Paradoxical effects of nitrous oxide on human memory.

Using the method of adjusted learning, subjects learned number-noun pairs while breathing either placebo or 30% nitrous oxide. Subjects breathing nitrous oxide required more acquisition trials to attain a learning criterion than did subjects breathing placebo. Two weeks later, half of the subjects from each group were administered either placebo or nitrous oxide and were asked to recall the noun that had accompanied each number cue. Results showed that: 1) nitrous oxide inhalation can decrease the accessibility of to-be-recalled material and 2) nitrous oxide administered during the acquisition of material can paradoxically improved the recall of that material 2 weeks later. The additional number of acquisition trials subjects received during nitrous oxide inhalation could potentially account for this paradoxical enhancement of delayed recall; however, correlational analyses suggest this was not the case. No evidence for any state-dependent effects of nitrous oxide on cued recall were found.

Do different metamemory judgments tap the same underlying aspects of memory?

We compared the predictions from several kinds of metamemory judgments (on the same set of items), both in terms of their predictive accuracy and in terms of the commonality of predictions. Undergraduates made judgments about the ease with which they could learn each item in a list (ease-of-learning judgments); then they learned every item, either to a minimal criterion of learning or with overlearning, and made judgments about how well they knew each item (judgments of knowing); finally, they returned 4 weeks later for a retention session and made feeling-of-knowing judgments on every time they could not recall, after which a recognition test assessed predictive accuracy. Ease-of-learning judgments had the least predictive accuracy. Surprisingly, however, the recognition of nonrecalled items was predicted equally well by judgments of knowing (made 4 weeks earlier) as by feeling-of-knowing judgments (made immediately prior to recognition). Moreover, those two kinds of judgments were only weakly correlated with each other, which implies that they do not tap memory in the same way.

Allocation of self-paced study time and the "labor-in-vain effect".

This research explored the possibility that a metacognitive control process (namely, the allocation of self-paced study time) might be affected by the output from metacognitive monitoring processes (i.e., ease-of-learning and/or feeling-of-knowing judgments). In three experiments, university undergraduates received instructions that emphasized either accuracy of learning or speed of learning. The major findings were: (a) ease-of-learning judgments and feeling-of-knowing judgments are reliably related to study-time allocation, with more self-paced study time being allocated to the supposedly more difficult items; (b) even when instructed to master every item and when allowed unlimited study time to do so, people terminate study before learning is completed; and (c) large increases in self-paced study time can yield little or no increase in the subsequent likelihood of recall (the "labor-in-vain effect"). Implications are drawn for a model of the interplay between metacognitive monitoring processes and metacognitive control processes.

Nonsudorific skin potential level: current hypothesis and psychophysiological significance.

Skin potential level has two mechanisms of generation: that due to sweat gland activity (sudorific) and that due to other causes (nonsudorific). These mechanisms have, in the past, been frequently confounded. This paper addresses the importance of discriminating between the two mechanisms and describes two kinds of nonsudorific skin potentials. There is reason to except nonsudorific skin potential level to be an important factor in embryogenesis, tissue regeneration and atypical growth. Early work that associated these potentials with changes in consciousness (e.g., sleep and hypnosis) is inconclusive. The literature concerning physiological and psychological correlates of skin potential levels that have been attributed to nonsudorific mechanisms is reviewed, and the methodological problem of measuring these potentials is considered.

A comparison of three predictors of an individual's memory performance: the individual's feeling of knowing versus the normative feeling of knowing versus base-rate item difficulty.

Distinctions are drawn between different predictors of an individual's memory performance, with emphasis on the notion of privileged access to idiosyncratic knowledge. Research is reported in which undergraduates attempted to recall the answers to general-information questions, then made feeling-of-knowing judgments on nonrecalled items, and subsequently had a criterion test (relearning, perceptual identification, or one of two versions of recognition). For predicting an individual's criterion performance, the individual's own feeling-of-knowing predictions were intermediate between two kinds of normative predictions: The individual's feeling-of-knowing predictions were more accurate than predictions derived from normative feeling-of-knowing ratings but were less accurate than predictions derived from base-rate item difficulty (normative probabilities of correct recall). Subsidiary analyses showed that factors other than unreliability are responsible for the partial inaccuracy of the individual's feeling of knowing. Ramifications are discussed for possible ways to improve the accuracy of an individual's feeling-of-knowing predictions.