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Biomedical subjects

A Arntz

Publications and source records attributed to A Arntz.

At least 55 records · Page 3Linked to original sources
PubMed1993

Endorphins stimulate approach behaviour, but do not reduce subjective fear. A pilot study.

The present study explored whether endorphins have a short-term influence on behavioural approach to a phobic object and on the experience of fear. In a double-blind design, spider phobics (n = 30) received a placebo, a low dose (25 mg) or a high dose (100 mg) of naltrexone, an endorphin blocker. Approach to a spider appeared to be negatively influenced by the endorphin blocker, but subjective fear was not significantly related to it. The findings support the view that endorphin release during anxiety stimulates courageous behaviour, but does not directly reduce the experience of fear.

Adult↗
PubMed1993

Anxiety, attention and pain.

In a within-subject design the hypothesis was tested that focus of attention rather than anxiety influences pain. Twenty-four spider phobics received a moderately painful electrical stimulation in each of four conditions: low anxiety/attention directed towards pain; low anxiety/attention distracted from pain; high anxiety/attention directed towards pain; high anxiety/attention distracted from pain. Anxiety was induced by means of exposure to a spider. Subjective pain ratings strongly supported the hypothesis: pain was rated lower when the subject diverted attention away from than when the subject attended to the pain stimulus, regardless of level of anxiety. The Skin Conductance Response to the first pain stimulus of the series of four in each condition was, however, higher when the subject distracted than when the subject attended to the pain stimulus. There were no experimental effects on later Skin Conductance Responses. Most importantly, there was no influence of anxiety on any of the pain responses. Attentional focus rather than anxiety per se seems to influence pain.

Adolescent↗
PubMed1993

Opioid antagonist affects behavioral effects of exposure in vivo.

This study tested the hypothesis that endogenous opioids are involved in the extinction of phobic fear through exposure in vivo. Forty-eight spider phobics participated in a 2-hr therapist-directed exposure in vivo treatment. Sixteen Ss were assigned to placebo, 16 to a low dose of naltrexone, and 16 to a high dose of naltrexone. Before intervention, after treatment, and at a 1-wk follow-up test, self-report, physiological, and behavioral measures of phobic fear were completed. At 1-wk follow-up, naltrexone was significantly related, in a dose-dependent way, to a greater relapse on avoidance measures but not on emotional, cognitive, and physiological measures. Endogenous opioids may be specifically involved in the extinction of avoidance behavior but not in the extinction of all aspects of phobic fear.

Adult↗
PubMed1992

Pathways to spider phobia.

Using a revised version of the Phobic Origin Questionnaire (POQ; Ost, L. G. & Hugdahl, K. Behaviour Research and Therapy, 19, 439-477; 1981), the present study examined whether conditioning experiences, modeling experiences, and/or informational learning experiences were more often reported by spider phobics (n = 41) than by non-fearful controls (n = 30). The two groups did not differ with regard to the overall frequency of conditioning or modeling events. Remarkably, the frequency of informational learning was higher among non-fearful Ss than among phobics. Although the limitations inherent to the retrospective nature of the present study should be borne in mind, the data suggest that, at least in spider phobics, conditioning events, modeling experiences, and/or informational learning do not necessarily give rise to phobic fears.

Adolescent↗
PubMed1992

Covariation detection in treated and untreated spider phobics.

Twenty treated and 18 untreated spider phobics were exposed to a series of 72 slides. Three different categories of slides were used: phobia-relevant slides (spiders), alternative fear-relevant slides (weapons), and neutral slides (flowers). Slides were randomly paired with either a shock, a tone, or nothing at all. Despite the absence of a systematic correlation between slides and outcomes, untreated phobics strongly overestimated the covariation between spider slides and shock. Treated phobics did not show a covariation bias, suggesting that such bias can be modulated by behavioral treatment. In addition, untreated subjects were more confident about their contingency estimates than were treated subjects. The present results fit with earlier studies.

Adolescent↗
PubMed1992

The interrater reliability of a Dutch version of the Structured Clinical Interview for DSM-III-R Personality Disorders.

This study presents data on the interrater reliability of a Dutch version of the Structured Clinical Interview for DSM-III-R Personality Disorders (SCID-II). Seventy outpatients were interviewed before the start of their treatment by one rater, while a second rater observed. Both raters were instructed to make independent ratings and the second rater was not allowed to participate in the discussion. On criterion level, interrater reliabilities appear to be very good, with a few exceptions (most reliabilities are higher than 0.75). However, all 5 observation criteria had poor interrater reliabilities. Agreement on personality disorder, on the whole, was excellent (overall kappa = 0.80). The possible reasons why relatively lower reliabilities are found with some criteria are discussed. Finally, problems encountered during the interviews are addressed and possible adjustments of the SCID-II are suggested.

