams, P, and Yeshurun, Y (2002). Journal of Vision 2, 467-479. • Previc, FH (1990). Behavioral and Brain Sciences13, 519-575. • Rovamo, J and Virsu, V (1979). Experimental Brain Research20, 495-510. • Rijsdijk, JP, Kroon, JN, and van der Wilt, GJ (1980). Vision Research20, 235-241. • Rubin, N, Nakayama, K, and Shapley, R (1996). Science271, 651-653. • Talgar, C and Carrasco, M (2002). Psychonomic Bulletin & Review 9(4), 714-722. Does the visual performance field change over the course of development? • *Stimulus duration varied for individual observer to maintain mean accuracy of about 70%

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