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R Baltissen

Publications and source records attributed to R Baltissen.

10 recordsLinked to original sources
PubMed1998

[Psychophysiologic reactions to predictable aversive stimuli in a delayed conditioning paradigm: reinstatement of the orientating reaction or informational control?].

The preception and orienting response (OR) reinstatement hypotheses are alternative explanations for the reduced responding to predictable as compared to unpredictable aversive stimuli. To test differential predictions from both theories, 60 subjects were presented with 30 stimuli varying in intensity (60 dB(A) vs 100 dB(A)) and predictability (constant vs variable warning) in a 2 x 2 between subject design. Impact ratings, SCR and heart rate were recorded as dependent variables. According to the preception hypothesis a steep and early decrease of responding in the predictable 100 dB(A) condition was expected, whereas according to the OR reinstatement hypothesis a slower decrease with differences between the predictable and unpredictable stimuli at both intensities was hypothesized. To control for response interference only those trials were selected for the analysis for which the interval was the same in the variable and constant warning condition. Results revealed an intensity effect for the SCRs and impact ratings, but no effect of predictability. Although for the heart rate magnitude the intensity by predictability was found in favor of preception, this result appeared to be due to differences in sensitivity between groups during the warning interval. It was concluded that neither hypothesis proved to provide a valid account for the reduced responding to predictable aversive stimuli, but that the data seemed to be most consistent with a safety signal interpretation. Time estimation was considered to be a crucial variable. It is suggested that beyond mere signalling, additional beneficial effects of predictability can be demonstrated in studies where procedures are used which make time estimation unnecessary.

Acoustic Stimulation↗
PubMed1995

Autonomic indicators of information processing related to conditioning.

The aim of the present study was to quantitatively investigate the role of information processing in conditioning using stimuli with varying amounts of information content. A letter reproduction task varying in complexity served as the unconditioned stimulus. In the first experiment, we tested the indicator function of electrodermal and cardiovascular variables. The amount of information processing resources required emerged most clearly in electrodermal reactions (EDRs), showing an increase with increasing stimulus information content. A second experiment was performed using the same design to confirm the role of processing resources allocation during conditioning by means of an independent indicator. A reaction time task was introduced as a measure of information processing resources utilized. The results paralleled the dependence of EDRs on stimulus information content, as was found in the first experiment.

Adult↗
PubMed1993

[Temporal stimulus structure, gestalt perception and electrodermal reaction pattern].

The presentation of tones with alternating interstimulus intervals (ISIs) of 10 and 70 s leads to an electrodermal response pattern with an increase in magnitude after long and a decrease after short ISIs. The present study investigated whether there is a relation between the occurrence of the response pattern and the perception of stimuli as a pattern and, furthermore, whether the greater response to the stimulus after the long ISI is due to the greater information content of this stimulus (announcing the occurrence of the pair of tones). Four groups, each consisting of 12 subjects, were subjected to a 1 s, 1000 Hz tone of 90 dB(A) intensity over 21 trials. Group I received the tones in randomized sequences of 10 and 70 s, groups II and III received alternating ISIs of 10 and 70 s. While in group II the regularity of the stimulus pattern was interrupted by the presentation of an extra stimulus, group III was confronted with a stimulus omission. As a control condition, group IV received regularly alternating tones with ISIs of 10 and 70 s. Skin conductance and heart rate were recorded as dependent physiological variables. The perception of the stimulus patterns was measured by means of a questionnaire. The electrodermal response pattern found in earlier studies was replicated, and this pattern even occurred in the random group when 10 and 70 s ISIs appeared directly after each other. The presentation of the extra stimulus and the stimulus omission did not have any effect. For heart rate, a deceleration to tones after long ISIs and an acceleration to tones after short ISIs was found. Subjective pattern perception and electrodermal response patterns did not coincide. In general, the results can be interpreted as showing that the relationship between the ISIs seems to be of importance for the occurrence of the response pattern.

Adult↗
PubMed1989

[The effect of temporal distribution in relation to constant frequency of stimuli on habituation of the orienting reaction].

