Table 1.

Timeline of experiment

	Experimental task
Part 1	Practice trials with regular pen
	Standard horizontal task with regular pen
	Participants performed a horizontal pointing task (Fig. 2a), as in Sirigu et al. (1996), using a regular, non-weighted Sharpie pen (Fig. 1a). Imagery trials preceded execution trials
Part 2a	Tracing and tapping task
	Horizontal task with bottom-heavy or top-heavy tool
	Participants performed the horizontal pointing task (Fig. 2a) using a top-heavy (Fig. 1b) or bottom-heavy tool (Fig. 1c). Half of the participants performed the task first using the top-heavy pen (T); the other half first used the bottom-heavy pen (B). Imagery trials preceded execution trials
Part 2b	Tracing and tapping task
	Horizontal task with other tool
Part 3a	Tracing and tapping task
	Vertical task with bottom-heavy or top-heavy tool
	Participants performed the vertical pointing task (Fig. 2b) using a top-heavy tool (Fig. 1b) or bottom-heavy tool (Fig. 1c). Half of the participants performed the task first using the top-heavy pen (t); the other half first used the bottom-heavy pen (b). Imagery trials preceded execution trials
Part 3b	Tracing and tapping task
	Vertical task with other tool
Part 4	Repeat standard task
	Participants repeated Part 1