Preattentive processing, preparedness and phobias: effects of instruction on conditioned electrodermal responses to masked and non-masked fear-relevant stimuli

Transition ability to safe states reduces fear responses to height

Previous studies on fear extinction have primarily focused on repeated exposure to fear-inducing context without negative consequences. However, it is also possible that an individual can reduce fear responses by predicting that they can transition to a safe environment through their own actions, even if a fear-inducing context appears. Here, by conducting two virtual reality (VR) experiments (Exp 1 and Exp 2) involving height and flight scenarios, we examined whether participants' fear responses to height decrease after actively experiencing low-altitude VR flight, which allowed them to predict that they would be in a safe state by flying even if they fell from a height. Specifically, participants in the flight group (n = 44 and 46) flew over a city at altitudes below 5 m for 7 min, while participants in the control group (n = 41 and 28) watched a video of a flight group participant's experience. Before and after the active flight or passive viewing task, both groups walked on a plank while having their skin conductance response (SCR) and subjective fear score (SFS) measured. In both Exp 1 and Exp 2, the active flight group exhibited a greater reduction in both SCR and SFS compared to the control group. Additionally, a multivariate regression of SCR using the questionnaires collected in Exp 2 revealed that the action-dependent safety prediction has a positive contribution to the SCR reduction in the flight group. These results clarified that the ability to transition to safe states by self-actions can reduce physiological and subjective fear responses.

Handedness and anxiety: a review

Handedness is a core phenotype in clinical laterality research and several different disorders such as schizophrenia and autism spectrum disorders have been linked to a higher prevalence of non-right-handedness. Moreover, subclinical personality traits like schizotypy have been linked to a higher prevalence of non-right-handedness. The association with handedness is poorly understood for generalized anxiety disorder and specific phobias, as well as for state and trait anxiety and fear of specific stimuli in nonclinical samples. Therefore, we performed a narrative review of studies investigating handedness in anxiety disorders patients and studies that compared anxiety scores between different handedness groups. Unlike schizophrenia and autism spectrum disorders, there seems to be no strong association between anxiety disorders and handedness in adult patients, except for specific phobias. Studies often had small sample sizes and therefore a high risk to report spurious findings. Similar findings were reported in most non-clinical studies. Importantly, familial handedness affects phobia risk and antenatal maternal anxiety increased the probability of mixed-handedness. This suggests that a transgenerational, developmental perspective is essential to better understand the complex interrelations between handedness and anxiety. Familial and especially maternal handedness and anxiety disorders should be integrated into future studies on handedness and anxiety whenever possible.

Angry and fearful compared to happy or neutral faces as conditional stimuli in human fear conditioning: A systematic review and meta-analysis

Some previous research has shown stronger acquisition and impaired extinction of fear conditioned to angry or fearful compared to happy or neutral face conditional stimuli (CS) - a difference attributed to biological 'preparedness'. A systematic review and meta-analysis of fear conditioning studies comparing face CSs of differing expressions identified thirty studies, eighteen of which were eligible for meta-analysis. Skin conductance responses were larger to angry or fearful faces compared to happy or neutral faces during habituation, acquisition and extinction. Significant differences in differential conditioning between angry, fearful, neutral, and happy face CSs were also found, but differences were more prominent between angry and neutral faces compared to angry/fearful and happy faces. This is likely due to lower arousal elicited by neutral compared to happy faces, which may be more salient as CSs. The findings suggest there are small to moderate differences in differential conditioning when angry or fearful compared to happy or neutral faces are used as CSs. These findings have implications for fear conditioning study design and the preparedness theory.

