Overreactivity of the psyche or the soma? Interindividual associations between psychosomatic symptoms, anxiety, heart rate, and end-tidal partial carbon dioxide pressure.

Current research has all but refuted previous suggestions about the role of hyperventilation as a proximal, common cause of psychosomatic symptoms. As an alternative, it has been proposed that the experience of psychosomatic symptoms is primarily associated with psychological mechanisms, i.e.

Seat-belt wearing and driving behavior: an instrumented-vehicle study.

Less-than-expected fatality reductions after seat-belt legislation has been introduced in a jurisdiction may be explained in terms of selective recruitment of parts of the driving population and/or behavioral adaptation by beginning belt users. The present investigation has compared the relative merits of these two hypotheses at the level of individual driver behavior. In the initial study the driving behavior of groups of habitual wearers and nonwearers of the belt was compared.

Effects of extended practice in a one-finger keypressing task.

This paper addresses skilled operations underlying the initiation and execution of rapid movement sequences in a task consisting of three sequential keypresses made with one finger. It sought to provide evidence for the notion that, as a result of practice, processes required to produce a keypressing sequence become concurrent. The results of the experiment show, first, that unpacking of the third keypress in a three-keypress sequence, which is assumed to occur normally after execution of the second keypress, is shifted in time during practice so as to occur during or before actual depression of the second key.

An adaptation-induced pop-out in visual search.

The present study demonstrates that an object embedded in an array of identical objects can pop-out. Dependent on the stimuli preceding the search display, local (chromatic) adaptation causes an identical object to pop-out because it appears to have a colour (Expt 1) or brightness (Expt 2) that is slightly different from the colour and brightness of the other objects in the display. Experiment 3 shows that this pop-out even occurs when the stimulus preceding the search display is presented for only 100 msec.

TNO stereopsis test as an aid to the prevention of amblyopia.

In this investigation, carried out under a Youth Health Care postgraduate course in Nijmegen, the stereopsis of a school population of 730 children, aged 4-18 years, was recorded and clinically evaluated. Stereopsis was measured using the TNO test, a random-dot stereo test especially designed for the early detection of amblyopia. The main aims of this study were to establish the validity of the TNO test as a screening test for amblyopia, obtain information about the variability and age dependence of stereopsis, and to evaluate the efficacy of amblyopia prevention.

Vapour transfer in two-layer clothing due to diffusion and ventilation.

An experiment was carried out to measure the vapour resistance of two-layer clothing ensembles as a function of air permeability of the outer layer, open or closed apertures, wind, and walking, both for the total ensemble and for the outer garment alone. Six subjects walked on a treadmill (0.0, 2.

Comparing the concepts of mental load and stress.

This paper delineates mental load and stress as two related concepts that originate from different theoretical frameworks. A proper distinction between the two concepts is important, not only for theory building, but because it may lead also to different interpretations of experimental results, and, consequently, to different recommendations in applied situations. High workload is regarded as an important but not a critical factor in the development of stress symptoms.

Visual selective attention: a theoretical analysis.

The present paper outlines a framework which allows a consistent interpretation of data regarding visual selection in visual search tasks. It organizes and reviews visual search tasks in which the target is defined by primitive features, by conjunctions of features and when the target is categorically different from non-targets. The special role of spatial attention is reviewed and different theoretical accounts are discussed.

Effects of age and task similarity on dual-task performance.

When a dual tracking task consisting of two incoherent (uncorrelated) subtasks is partly integrated, such that it is characterized by incompatibility of similarity, or when axis similarity of subtasks is high, it may be difficult to map subtask stimuli to the proper responses. Especially for older adults, an increase in mapping demands may be a source of confusion (cross talk). In the present experiment this issue was addressed with a dual task consisting of two unrelated one-dimensional compensatory tracking tasks with position dynamics.

Quantifying color constancy: evidence for nonlinear processing of cone-specific contrast.

Color constancy was studied by the method of comparing color samples under two different illuminants using a CRT color monitor. In addition to the classical approach in which one of the illuminants is a (standard) white, we performed experiments in which the range of differential illumination was extended by using pairs of lights that were both colored. The stimulus pattern consisted of an array of thirty-five color samples (including five neutral samples) on a white background.

A model for context effects in speech recognition.

A model is presented that quantifies the effect of context on speech recognition. In this model, a speech stimulus is considered as a concatenation of a number of equivalent elements (e.g.

Postural consequences of long duration centrifugation.

In the present paper a series of experiments will be described in which the postural consequences of long (up to 1.5 h) duration 3G-centrifugation have been subject to investigation. A vestibular model is presented in order to explain for the postural imbalance found in specific conditions after the centrifuge run, and for the often concomitant feelings of motion sickness (50% of the subjects suffer from Sickness Induced by long duration Centrifugation).

Comparison of four noninvasive rewarming methods for mild hypothermia.

