The Role of Dorsal Stream Development in Form and Motion Coherence and Object Recognition: The Childhood Challenge of Processing Transient Events

Abstract

The Magnocellular Advantage model of the visual system was used to investigate the impact of differential timing of the development of the dorsal and ventral visual streams in children in comparison to adults. Specifically, it was aimed to determine how attention to, and the processing of, form and motion coherence and object information differs across ages as dorsally-driven, bottom-up attention mechanisms mature. Typically developing Younger Children (4-7 yrs), Older Children (10-13 yrs) and Adults (18-30 yrs) (N = 110) completed custom computerised motion and form coherence tasks and an object recognition contrast-sensitivity task designed to provide a functional measure of dorsal/ventral pathway performance. Both abrupt and ramped contrast onset/offset conditions were used. Whilst both conditions required ventral stream related object processing, the abrupt task has previously been shown to be related to better dorsal stream functioning. Thus the difference between ramped and abrupt threshold scores was deemed to indicate an advantage in processing transient information. No difference between age groups was seen on the form coherence task, except for the easiest condition. A significant improvement in performance was seen between younger children and older groups on the motion coherence task. Adults performed better than children on the object recognition tasks, whilst older children showed greater performance in processing in abrupt versus ramped conditions, in comparison to younger children. These psychophysical findings provide further support for a delay in the maturation of the dorsal pathway, in comparison to the ventral pathway. Further, they demonstrate that there is a measureable effect of this difference in maturation on the ability of children to direct attention to the processing of transient information. This suggests that young children may rely more on ventral stream visual processing for the perception of transient events, compared with older children and adults who utilize the dorsal stream to direct transient attention.

Meeting abstract presented at VSS 2012