Search PubMed⌕ Search

Biomedical subjects

H Merckelbach

Publications and source records attributed to H Merckelbach.

At least 109 records · Page 6Linked to original sources
PubMed1994

Handedness, symptom reporting, and accident susceptibility.

A cross-sectional design was used to examine the relationship among handedness, self-reported symptoms, and accident susceptibility in a nonclinical sample (N = 285). Left-handedness was not found to be associated with elevated symptom reporting (and, consequently, health problems) and accident susceptibility. Thus, the present findings do not support the hypothesis that left-handedness is accompanied by reduced physical fitness or accident proneness.

Accident Proneness↗
PubMed1994

Personality disorders and features in social phobia and panic disorder.

The hypothesis that there is a specific relationship between social phobia (SP) and avoidant personality disorder (APD) was investigated. Using the Structured Clinical Interview for DSM-III-R Personality Disorders, we screened 32 patients with SP and 85 patients with panic disorder (PD) for the presence of personality disorders. Avoidant features were found significantly more often in SP than in PD, although the diagnosis of APD could not be established significantly more often. On the item level, APD Criterion 6 (fears being embarrassed) discriminated the strongest. Social phobics appeared to be more disturbed on Axis II than PD patients.

Adult↗
PubMed1993

Effects of endorphin blocking on conditioned SCR in humans.

In order to test the hypothesis that low levels of endogenous opioids (endorphins) predispose to strong conditioning effects, female Ss (N = 36) were assigned to a placebo group, a low-dose naltrexone group, or a high-dose naltrexone group and then underwent a classical conditioning procedure. This procedure consisted of an acquisition phase in which all Ss received 5 pairings of a CS+ (neutral picture) and a UCS (100 dB white noise). The CS- (neutral picture) was never followed by a UCS. During extinction, Ss received 4 unreinforced presentations of CS+ and CS-. Throughout the experiment, skin conductance responses (SCRs) to the CSs and UCSs were recorded. Acquisition was successful in that CS+ slides elicited stronger SCRs than CS- slides. However, during acquisition, there was no interaction between drug and differential response (CS+ vs CS-). During extinction, there was no overall remaining effect of conditioning. Again, no evidence was found to suggest that (remaining) effects of conditioning were stronger in the naltrexone treated Ss than in the placebo Ss. If anything, the opposite seemed to be true with especially high-dose naltrexone Ss showing relatively weak conditioning effects.

Acoustic Stimulation↗
PubMed1993

Verbalization and environmental cuing in thought suppression.

Research on thought suppression has yielded a morass of conflicting results. While some studies show that suppression of a thought results in a rebound effect (i.e. a heightened frequency of this thought later on), other studies failed to demonstrate this phenomenon. The first aim of the present study was to investigate whether the method used to study stream of consciousness (verbalization vs thinking silently) affects the report of target thoughts in a thought suppression experiment. Second, the claim that environmental cuing (i.e. distraction by directing attention towards external cues) is the mechanism behind the recurrence of suppressed items was examined. Results indicated that the method used to monitor stream of consciousness did not modulate the report of target thoughts: in fact, no rebound effect occurred. However, results did support the suggestion that heightened frequencies of suppressed material are related to environmental cuing.

Adult↗
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

Suppression of emotional and neutral material.

Previous studies have indicated that suppression of a thought results in an immediate increase of the frequency of this thought and/or in a rebound effect, i.e. in a heightened frequency of this thought later on. The present study (n = 53) examined the relationship between suppression and emotionality of the to-be-suppressed material. More specifically, it was investigated whether suppression of an emotional story results in stronger immediate enhancement or thought rebounds than suppression of a neutral story. There was a clear initial enhancement effect in the group suppressing a neutral story: subjects who tried to suppress experienced more target thoughts than subjects who did not try to suppress. In the neutral-story conditions, no rebound effect occurred. In the groups exposed to an emotional story, there was neither evidence of initial enhancement nor of a rebound. As most obsessions are related to emotional themes, the present findings cast doubt on the claim that the rebound phenomenon represents a valid laboratory model for clinical obsessions.

Adolescent↗
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↗
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

Covariation bias and electrodermal responding in spider phobics before and after behavioural treatment.

The present study investigated whether a covariation bias is present in severe spider phobics and whether such bias is modified by successful treatment. In addition, this study sought to examine whether a covariation bias is linked to differential autonomic responding. Subjects were 20 untreated phobics, 19 treated phobics, and 18 no-fear controls. Subjects were exposed to a series of 72 slides comprising three categories: spiders (fear-relevant), mushrooms, and flowers. At slide offset one of three possible outcomes occurred: a shock, a tone, or nothing at all. All slide-outcome combinations occurred equally frequent. The results show that an equally strong covariation bias is present in severe spider phobics, in successfully treated phobics, and in no-fear controls. Thus, the present data only partially sustain earlier findings of Tomarken, A. J., Mineka, S. & Cook, M. (1989) (Journal of Abnormal Psychology, 98, 381-394). The covariation bias appeared to be mimicked by differentially heightened autonomic responding. The current data suggest that both the covariation bias and the heightened physiological responding reflect a "beloningness" between spider slides and aversive outcome.

