Structuring temporal sequences: Comparison of models and factors of complexity

Two stages for structuring tone sequences have been distinguished by Povel and Essens (1985). In the first, a mental clock segments a sequence into equal time units (clock model); in the second, intervals are specified in terms of subdivisions of these units. The present findings support the clock model in that it predicts human performance...

Efficient adaptive fuzzy control scheme

The paper presents an adaptive nonlinear (state-) feedback control structure, where the nonlinearities are implemented as smooth fuzzy mappings defined as rule sets. The fine tuning and adaption of the controller is realized by an indirect adaptive scheme, which modifies the parameters of the fuzzy mapping. The performance index gradients are...

Gezondheidsproblemen na ernstige vroeggeboorte: 9 jaar naonderzoek [Health problems after very premature birth; nine years follow-up]

Behavioral performance, brain histology, and EEG sequela after immediate combined atropine/diazepam treatment of soman-intoxicated rats

It is known that rats poisoned with near-lethal doses of pinacolyl methylphosphonofluoridate (soman) develop brain lesions, particularly when convulsions are induced. When rats were intoxicated with a LD50 of soman and treated immediately thereafter with a combination of low doses of atropine and diazepam (LOW AS/DZ treatment), large decrements...

Active avoidance behavior in guinea pigs: Effects of physostigmine and scopolamine

Behavioral training of guinea pigs by conventional methods, such as used for rats and mice, appears difficult. Hence, only a few behavioral experiments with guinea pigs have been described in the literature. An active avoidance technique in an automated two-way shuttlebox is described using sound as a conditioned (CS) and a tactile stimulus (a...

Exogenous and endogenous control of attention: The effect of visual onsets and offsets

Two experiments were carried out to investigate the relation between exogenous and endogenous control of visual attention. Subjects searched for a target letter among three nontarget letters that were positioned on an imaginary circle around a fixation point. At different cue-display intervals, a centrally located arrowhead cue reliably...

An acceleration illusion caused by underestimation of stimulus velocity during pursuit eye movements: Aubert-Fleischl revisted

When the eyes pursue a fixation point that sweeps across a moving background pattern, and the fixation point is suddenly made to stop, the ongoing motion of the background pattern seems to accelerate to a higher velocity. Experiment I showed that this acceleration illusion is not caused by the sudden change in (i) the relative velocity between...

Polyunsaturated fatty acid consumption, plasma cholesterol concentration and neuroendocrine response to mental and physical task load

This study was designed to investigate the relation between fatty acid consumption, total plama cholesterol and neuroendocrine response to exposure to stress, factors thought to play a role in the development of coronary heart disease. For this purpose 32 apparently healthy male volunteers were classified on the basis of their plasma cholesterol...

A neurofunctional test battery for evaluating the effects of long-term exposure to chemicals

Behavioral effects of etiracetam in rats

The effects of etiracetam, a structural analogue or piracetam, were investigated in rats on Y-maze discrimination acquisition, on open field behavior, on one-trial passive avoidance learning and on shuttlebox acquisition and extinction. The results indicate that this drug significantly enhances acquisition and may improve retention without...

Searching for traffic signals while engaged in compensatory tracking

An experiment is described in which subjects were required to search for familiar traffic signals. Half the time this was done while also engaged in a manual compensatory tracking task. The experimental variables of the visual search task were color, total number of signals exposed, the number of relevant signals, and the density of the signals....

Some effects of an ACTH 4-9 analog (Org 2766) on human performance

The effects (on human beings) of the ACTH analog Org 2766 were investigated for a range of performance tests: complicated serial reaction task, running memory span, verbal learning and non-verbal mental ability tests (closure flexibility and non-verbal abstraction). Subjective ratings on feeling were taken and heart rate was measured. Only the...

The terminal CNV and stimulus discriminability in motor and sensory tasks

Slow EEG potentials were recorded during the foreperiod of a signal detection task which involved different levels of discrimination difficulty. The subject was requried to react to S2 as quickly as possible or to delay his responses by 1 s. It was found that the contingent negative variation (CNV) was attenuated when no speeded response was...

Slow cortical and heart rate correlates of discrimination performance

Slow EEG potentials (Fz, Cz, Pz) and heart rate were recorded during the foreperiod of a reaction task, which involved different levels of discrimination difficulty. A simple reaction task was compared with a selective reaction task where either an easy or a difficult discrimination was required. In general, the terminal amplitude of the CNV was...