The determination of optimal exposure to phobic stimuli in flooding therapy

The present study compared the value of various criteria for determining exposure duration to phobic stimuli in flooding therapy. Results indicated that basing exposure termination on a return to resting ranges of HR was not effective in increasing approach behavior, whereas basing termination on observer's judgements was quite effective. Employing self-reported anxiety reduction as the termination criterion was no more effective than using either the HR criterion or a procedure that combined all three criteria (HR, self-report, and observer's judgements). Self-reported fear data showed similar trends with the HR criterion again failing to produce any greater benefits than control procedures. Nine-weeks follow-up indicated a persistence of the behavioral changes with some loss of the gains in subjective anxiety, and a reduction in the differences between groups.     

Effects of experienced disgust on habituation during repeated exposure to threat-relevant stimuli in blood-injection-injury phobia

Despite growing evidence implicating disgust in the etiology of blood-injection-injury (BII) phobia, the relevance of disgust for exposure-based treatment of BII phobia remains largely unknown. Individuals with BII phobia were randomly assigned to a disgust (view vomit videos) or neutral activation (view waterfall videos) condition. They were then exposed to 14 videotaped blood draws, during which fear and disgust levels were repeatedly assessed. Participants then engaged in a behavioral avoidance test (BAT) consisting of exposure to threat-relevant stimuli. Examination of outcome comparing the identical first and last blood-draw clips revealed that fear and disgust toward blood draws was significantly reduced in both groups. Disgust levels were also found to be more intense for the video stimuli relative to fear levels whereas the opposite was true for BAT stimuli. Contrary to predictions, the disgust induction did not enhance reductions in negative responses to the target video or reduce behavioral avoidance. Growth curve analyses did show that individuals with BII phobia exposed to the disgust induction showed greater initial fear levels during repeated exposure than those in the neutral condition. However, this effect was not consistently observed across different analytic approaches. Changes in fear during exposure were also found to be independent of changes in disgust but not vice versa, and greater initial fear levels during repeated exposure to threat was associated with fear and disgust levels during the BAT. The implications of these findings for conceptualizing the role of disgust in etiology and treatment of BII phobia are discussed.     

Affective habituation: subliminal exposure to extreme stimuli decreases their extremity

Following a functional perspective on evaluation, the authors hypothesized that subliminal exposure to extreme stimuli (e.g., extremely negative or positive words) would lead these stimuli to be perceived as less extreme. This process--affective habituation--was tested in 4 experiments. In Experiment 1, participants were subliminally exposed to extremely positive and extremely negative words. In a subsequent explicit-judgment task, these words were rated as less extreme than extreme words that had not been presented. In Experiment 2, these results were replicated with an implicit evaluation measure. In Experiments 3 and 4, subliminal exposure to extreme positive and negative words made the words "behave" as words that are only moderately positive or negative. Several implications are discussed.     

Attention to phobic stimuli during exposure: the effect of distraction on anxiety reduction, self-efficacy and perceived control

To replicate and extend the finding that distraction facilitates between session anxiety reduction (), 27 spider phobics underwent three 10-min sessions of in vivo exposure followed by one 10-min exposure session at a 4-week follow-up, while having either stimulus-relevant focused conversation or stimulus-irrelevant distracting conversation with the experimenter. Physiological arousal and subjective anxiety were measured during exposure, and self-efficacy, perceived control and performance on a behavioural task were measured at pre-treatment, post session-3, and follow-up. Monitoring and blunting coping styles were also measured at pre-treatment to assess their impact on treatment outcome. Despite equal physiological activation between the groups, those who underwent distracted exposure showed greater reductions in subjective fear within and between sessions, and showed greater increases in self-efficacy ratings, internal perceived control and performance on a behavioural task. Coping style did not interact with the effect of distraction or focusing during exposure, however blunters had less subjective anxiety reduction overall, particularly when they underwent focused exposure. Results are discussed in terms of the emotional processing model and self-efficacy theory.     

Processing of phobic stimuli and its relationship to outcome

In the present study, we explored factors related to successful treatment outcome in a sample of participants with fear of spiders. We specifically examined the relationship of general memory, memory for the phobic stimulus, memory for anxious responses, and perceived self-efficacy to treatment outcome. Forty-eight participants who were afraid of spiders participated in two sessions of in vivo exposure therapy. On day 1, participants completed measures of general memory, memory for the phobic stimulus, recall of anxiety level during exposure tasks, and self-efficacy during exposure tasks. At post-treatment, better memory for anxious responses, but not memory for the phobic stimulus, was related to lower anticipatory and actual anxiety. Greater self-efficacy, on the other hand, was related to better behavioral performance.     