Venomous snakes elicit stronger fear than nonvenomous ones: Psychophysiological response to snake images

Snakes have been important ambush predators of both primates and human hunter-gatherers throughout their co-evolutionary history. Viperid snakes in particular are responsible for most fatal venomous snakebites worldwide and thus represent a strong selective pressure. They elicit intense fear in humans and are easily recognizable thanks to their distinctive morphotype. In this study, we measured skin resistance (SR) and heart rate (HR) in human subjects exposed to snake pictures eliciting either high fear (10 venomous viperid species) or disgust (10 nonvenomous fossorial species). Venomous snakes subjectively evaluated as frightening trigger a stronger physiological response (higher SR amplitude) than repulsive non-venomous snakes. However, stimuli presented in a block (more intense stimulation) do not trigger a stronger emotional response compared to sequentially presented stimuli (less intense stimulation). There are significant interindividual differences as subjects with high fear of snakes confronted with images of viperid snakes show stronger, longer-lasting, and more frequent changes in SR and higher HR compared to low-fear subjects. Thus, we show that humans demonstrate a remarkable ability to discriminate between dangerous viperids and harmless fossorial snakes, which is also reflected in distinct autonomous body responses.

"Prepared" fear or socio-cultural learning? Fear conditioned to guns, snakes, and spiders is eliminated by instructed extinction in a within-participant differential fear conditioning paradigm

Across three experiments, we investigated whether electrodermal responses conditioned to ontogenetic fear-relevant (pointed guns) and phylogenetic fear-relevant stimuli (snakes and spiders) would resist instructed extinction in a within-participant differential fear conditioning paradigm. Instructed extinction involves informing participants before extinction that the unconditional stimulus (US) will no longer be presented. This manipulation has been shown to abolish fear conditioned to fear-irrelevant conditional stimuli, but is said to leave fear conditioned to images of snakes and spiders intact. The latter finding, however, has only been demonstrated when fear-relevance is manipulated between-groups. It is also not known whether instructed extinction affects fear conditioned to ontogenetic fear-relevant stimuli, such as pointed guns. In Experiment 1, we demonstrated that fear conditioned to images of pointed guns does not resist instructed extinction. In Experiment 2, we detected some evidence to suggest that fear conditioned to images of snakes and spiders survives instructed extinction but this evidence was not conclusive. In Experiment 3, we directly compared the effects of instructed extinction on fear conditioned to snakes and spiders and to guns and provide strong evidence that fear conditioned to both classes of stimuli is reduced after instructed extinction with no differences between ontogenetic and phylogenetic stimuli. The current results suggest that when fear relevance is manipulated within-participants fear conditioned to both phylogenetic and ontogenetic, fear-relevant stimuli responds to instructed extinction providing evidence in favor of a socio-cultural explanation for "preparedness" effects.

Cooperate or not cooperate EEG, autonomic, and behavioral correlates of ineffective joint strategies

Introduction

The neural activity in response to ineffective joint actions was explored in the present study. Subjects involved in a cooperative but frustrating task (poor performance as manipulated by an external feedback) were required to cooperate (T1) during an attentional task in a way to synchronize their responses and obtain better outcomes.

Methods

We manipulated their strategies by providing false feedbacks (T2) signaling the incapacity to create a synergy, which was reinforced by a general negative evaluation halfway through the game. A control condition was provided (no cooperation required, T0) as well as a check for possible learning effect (time series analysis). The effects of the feedback in modulating subjects' behavioral performance and electrocortical activity were explored by means of brain oscillations (delta, theta, alpha, beta) and autonomic activity (heart rate, HR; skin conductance activity, SCR).

Results

Results showed a specific pattern of behavioral, neural, and peripheral responses after the social feedback. In fact, within this condition, worse behavioral outcomes emerged, with longer response times with respect to the prefeedback one. In parallel, a specific right-lateralized effect was observed over the dorsolateral prefrontal cortex (DLPFC), with increased delta and theta power compared to the previous condition. Moreover, increased SCR was observed with respect to the first part.

Conclusions

Two interpretations are put forward to explain the present findings: 1) the contribution of negative emotions in response to failing interactions or 2) a motivational disengagement toward goal-oriented cooperation elicited by frustrating evaluations.