The lack of empirical evidence for faster habituation with the regular presentation of stimuli suggests that it is not the constancy of presentation of stimuli, but rather the rate of stimulation--defined as the reciprocal of the harmonic mean of the interstimulus intervals--that determines the speed of habituation. Using alternation of 10-70 and 30-50 sec and a constant sequence of 40 sec, three different rates of stimulation were realized. The hypothesis of faster habituation of skin conductance reactions with higher rates of stimulation was not confirmed. However, a consistent pattern of skin conductance reactions, with an increase in reaction after long intervals and a decrease after short intervals, was found, especially in the group with alternating intervals of 10 and 70 sec. The analysis of an additional group with a random sequence of intervals showed that the response pattern did not result simply from the expired time since last stimulus, i.e., a simple mechanical effect. The possibility of anticipating the stimuli and differing information content of the stimuli are discussed as possible determining factors.

Adult↗
PubMed1977

Neurobehavioral and systemic effects of longterm blood lead-elevation in rats. I. Discrimination learning and open field-behavior.

In order to assess neurobehavioral deficit subsequent to early low-level lead-exposure, Wistar-rats were prenatally Pb-exposed via their mothers, neonatally via their dams' milk, and later on via their diet containing lead acetate (745 mg Pb/kg diet). Blood-lead levels (PbB) of dams increased from 24.2-31.2 microgram-% during pregnancy and suckling-periods, those of offsprings were 26.6 microgram-% at about 16 days of age and 28.5 microgram-% at about 190 days of age. Between 100 and 200 days of age 40 male offsprings were subjected to behavioral testing, namely an open field-test and a visual discrimination-learning task. Two learning-tasks of different complexity, i.e. orientation- and size-discrimination, were used. Data of 20 lead-treated animals were compared with those of 20 age-matched controls. In the open-field test lead-fed animals were significantly more restless than controls; an increase of ambulation, rearing and grooming was observed. In the difficult learning-task, i.e. size discrimination, only the controls did learn the problem, whereas only one of the lead-group did; there was, however, no difference between lead- and control-animals for the easy task, i.e. orientation-discrimination. The observed effects, namely overreaction in the open field and a deficit of visual discrimination learning, may be interpreted in terms of lead-induced CNS-dysfunction. They clearly suggest that the "no-response level" for neurobehavioral damage in the rat, subsequent to early lead-exposure, must be assumed to be lower than 35 microgram/100 ml.

Animals↗
PubMedDate not supplied

Electrodermal activity as an indicator of information processing in a nonaversive differential classical conditioning paradigm.

Most investigations of information processing in human Pavlovian autonomic conditioning focussed on the role of awareness of the contingency of the conditioned stimulus (CS) and the unconditioned stimulus (UCS). While in these studies only the qualitative information of the CS (UCS occurring vs not occurring) was varied, the present experiment was designed to vary the quantitative information of the CS. In a differential conditioning paradigm, using a letter reproduction task as nonaversive UCS, electrodermal responses to different degrees of CS information content were investigated. Twenty subjects experienced two different conditions in a within subject design. In one condition only the number of letters used in the following UCS was presented as CS+, while in the other condition the CS already contained the whole UCS information. Both conditions led to significant differences in magnitudes of electrodermal responding.

Adult↗
PubMedDate not supplied

Effects of vasopressin on the habituation of the orienting reaction in men.

Effects of arginine-vasopressin (AVP) on the habituation of the orienting reaction and response to stimulus mismatch were investigated in a between-group design with 40 healthy male volunteers using skin conductance and heart rate responses as dependent measures. Twenty-one 1000 Hz tones of 90 dB(A) intensity and 2 s duration were presented with alternating intervals of 20 and 140 s. Stimulus mismatch responses were analyzed to the tones after the long intervals and to a change of the interval duration. The expected prevention of habituation as an indicator of a general stimulus-related increase of phasic arousal under AVP could not be confirmed. There were no differences between the AVP and the placebo group in the skin conductance and heart rate responses. The interval change did not provoke a dishabituation reaction, but responses to the tones after the long intervals were reliably enhanced. However, AVP did not increase the reaction to stimulus mismatch. It is concluded that autonomic indicators of the habituation of the OR remain unaffected by AVP.

Acoustic Stimulation↗
PubMedDate not supplied

[Problems in assessing emotional reactions in the aged by means of experimental methods].

This paper critically discusses the usually used assessment methods (self-report measures) of emotional behaviour in old persons and presents a "reactive approach" to measure emotions in old and young subjects. "Reactive" means the registration of emotional changes to defined emotion inducing stimuli or situations. Advantages, problems, and limitations of the reactive approach are discussed in relation to some results of an experiment using 12 stimuli of different emotional qualities to assess emotional reactivity in 20 young (25-35 years) and 20 old (65-75 years) subjects.

Adult↗