In addition to these primary goals, we created a custom-built apparatus, the shutter window (see
Fig. 1A), to control stimuli presentation time. Experiment 1 used two different shutter devices to control
stimuli presentation time in both the perceptual classification and grasping tasks. Half of the participants
used the well-established PLATO (portable liquid crystal apparatus for tachistoscopic
occlusion) goggles (Milgram, 1987), and the other half used the shutter window. This procedure
was necessary because all children in Experiment 2 used the shutter window for practical reasons
(i.e., the PLATO goggles are uncomfortable and restrain and distract children). Therefore, we analyzed
whether performance in the shutter window condition is comparable to performance in the PLATO
goggles condition