Don't fear 'fear conditioning': Methodological considerations for the design and analysis of studies on human fear acquisition, extinction, and return of fear

The so-called 'replicability crisis' has sparked methodological discussions in many areas of science in general, and in psychology in particular. This has led to recent endeavours to promote the transparency, rigour, and ultimately, replicability of research. Originating from this zeitgeist, the challenge to discuss critical issues on terminology, design, methods, and analysis considerations in fear conditioning research is taken up by this work, which involved representatives from fourteen of the major human fear conditioning laboratories in Europe. This compendium is intended to provide a basis for the development of a common procedural and terminology framework for the field of human fear conditioning. Whenever possible, we give general recommendations. When this is not feasible, we provide evidence-based guidance for methodological decisions on study design, outcome measures, and analyses. Importantly, this work is also intended to raise awareness and initiate discussions on crucial questions with respect to data collection, processing, statistical analyses, the impact of subtle procedural changes, and data reporting specifically tailored to the research on fear conditioning.

Glucocorticoid Administration Improves Aberrant Fear-Processing Networks in Spider Phobia

Glucocorticoids reduce phobic fear in patients with anxiety disorders. Previous studies have shown that fear-related activation of the amygdala can be mediated through the visual cortical pathway, which includes the fusiform gyrus, or through other pathways. However, it is not clear which of the pathways that activate the amygdala is responsible for the pathophysiology of a specific phobia and how glucocorticoid treatment alleviates fear processing in these neural networks. We recorded the brain activity with functional magnetic resonance imaging in patients with spider phobia, who received either 20 mg of cortisol or a placebo while viewing pictures of spiders. We also tested healthy participants who did not receive any medication during the same task. We performed dynamic causal modelling (DCM), a connectivity analysis, to examine the effects of cortisol on the networks involved in processing fear and to examine if there was an association between these networks and the symptoms of the phobia. Cortisol administration suppressed the phobic stimuli-related amygdala activity to levels comparable to the healthy participants and reduced subjective phobic fear. The DCM analysis revealed that cortisol administration suppressed the aberrant inputs into the amygdala that did not originate from the visual cortical pathway, but rather from a fast subcortical pathway mediated by the pulvinar nucleus, and suppressed the interactions between the amygdala and fusiform gyrus. This network changes were distinguishable from healthy participants and considered the residual changes under cortisol administration. We also found that the strengths of the aberrant inputs into the amygdala were positively correlated with the severity of spider phobia. This study demonstrates that patients with spider phobia show an aberrant functional connectivity of the amygdala when they are exposed to phobia-related stimuli and that cortisol administration can alleviate this fear-specific neural connectivity.

The Body and the Brain: Measuring Skin Conductance Responses to Understand the Emotional Experience

In this article, we introduce the method of measuring skin conductance responses (SCR) reflecting peripheral (bodily) signals associated with emotions, decisions, and eventually behavior. While measuring SCR is a well-established, robust, widely used, and relatively inexpensive method, it has been rarely utilized in organizational research. We introduce the basic aspects of SCR methodology and explain the behavioral significance of the signal, especially in connection with the emotional experience. Importantly, we describe in detail a specific research protocol (fear conditioning) that serves as an illustrative example to support the initial steps for organizational scholars who are new to the method. We also provide the related scripts for stimulus presentation and basic data analysis, as well as an instructional video, with the aim to facilitate the dissemination of SCR methodology to organizational research. We conclude by suggesting potential future research questions that can be addressed using SCR measurements.

Instructed fear learning, extinction, and recall: additive effects of cognitive information on emotional learning of fear

The effects of instruction on learning of fear and safety are rarely studied. We aimed to examine the effects of cognitive information and experience on fear learning. Fourty healthy participants, randomly assigned to three groups, went through fear conditioning, extinction learning, and extinction recall with two conditioned stimuli (CS+). Information was presented about the presence or absence of conditioned stimulus-unconditioned stimulus (CS-US) contingency at different stages of the experiment. Information about the CS-US contingency prior to fear conditioning enhanced fear response and reduced extinction recall. Information about the absence of CS-US contingency promoted extinction learning and recall, while omission of this information prior to recall resulted in fear renewal. These findings indicate that contingency information can facilitate fear expression during fear learning, and can facilitate extinction learning and recall. Information seems to function as an element of the larger context in which conditioning occurs.

