ERP correlates of attentional processing in spider fear: evidence of threat-specific hypervigilance

Attentional bias towards threat can be demonstrated by enhanced processing of threat-related targets and/or greater interference when threat-related distractors are present. These effects are argued to reflect processing within the orienting and executive control networks of the brain respectively. This study investigated behavioural (RT) and electrophysiological correlates of early selective attention and top-down attentional control among females with high (n?=?16) or low (n?=?16) spider fear (Mean age?=?22 years). Participants completed a novel flanker go/nogo task in which a central schematic flower or spider stimulus was flanked by either congruent or incongruent distractors. Participants responded to green stimuli (go trials) and withheld response to yellow stimuli (nogo trials). High fear participants demonstrated significantly shorter reaction times and greater P1 amplitude to spider targets, suggesting specific hypervigilance towards threat-relevant stimuli. In contrast to predictions, there was little evidence for behavioural interference effects or differences in N2 amplitude when distractor stimuli were threat-relevant.     

Depth of processing and recall of threat material in fearful and nonfearful individuals

Although many studies have examined the nature of memory distortions in anxious individuals, few have considered biases in specific memory processes, such as encoding or retrieval. To investigate whether the presentation of threat material facilitates encoding biases, spider fearful (n=63), blood fearful (n=73), and nonfearful (n=75) participants encoded spider related, blood related, and neutral words as a function of three levels of processing (i.e., structural, semantic, and self referent). Participants subsequently completed either a free recall or a recognition task. All participants demonstrated a partial depth of processing effect, such that they recalled more words encoded in the self referent condition than in the other two conditions, but groups did not differ in their recall of stimuli as a function of word type. Relative to participants in the other groups, spider fearful participants had fewer spider related intrusions in the recall condition, and they made fewer errors in responding to structural and semantic encoding questions when spider related words were presented. These results contribute to an increasingly large body of literature suggesting that anxious individuals are not characterized by a memory bias toward threat, and they raise the possibility that individuals with spider fears process threat-relevant information differently than individuals with blood fears.     

Depth of processing and recall of threat material in fearful and nonfearful individuals

Abstract

Although many studies have examined the nature of memory distortions in anxious individuals, few have considered biases in specific memory processes, such as encoding or retrieval. To investigate whether the presentation of threat material facilitates encoding biases, spider fearful (n=63), blood fearful (n=73), and nonfearful (n=75) participants encoded spider related, blood related, and neutral words as a function of three levels of processing (i.e., structural, semantic, and self referent). Participants subsequently completed either a free recall or a recognition task. All participants demonstrated a partial depth of processing effect, such that they recalled more words encoded in the self referent condition than in the other two conditions, but groups did not differ in their recall of stimuli as a function of word type. Relative to participants in the other groups, spider fearful participants had fewer spider related intrusions in the recall condition, and they made fewer errors in responding to structural and semantic encoding questions when spider related words were presented. These results contribute to an increasingly large body of literature suggesting that anxious individuals are not characterized by a memory bias toward threat, and they raise the possibility that individuals with spider fears process threat-relevant information differently than individuals with blood fears.     

When spiders appear suddenly: spider-phobic patients are distracted by task-irrelevant spiders

Fear is thought to facilitate the detection of threatening stimuli. Few studies have examined the effects of task-irrelevant phobic cues in search tasks that do not involve semantic categorization. In a combined reaction time and eye-tracking experiment we investigated whether peripheral visual cues capture initial attention and distract from the execution of goal-directed eye movements. Twenty-one spider-phobic patients and 21 control participants were instructed to search for a color singleton while ignoring task-irrelevant abrupt-onset distractors which contained either a small picture of a spider (phobic), a flower (non-phobic, but similar to spiders in shape), a mushroom (non-phobic, and not similar to spiders in shape), or no picture. As expected, patients' reaction times were longer on trials with spider distractors. However, eye movements revealed that this was not due to attentional capture by spider distractors; patients more often fixated on all distractors with pictures, but their reaction times were delayed by longer fixation durations on spider distractors. These data do not support automatic capture of attention by phobic cues but suggest that phobic patients fail to disengage attention from spiders.     

