Active vision in passive locomotion: real-world free viewing in infants and adults.

Visual exploration in infants and adults has been studied using two very different paradigms: free viewing of flat screen displays in desk-mounted eye-tracking studies and real-world visual guidance of action in head-mounted eye-tracking studies. To test whether classic findings from screen-based studies generalize to real-world visual exploration and to compare natural visual exploration in infants and adults, we tested observers in a new paradigm that combines critical aspects of both previous techniques: free viewing during real-world visual exploration. Mothers and their 9-month-old infants wore head-mounted eye trackers while mothers carried their infants in a forward-facing infant carrier through a series of indoor hallways. Demands for visual guidance of action were minimal in mothers and absent for infants, so both engaged in free viewing while moving through the environment. Similar to screen-based studies, during free viewing in the real world low-level saliency was related to gaze direction. In contrast to screen-based studies, only infants - not adults - were biased to look at people, participants of both ages did not show a classic center bias, and mothers and infants did not display high levels of inter-observer consistency. Results indicate that several aspects of visual exploration of a flat screen display do not generalize to visual exploration in the real world.