Updated meta-analysis of classical fear conditioning in the anxiety disorders

The aim of the current study was twofold: (1) to systematically examine differences in fear conditioning between anxiety patients and healthy controls using meta-analytic methods, and (2) to examine the extent to which study characteristics may account for the variability in findings across studies. Forty-four studies (published between 1920 and 2013) with data on 963 anxiety disordered patients and 1,222 control subjects were obtained through PubMed and PsycINFO, as well as from a previous meta-analysis on fear conditioning (Lissek et al.). Results demonstrated robustly increased fear responses to conditioned safety cues (CS-) in anxiety patients compared to controls during acquisition. This effect may represent an impaired ability to inhibit fear in the presence of safety cues (CS-) and/or may signify an increased tendency in anxiety disordered patients to generalize fear responses to safe stimuli resembling the conditioned danger cue (CS+). In contrast, during extinction, patients show stronger fear responses to the CS+ and a trend toward increased discrimination learning (differentiation between the CS+ and CS-) compared to controls, indicating delayed and/or reduced extinction of fear in anxiety patients. Finally, none of the included study characteristics, such as the type of fear measure (subjective vs. psychophysiological index of fear), could account significantly for the variance in effect sizes across studies. Further research is needed to investigate the predictive value of fear extinction on treatment outcome, as extinction processes are thought to underlie the beneficial effects of exposure treatment in anxiety disorders.

From threat to safety: instructed reversal of defensive reactions

Cues that signal the possibility of receiving an electric shock reliably induce defensive activation. To determine whether cues can also easily reverse defensive reactions, a threat reversal paradigm was developed in which a cue signaling threat of shock reversed its meaning across the course of the study. This allowed us to contrast defensive reactions to threat cues that became safe cues, with responses to cues that continued to signal threat or safety. Results showed that, when participants were instructed that a previously threatening cue now signaled safety, there was an immediate and complete attenuation of defensive reactions compared to threat cues that maintained their meaning. These findings highlight the role that language can play both in instantiating and attenuating defensive reactions, with implications for understanding emotion regulation, social communication, and clinical phenomena.

Unconscious Learning. Conditioning to Subliminal Visual Stimuli

The role of consciousness in Pavlovian conditioning was examined in two experiments in which visually masked neutral words were used as the conditioned stimuli (CS) and an electric shock as the unconditioned stimulus (US). The inter-stimulus interval (ISI) was established individually. A detection threshold was used in Experiment 1 and an identification threshold in Experiment 2. The primary dependent variable was the skin conductance response (SCR). Results showed that the conditioned response (CR) was acquired by 58% of participants who perceived stimuli above the identification threshold, 50% of participants who perceived stimuli below the detection threshold, and 11% of participants who perceived stimuli below the identification threshold, but above the detection threshold. These results suggest that consciousness of the CS-US contingency is not a necessary condition for acquiring a CR of the autonomous nervous system (ANS).

The role of "interoceptive" fear conditioning in the development of panic disorder

More than 20% of the general population experience a panic attack at least once in their lives; however, only a minority goes on to develop panic disorder (PD). Conditioning mechanisms have been proposed to explain this evolution in persons who are susceptible to developing panic disorder upon a "traumatic" panic attack. According to preparedness theory, some cues are more likely to condition than others, namely, those referring to internal, bodily signals of danger. The aim of the present study was to test this theory in a differential conditioning paradigm, making use of scripts referring to different internal, bodily sensations as conditioned stimulus (CS) and inhalation of 35% CO(2) as unconditioned stimulus (UCS). Thirty-three healthy volunteers were assigned to three scripts conditions: "suffocation," "neutral," or "urgency." During acquisition, one of two versions of a particular script was always followed by an inhalation of 35% CO(2) (CS+) and the other by room air (CS-). Acquisition was followed by a test phase, where only inhalations of room air were administered. In line with our hypothesis, only participants in the suffocation condition exhibited a selective conditioning effect. They were more fearful and showed a significantly higher increase in tidal volume than participants in the two control conditions. Results are discussed with relation to interoceptive conditioning, preparedness, and the possible role of tidal volume in PD.

