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Biomedical subjects

H Merckelbach

Publications and source records attributed to H Merckelbach.

At least 127 records · Page 7Linked to original sources
PubMed1990

Eyeblink frequency, rehearsal activity, and sympathetic arousal.

Previous studies have suggested that the endogenous eyeblink rate (EBR) is inhibited by visual attention and increased by sympathetic arousal as well as by verbalization. As for the latter variable, it has been suggested that verbalization increases EBR by spreading of electric activity in efferent adjacent vocal and eye-motor pathways. The present study was designed in order to examine whether subvocal ("rehearsal") activity also elicits an increase in EBR. Subjects saw slides depicting either verbal or pictorial information. Subsequently, they were asked to rehearse this information silently. Spontaneous electrodermal fluctuations (SFs) were monitored throughout the experiment. The results clearly show that slide presentation ("information uptake") is accompanied by decrease in EBR, while silent rehearsal of information is accompanied by increase in EBR. Furthermore, this increase in EBR was found to correlate positively with SFs. Thus, results confirm the modulatory influences of visual attention, arousal and (sub)vocal activity on EBR. Furthermore, they suggest an explanation for the relationship that has been found between depressive mood and increased EBR. That is, heightened EBR in depression may reflect subvocal activity ("rumination").

Adult↗
PubMed1989

Effects of gaze manipulation on subjective evaluation of neutral and phobia-relevant stimuli. A comment on Drake's (1987) 'Effects of Gaze Manipulation on Aesthetic Judgments: Hemisphere Priming of Affect'.

Using neutral stimuli (mushrooms and flowers) and phobia-relevant stimuli (snakes and spiders), the present investigation examined the effect of gaze shifts on subjective evaluation of stimuli in female subjects (N = 29). One group of subjects had to orient to the right, whereas the other group had to orient to the left in order to see the stimuli. When left-handed subjects were excluded from the analysis, the results showed that subjects in the 'orient right' group gave a significantly more positive evaluation than subjects in the 'orient left' group. The results provide a replication of the phenomenon described by Drake (1987).

Adult↗
PubMed1989

Restrained eaters are rapidly habituating sensation seekers.

Several authors have pointed to similarities between eating disorders and addictive behaviors. In earlier studies, addicts were found to score high on the Sensation Seeking Scale (SSS) and to habituate rapidly to neutral stimuli. In this study, we found experimental support for an addiction model of eating disorders: restrained eaters also scored significantly higher on the Sensation Seeking Scale and also habituated significantly quicker to a series of neutral stimuli than unrestrained eaters. No clear evidence was found for the hypothesis that restrained eaters score lower on measurements of anxiety. It is hypothesized that rapid habituation promotes sensation seeking, which may be manifested in excessive consumption of either drugs or food. Restraint may be a strategy to prevent negative consequences of sensation seeking and excessive consumption. The model is related to earlier experimental findings.

Adult↗
PubMed1989

Psychophysiological and subjective reactions of social phobics and normals to facial stimuli.

Nine social phobics and 9 normal control subjects were exposed to slides of angry faces, happy faces, and neutral objects (i.e. flowers or mushrooms). Skin conductance responses (SCRs) to the stimuli and eyeblink rate (EBR) during stimulus exposure were recorded. In addition, subjects were asked to rate the stimuli in terms of pleasantness. While angry face stimuli elicited greater SCRs, stronger inhibition of EBR, and were evaluated more negatively than the other stimuli, there were no differences between social phobics and normals in these respects. Thus, the findings lend no support to the idea that social phobics are particularly sensitive to facial cues in general or to negative facial cues in particular.

Adolescent↗
PubMed1989

Selective recall of surprising visual scenes. An experimental note on Seligman and Yellen's theory of dreams.

