Search

The psychological refractory period (PRP) refers to a delay of response times (RT) to the second of two stimuli when these stimuli are presented in rapid succession. If this limitation of rapidly processing the second stimulus contributes to the well-known differences in speed of information processing between individuals with higher and lower mental ability, individuals with lower mental ability should exhibit a more pronounced PRP effect than individuals with higher mental ability. Previous studies on this question, however, yielded inconsistent results. In the present study, we assessed mental ability-related differences in the PRP by measuring lateralized readiness potentials (LRPs) to separate premotor and motor aspects of speed of information processing in 95 individuals with higher and 95 individuals with lower mental ability. Although individuals with higher mental ability processed information faster than individuals with lower mental ability as indicated by shorter RTs and shorter premotor LRP latencies, the PRP effect was equally pronounced in both groups. These findings suggest that the processes underlying the PRP effect do not contribute to mental ability-related differences in speed of information processing. Rather, these differences seem to occur at an earlier stage of information processing such as stimulus encoding, stimulus analysis, or stimulus evaluation.

The present study was designed to explore extraversion-related differences in the psychological refractory period (PRP). PRP refers to a bottleneck of information processing that becomes evident when participants are required to respond to two signals (S1 and S2) presented in rapid succession. If this capacity limit of premotor information processing is essential for differences in speed of information processing between introverts and extraverts, magnitude of the PRP effect should vary as a function of extraversion. Due to the failure of previous attempts to establish extraversion-related differences in the PRP effect, we also obtained lateralized readiness potentials (LRPs). For this purpose, 63 introverted and 63 extraverted female participants were tested with a standard PRP design. Extraverts responded faster to S2 and exhibited shorter stimulus-locked LRP latencies compared to introverts. Although a general PRP effect could be shown at the behavioral and psychophysiological level, there was no indication for any extraversion-related differences in PRP. Thus, extraversion-related differences in speed of information processing at the premotor level appear unlikely to originate from individual differences in the capacity limits underlying the PRP phenomenon. Furthermore, our findings provide converging evidence for the notion that extraversion-related individual differences in processing speed depend on specific task demands.

Objectives: We sought to test whether myocardial blood flow (MBF) can be quantified by myocardial contrast echocardiography (MCE) using a volumetric model of ultrasound contrast agent (UCA) kinetic...

A newly designed thin-layer STM (TLSTM) technique is presented based on a microfabricated probe combining an electrolytic STM probe with an annular iridium oxide microelectrode operating as a potential-controlled generator or scavenger of H+. This TLSTM configuration can be used to combine in situ STM studies of electrode processes with the simultaneous investigation of H+ flux integrals associated with the electrode reaction. In this paper, the technique is applied to investigate the H+ exchange behaviour of electropolymerised polyaniline films and associated STM-relevant properties in 0.5 M NaClO4 + 10-2 M HClO4. For a polyaniline film kept in the intermediate (emeraldine) oxidation state at 0 mV versus MSE it is shown that its thickness increases due to H+ insertion if the pH is lowered from pH 2 to ca. 1.6, and that its conductivity decreases significantly if the pH is increased from 2 to ca. 12. In a second experiment, where the exchange of H+ at pH 2 is monitored during film oxidation and reduction within the potential range of both redox transfer steps, it is shown that significant exchange of H+ occurs only in the interval of the second (emeraldine/pernigraniline) redox transfer. © 2001 Elsevier Science Ltd. All rights reserved.

Analysis of air trapped in polar ice provides the most direct information on the natural variability of Greenhouse Trace Gases (GTG). It gives the context for the dramatic change in their atmospheric concentrations induced by anthropogenic activities over the last 200 yr, leading to present-day levels which have been unprecedented over the last 400,000 yr. The GTG ice record also provides insight into the processes generally involved in the interplay between these trace gases and the climate and in particular those which are likely to take place in the next centuries in terms of climate changes and climate feedbacks on ecosystems. The paper gives selected examples of the GTG record, taken during different climatic periods in the past, and illustrating what we can learn in terms of processes.

A novel scanning probe allowing STM measurements in electrolytic thin layer conditions was fabricated by achieving electrochemical metal growth in photostructurable glass. The concept of this new scanning probe is explained, then the fabrication process is described in detail and first results are presented.