Amygdala activation to threat under attentional load in individuals with anxiety disorder

Background

Previous studies in healthy subjects have shown that strong attentional distraction prevents the amygdala from responding to threat stimuli. Here, we investigated the effects of attentional load on amygdala activation to threat-related stimuli in individuals suffering from an anxiety disorder.

Methods

During functional magnetic resonance imaging, spider-phobicand healthy control subjects were presented with phobia-related and neutral stimuli while performing a distraction task with varying perceptual load (high vs low).

Results

Our data revealed a pattern of simultaneously increased amygdala and visual cortical activation to threat vs neutral pictures in phobic individuals, compared with controls, occurring regardless of attentional load.

Conclusions

These results suggest that, in contrast to studies in healthy subjects, amygdala activation to clinically relevant threat stimuli is more resistant to attentional load.

Emotion processing without awareness: features detection or significance evaluation?

Studies on the physiological responses to emotional stimuli demonstrated that they can occur even when emotional stimuli are not consciously perceived. In this study, the subliminal stimulation was obtained by means of Backward Masking. Specifically, we analyzed the cardiac and electrodermal responses evoked by the unmasked and masked presentation of spider shapes in arachnophobic individuals. To evaluate whether unaware processing entails discrimination of physical features vs emotional significance, crabs, morphologically similar to the spiders but different for emotional significance, and squirrels, different in both shape and emotional content, were also employed. The response to unmasked spiders consisted of a typical defense response (sympathetic activation), while that to innocuous stimuli of an orienting response (moderate electrodermal and vagal activations). In the subliminal condition, the electrodermal response to masked spiders was greater than that to the other animals suggesting an early detection of emotional content rather than of physical characteristics. In contrast, cardiac responses to the masked stimuli did not show any differences as a function of valence. These findings suggest that individuals can appraise the emotional content of unconsciously perceived stimuli and react with an arousal response. However, subliminal emotional stimuli does not seem able to elicit the complete pattern of autonomic responses typical of the defense response.

Aversive Conditioning under Conditions of Restricted Awareness: Effects on Spatial Cueing

In the literature on aversive conditioning there is still debate on the role of awareness. According to some authors, affective learning can occur with or without contingency learning (dual-process model), whereas others argue that a single process produces both affective responses and contingency knowledge. Although many studies have investigated these models, the results to date are inconclusive. Based on a review of the literature, a new series of experiments was designed to examine aversive conditioning in the absence of contingency awareness. In the present study we examined the effects of subliminal aversive conditioning on a spatial cueing task. Awareness was stringently tested after conditioning. Three kinds of awareness were distinguished: contingency awareness (awareness of the CS−US contingencies, where CS is the conditioned stimulus, and US is the unconditioned stimulus), perceptual awareness (awareness of the perceptual differences between the CSs), and US expectancy (awareness of a threat feeling when confronted with the CS+, but not when confronted with the CS−). The results of three experiments demonstrated that responses on the spatial cueing task were modulated by subliminal aversive conditioning. Importantly, none of the participants was contingency aware or able to perceptually discriminate between the conditioned stimuli. However, in Experiment 3, only those participants showing some level of postconditioning expectancy awareness exhibited conditioning effects. These experiments suggest that subliminal aversive conditioning produces small but significant effects, which may be modulated by expectancy awareness.

Responses conditioned to fear-relevant stimuli survive extinction of the expectancy of the UCS

Davey suggests that increased resistance to extinction of CRs conditioned to fear-relevant stimuli may be due to more persistent expectancies of the UCS following these stimuli. However, this viewpoint is contradicted by existing empirical evidence that fear-relevant CRs survive an extinction trials series producing extinction of expectancies whereas CRs conditioned to non-fear-relevant CSs do not.