Attention allocation and habituation to anger-related stimuli during a visual search task

A substantial amount of data has accumulated demonstrating that emotionally disordered subjects are prone to bias their attention toward threatening, emotionally relevant stimuli. Little attention has been reserved for the study of cognitive processes involved in anger arousal. In the present study, we investigated whether mood-congruent attentional biases could be demonstrated in subjects of varying levels of trait anger using a visual search task. This task also assessed whether mood-congruent biases diminished with repeated exposure to specific emotion stimuli. To investigate state-trait interaction effects, a naturalistic, anger-inducing insult was administered to half the subjects. There was a positive relation between participants' level of trait anger and their degree of mood-congruent attentional bias toward anger-related cues only after an insult. As predicted, this effect diminished across blocks of trials. Aggr. Behav. 24:399–409, 1998. © 1998 Wiley-Liss, Inc.     

The fate of unattended stimuli and emotional habituation: Behavioral interference and cortical changes

The interference produced by the viewing of emotional distractors has been interpreted as evidence that emotional cues are processed in a fairly mandatory fashion, and that they divert attention from the primary ongoing task. However, few studies have examined how behavioral emotional interference varies with repeated presentation of the same emotional distractors. In two experiments, while participants were engaged in a parity judgment task, we investigated the effects of repetition of task-irrelevant emotional pictures, as reflected in both behavioral interference (Experiments 1 and 2) and neural activity (Experiment 2). Both experiments showed that the slowing of reaction times that was observed when viewing emotional, compared to neutral, scenes disappeared after only a few repetitions, suggesting diminished attention allocation to repeated emotional pictures. Conversely, in Experiment 2, neural correlates of picture processing revealed that the late positive potential (LPP) amplitude continued to be enhanced for emotional, compared to neutral, distractors despite picture repetition and the presence of a concurrent task. Altogether, these findings suggest that while evaluative processes are mandatory, and continue to engage cortico-limbic appetitive and defensive systems even after massive repetition, as suggested by the affective modulation of the LPP, attentional processes are not necessary after several repetitions of the same stimulus, as indicated by the rapid decline of behavioral emotional interference.     

Psychophysiological assessment during exposure in driving phobic patients

A comprehensive assessment of fear or anxiety requires measurement of both self-report and physiological responses. Respiratory abnormalities have been rarely examined during real-life exposure, although they are an integral part of fear. Twenty-one women with a specific driving phobia and 17 nonphobic women were psychophysiologically monitored during 2 highway-driving sessions; phobic women completed an additional session. Respiratory movements, end-tidal partial pressure of carbon dioxide, an electrocardiogram, skin conductance, and skin temperature were recorded. Phobic patients differed from control participants both physiologically and experientially before, during, and after exposure. Effect size during exposure was large for the authors' measure of hyperventilation. Discriminant analysis indicated that multiple physiological measures contributed nonredundant information and correctly classified 95% of phobic and control participants. Thus, selected respiratory and autonomic measures are valid diagnostic and therapeutic outcome criteria for this situational phobia.     

Napping promotes inter-session habituation to emotional stimuli

The effects of a daytime nap on inter-session habituation to aversive visual stimuli were investigated. Healthy young adult volunteers viewed repeated presentations of highly negative and emotionally neutral (but equally arousing) International Affective Picture System (IAPS) photographs during two afternoon sessions separated by 2.5h. Half of the photographs were shown at both sessions (Repeated Sets) and half differed between sessions (Novel Sets). For each stimulus presentation, evoked skin conductance response (SCR), heart-rate deceleration (HRD) and corrugator supercilii EMG response (EMG), were computed and range corrected using respective maximum session-1 responses. Following each presentation, subjects rated each photograph on dimensions of pleasantness and arousability. During the inter-session interval, Nap subjects had a 120-min polysomnographically monitored sleep opportunity, whereas Wake subjects watched a non-stimulating video. Nap and Wake subjects did not differ in their subjective ratings of photographs. However, for Repeated-Set photographs, Nap subjects demonstrated greater inter-session habituation in SCR and EMG but a trend toward lesser inter-session habituation in HRD. These group differences were absent for Novel-Set photographs. Group differences across all measures were greater for negative stimuli. Occurrence of SWS during the nap was associated with greater inter-session habituation of EMG whereas occurrence of REM was associated with lesser inter-session habituation of SCR to negative stimuli. Sleep may therefore promote emotional adjustment at the level of somatic responses. Physiological but not subjective inter-session habituation to aversive images was enhanced by a daytime nap.     

Very brief exposure II: the effects of unreportable stimuli on reducing phobic behavior

This experiment compared the effects of exposure to masked phobic stimuli at a very brief stimulus-onset asynchrony on spider-phobic and non-phobic individuals. Participants were identified through a widely used questionnaire and a Behavioral Avoidance Test (BAT) with a live, caged tarantula to establish baseline levels of avoidance. One week later, they were individually administered one of two continuous series of masked images: spiders or flowers. Preliminary masking experiments showed that independent samples of participants from the same populations failed to recognize these stimuli. Participants in the main experiment reported ratings of subjective distress immediately before and after the exposure manipulation. Then they engaged in the BAT once again. Very brief exposure to images of spiders reduced phobic participants' avoidance of the tarantula. No effects were evidenced on subjective distress, or on non-phobic participants. Theoretical implications for the non-conscious basis of fear are discussed.     

