Confidence level and feeling of knowing for episodic and semantic memory: an investigation of lorazepam effects on metamemory.

The effects of lorazepam (0.026 or 0.038 mg/kg), a benzodiazepine, and of a placebo on metamemory, i.e. knowledge about one's own memory capabilities, were investigated in 36 healthy volunteers. Accuracy of confidence levels (CL) in the correctness of recalled answers and accuracy of feeling of knowing (FOK) the answers when recall fails were measured using a sentence memory task assessing episodic memory and a task consisting of general information questions and assessing semantic memory. Lorazepam impaired episodic memory. Unexpectedly, it also impaired performance in both the recall and recognition phases of the task assessing semantic memory, suggesting that it decreased the ability to distinguish between correct and incorrect information. In episodic memory, lorazepam 0.038 mg/kg-treated subjects exhibited an impaired CL accuracy, compared to placebo-treated subjects, and their FOK accuracy was at chance. In semantic memory, their overall CL and FOK accuracy was apparently spared. However, these subjects selectively overestimated their CL judgements for incorrect answers; moreover, secondary analyses showed that FOK accuracy for a subset of low-accuracy items was virtually nil. These results suggest that lorazepam impairs metamemory for both episodic and semantic memory.

What does Daneman and Carpenter's reading span really measure?

Reading span was assessed in three conditions aiming at varying the processing demands of a reading task. In a Sentence Reading Condition, the participants read aloud lists of sentences and memorize the final word of each sentence as in the original task of Daneman and Carpenter. In two other conditions, each sentence was replaced either by a series of unrelated words (Word Reading Condition) or by a series of meaningless syllables (Syllable Reading Condition); in these two conditions, however, each series ended with the same test words as in the Sentence Reading Condition. There was no significant effect of the condition on the scores for reading span. It is concluded that the typically low scores on reading span are not so much due to the processing demands of the task as to the disruptive effects of the articulatory suppression which characterizes the original task.

The estimation of 'available lysine' in human foods by three chemical procedures.

Seventeen test foods were each analyzed by four methods. Total lysine was measured by conventional amino acid analysis. Reactive lysine was measured with either fluorodinitrobenzene, o-phthalaldehyde or a differential dye-binding procedure. The results were then compared with another group's results from rat growth assays of the same samples for availably lysine. A sample of deliberately heat-damaged milk powder gave a rat assay value corresponding to 64% of its total lysine content; other values were all higher and on average 99% for 7 animal products, and 87% for 9 vegetable products. The correlation coefficient between the two sets of values was 0.95. The 'reactive lysine' procedures failed to give a better prediction of the rat values.

Immature corn as a source of niacin for rats.

The variability in the concentration and biological availability of niacin in corn was investigated. Plots of both sweet and field corn were harvested at different stages. In rat growth assays for available niacin, grains harvested at the immature, "milky" stage and then dried gave values of 88 and 74 micrograms/g, respectively. These values were in contrast to the low growth assay values of 18 and 16 micrograms/g for grain harvested at maturity, and even higher than the value of approximately 56 micrograms/g obtained for each immature corn in both the Association of Official Analytical Chemists procedure of chemical analysis and a standard microbiological procedure. However, when the milky grains were precooked at neutral pH, the values from these procedures were higher and agreed with the biological assay results. It is suggested that, during the initial alkaline digestion used for these two procedures, a proportion of the niacin in NAD, the major form of niacin in milky corn, degrades. However, when the materials are first cooked at neutral pH, nicotinamide is released without loss, and the pyridine ring is then stable. The traditional American Indian practice of roasting and drying "green corn" apparently provided a valuable source of niacin.

Composition of miner's lettuce (Montia perfoliata).

Miner's lettuce, a wild, edible plant that grows prolifically in the western U.S., was analyzed for proximate composition, vitamins, minerals, and oxalic and phytic acids. In the raw state, it contained 20 kcal per 100 gm, and 33 per cent of the adult U.S. RDA for ascorbic acid, 22 per cent of the vitamin A allowance, and 10 per cent of the iron. Oxalic acid concentration was low. Nutrient density ratios, compared with 100 kcal of the U.S. RDAs, were greater than one for all constituents analyzed. In terms of nutrient content, miner's lettuce also compared favorably with twenty-one other green, leafy vegetables.