Eggs in more than one basket: Mediating mechanisms between evolution and phobias

The evolutionary origin of phobias is strongly supported by behavioral genetics and monkey vicarious conditioning data. Prepared Pavlovian conditioning may be only one of the mechanisms mediating the evolutionarily determined outcome in phobias, avoidance. Davey's alternative biased expectancy hypothesis has merit in accounting for some aspects of laboratory data, but it is insufficient to explain the unconscious origin of phobic fear.

Preparedness, phobias, and the Panglossian paradigm

In his critique of preparedness theory, Davey does not address the limitations of adaptationism. The purpose of this commentary is to outline problems that arise when one assumes that mental illness (e.g., phobic disorder) must have had adaptive significance for it to have survived the vicissitudes of natural selection.

Natural selection and fear regulation mechanisms

Expectations can facilitate rapid fear conditioning and this may explain some phenomena that have been attributed to preparedness. However, preparedness remains the best explanation for some aspects of clinical phobias and the difficulty of creating fears of modern dangers. Rapid fear conditioning based on expectancy is not an alternative to an evolutionary explanation, but has, like preparedness, been shaped by natural selection.

Innateness versus expectation in human fears: Causal versus maintaining factors?

This commentary focuses upon two issues raised by Davey's target article: (1) whether there are certain core features of stimuli we learn to fear, rather than specific types of objects or situations, which implies some element of innateness; and (2) whether expectancy biases serve to maintain rather than generate anxiety.

Expectancy bias as sole or partial account of selective associations?

Davey reviews evidence purporting to distinguish between two accounts of selective associations – expectancy bias and evolved predispositions, although these hypotheses largely apply to different levels of causal analysis. Criticisms of primate studies in which subjects lack prior exposure to stimuli seem uncompelling. Expectancies may sometimes serve as proximal mediators in selective associations, but other factors, both proximate and ultimate, are clearly also involved.

The uneven distribution of fears and phobias: A nonassociative account

A review of data concerning the uneven distribution of phobias suggests that nonassociative, ethological models can account for most of tile important findings that cannot be attributed to expectancy biases. The origin of a variety of fears that appear in fixed developmental patterns across divergent cultures and species can best be explained by biological models.

Preparedness and phobias: Specific evolved associations or a generalized expectancy bias?

Most phobias are focussed on a small number of fear-inducing stimuli (e.g., snakes, spiders). A review of the evidence supporting biological and cognitive explanations of this uneven distribution of phobias suggests that the readiness with which such stimuli become associated with aversive outcomes arises from biases in the processing of information about threatening stimuli rather than from phylogenetically based associative predispositions or “biological preparedness.” This cognitive bias, consisting of a heightened expectation of aversive outcomes following fear-relevant stimuli, generates and maintains robust learned associations between them. Some of the features of such stimuli which determine this expectancy bias are estimates of how dangerous they are, the semiotic similarity between them and their aversive outcomes, and the degree of prior fear they elicit. Ontogenetic and cultural factors influence these features of fear-relevant stimuli and are hence important in determining expectancy bias. The available evidence does not exclude the possibility that both expectancy biases and specific evolved predispositions coexist, but the former can explain a number of important findings that the latter cannot.

A stochastic optimality theory of preparedness and plasticity

Many now consider “instinct” and “learning” opposite poles of a unidimensional continuum. An alternative model with two independently varying parameters predicts different selective pressures. Behavioral adaptation matches the organism's utilizations of stimuli and responses to their ecological validities: the mean validity over evolutionary time specifies the optimal initial potency of the prepared association; the variance specifies the optimal prepared plasticity.

