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G Crombez

Publications and source records attributed to G Crombez.

34 records · Page 2Linked to original sources
PubMed1998

Negative affect, respiratory reactivity, and somatic complaints in a CO2 enriched air inhalation paradigm.

Subjects scoring high on negative affectivity (NA) are known to report more psychosomatic complaints than subjects scoring low. According to the symptom perception hypothesis, high NA subjects attend more to somatic sensations and interpret these as more threatening. We investigated the relationship between NA and psychosomatic complaints in a group of high and low NA subjects (N = 72) in, (a) a questionnaire study, and (b) in a laboratory setting. The latter involved the inhalation of three different gas mixtures (room air, 5.5% and 7.5% CO2-enriched air) while respiratory responses were registered. Subjective complaints were measured after each trial. High NA subjects reported more complaints than low NA subjects in the questionnaire study. However, NA had no main effects on complaints in the laboratory study and did not interact with the effects of gas mixture on complaints. During room air trials, NA correlated only with general arousal complaints when a strong respiratory challenge had not been given before. The pattern of results suggests that experimental inductions of complaints may largely wipe out NA-related differences in attentional/interpretative processes that may mediate the NA complaints link.

Adolescent↗
PubMed1998

When somatic information threatens, catastrophic thinking enhances attentional interference.

Styles of catastrophic thinking about pain have been related to an inability to divert attention away from pain. We investigated whether pain catastrophizers displayed high attentional interference during a threatening low-intensity electrocutaneous stimulus (ES). In Experiment 1, 44 undergraduates performed a tone discrimination task whilst experiencing several times an ES on the left or right arms. Tones were also presented 250 ms and 750 ms after ES onset. Participants were threatened that a high-intensity painful stimulus would occur at one site. As predicted, pain catastrophizers displayed pronounced task interference immediately after threat stimulus onset. In Experiment 2, threat was induced in 36 undergraduates by informing them that an ES excites pain fibres. Again, catastrophizers had marked interference immediately after onset. The results are discussed in terms of how catastrophizing amplifies somatosensory information and primes fear mechanisms.

Adolescent↗
PubMed1998

Avoidance and confrontation of painful, back-straining movements in chronic back pain patients.

Avoidance of painful activities has been proposed to be an important risk factor for the initiation and maintenance of chronic low back suffering, whereas exposure to these activities has been suggested to be beneficial for recovery. In a cross-sectional study, the differences between chronic patients with avoidant and confrontational styles were investigated using self-report measures and a behavioral test. Participants were first classified as avoiders or confronters. In comparison with confronters, avoiders reported greater frequency and duration of pain, higher fear of pain and injury, more disability in daily living, and more attention to back sensations. Finally, avoiders reported more fear of (re)injury during the behavioral test and had a worse performance than confronters. The results suggest a close link between the fear of pain/(re)injury on one hand and avoidance behavior and physical deconditioning on the other hand.

Activities of Daily Living↗
PubMed1998

Extinction in fear conditioning: effects on startle modulation and evaluative self-reports.

A basic feature of human evaluative conditioning is that the reported acquired valence of a previously neutral conditioned stimulus (CS) that has been paired with a valenced unconditioned stimulus (US), is resistant to extinction. The present study investigated whether startle modulation, sometimes presented as an index of acquired valence, reflected this basic feature. In a differential fear conditioning paradigm (n = 38) with an electrocutaneous stimulus as the US, a strong extinction manipulation was conducted by removing the US-electrodes and by extended extinction trials. At the end of extinction, the results corroborated previous findings of evaluative conditioning in that the reported valence for CS+ was still more negative than for CS-, despite disappearance of the differential skin conductance responses. However, startle modulation did not show resistance-to-extinction. Results were discussed in terms of recent conceptualizations of extinction.

Adolescent↗
PubMed1997

Habituation and the interference of pain with task performance.

Pain interrupts, distracts and is difficult to disengage from. In this experiment the attentional interference during pain is studied with a primary task paradigm. We were interested in the strength of attentional interference with repeated presentations of pain. Healthy volunteers (n = 24) performed a tone discrimination task in the presence of two types of distractors (an electrical pain stimulus and a control stimulus) which they were instructed to ignore. On some trials, tone probes were presented immediately (250 ms) after distractor onset, further on (750 ms) during the distractor, and immediately (250 ms) after distractor offset. Habituation of the task interference during the early processing of both the pain and the control stimulus was observed. It was also found that the attentional interference during pain did not completely disappear with repeated presentations. Finally, results clearly showed a more prolonged processing time of the tones during pain trials than during control trials. These results are discussed in terms of cognitive theories of habituation.

Acoustic Stimulation↗
PubMed1997

Attention and somatic awareness in chronic pain.

