P2-8: Applications of the Magnocellular Advantage Model: Developmental Aspects of Dorsal Stream Processing

• Published in: i-Perception (London) Vol. 3; no. 9; p. 669
• Main Authors: Murphy, Melanie, Crewther, Sheila G, Laycock, Robin, Goharpey, Nahal, Brown, Alyse, Crewther, David P
• Format: Journal Article
• Language: English
• Published: London, England SAGE Publications 01.10.2012; SAGE Publishing
• ISSN: 2041-6695; 2041-6695
• DOI: 10.1068/if669

Differential timing of the development of the dorsal and ventral visual streams is well accepted, with the latency of the M pathway to V1 not reaching adult levels until 10 years of age (Crewther et al., 1999 Electroencephalography and Clinical Neurophysiology 49 123–128). This could have major consequences for how children perceive and attend to the environment. Thus, how the later development of the dorsal visual stream impacts the transient visual processing abilities in children was investigated within a framework of the Magnocellular Advantage model of the mature visual system. Typically developing participants (N= 110) grouped as Younger Children (4–7 yrs), Older Children (10–13 yrs), and Adults (18–30 yrs) completed a series of customised computer motion and form coherence tasks designed to provide a functional measure of dorsal/ventral pathway performance. Dorsal involvement in a traditionally ventrally dominated object-recognition task was achieved by biasing onset/offset conditions to preferentially stimulate the temporal characteristics of both pathways. Adults performed better than children on all tasks except motion coherence thresholds. A significant improvement in performance was seen between younger children and older groups on dorsal tasks (Motion Coherence and Navon Global Accuracy) but not on all ventral tasks (Form Coherence and Navon Local Exposure Time). Results support earlier psychophysical and electrophysiological investigations indicating that the dorsal stream matures later than the ventral stream. Therefore, in young children the underdeveloped dorsal visual pathway may rely more on slower ventral stream visual processing, which has important implications for the perception and attentional processing of transient events.