Understanding the Development of Manual Tool use: Object Structure and Spatial Processes

• In Event: 3-135 - Understanding Spatial Processes: Spatial Behavior in Real Time and in Real-World Settings

Integrative Statement

Many everyday tool use and problem-solving tasks require individuals to plan actions in manual space with respect to an object’s spatial structure. In research on manual tool use in young children, investigators often rely on outcome measures (e.g., whether children succeed, select an appropriate grip). Although these measures indicate when children begin to solve a task, they do not provide direct information about developmental changes in the processes by which they do so. Here, we investigate how spatial behavior unfolds in real time as young children use tools and solve problems. We employ motion-tracking technology to illustrate how a focus on spatial processes in real time can illuminate change over developmental time.

In the first series of studies, we examine the development of hammering. We exploited the dense sampling afforded by motion-tracking technology to describe how the percussive actions of 6- to 15-month-old children with objects (e.g., wooden cubes; Study 1, N=24) and objects attached to handles--which resembled hammers (Study 2, N =20) become spatially efficient. Results indicate that with increasing age, these percussive actions become well suited for instrumental hammering—spatial trajectories become straighter, cover less distance, and are overall more efficient. The addition of a handle to the objects (Study 2), however, delayed advances in spatial efficiency. The findings illustrate how a focus on object structure and spatial dynamics in real time can illuminate how tool use unfolds developmentally.

In a second series of studies, we focused on the process of object fitting, an important element of many everyday tool use tasks. Here, we used motion-tracking technology to examine how young children transport and orient handled objects when fitting the distal end of these objects into a slot. In Study 3, we attached a handle orthogonal to a rod (Figure 1a) and asked 17- to 36-month-old children (N=35) to insert the rod into a tabletop slot--as they held the handle. Motion-tracking results indicated that 30-month-old but not younger children consistently pre-aligned the rod with the slot before it contacted the slot, suggesting that the older children planned their actions with respect to the object’s overall spatial structure.

In Study 4, we added a handle parallel to the rod (Figure 2a) or another handle that was perpendicular to the rod (Figure 2b). A new sample of 18- to 48-month-old children (N=36) was asked to insert the handled object’s distal segment (rod) into a slot. Motion-tracking results indicated that children had more difficulty pre-aligning the rod with the perpendicular than parallel handle. Children did not consistently pre-align the rod attached to the perpendicular handle until 48 months, suggesting that the increased complexity of this object interfered with spatial planning.

Collectively, the reported studies suggest that during the early childhood years, children become increasingly able to use tools efficiently and plan manual behaviors that are geared to an object’s spatial structure. More broadly, the results highlight how a focus on process can illuminate developmental changes in spatial thinking.

Authors

• Wendy P. Jung, Tulane University
  Presenting Author

• Bjoern A. Kahrs, Tulane University
  Non-Presenting Author

• Jeffrey J. Lockman, Tulane University
  Non-Presenting Author