Adolescent↗
PubMed1991

The effects of incorrect pain expectations on acquired fear and pain responses.

Previous experimental research on the effects of incorrect intensity expectations of aversive events can be criticized because intensity expectations were not manipulated independently from changes in objective intensity. The present study aims at investigating the effects of incorrect intensity expectations on the immediate and later responses to a painful stimulus, and on the acquisition of anticipatory responses, with proper experimental control. Subjects (n = 62) received 20 painful stimuli of varying intensity. In the control group intensities were correctly signalled on all trials by an analogue signal. On 3 trials the signal was too large in the overprediction condition, and too small in the underestimation condition. Underpredicted painful experiences were related to subsequent higher pain responses on the physiological level, but not on the subjective level; and to increased anticipatory responses (increased pain expectations, uncertainty, subjective fear, skin conductance responses). Skin conductance level also indicated increased fear after underpredicted experiences. Overpredicted painful experiences were related to a faster decrease in subjective fear compared to the control group, but did not influence other variables. The findings support the notion that underpredictions contribute to the acquisition of fear and disrupt habituation processes. The asymmetrical processing of the two kinds of incorrectly predicted experiences is discussed.

Adult↗
PubMed1991

Avoidance of pain of unpredictable intensity.

Unpredictability of the intensity of an aversive event might be an important factor in producing negative effects of the event, especially if the UCS becomes stronger than could have been expected. The present experiment tested the hypothesis that unpredictability of intensity of a painful stimulus contributes to avoidance behaviour. The experiment was concealed in a shock working-up procedure, which was done to assess the pain level subjects were willing to tolerate in a subsequent experiment. The experimental subjects, who received an unannounced sudden increase of the pain stimulus during the working-up procedure, tolerated less pain on a subjective as well as on an objective level (avoidance of high levels of pain) than the control subjects, who received the stimuli in a predictable pattern. The results support the hypothesis that unpredictability of intensity of an aversive event contributes to avoidance behaviour.

Adult↗
PubMed1991

Imagery ability and exposure in vivo in spider phobia.

The present study deals with the effect of imagery ability on treatment outcome in spider phobias. Thirty-eight spider phobics completed the Questionnaire on Mental Imagery (QMI) and the Spider Questionnaire (SPQ). Subjects also went through a behavioral approach task (BAT) during which heart rate and avoidance behavior were measured. Each subject was then given one-session treatment as described by Ost. Immediately after treatment, SPQ and BAT data were again obtained. On the basis of their QMI scores, subjects were assigned to a 'good', 'moderate', or 'poor' imagers group. Neither pre-treatment nor post-treatment measures were found to vary as a function of imagery ability. Thus it appears that, at least for specific phobias such as spider fear, imagery ability is not a relevant variable for predicting the effects of in vivo exposure.

Adolescent↗
PubMed1991

Conditioning experiences in spider phobics.

Using the Phobic Origin Questionnaire (Ost, L. G. & Hugdahl, K. Behaviour Research and Therapy, 19, 439-477, 1981), the present study examined the extent to which severe spider phobics (N = 42) attributed their phobia to conditioning experiences, modeling experiences and/or informational learning experiences. Modeling was most often reported (71%), followed by conditioning (57%), and informational learning experiences (45%). It was also found that patients with a conditioning background reported less extreme cognitive symptoms when confronted with the phobic stimulus than patients with an indirect mode of acquisition (modeling and/or informational learning).

Adolescent↗
PubMed1991

Attention, not anxiety, influences pain.

Four hypotheses about the influences of anxiety and attention on pain impact were tested in a critical experiment: (1) anxiety increases pain; (2) anxiety decreases pain; (3) attention to pain increases pain; (4) only the combination of anxiety and attention to pain increases pain (interaction hypothesis). In a 2 x 2 design, anxiety (low vs high) and attention (attention vs distraction from the pain) were experimentally manipulated. Subjects received 20 electrically produced painful stimuli. Subjective pain experiences, skin conductance responses and heart rate responses gave no support for a pain impact increasing effect of anxiety. The anxiety-attention interaction hypothesis did not receive any support either. There was some support, only from the heart rate responses, that anxiety reduces pain impact. The critical factor appeared to be attention. Attention to the pain stimulus was related to a stronger pain impact (indicated by all measures) and to less subjective habituation, compared to distraction.

Adolescent↗
PubMed1990

Is the match/mismatch model based on a statistical artefact?