Four noninvasive rewarming techniques for mildly hypothermic subjects were compared. Seven subjects were cooled in a water bath of 15 degrees C for 2 h to an average esophageal temperature (Tes) of 36 degrees C. Thereafter, the subjects were rewarmed by immersion of the body in a water bath of 42 degrees C (Method 1), the body but not the extremities in water of 42 degrees C (Method 2), only the extremities in water of 42 degrees C (Method 3), or spontaneous rewarming in blankets (Method 4).

Respiration in psychophysiology: methods and applications.

With the use of advanced equipment, respiratory measures can unobtrusively and reliably be assessed in a variety of psychophysiological research settings. New computerized analysis techniques can break down respiration into a number of components that provide valid estimates of variations in respiratory control mechanisms in the brain stem. Thus analysed, respiratory responses may vary in at least two dimensions: (A) with regard to drive and timing aspects, and (B) with regard to the metabolic appropriateness of the respiratory response.

Perceptual selectivity for color and form.

Three visual-search experiments tested whether the preattentive parallel stage can selectively guide the attentive stage to a particular known-to-be-relevant target feature. Subjects searched multielement displays for a salient green circle that had a unique form when surrounded by green nontarget squares or had a unique color when surrounded by red nontarget circles. In the distractor conditions, a salient item in the other dimension was present as well.

Annoyance caused by simultaneous impulse, road-traffic, and aircraft sounds: a quantitative model.

In this study, total annoyance caused by different simultaneous environmental sounds is investigated. In spite of a number of puzzling data in the literature, it is fairly well established that in combinations in which the annoyance of one source is considerably higher than that of another source, total annoyance is equal to the maximum annoyance of the separate sources. For combinations in which both sounds are about equally annoying, total annoyance seems to be higher than the maximum source-specific annoyance.

Speech reception in quiet and in noisy conditions by individuals with noise-induced hearing loss in relation to their tone audiogram.

Tone thresholds and speech-reception thresholds were measured in 200 individuals (400 ears) with noise-induced hearing loss. The speech-reception thresholds were measured in a quiet condition and in noise with a speech spectrum at levels of 35, 50, 65, and 80 dBA. The tone audiograms could be described by three principal components: hearing loss in the regions above 3 kHz, from 1 to 3 kHz and below 1 kHz; the speech thresholds could be described by two components: speech reception in quiet and speech reception in noise at 50-80 dBA.

Signal detection in temporally modulated and spectrally shaped maskers.

The first part of this paper presents several experiments on signal detection in temporally modulated noise, yielding a general approach toward the concept of comodulation masking release (CMR). Measurements were made on masked thresholds of both long- and short-duration, narrow-band signals presented in a 100% sinusoidally amplitude-modulated (SAM) noise masker (modulation frequency 32 Hz), as a function of masker bandwidth from 1/3 oct up to 13/3 octs, while the masker band was geometrically centered at signal frequency. With the short-duration signals placed in the valley of the masker, a substantial CMR (i.

Simulation of hand cooling due to touching cold materials.

A simple analytical model has been developed to simulate the cooling of the hands due to touching various types of cold material. The model consisted of a slab of tissue, covered on both sides with skin. The only active mechanism was the skin blood flow.

Pain, thermal sensation and cooling rates of hands while touching cold materials.

Hand cooling and resulting comfort and pain were studied in 12 subjects, while touching six different materials (polyurethane foam, wood, nylon, rustproof steel, aluminium, and temperature-controlled metal) which were initially at ambient temperature. This was done for three ambient temperatures (-10 degrees, 0 degree and 10 degrees C), after pre-exposure exercise or rest, with bare hands or while wearing gloves. The observed cooling curves were analysed as Newtonian cooling curves.

Physiological strain due to load carrying in heavy footwear.

To determine the effects of wearing heavy footwear on physiological responses five male and five female subjects were measured while walking on a treadmill (4, 5.25, and 6.5 km.

Influence of visual, vestibular, cervical, and somatosensory tilt information on ocular rotation and perception of the horizontal.

By combining a tilting chair and a tilting room we investigated the subjective horizontal (SH) and ocular counterrotation (OCR) as a function of body tilt, trunk tilt, and tilt of a visual frame. Significant influences of (isolated or combined) vestibular and visual information were found, but no influence of neck proprioception. A second and similar experiment, however, now conducted with subjects devoid of labyrinthine function, suggested a contribution of the neck as well as of somatosensory origin.

Cross-dimensional perceptual selectivity.

Three visual search experiments tested whether top-down selectivity toward particular stimulus dimensions is possible during preattentive parallel search. Subjects viewed multielement displays in which two salient items, each unique in a different dimension--that is, color and intensity (Experiment 1) or color and form (Experiments 2 and 3)--were simultaneously present. One of the dimensions defined the target; the other dimension served as distractor.

Effects of skill integration and perceptual competition on age-related differences in dual-task performance.

Age-related differences in dual-task performance may be affected by factors such as skill integration and perceptual competition. Therefore these factors were examined in a dual-task experiment with young and older adults involving two one-dimensional compensatory tracking tasks. Single-task difficulty was individually adjusted for each subject.