Seligman and Yellen (Behav. Res. Ther. 25, 1-24, 1987) reported that dream fragments that are unrelated to the preceding fragments of the same dream are recalled as being more vivid and colorful and are remembered in more detail than dream fragments that are plot related and that lack an element of surprise. The authors take this as support for their hypothesis that while one dreams, two distinct types of visualization occur: one consisting of sudden, emotional bursts and the other occurring as a product of cognitive integration. An alternative explanation of Seligman and Yellen's data is that surprisingness of visual scenes is, in itself, sufficient to produce vivid, detailed, and colorful recall. In order to test this alternative hypothesis, 239 volunteers evaluated target slides that were preceded by either related or unrelated slides. When preceded by unrelated slides, the target slide was experienced as more surprising, was forgotten less often, and was evaluated as more colorful, more detailed, and more vivid. It is concluded that the data given by Seligman and Yellen do not constitute unequivocal support for their hypothesis.

Adult↗
PubMed1989

The effect of hypocapnia on extinction of conditioned fear responses.

Conditioning models have been very helpful in the understanding of the etiology and maintenance of anxiety. Such laboratory models, however, leave unexplained why in many cases of naturally occurring anxiety, as in the case of agoraphobia, the fear responses do not extinguish. Literature on experimental anxiety provocation suggests that a systemic alkalosis might play a role in the maintenance of phobic fear. It was hypothesized that a subject in a state of respiratory alkalosis would show delayed extinction to classical conditioned anxiety. In a differential classical conditioning paradigm, consisting of a habituation-, an acquisition-, and an extinction-phase, slides and electric shocks were used as conditioned stimuli (CS) and unconditioned stimuli (US) respectively. The skin conductance response was taken as (U)CR. Subjects were randomly assigned to two groups: hyperventilation or control. It was shown that the extinction was not delayed when subjects were hypocapnic during the extinction. These data support the view that a respiratory alkalosis per se is not a sufficient condition for the maintenance of neurotic fears. The data of the present study are discussed in the context of existing literature on a psychological interpretation of the maintenance of anxiety.

Adult↗
PubMed1989

Conditioning experiences and phobias.

A retrospective study was conducted to examine the extent to which phobias are associated with a conditioning pathway to fear. The Phobic Origin Questionnaire (Ost and Hugdahl, Behav. Res. Ther. 19, 439-477, 1981) was administered to a sample of 91 phobic outpatients (patients with panic disorder with agoraphobia, social phobics, simple phobics). Results show clearly that conditioning experiences occur more frequently than either vicarious or informational, learning experiences, which confirms the findings previously reported by Rimm, Janda, Lancaster, Nahl and Dittmar (Behav. Res. Ther. 15, 231-238, 1977) and by Ost and Hugdahl (1981; Behav. Res. Ther. 21, 623-631, 1983). Yet, conditioning experiences consist mainly of panic attacks in confirmed environments. The findings also suggest that a considerable number of phobias are based on a combination of different pathways to fear.

Adult↗
PubMed1989

Handedness and anxiety in normal and clinical populations.

Previous research has yielded inconclusive evidence as to the relationship between handedness and anxiety. In order to further examine this relationship, two studies were carried out. In the first study, university students (N = 167) completed the Edinburgh Handedness Inventory, the Fear Questionnaire, and the Maudsley Obsessive Compulsive Inventory. No evidence was found to suggest that phobic fears are more prevalent or more severe among individuals with a tendency to left-handedness than among pure right-handers. Statistical tests reveled a marginally significant positive association between social phobia scores and right-handedness. In the second study, handedness was assessed in 77 anxiety disorder patients and compared with handedness patterns in normal controls. Again, no support was found for the claim that anxiety and left-handedness are related to each other. However, the normal pattern of women being more right-handed than men was reversed in the anxiety disorder group.

Adult↗
PubMed1988

The possible relation of the menstrual cycle to susceptibility to fear acquisition.

Biological changes due to the menstrual cycle may account for the fact that fears are not equally distributed between the sexes. In a differential, classical conditioning paradigm, women in premenstrual phase of their menstrual cycles were compared with a control group of women at other points in their cycles except within seven days before menstruation. Electric shock and pictures of natural scenes were used as UCS and CS respectively. Premenstrual women showed an enhanced susceptibility to the acquisition of a conditioned skin conductance response and to delayed extinction, while control women did not. The possible role of an altered physiological state during the premenstrual phase in the acquisition of fear responses is discussed.

Adolescent↗
PubMed1988

Failure to condition evaluative and electrodermal responses to neutral stimuli by means of prepared cues.

