Exploring Children's Optic Flow Sensitivity

Open Access
Author:
Elam, Amanda Lynee
Graduate Program:
Psychology
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
June 13, 2012
Committee Members:
  • Rick Owen Gilmore, Thesis Advisor
Keywords:
  • optic flow
  • visual development
  • steady-state visual evoked potentials
  • EEG
  • global motion
Abstract:
Motion cues are important for successful navigation in an environment. The structured global motion pattern, optic flow, provides a person with speed and direction information about her self-motion. Prior research has shown that, radial (expansion/contraction) optic flow patterns elicit robust evoked potential responses in adults, while responses to rotation and translation (left/right) patterns are weaker. Comparatively, infants show the strongest evoked responses to lateral translation. Previous studies also suggest that adult-like spatial and temporal tuning to global motion develops over a prolonged time period. However, the literature is still lacking a component that connects adult and infant optic flow research and provides a clear trajectory of optic flow sensitivity over time. The current study attempts to provide this missing information. For this study, steady-state visual evoked potential (SSVEP) responses were recorded from children of 4 to 8-years to coherence modulations of three optic flow pattern types (lateral translation, rotation, and radial expansion/contraction) at 3 different speeds (2, 4, and 8 deg/s), using an electrode net of 128 channels. Children viewed moving dot displays (7 amin dots, 79.4 cd/m2, density = 10%) that modulated in time from incoherent to 100% coherent global motion at 1.2 Hz (F1). All displays had the same dot update rate (24 Hz, F2). Overall, responses to coherence modulation were largest for the radial patterns and were tuned for fast speeds. The oldest children were the most adult-like, with weak responses to translation and rotation, but the strongest responses to radial motion. Robust responses to translation were still observed in the youngest children. The results suggest that adult-like sensitivity to optic flow patterns emerges in middle childhood and that there are multiple trajectories associated with the development of optic flow processing.