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Read about the latest research published in Psychological Science:

Power Anomalies in Testing Mediation

David A. Kenny and Charles M. Judd
In this article, the authors describe several peculiarities of mediation analysis in which the power for the test of the total effect and the power for the test of the direct effect can be dramatically different than the power for the test of the indirect effect. The authors describe when and why these peculiarities might occur and their implications for interpretation of mediation analyses.

“Top-Down” Effects Where None Should Be Found: The El Greco Fallacy in Perception Research

Chaz Firestone and Brian J. Scholl

Several studies have reported circumstances in which extraperceptual states affect how things look. To determine whether these states influence perception itself, rather than peoples’ judgments and responses, the authors examined the phenomenon in which recalling an unethical act makes a room seem darker. Participants wrote about an unethical or ethical act and then rated the brightness of a room from 1 (low) to 7 (high). A new set of participants performed the same task, but rated the brightness using a scale of seven grayscale patches. The authors posited that an effect on perception of light in the room would also affect perception of the shades of gray in the patches. The finding that participants who recalled unethical deeds reported the room to be darker than did those who recalled ethical deeds using either scale indicates that extraperceptual states do not influence perception itself.

What Does Physical Rotation Reveal About Mental Rotation?

Aaron L. Gardony, Holly A. Taylor, and Tad T. Brunyé

Experiments examining mental rotation have found that the amount of time it takes to determine whether two figures are identical is related to the two figures’ relative angular disparity. The authors examined whether the same effect is seen when a person physically rotates two figures. Participants were asked to determine whether two block figures presented on a three-dimensional screen were identical by rotating one of the figures mentally or rotating it physically using a handheld apparatus. Although mental rotation was faster and less accurate than physical rotation, both produced similar angular-disparity effects, suggesting that mental and physical rotation processes overlap.