To test Gray's proposal (1979, 1982) that prepared cues (snakes, spiders) are unconditioned, innate fear stimuli, a classical conditioning procedure was carried out in which a neutral, conditioned stimulus (CS; slides of flowers, mushrooms or apples) was repeatedly followed by a prepared, unconditioned stimulus (US; slides of snakes or spiders). Dependent variables were subjective evaluation of, and skin conductance responses to the CS slides, while respiration was used as a control variable. In one group of subjects (n = 12), skin conductance was recorded from the left hand, whereas in a second group (n = 11) it was recorded from the right hand. No evidence of skin conductance response - or of evaluative conditioning to the neutral CS as a result of its being paired with the prepared US was found. Thus, the results lend no support to Gray's proposal. No differences in skin conductance responses as a function of left versus right hand recording were found.

Adult↗
PubMedDate not supplied

Covariation bias, classical conditioning, and phobic fear.

The present study investigated whether phobics show an illusory correlation (IC) between phobia-relevant stimuli and aversive events. Nineteen treated and 19 untreated spider phobics were exposed to a series of 72 slides. Three different categories were used: Phobia-relevant slides (spiders), alternative fear-relevant slides (weapons), and neutral slides (flowers). Slides were randomly paired with either a shock, a siren, or nothing at all. All slide/outcome combinations occurred equally frequently. A posteriori recorded contingency estimates indicated that untreated phobics dramatically overestimate the covariation of spiders and shock. On-line recorded outcome expectancies revealed that the bias to overestimate the spider-shock contingency is highly resistant to extinction. The covariation bias was accompanied by differentially heightened electrodermal first interval responses (FIR) and unconditioned electrodermal responses (third interval responses: TIR) on phobia-relevant trials. Treated phobics did not show a covariation bias, indicating that such bias can be modulated by behavioral treatment. The present findings sustain the hypothesis that phobic subjects process information in a fear-confirming way.

Adult↗
PubMedDate not supplied

Individual differences in thought suppression. The White Bear Suppression Inventory: factor structure, reliability, validity and correlates.

The White Bear Suppression Inventory [WBSI; Wegner, D.M. & Zanakos, S. (1994), Journal of Personality, 62, 615-640] is a self-report questionnaire measuring people's general tendency to suppress unwanted negative thoughts. The current article describes two studies investigating the reliability, factor structure, validity, and correlates of the WBSI. Study 1 (n = 172) showed that the WBSI is a reliable instrument in terms of internal consistency and test-retest stability. Factor analyses of the WBSI revealed a 1-factor solution. Furthermore, the WBSI was found to correlate positively with measures of emotional vulnerability and psychopathological symptoms. In Study 2 (n = 40), the relationship between WBSI and levels of intrusive thinking was examined in more detail, using a thought suppression task. In general, results of this thought suppression experiment provided evidence for the validity of the WBSI. That is, subjects with high WBSI scores exhibited higher frequencies of unwanted intrusive thoughts than subjects with low WBSI scores.

Adolescent↗
PubMedDate not supplied

Pathways to fear in spider phobic children.

Twenty-two children with spider phobia were interviewed about the origins of their fear. More specifically, children were asked about conditioning events, modeling experiences, and negative information transmission. To evaluate the reliability of the information provided by the children, parents were independently interviewed about the origins of their children's phobias. While 46% of the children claimed to have always been afraid, 41% ascribed the onset of their fear to aversive conditioning events. The large majority of these events were confirmed by parents. These findings cast doubts on a strong version of the non-associative account of spider phobia, i.e. the idea that spider phobia is acquired in the complete absence of learning experiences.

Adolescent↗
PubMedDate not supplied

A cross-cultural study of animal fears.

The present study represents a cross-cultural study of animal fears in which subjects from seven Western and Asian countries were asked to rate their fear of a range of familiar animals. Factor analyses of these ratings in all samples revealed a coherent three factor solution in which animals fell into a fear-irrelevant, fear-relevant (fierce) or disgust-relevant category. The core group of animals making up the disgust-relevant category were similar across cultures. Some views on how a universal disgust-relevant category of feared animals may have developed are discussed.

Adolescent↗