Differences in eye movements might also explain the discrepancy of our results with those of
Schwartz and colleagues (Schwartz, 1999; Schwartz & Black, 1999). In their experiments, adults tilted
the thin glasses farther than wide ones even without visual feedback. However, in their experiments
participants had their eyes closed, whereas in our experiment participants had their eyes open and a
curtain was lowered between the participants and the apparatus. With the eyes closed, it is possible to
simulate smooth pursuit eye movements, whereas with the eyes open and no possibility of visual
tracking, participants probably executed saccades (Lenox, Lange, & Graham, 1970). Alternatively,
the restrictions in our task (tilting in one plane only vs. tilting freely in the air) might account for
the different results. It is possible that our more technical apparatus facilitated a more cognitive
approach