Framing the figure: Mental rotation revisited in light of cognitive strategies.

The mental rotation literature commonly reports a sex difference, almost always favoring men. Two strategies have been proposed in the literature to account for this difference: holistic and piecemeal. However, there is great variability in rotation performance suggesting other possible contributing factors. This study investigated the effects of stimuli characteristics and habitual spatial thinking on mental rotation performance. In three experiments, participants completed a mental rotation task with two modifications: (1) 3-D figures were presented with their cut versions to promote piecemeal strategy, and (2) block figures were either presented within a frame or none, in light of reference framework model or perceptual grouping model. Overall, whole figures generated faster responses than cut figures and this was more pronounced with greater angular disparity. Shape or the presence of a frame affected rotation performance. Having a frame seemed to impede overall rotation, especially for cut figures, supporting an object-based reference frame. However, a 3-D frame did not have the same effect, possibly suggesting the unitary configuration idea. Men rotated more accurately than women, but still sex was not as robust as it was suggested in the literature. Interestingly, there were similarities between possible strategy use and habitual spatial thinking. People who were categorized as having landmark-centered representations and who preferred verbal directions showed a pattern suggesting the use of a piecemeal strategy, and survey-centered representations and map preference seemed to reflect a holistic strategy.

Cyst fluid carcinoembryonic antigen is an accurate diagnostic marker of pancreatic mucinous cysts.

OBJECTIVES: Endoscopic ultrasound (EUS) may offer a diagnostic tool through the combination of imaging and guided fine-needle aspiration of pancreatic cysts. The purpose of this investigation was to determine the most accurate test for differentiating mucinous from nonmucinous cysts. METHODS: The results of EUS imaging, cytology, and cyst fluid biochemical markers were prospectively collected and compared in a large single-center study (776 patients) using histology or malignant cytology as the final diagnostic standard in 198 patients. RESULTS: The mean cyst fluid carcinoembryonic antigen (CEA) was greater in mucinous cysts (4703.0 ng/mL) compared with nonmucinous cysts (25.8 ng/mL) (P = 0.008). When using the optimal cutoff value of 109.9 ng/mL, the CEA was more accurate (86%, receiver operating characteristic area = 0.928) than EUS imaging (48%) and cytology (58%) in predicting a mucinous cyst (P < 0.0001). Malignant cysts had a mean cyst fluid CEA value (2558.2 ng/mL) similar to benign cysts (4700.2 ng/mL). Cytology (75%) more accurately diagnosed malignant cysts than EUS (66%) and CEA (62%) (P < 0.05). CONCLUSIONS: Cyst fluid CEA concentration provides a highly accurate test for the diagnosis of a mucinous cyst, but does not distinguish benign from malignant cysts. Cytology is the most accurate test for the diagnosis of a malignant cyst.