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↗
PubMed1991

Fear relevance and diminution of unconditioned skin conductance responses.

According to Donegan and Wagner's priming model [1987], a signalled UCS will elicit a smaller UCR than an unsignalled UCS. Assuming that fear-relevant CSs are good predictors of aversive UCSs, while fear-irrelevant CSs are relatively bad predictors of aversive UCSs, the present study examined the effect of fear relevance on electrodermal UCR diminution during the acquisition phase of a single cue conditioning procedure. Four groups were studied, each of which consisted of 12 subjects. Group 1 had a fear-relevant CS (a slide of an angry face) paired with a UCS (7 mA shock), whereas group 2 had a fear-irrelevant CS (a slide of a happy face) paired with a UCS. Groups 3 and 4 had unpaired presentations of the CS and UCS and served as control groups for 1 and 2. There were 4 habituation, 8 acquisition, 4 recovery (UCS-only), and 6 extinction (CS-only) trials. While overall UCR levels were lower in the paired than in the unpaired control groups, it was also found that the size of UCR decrement and subsequent recovery was greater in the angry face CS-paired group than in the happy face CS-paired group. This finding is in line with the predictions that flow from the Donegan and Wagner model.

Adolescent↗
PubMed1990

Classical conditioning and attentional bias.

The present study was designed to test whether an attentional bias can arise from aversive classical conditioning. Using a differential conditioning paradigm in which slides of angry faces served as conditioned stimuli (CS+/CS-) and electric shock served as unconditioned stimulus (UCS), skin conductance responses (SCRs) of normal subjects (N = 20) were recorded. The effectiveness of the conditioning procedure was proved by differential SCRs to CS+ and CS- slides during the later acquisition trials. During a subsequent extinction phase, sets of three numbers were superimposed on CS+ and CS- slides. subjects were asked to add up these numbers as quickly as possible and to vocalize the results. Vocalization latencies as indexed by chin EMG activity were significantly longer with CS+ than with CS- trials. This result is explained in terms of the attention attracting properties that the CS+ acquires as a result of its pairing with the UCS. It is argued that these properties compete with the attentional resources that are needed for an ongoing task (i.e., addition task). The data suggest that a learning approach to the origins of attentional biases in anxious subjects might be fruitful.

Adult↗
PubMed1990

Waning of panic sensations during prolonged hyperventilation.

Recent theories about panic emphasize that a hyperventilatory positive feedback loop is involved in panic: catastrophic misinterpretation of bodily sensations may trigger anxiety, anxiety may stimulate hyperventilation, hyperventilation may promote the salience of feared sensations etc. Such models leave unexplained how and when panics come to an end. It was hypothesised that panic with hyperventilation may end because pronounced hyperventilation becomes, in the course of time, less powerful in generating perceivable bodily sensations. Twenty healthy subjects hyperventilated forcefully and experienced clear panic symptoms as defined by DSM IIIR. When pCO2 was kept 55% below base line for 90 min, panic symptoms waned. The mean intensity of the symptoms declined as did the number of symptoms occurring. No panic symptoms were observed in the control group (n = 20) who ventilated normally. In so far as hyperventilation is involved in the positive feedback loops that characterize panic, panic attacks may be time-limited because sensations induced by hyperventilation become less salient even if massive hyperventilation continues. As to the explanation of the reported phenomenon, it is suggested that, apart from habituation, local physiological changes due to prolonged hyperventilation may produce a decrease in interoceptive input.

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↗
PubMed1990

Hemisphere preference, phobia, and depression.

The present study was undertaken in order to examine whether depression and anxiety are related to preference for a right hemisphere mode of thinking. On the basis of a paper-and-pencil test presumably measuring hemisphere preference (Preference Test; Zenhausern, 1978), normal subjects (N = 75) were assigned to a group characterized by a left hemisphere thinking style, a group characterized by a right hemisphere thinking style and a group with mixed tendencies (left and right hemisphere tendencies). Additionally, subjects completed the Fear Questionnaire and the Depression Symptom Inventory. It was found that subjects with a right hemisphere thinking style reported more depressive and fear symptoms than subjects with a left hemisphere thinking style. This finding is in line with theories which assume that the right hemisphere is characterized by a negative, dysphoric emotional tendency.

Adult↗