The snake in the grass revisited: An experimental comparison of threat detection paradigms

The current investigation compares the results of two commonly used visual detection paradigms—the standard adult button-press detection paradigm used in Öhman, Flykt, and Esteves (2001), and the new child-friendly touch-screen detection paradigm used in LoBue and DeLoache (2008)—within the same samples of adult participants. Results suggest that both paradigms produce the same pattern of findings with regard to detection latency for threat-relevant versus threat-irrelevant stimuli: Adults detected threat-relevant targets more quickly than threat-irrelevant targets across the varying procedures. However, results with respect to automaticity of detection as suggested by Öhman et al. (2001) were only replicated with the classic button-press paradigm. The findings validate the touch-screen visual search procedure and have important implications for choosing an appropriate methodology for studying threat detection.     

The use of stimulus dimensions in judgement making in spider fearful and nonfearful individuals

This study uses a multidimensional scaling approach to investigate the hypothesis that spider fearful individuals give priority to a threat-safety dimension when making judgments. The results show that when making judgments about stimuli, spider fearful individuals (1) placed significantly greater comparative weighting on a threat-relevant dimension than on a non-emotive dimension (colour), and (2) tended to rate threatening pairs of stimuli and safe pairs of stimuli as more similar than did the nonfearful group. This prioritised dimensional processing suggests a mechanism by which phobics can exhibit what initially appear to be paradoxical tendencies to give priority to both threat and safety information.     

Interrelationships between spider fear associations,attentional disengagement and self-reported fear: A preliminary test of a dual-systems model

Recent conceptualisations of anxiety posit that equivocal findings related to the time-course of disengaging from threat-relevant stimuli may be attributable to individual differences in associative and rule-based processing. The current study was designed to test the hypothesis that strength of spider-fear associations would indirectly predict reported spider fear via impaired disengagement. One hundred and thirty-one undergraduate volunteer participants completed the Go/No-go Association Task, a visual search task, and self-report spider fear questionnaires. Stronger spider-fear associations were associated with reduced disengagement accuracy, whereas higher levels of reported spider fear were related to faster engagement with and disengagement from spiders. Bootstrapping multiple mediation analyses demonstrated that stronger-spider fear associations evidenced an indirect relationship with reported spider fear via reduced disengagement accuracy, highlighting the importance of fine-grained analyses of different aspects of cognitive bias. Results are discussed in terms of cognitive models of anxiety.     

Lexical Decision Paradigms do not Differentiate between Fearful and Non-fearful Individuals

Thirty-two spider-fearful, 33 blood/injury/injection fearful, and 28 non-fearful individuals (N = 93) participated in dual-task study. Participants were presented with blood, spider, neutral, positive and pseudo-word stimuli while having to also verbally identify numbers as either even or odd. Blood-fearful individuals responded slower than spider and non-fearful individuals. However, there was no interaction of group membership with stimuli type. This study replicates the results of two previous studies that have used a lexical decision task in an effort to differentiate between fearful and non-fearful individuals and found no significant differences between these two groups on this task. These results suggest that the lexical decision task in general may not be sensitive enough to elicit processing differences in non-clinical samples.     

Superior detection of threat-relevant stimuli in infancy

The ability to quickly detect potential threat is an important survival mechanism for humans and other animals. Past research has established that adults have an attentional bias for the detection of threat-relevant stimuli, including snakes and spiders as well as angry human faces. Recent studies have documented that preschool children also detect the presence of threatening stimuli more quickly than various non-threatening stimuli. Here we report the first evidence that this attentional bias is present even in infancy. In two experiments, 8- to 14-month-old infants responded more rapidly to snakes than to flowers and more rapidly to angry than to happy faces. These data provide the first evidence of enhanced visual detection of threat-relevant stimuli in infants and hence offer especially strong support for the existence of a general bias for the detection of threat in humans.     

The spread of fear: Symbolic generalization mediates graded threat-avoidance in specific phobia

Overgeneralization of fear and threat-avoidance represents a formidable barrier to successful clinical treatment of anxiety disorders. While stimulus generalization along quantifiable physical dimensions has been studied extensively, less consideration has been given to symbolic generalization, in which stimuli are indirectly and arbitrarily related. The present study examined whether the magnitude and extent of symbolic generalization of threat-avoidance and threat-beliefs differed between spider-phobic and nonphobic individuals. Initially, participants learned two sets of stimulus equivalence relations (A1?=?B1?=?C1; A2?=?B2?=?C2). Next, one cue (B1) was established as a conditioned stimulus (CS?+?; threat) that signalled onset of spider images and prompted avoidance, and another cue (B2) was established as a CS– (safety cue) that signalled the absence of such images. Subsequent testing showed that phobics compared to nonphobics exhibited greater symbolic generalization of threat-avoidance to threat cues A1 and C1 (indirect CS+ threat cues related via symmetry and equivalence, respectively), while all individuals showed nonavoidance to indirect safety cues A2 and C2. The enhanced symbolic generalization of threat-beliefs and avoidance behaviour observed in spider phobics warrants further investigation.     