Empirical methods are used to explore the relationship between chronic pain, somatic awareness and attention. Using a primary task paradigm, 46 chronic pain patients performed an attentionally demanding task. Patients were classified according to self reported pain intensity and the extent of their reporting of the perception of bodily sensations (somatic awareness). Results showed that, as predicted, disruption of attentional performance was most pronounced in those who reported high pain intensity and high somatic awareness. Further analysis revealed that these patients also reported high negative affect. These findings are discussed in terms of their theoretical implications for the concept of hypervigilance and their clinical implications for chronic pain control.

Adult↗
PubMed1997

Startle intensification during painful heat.

Applying affective-motivational theories of emotions to pain presupposes that the immediate emotional reaction to pain can be conceptualized as an action disposition or an urge to escape. According to these emotion theories, an aversive emotional state should potentiate low-level reflexes with a matching affective tone. In line with this view, this study investigated whether the startle reflex, measured as the EMG peak amplitude of the eyeblink to a white noise burst, was intensified during painful heat. Twenty-four healthy volunteers were exposed twice to four heat stimuli (43, 45, 47 and 49 degrees C; 5 s duration). As predicted, an intensification of the startle reflex to the noise burst was observed during the high-intensity stimuli (47 and 49 degrees C) in comparison with the low-intensity stimuli (43 and 45 degrees C). The startle modulation was effective within a limited temporal window. Five seconds after heat offset, the startle intensification had disappeared.

Journal Article↗
PubMed1996

Observational conditioning of food valence in humans.

It has been suggested that the observation of a model consuming a food (CS) and facially expressing either to like or to dislike (US') the food, may be a sufficient condition to bring about a change in the valence of the food for the observer. Unfortunately, up to now this hypothesis has not been investigated in a straightforward manner. In this study, during acquisition, children consumed a series of evaluatively neutral colored and flavored drinks, while simultaneously they watched a videotaped model synchronically drinking identical drinks and facially expressing his evaluation (neutral or dislike) of the liquids. In one condition, the presence of a particular flavor in the drinks was designated to function as the CS+ or the CS-, whereas in the other condition it was the color of the drinks which was the critical CS+ or CS-. Next, the children evaluated a series of drinks containing the critical CSs. A clear evaluative learning effect was obtained when the flavor but not when the color of the drinks was systematically paired with the model's facial expression of dislike. Moreover, the flavor conditioning effect was dependent on the presence in the test drinks of the local context cues (c.q. the colors of the drinks) which were used during acquisition. Finally a double dissociation was observed between explicit beliefs and the "evaluative knowledge" expressed in the ratings of the drinks, in that none of the children in the CS = Flavor groups evidenced any explicit knowledge about the crucial CS-US' contingency but showed evaluative conditioning, whereas the majority of the children in CS = Color groups were aware of the CS-US' relation but failed to demonstrate an evaluative CS-/CS-differentiation.

Attitude↗
PubMed1996

[Pain and fear: a pair apart].

The experience of pain is always affectively negative, and thus often evokes fear. Since the fearful response to pain is not completely determined by the intensity of the pain, dentists should, besides trying to minimize pain, try to minimize this fear. In this article several psychological techniques to achieve that goal are presented and discussed.

Adaptation, Psychological↗
PubMed1994

Sensory and temporal information about impending pain: the influence of predictability on pain.

Theories disagree about whether a verbal warning for pain has a detrimental or beneficial effect on the impact of an actual pain stimulus. Scheme-based theories predict a detrimental effect, whereas more representation-based, stimulus-comparator theories propose a beneficial effect. In this study, the influence of sensory predictability and temporal predictability is investigated. To control for attentional processes and to obtain a behavioral measure of the intrusive character of pain, an auditory discrimination task was introduced. This study firmly demonstrates that information about the painful nature of a heat stimulus does not a priori have detrimental effects on the impact of the stimulus. In fact, conditions in which a pain warning was given displayed a diminished impact in the SCR amplitude as well as in the subjectively reported intensity of the heat stimulus. Informing Ss about the exact time of administration did not add to the impact modulation, but instead resulted in a less-anxious state between signals. Although an overall behavioral disruption, particularly at onset, was observed, the behavioral data did not parallel the results of the two other response systems. Results are discussed in terms of scheme-based models, stimulus-comparator theories and the safety-signal hypothesis.

Adolescent↗
PubMed1992

Human evaluative conditioning: acquisition trials, presentation schedule, evaluative style and contingency awareness.