Fear generalization in humans: impact of verbal instructions

Fear generalization lies at the heart of many anxiety problems, but little is known about the factors that can influence this phenomenon. The present study investigated whether verbal instructions about specific stimulus features can influence conditioned fear generalization. All participants were fear conditioned to a yellow triangle, using an electric shock. Participants had received pre-experimental instructions saying that the shapes (or colours) of the stimuli were informative for the occurrence of shock (group Shape and group Colour, respectively). Next, generalization was tested to presentations of a blue triangle (same shape) as well as a yellow square (same colour). Fear reactions were measured through skin conductance and online ratings of shock-expectancy. The results showed strongest generalization to the same shape stimulus in group Shape, versus the same colour stimulus in group Colour. Hence, the same learning experience can have opposite effects in terms of fear generalization, depending on verbally transmitted information about the relative importance of individual stimulus features.

Unconscious processing of facial affect in children and adolescents

In a previous study, with adults, we demonstrated that the amygdala and anterior cingulate gyrus are differentially responsive to happy and sad faces presented subliminally. Because the ability to perceive subtle facial signals communicating sadness is an important aspect of prosocial development, and is critical for empathic behavior, we examined this phenomenon from a developmental perspective using a backward masking paradigm. While undergoing functional magnetic resonance imaging (fMRI), 10 healthy adolescent children were presented with a series of happy and sad facial expressions, each lasting 20 ms and masked immediately by a neutral face to prevent conscious awareness of the affective expression. Relative to fixation baseline, masked sad faces activated the right amygdala, whereas masked happy faces failed to activate any of the regions of interest. Direct comparison between masked happy and sad faces revealed valence specific differences in the anterior cingulate gyrus. When the data were compared statistically to our previous sample of adults, the adolescent group showed significantly greater activity in the right amygdala relative to the adults during the masked sad condition. Groups also differed in several non-hypothesized regions. Development of unconscious perception from adolescence into adulthood appears to be accompanied by reduced activity within limbic affect processing systems, and perhaps increased involvement of other cortical and cerebellar systems.

Skin conductance responses to masked conditioned stimuli: Phylogenetic/ontogenetic factors versus direction of threat?

Evolutionarily old threat stimuli are likely to require less conscious information processing than threat stimuli of a more recent date. To test this proposal two differential conditioning experiments, with biological threat stimuli (e.g. snakes) in half the groups and cultural threat stimuli (e.g. guns) in the other half, were conducted. The conditioned (CS+) and the control (CS-) stimuli were backward masked during the extinction phase to prevent conscious recognition. The differential skin conductance responding for both biological and cultural threat stimuli survived the masking procedure when the conditioned stimuli were directed towards the participants (Experiment 1), but for neither type of CS when stimuli were not directed towards the participants (Experiment 2). These findings are discussed in relation to the previous finding by Ohman and co-workers and in relation to imminence of threat.

Cognitive vulnerability: a model of the etiology of fear

This paper attempts to fill the partial theoretical vacuum surrounding the understanding of fear acquisition. A review of recent and contemporary theories of the etiology of fear is presented, serving as a justification for further theorizing and allowing for greater understanding of those aspects of fear that remain to be adequately explained. A new model of the etiology of specific fears is subsequently put forward and the various aspects and implications of this model are discussed. How an individual perceives a stimulus is proposed as being critical in determining fear in relation to the stimulus. In particular, perceptions of the stimulus as uncontrollable, unpredictable, dangerous and disgusting create a schema of vulnerability. The Cognitive Vulnerability Model integrates much of the extensive body of research on fears and specific phobias into a unifying theory of the etiology of fear. The model offers parsimonious explanations for the various characteristics of specific fears and phobias.

Emotional Conditioning to Masked Stimuli and Modulation of Visuospatial Attention

Two studies investigated the effects of conditioning to masked stimuli on visuospatial attention. During the conditioning phase, masked snakes and spiders were paired with a burst of white noise, or paired with an innocuous tone, in the conditioned stimulus (CS)+ and CS- conditions, respectively. Attentional allocation to the CSs was then assessed with a visual probe task, in which the CSs were presented unmasked (Experiment 1) or both unmasked and masked (Experiment 2), together with fear-irrelevant control stimuli (flowers and mushrooms). In Experiment 1, participants preferentially allocated attention to CS+ relative to control stimuli. Experiment 2 suggested that this attentional bias depended on the perceived aversiveness of the unconditioned stimulus and did not require conscious recognition of the CSs during both acquisition and expression.