Cognitive Bias in Spider-Phobic Children: Comparison of a Pictorial and a Linguistic Spider Stroop

The relation between spider fear in children and cognitive processing bias toward threatening information was examined. It was investigated whether spider fear in children is related to a cognitive bias for threatening pictures and words. Pictorial and linguistic Stroop stimuli were administered to 28 spider phobic and 30 control children aged 8–12. Spider-phobic children showed a moderate bias for threatening words. Surprisingly, no bias was found for spider pictures, while the spider-phobic children judged the pictures as more aversive. Moreover, in a recent similar study in adults (Kindt & Brosschot, 1997), a strong relation between spider phobia and bias toward threat words and pictures was found. Several explanations are given to account for this divergence.     

Threat-relevance impairs executive functions: negative impact on working memory and response inhibition

The effects of emotional stimulus content on attention are well-known. In contrast, the impact of emotional information on higher executive control functions is undetermined. To elucidate the role of negative emotion in cognitive control, 56 adult female participants performed a combined working memory and response inhibition task, with threat-relevant (spider and snake) and neutral (flower and mushroom) stimuli. Threat-relevant stimuli impaired performance, by causing prolonged response times to working memory items and increased response inhibition error rate relative to neutral stimuli. The impaired response inhibition was only evident when threat-relevant stimuli co-occurred with working memory matches, in line with a common resource pool view of executive functions and emotion processing. Individual differences in reported fear of spiders were associated with differences of inhibitory control, while fear of snakes was associated with impaired overall accuracy on working memory trials. The results are discussed in relation to the dual-competition framework for interaction between executive functions and emotion (Pessoa, 2009).     

The spider does not always win the fight for attention: Disengagement from threat is modulated by goal set

Stimulus-driven preferential attention to threat can be modulated by goal-driven attention. However, it remains unclear how this goal-driven modulation affects specific attentional components implied in threat interference. We hypothesise that goal-driven modulation most strongly impacts delayed disengagement from threat. A spatial cueing task was used that disentangles delayed disengagement from attentional capture by tightly manipulating the locus of attention at the time of target onset. Different top-down goals were induced by instructing participants to identify bird/fish targets (Experiment 1) or spider/cat targets (Experiment 2) among animal non-targets. Delayed disengagement from a non-target spider was observed only when the spider was part of the target set, not when it was task-irrelevant. This corroborates evidence that threat stimuli do not necessarily override goal-driven attentional control and that extended processing of threatening distractors is not obligatory.     

Sensitivity and response bias in fear of spiders

According to cognitive theories of anxiety, phobic patients are searching the environment for threatening stimuli, and detecting them rapidly. However, previous studies failed to find a lowered perceptual threshold for threatening stimuli in specific phobias. Therefore, two experiments applying a signal detection paradigm were conducted. Highly spider fearful and nonfearful participants were asked to decide whether a picture of a spider, beetle, or butterfly was presented. In both experiments, spider fearfuls were not better at detecting spiders, or any other animal, than healthy controls. Instead, spider fearfuls were more liberal in assuming that they had seen a spider or a beetle. In accord with earlier studies, these results suggest that spider phobics may exhibit an interpretation bias rather than improved detection of threat.     

The effect of spatial frequency information and visual similarity in threat detection

In the current research, we sought to examine the role of spatial frequency on the detection of threat using a speeded visual search paradigm. Participants searched for threat-relevant (snakes or spiders) or non-threat-relevant (frogs or cockroaches) targets in an array of neutral (flowers or mushrooms) distracters, and we measured search performance with images filtered to contain different levels (high and low) of spatial frequency information. The results replicate previous work demonstrating more rapid detection of threatening versus non-threatening stimuli [e.g. LoBue, V. & DeLoache, J. S. (2008). Detecting the snake in the grass: Attention to fear-relevant stimuli by adults and young children. Psychological Science, 19, 284–289. doi:10.1111/j.1467-9280.2008.02081.x]. Most importantly, the results suggest that low spatial frequency or relatively coarse levels of visual information is sufficient for the rapid and accurate detection of threatening stimuli. Furthermore, the results also suggest that visual similarity between the stimuli used in the search tasks plays a significant role in speeded detection. The results are discussed in terms of the theoretical implications for the rapid detection of threat and methodological implications for properly accounting for similarity between the stimuli in visual search studies.     