Two different processes may be operative in human Pavlovian conditioning: signal learning and evaluative learning. Whereas most studies on evaluative conditioning focused on a mere demonstration of the phenomenon or on a theoretical analysis of the underlying processes, some basic parameters of evaluative learning are still unexplored. Hence, using the standard neutral picture--(dis)liked picture pairing paradigm (Baeyens, Eelen & Van den Bergh, 1990), in this study the effect of two parameters of evaluative conditioning was assessed on a between-subjects base, namely the Number of Acquisition Trials (2/5/10/20) and the Presentation Schedule of the stimulus pairs (blockwise or random). Additionally, the study included an exploratory analysis of the potential effects of the Evaluative Style of subjects (Feelers vs Thinkers, operationalized in terms of speed of emitting evaluations). Finally, the relationship between contingency awareness and evaluative learning was reassessed. Neutral-liked conditioning was found to be quadratically related to the number of acquisition trials (increase in effect up to 10 trials, decrease from 10 to 20 trials), whereas neutral-disliked conditioning linearly increased with increasing numbers of trials. Randomized vs blockwise presentation schedules of the stimulus pairs did differentially affect the overall pattern of conditioning, but in a way which was both unexpected and difficult to account for theoretically. Both the Evaluative Style of subjects and contingency awareness were demonstrated to be generally orthogonal to conditioned shifts in CS valence. Based on these findings, some practical suggestions are provided for the application of evaluating conditioning based therapeutical interventions to affective-behavioral disorders which are centred around inappropriate (dis)likes.

Adult↗
PubMed1991

The effects of a single oral dose of lorazepam and alprazolam on reaction times in young healthy volunteers.

Lorazepam (Temesta) and alprazolam (Xanax) are two benzodiazepines which are widely used for their anxiolytic activity. In this study their effect on psychomotor functions was investigated. Eight young healthy volunteers participated in the experiments. Using a double-blind cross-over design, the effect of single oral doses of lorazepam (2.5 mg) and alprazolam (0.5 mg) on a choice reaction time test to visual stimuli (letter pairs presented on a computer screen), were assessed. The experimental procedure consisted of three sessions which differed from each other either by the stimulus presentation rate, or by the presence or absence of a warning signal. In all three sessions, lorazepam, when compared with placebo, significantly prolonged the reaction times (RT), while alprazolam did not. Increasing the interstimulus interval resulted in an equal increase of the reaction times in the three conditions. On the other hand, the introduction of a warning signal which preceded the presentation of the letter pairs, improved performance in the three conditions. This improvement was more pronounced after lorazepam than after placebo. This finding is interpreted as a partial recuperative effect for the impaired performance in the baseline condition after intake of lorazepam.

Administration, Oral↗
PubMed1989

Acquired affective-evaluative value: conservative but not unchangeable.

In a previous study on Evaluative Conditioning it was found that unlike signal-learning, evaluative learning is resistant to extinction. In the present experiment we tried to replicate and corroborate this finding. In addition, we investigated the effectiveness of a counterconditioning procedure to alter acquired evaluative value. On a within-subject base (n = 30), it was found that the mere contingent presentation of neutral with (dis)liked pictures of human faces was sufficient to change the affective-evaluative tone of the originally neutral stimuli in (negative) positive direction. Next, we replicated the finding that an extinction procedure does not have any influence on the acquired evaluative value of the originally neutral stimuli, and this even in subjects fully aware of the extinction presentations. We demonstrated the effectiveness of a counterconditioning procedure to alter acquired evaluative value, and in addition, found some evidence that awareness of the counterconditioning manipulations is not a prerequisite for its effectiveness. The theoretical consequences of these findings are phrased in terms of a fundamental distinction between signal-learning and evaluative learning, and some important implications for the behavioral treatment of affective-emotional disorders are suggested.

Cognition↗
PubMedDate not supplied

Do pain expectancies cause pain in chronic low back patients? A clinical investigation.

The present study investigated whether pain expectancies cause pain in chronic low back patients. Back patients (N = 29) were requested to perform four exercise bouts (two with each leg), each consisting of flexing and extending the knee three times at maximal force (Cybex 350 System). During each exercise bout the baseline pain, the expected pain and experienced pain were recorded. Patients also reported their experienced fear of further injury to the back. Furthermore, the peak force of both knee flexors and extensors was assessed. Although patients did expect a back pain increase during the first exercise bout with each leg, no evidence was found for the thesis that pain expectancies generate increases in subjective pain experiences. Instead, the reported pain expectancy was readily corrected during the next exercise bout, whereas the experienced pain remained unchanged. Furthermore, a high pain expectancy co-occurred with (1) a marginally significant fear of (re)injury, and (2) a significant lower peak torque of the knee flexors. These results are consistent with conditioning models which state that pain expectations are associated with a fear response and an urge to avoid the pain.

Adult↗
PubMedDate not supplied

The disruptive nature of pain: an experimental investigation.

Pain interrupts, distracts and takes effort to ignore. Focusing our research attention upon this central aspect of pain experience, an experimental paradigm is introduced to study the disruptive nature of pain. Healthy volunteers were exposed several times to an electrical pain stimulus and a control stimulus. Tone probes were presented immediately (100 ms) and later on (1500 ms) after pain/control onset, and after pain/control offset (1000 ms). Results clearly showed disruption during pain. This disruptive effect was most marked immediately after onset. No differential results between pain and control conditions were observed later on during the pain experience. These results are interpreted within current cognitive and psychophysiological theories of attention. Emphasis is placed upon the importance of the experimental investigation of the role of attention in pain processing.

Adolescent↗