Representational momentum is a positive memory distortion for an object's final position following the presentation of an implied event (J.J. Freyd, 1987). Positive memory distortions occur when observers accept test positions beyond the final presented position, or forward along the implied trajectory, as the same more readily than positions behind the final position. Four experiments explored implied events depicting rotations about various depth axes in shaded and silhouette conditions. Positive memory distortions were observed for all depth rotations under certain shading conditions, with some differences in the size of the distortion between axes. No directional effects (e.g., right vs. left) were observed. The overall positive memory distortions observed for depth rotations contrasted with the negative distortions previously observed for translation motion in depth (T.L. Hubbard, 1995 ).

Two experiments explored a possible relationship between mental rotation and representational momentum, a task in which participants were asked to remember an object's position following a sequence of images implying motion. Typically, participants misremember the position as distorted forward along the implied trajectory. If representational momentum relies on mental imagery, the magnitude of memory distortion in a representational momentum task should be positively correlated with the rate of mental rotation. As predicted, faster mental rotation rates and larger memory distortions for object position were observed for rotational axes aligned with the viewers' coordinate system. In addition, participants with slower mental rotation rates produced smaller memory distortions in the implied-event task.

This study investigated the possibility of sex differences in spatial frequency processing by measuring contrast sensitivity and reaction time to spatial frequency in the same 20 men and 20 women. This is the first study to investigate sex differences in reaction time to spatial frequency and the first to study sex differences in contrast sensitivity and reaction time within the same participants. No sex differences were found in either contrast sensitivity or reaction time measures, suggesting that women and men process spatial frequency information similarly.

This study investigated the possibility of sex differences in spatial frequency processing by measuring contrast sensitivity and reaction time to spatial frequency in the same 20 men and 20 women. This is the first study to investigate sex differences in reaction time to spatial frequency and the first to study sex differences in contrast sensitivity and reaction time within the same participants. No sex differences were found in either contrast sensitivity or reaction time measures, suggesting that women and men process spatial frequency information similarly.

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