Table 1.

Summary of notes for trials in the task familiarization and test phases. Each trial was 14 seconds long. See Figure 1 for time course of audio.

Task familiarization phase
Trials	Notes
A1, A2	There was one Same Speaker and one Different speaker trial. For each trial:
	In the first 2 seconds, two animal cartoons appeared silently side-by-side
	At the 2 second mark, one animal made a sound and wiggled
	At the 9 second mark, either the same or different animal makes a sound and wiggled. No ferns descended.
A3, A4	There was one Same Speaker and one Different speaker trial. For each trial:
	In the first 2 seconds, two animals appeared silently side-by-side
	At the 2 second mark, one animal made a sound and wiggled
	At the 9 second mark, ferns descended. Then, either the same or different animal made a sound and wiggled.
A5, A6	There was one Same Speaker and one Different speaker trial. For each trial:
	In the first 2 seconds, two human cartoons appeared silently side-by-side
	At the 2 second mark, one human made a sound and wiggles
	At the 9 second mark, ferns descended. Then, either the same or different human made a sound and wiggled.
Test Phase
Trials	Notes
B1-B4	Each set of four trials had:
B6-B9	Two Same Speaker and one Different speaker trial Two High and two Low talker information trials
B11-B14
	For each trial (see Figure 1): In the first 2 seconds, two human cartoons appeared silently side-by-side At the 2 second mark, one human made a sound. At the 9 second mark, ferns descended. Then, either the same or different human made a sound.
B16-
B19
B5	Across the four animal trials, there were:
B15	Two Same speaker and two Different speaker trialsFor each trial: In the first 2 seconds, two animal cartoons appeared silently side-by-side At the 2 second mark, one animal made a sound. At the 9 second mark, ferns descended. Then, either the same or different animal made a sound.
B20
B10