Simulation of the filtering role of habituation to stimuli

In the context of a medium-term study designed to integrate the simulation of different types and processes of learning-such as classical, operant, and some cognitive types--one must start with other more elementary ones that are facilitators of the more complex types and processes. Of special interest is habituation, owing to the filtering out of irrelevant stimuli, which means that the simulated agent does not have to respond to them. This paper presents two difference functions constructed to computationally simulate the characteristics that define habituation. The behavior of these functions is described, as are differences arising from stimulus intensity and interstimulus intervals. Results are compared with existing empirical data.     

Extraversion and the orienting reaction habituation rate to visual stimuli

Eysenck's (1967) proposal that introversion is characterized by increased levels of activity in the cortico-reticular loop was treated in a series of experiments which compared high, middle, and low extraversion groups on the basis of OR habituation rate to visual stimulation. Generally, introverts were observed to have longer OR habituation rates to chromatic and word stimulation than extraverts as evidenced by cardiac, electrodermal, and vasomotor indices of habituation rate, a result which endorses Eysenck's hypothesis. Results are also discussed from the standpoint of individual differences in autonomic response.     

Eye movements and behavioral responses to threatening and nonthreatening stimuli during visual search in phobic and nonphobic subjects

Spider-phobic and nonphobic subjects searched for a feared/fear-relevant (spider) or neutral target (mushroom) presented in visual matrices of neutral objects (flowers). In half of the displays, the mushroom target was paired with a spider distractor, or a spider target was paired with a mushroom distractor. Although all subjects responded faster to the neutral target than to the feared/fear-relevant target, phobics were slower to respond than nonphobics when a mushroom target was presented with a spider distractor. Their eyes appeared to be drawn to the feared distractor before fixating neutral targets. A further experiment indicated no group differences when subjects merely judged the homogeneity of matrices. Thus, threat seems to capture the attention of phobics only when it is part of a background that subjects are explicitly instructed to ignore.     

Electrodermal conditioning to potentially phobic stimuli: Effects of instructed extinction

It was hypothesized that electrodermal responses to potentially phobic stimuli “conditioned” through verbal threats about an aversive UCS should be equally resistant to instructed extinction as the responses obtained by actual CS-UCS pairings. Two groups of human subjects were exposed to pictures of either snakes and spiders (phobic CSs), or circles and triangles (neutral CSs) in a differential Pavlovian conditioning paradigm. Changes in skin conductance were recorded. Half of the subjects in each group were threatened with a shock-UCS while the other half were given shock-reinforced CS presentations. At the onset of extinction, all subjects in each of the four groups were informed that no more UCSs were to be delivered, and the shock electrodes were removed. All groups showed evidence of conditioning during acquisition. During extinction there was an immediate drop in responding in the two neutral groups, whereas the two phobic groups showed reliable evidence of resistance to extinction, with no differences between the threatened- and the CS-UCS-group. The observed resistance to extinction found in the phobic groups implies a similarity to the irrationality of real-life phobias. Furthermore, the data are in accordance with analysis of electrodermal fear-conditioning as a case of prepared learning.     

Resistance to extinction following habituation to behaviourally disruptive novel stimuli

Three experiments tested the prediction, derived from generalized frustration theory (Amsel, 1972), that habituation to behaviourally disruptive stimuli increases resistance to extinction in the runway. In each experiment, rats received initial consistent reinforcement (CRF) training and then either continued CRF (Groups C), partial reinforcement (PRF) training (Groups P), or CRF accompanied by presentations of a novel tactile, tone, or obstacle stimulus (Groups D) in Experiments 1-3, respectively. PRF increased resistance to extinction whether non-reinforcement disrupted behaviour (Experiment 1) or not (Experiments 2 and 3). The tactile and obstacle stimuli very substantially disrupted behaviour, and the tone produced a modest disruption of behaviour. All subjects habituated to the disruptive effects of these stimuli, but Group D was not more resistant to extinction than Group C in any experiment. The results suggest that non-reinforcement has unique stimulus properties, a consequence of which is that habituation to other sources of disruptive stimulation does not promote responding to non-reinforcement in extinction.     

Self-implication and heart rate variability during simulated exposure to flight-related stimuli

In the present study, the relationship between self-implication during simulated exposure to feared stimuli and Heart Rate Variability (HRV) was explored within the framework of the dynamical systems model of emotion regulation proposed by Thayer and Lane (Thayer, J.F., and Lane, R.D. (2000). A model of neurovisceral integration in emotion regulation and dysregulation. Journal of Affective Disorders, 61, 201–216.). An analogue sample of flight phobics (n=15) and a matched non-phobic control group (n=15) were presented with flight-related pictures, flight-related sounds or flight-related pictures and sounds. Significant differences on self-implication during exposure to flight-related sounds were found between low and high HRV fearful flyers, the former being more self-implied. However, the expected HRV decreases in the phobic participants exposed to feared stimuli were not found. These results emphasize the need to distinguish between high and low HRV fearful flyers in order to make a better use of the simulated exposure treatments.