Across three studies, this dissertation evaluates how different influences on visual attention in dynamic scenes develop over infancy and childhood. Features of a visual scene are typically considered either bottom-up (visually salient factors) or top-down (meaningful semantic factors) influences. The first study (Chapter 2) tested whether influences of visual attention developmentally shift from bottom-up to top-down. Attention to visually salient locations and faces was measured across a wide age range and a wide set of video stimuli to operationalize bottom-up and top-down influences. Results indicate that attention does not shift from primarily bottom-up to top-down; attention to salient areas and faces were similar across ages for most stimulus videos. In considering the dynamic nature of attention, the second study (Chapter 3) measured developmental change in attention to hand and hand-object actions. By measuring attention in ways that are sensitive to movement of features in the scene over time, I found age-related increases in looking to hands and hand-object actions. Age differences suggest attention develops by more mature observers increasingly prioritizing meaningful information from moment to moment. The final study (Chapter 4) investigated the role of comprehension of actions while 4-year-olds viewed a video of a person performing a sequence of goal-directed movements. I manipulated children's prior visual experience with a novel action to assess whether comprehension of manual action changes visual attention, hypothesizing that previous experience viewing the action sequence would bolster children's comprehension. However, results showed no differences in attention to hand-object actions regardless of prior visual experience. Influences of visual attention are complex, but refining our perspective and methodological approach is important for characterizing the development of visual attention.

The aim of the dissertation is to investigate how people trade off between expending motor effort and memorization effort when visually exploring in different directions to gather information. Specifically, Chapter 2 studied how the motor effort of eye-head-body movements and memorization difficulty affected the motor-memory trade-off in a copying task. Chapter 3 studied how people adjusted the motor-memory trade-off after repeated practice with the task. Lastly, Chapter 4 studied whether inducing people to test a different strategy led to discovery and later adoption of a more efficient strategy. Each chapter examined both the copying strategies (i.e. the trade-off between using more motor effort versus more memory) and the eye-head-body coordination underlying the task. Results showed that participants expended more motor effort when the eye-head-body movements to make gaze shifts were less effortful and when the information was difficult to remember (Chapter2); participants used more memory after repeated practice with the task (Chapter 3); exposing participants to test a different strategy led them to adopt a memory-based strategy (Chapter 4). Overall, participants coordinated their eyes, head, and body differently according to the task conditions such as angle and external restriction. They also changed the eye-head-body coordination to decrease total motor cost over the course of doing the task. The findings suggested that people are adaptive in trading off between motor effort and use of memory.