In the match/mismatch model, recently formulated by Rachman and coworkers, it is stated that incorrectly predicted aversive experiences are generally followed by an immediate adjustment of the predictions concerning aversiveness of the next experience. This model can be considered to reflect a psychological process of the formation of expectations. In the present article it is argued that a simple H0 model, assuming that predictions are completely randomly generated by the subject, may account for the same effects. This H0 model is used in a stringent test of empirical data to determine if there are any effects of the discrepancy between prediction and experience on next prediction that exceed the effects explained by the H0 model. Although the H0 model produces effects very similar to the empirically observed effects, there is clear support for the hypothesized influence of the discrepancy between prediction and experience. Therefore, the model appears to reflect 'real' psychological processes and not chance findings.

Agoraphobia↗
PubMed1990

The effects of underestimated pain and their relationship to habituation.

The intensity of a painful stimulus was experimentally manipulated in order to induce underpredictions of pain. The experiment aimed at (1) replicating previous findings on the effects of underpredicted pain and (2) investigating the relationship between underpredicted pain and habituation. Most previous findings were replicated: underpredictions of pain were followed by raised expectations of pain and increased fear of pain. In addition, the underprediction had long-term effects on fear of pain, uncertainty about predictions, and expected aversiveness of the painful stimulus. In contrast to previous findings and to Rachman's match/mismatch model, it was found that underpredicted pain can have dishabituating effects. It is theorized that inaccurately predicted pain can cause dishabituation, depending on the extent of the underprediction and on the subjective certainty of the prediction. Theoretical and clinical implications are discussed.

Adolescent↗
PubMed1990

Predictions of dental pain: the fear of any expected evil, is worse than the evil itself.

In a study of 40 subjects, who twice underwent extensive dental treatment, the relationships between expectations and experiences of pain and of anxiety were investigated. Inaccurate expectations were adjusted in the same way as observed in the laboratory. Especially anxious subjects expected more pain and anxiety than they experienced, and they appeared to need more experiences before their predictions became accurate. In the course of time, the expectations (and memories) of anxious subjects returned to their original more inaccurate level of prediction. The results suggest that the old schema is ultimately reinstated if disconfirmations are few and far between. Anxious subjects did not experience more pain, but they did experience more anxiety than fearless subjects. Detailed investigation of processes of change after disconfirmation showed that anxiety experienced during treatment is a factor that plays a part in maintaining the problem of inaccurate expectations and fear of treatment. Theoretical and clinical implications of these findings are discussed.

Adolescent↗
PubMed1990

Effects of matches and mismatches in agoraphobic and neutral situations.

An experiment was conducted to investigate the generalizability of Rachman's match/mismatch model and to explore if environmental conditions affect the consequences of an underprediction. Twenty subjects walked around in agoraphobic, and 15 did so in neutral, situations. Both groups carried a walkman and 7 aversive human screams were administered to them at random times. The results gave strong support to previous investigations on matches and mismatches, but no differences were shown between agoraphobic and neutral situations. Possible explanations are discussed.

Adolescent↗
PubMed1990

The relationship between underpredicted pain and escape.

Escape and avoidance that are disproportional to the danger of the pertinent stimulus are important clinical problems that are often related to inaccurate (catastrophic) expectations. One possible source of such expectations is a prior, underestimated aversive experience. In the present experiment the hypotheses that underestimated pain leads to escape and that it leads to avoidance were tested. In order to control for the effect of the intensity of the pain stimulus, a control group that received 20 pain stimuli of high intensity was formed. Subjects in the experimental condition received 17 pain stimuli of low intensity and 3 of (unexpectedly) high intensity (experimentally induced underprediction). Underprediction of the high intensity stimulus was significantly related to escape, but not to avoidance. The results suggest that the way in which avoidance was operationalized accounts for this. The strong support of the hypothesized relationship between underpredicted pain and escape is an important finding, however.

Adult↗
PubMed1990

Illusory correlation, on-line probability estimates, and electrodermal responding in a (quasi)-conditioning paradigm.

Twenty normal subjects were exposed to two series of two different slides randomly paired with the occurrence or non-occurrence of shock. The first series started with a greater number of pairings of one slide with shock ("target slide") than the other to induce an illusory correlation (IC). Meanwhile, across all trials shock/slide contingency was equal for both slides. During the second series, a truly random sequence of slide-shock trials was used in order to examine whether IC was resistant to disconfirmational information. Subjects' contingency estimates were recorded a posteriori as well as on-line. In addition, electrodermal responding was recorded on a trial-by-trial basis. Data show that it is possible to induce an IC between a neutral stimulus and an aversive outcome by means of a conditioning-like procedure. Moreover, data strongly suggest that an IC can act in such a way as to maintain or enhance covariation bias as indexed by on-line probability estimates. Finally, data sustain the hypothesis that a covariation bias is associated with differential autonomic responding.

Adult↗