Autonomic responding to aversive words without conscious valence discrimination

A growing body of data suggests that the emotional dimension of a stimulus can be processed without conscious identification of the stimulus. The arousal system could be activated by unrecognised biologically significant stimuli through simple physical stimulus features related to threat, without any evaluation of the meaning of the stimulus. However, unconscious processing of emotionally laden words cannot rely only on perceptual features but must include some analysis of symbolic meaning. The first aim of the present study was to assess whether masked (unrecognised) aversive words can elicit enhanced skin conductance responses (SCRs), a major autonomic index of emotional arousal, in normal participants. Our second aim was to determine whether any autonomic activation related to affective value of words is independent from access of this value to consciousness. Thus, the presentation duration of masked aversive and neutral words was determined, for each participant, in such a way that (1) identification was precluded, (2) valence discrimination was at chance, as indicated by performance in a forced-choice two-alternative task and by confidence ratings of the responses, and (3) emotional and neutral words were not detected differentially. SCRs were recorded during masked and unmasked presentations of both types of word. SCRs elicited by unmasked words, and also by masked words, were of greater magnitude when the words were emotional than when they were neutral. Consequently, in normal participants, autonomic activation can be a discriminative marker of the affective dimension of unrecognised verbal material in the absence of conscious valence identification.

Activity in ventromedial prefrontal cortex covaries with sympathetic skin conductance level: a physiological account of a “default mode” of brain function

We examined neural activity related to modulation of skin conductance level (SCL), an index of sympathetic tone, using functional magnetic resonance imaging (fMRI) while subjects performed biofeedback arousal and relaxation tasks. Neural activity within the ventromedial prefrontal cortex (VMPFC) and the orbitofrontal cortex (OFC) covaried with skin conductance level (SCL), irrespective of task. Activity within striate and extrastriate cortices, anterior cingulate and insular cortices, thalamus, hypothalamus and lateral regions of prefrontal cortex reflected the rate of change in electrodermal activity, highlighting areas supporting transient skin conductance responses (SCRs). Successful performance of either biofeedback task (where SCL changed in the intended direction) was associated with enhanced activity in mid-OFC. The findings point to a dissociation between neural systems controlling basal sympathetic tone (SCL) and transient skin conductance responses (SCRs). The level of activity in VMPFC has been related to a default mode of brain function and our findings provide a physiological account of this state, indicating that activity within VMPFC and OFC reflects a dynamic between exteroceptive and interoceptive deployment of attention.

Activation of the amygdala and anterior cingulate during nonconscious processing of sad versus happy faces

Previous functional neuroimaging studies have demonstrated that the amygdala activates in response to fearful faces presented below the threshold of conscious visual perception. Using a backward masking procedure similar to that of previous studies, we used functional magnetic resonance imaging (fMRI) to study the amygdala and anterior cingulate gyrus during preattentive presentations of sad and happy facial affect. Twelve healthy adult females underwent blood oxygen level dependent (BOLD) fMRI while viewing sad and happy faces, each presented for 20 ms and "masked" immediately by a neutral face for 100 ms. Masked happy faces were associated with significant bilateral activation within the anterior cingulate gyrus and amygdala, whereas masked sadness yielded only limited activation within the left anterior cingulate gyrus. In a direct comparison, masked happy faces yielded significantly greater activation in the anterior cingulate and amygdala relative to identically masked sad faces. Conjunction analysis showed that masked affect perception, regardless of emotional valence, was associated with greater activation within the left amygdala and left anterior cingulate. Findings suggest that the amygdala and anterior cingulate are important components of a network involved in detecting and discriminating affective information presented below the normal threshold of conscious visual perception.