Mental rotation of random lined figures

The present study investigated the possible occurrence of mental rotation in judgments of whether pairs of line figures were identical. The feasibility of two discrete cognitive explanations based on holistic transformation and on feature computation was examined with varied levels of complexity controlled by the numbers of lines in a figure. In the experiment, participants were required to judge whether simultaneously presented pairs of figures were the same or different. When the participants' data were collapsed for regression analyses, evidence for mental rotation was not detected at any level of complexity, but reanalysis of the data revealed that some participants employed mental rotation in the cognition of complex figures. A monotonous increase in reaction times as a function of the number of lines was evident in identical pairs of figures but not in nonidentical pairs. It is argued that the feature computation explanation would better account for these results than would the holistic transformation explanation.