Cue quality and criterion setting in recognition memory.

Previous studies on how people set and modify decision criteria in old-new recognition tasks (in which they have to decide whether or not a stimulus was seen in a study phase) have almost exclusively focused on properties of the study items, such as presentation frequency or study list length. In contrast, in the three studies reported here, we manipulated the quality of the test cues in a scene-recognition task, either by degrading through Gaussian blurring (Experiment 1) or by limiting presentation duration (Experiment 2 and 3). In Experiments 1 and 2, degradation of the test cue led to worse old-new discrimination. Most importantly, however, participants were more liberal in their responses to degraded cues (i.e., more likely to call the cue "old"), demonstrating strong within-list, item-by-item, criterion shifts. This liberal response bias toward degraded stimuli came at the cost of increasing the false alarm rate while maintaining a constant hit rate. Experiment 3 replicated Experiment 2 with additional stimulus types (words and faces) but did not provide accuracy feedback to participants. The criterion shifts in Experiment 3 were smaller in magnitude than Experiments 1 and 2 and varied in consistency across stimulus type, suggesting, in line with previous studies, that feedback is important for participants to shift their criteria.

Physiological responses to digestion in low salinity in the crabs Carcinus maenas and Cancer irroratus.

Osmoregulation and digestion are energetically demanding, and crabs that move into low salinity environments to feed must be able to balance the demands of both processes. Achieving this balance may pose greater challenges for weak than for efficient osmoregulators. This study examined the rate of oxygen consumption (MO2) of Carcinus maenas (efficient osmoregulator) and Cancer irroratus (weak osmoregulator) as a function of feeding and hyposaline stress. The MO2 increased 2-fold in both species following feeding. The MO2 increased and remained elevated in fasted crabs during acute hyposaline exposure. When hyposaline stress occurred after feeding, C. maenas responded with an immediate summation of the MO2 associated with feeding and hyposaline stress, whereas C. irroratus reacted with a partial summation of responses in a salinity of 24‰, but were unable to sum responses in 16‰. C. irroratus exhibited longer gut transit times. This may be due to an inability to regulate osmotic water onload as efficiently as C. maenas. Mechanical digestion in crabs can account for a significant portion of SDA, and a short term interruption led to the delay in summation of metabolic demands. Although protein synthesis is reported to account for the majority of SDA, this did not appear to be the case here. Protein synthesis rates were higher in C. irroratus but neither feeding or salinity affected protein synthesis rates of either species which suggests that protein synthesis can continue in low salinity as long as substrates are available.

Innovation for reducing blood culture contamination: initial specimen diversion technique.

We hypothesized that diversion of the first milliliter of venipuncture blood-the initial specimen diversion technique (ISDT)-would eliminate incompletely sterilized fragments of skin from the culture specimen and significantly reduce our blood culture contamination rate (R). We studied our hypothesis prospectively beginning with our control culture (C) definition: one venipuncture with two sequentially obtained specimens, 10 ml each, the first specimen (M1) for aerobic and the second (M2) for anaerobic media. The test ISDT culture (D) was identical, with the exception that each was preceded by diverting a 1-ml sample (DS) from the same venipuncture. During the first of two sequential 9-month periods, we captured D versus C data (n=3,733), where DMXR and CMXR are R for D and C specimens. Our hypothesis predicted DS would divert soiled skin fragments from DM1, and therefore, CM1R would be significantly greater than DM1R. This was confirmed by CM1R (30/1,061 [2.8%]) less DM1R (37/2,672 [1.4%]; P=0.005), which equals 1.4%. For the second 9-month follow-up period, data were compiled for all cultures (n=4,143), where ADMXR is R for all (A) diversion specimens, enabling comparison to test ISDT. Our hypothesis predicted no significant differences for test ISDT versus all ISDT. This was confirmed by DM1R (37/2,672 [1.4%]) versus ADM1R (42/4,143 [1.0%]; P=0.17) and DM2R (21/2,672 [0.80%]) versus ADM2R (39/4,143 [0.94%]; P=0.50). We conclude that our hypothesis is valid: venipuncture needles soil blood culture specimens with unsterilized skin fragments and increase R, and ISDT significantly reduces R from venipuncture-obtained blood culture specimens.

Three- to six-year followup for 379 benign image-guided large-core needle biopsies of nonpalpable breast abnormalities.

BACKGROUND: Determining the negative predictive value of benign large-core needle biopsy of nonpalpable mammographically detected breast abnormalities has been difficult because benign results generally preclude surgical excision. Longterm followup of these patients is important to ensure timely diagnosis of new abnormalities and to identify false negatives. STUDY DESIGN: This cohort study comprised 379 patients, all with benign diagnoses following imaging-guided large-core needle biopsy of nonpalpable mammographically detected abnormalities. Mammographic, clinical, and laboratory records (when appropriate) were reviewed for all patients followed at our institution. For patients followed elsewhere, these data were provided by each patient's current primary-care physician after obtaining written informed consent from the patient. RESULTS: We obtained followup for 312 patients (82.3% of 379), for whom the mean followup period was 55 months; 67 patients were either lost to followup (44, 11.6%), had no followup by patient choice (18, 4.7%), or died of causes other than breast cancer (5, 1.3%). Of these 312 patients, we found only 1 (0.3%) false negative in which a 4-mm lesion was observed to have grown to approximately 11 mm eight months later, and was found to be an infiltrating ductal cancer at rebiopsy. The negative predictive value was calculated as 0.997 (311/312). Analysis of core histologies indicated the followup group was a representative sample. CONCLUSIONS: These data suggest that benign mammographically detected abnormalities can be diagnosed with a high level of confidence using image-guided large-core needle biopsy, and that mammographic or ultrasonographic screening or both at 6 and 12 months might be sufficient before returning the patient to routine screening mammography.