Tracking fear in snake and spider fearful participants during visual search: A multi-response domain study

In visual search tasks snake or spider fearful participants showed shorter reaction times (RTs) to respond to their feared animal (e.g., snake) than to the nonfeared animal (i.e., spider) (Öhman, Flykt, & Esteves, 2001). Here, we used this paradigm with heart rate (HR), RTs, and event-related potential (ERP) measures, to investigate the nature of the responses to the feared animal, a nonfeared (but fear-relevant) animal, and fear-irrelevant target stimuli with snake fearful, spider fearful, and nonfearful participants. Fearful participants showed shorter RTs and evoked larger amplitudes on a late positive potential (LPP; 500–700 ms) for their feared compared to the nonfeared and the fear-irrelevant targets. No relevant significant differences were found on early ERP components and HR measures. These findings do not support an involvement of early information processing in the detection of the feared animal in fearful participants, they favour instead a more elaborated analysis of these complex stimuli to achieve the detection.     

Cognitive Bias for Pictorial and Linguistic Threat Cues in Children

The present study was designed to test the conditions under which threat-related cognitive bias can be observed in anxious children. Measures of cognitive bias for threatening words and pictures were obtained from spider fearful children (N = 55) and non-fearful children (N = 58) aged 8–11 in the first experiment, and from spider fearful children (N = 44), and two control groups (N = 41; N = 36) aged 8 in the second experiment. Cognitive bias was assessed by the emotional Stroop task. In line with our previous findings, all children aged 8 showed a bias for spider words, but not for spider pictures. However, a relation between spider fear and bias was observed when age was taken into account: bias for spider words decreased with age in the non-fearful children whereas this bias maintained in the fearful group. This differential age effect too replicated earlier findings (Kindt, Bierman, & Brosschot, 1997). It is suggested that a bias for threat words is a normal characteristic in children aged 8. During development, normal children learn to inhibit this processing bias, whilst fearful children fail to learn this ability.     

Learning to avoid spiders: fear predicts performance,not competence

We used an immersive virtual environment to examine avoidance learning in spider-fearful participants. In 3 experiments, participants were asked to repeatedly lift one of 3 virtual boxes, under which either a toy car or a spider appeared and then approached the participant. Participants were not told that the probability of encountering a spider differed across boxes. When the difference was large (Exps. 1 and 2), spider-fearfuls learned to avoid spiders by lifting the few-spiders-box more often and the many-spiders-box less often than non-fearful controls did. However, they hardly managed to do so when the probability differences were small (Exp. 3), and they did not escape from threat more quickly (Exp. 2). In contrast to the observed performance differences, spider-fearfuls and non-fearfuls showed equal competence, that is comparable post-experimental knowledge about the probability to encounter spiders under the 3 boxes. The limitations and implications of the present study are discussed.     

To look or not to look: an eye movement study of hypervigilance during change detection in high and low spider fearful students

Previous eye movement studies of attentional bias in spider fear reported inconsistent results with respect to early attentional capture, suggesting that overt attentional capture only reliably occurs under specific circumstances. In addition, none of these studies explored covert attention. The present study examined attentional bias in spider phobia using a change detection paradigm that was expected to provide good conditions for documenting attentional capture. In contrast to our expectations, eye movement data showed that all participants' first fixations were fastest on general negative targets, whereas participants' first fixations on spider targets were slower in the spider fearful than in the nonfearful group. In addition, spider fearful participants made more nontarget fixations before fixating on a spider target than did nonfearful participants. Thus, we found that participants' overt attention was more quickly focused on general negative targets, whereas covert attentional processes enabled initial avoidance of fear-relevant (i.e. spider) stimuli. The present findings have important implications for research on attention and fear as they indicate that fearful individuals are not characterized by static attentional orienting toward threat but, under certain conditions, may avert attention from threat automatically.     

Attentional biases in PTSD: More evidence for interference

Attentional biases to trauma-related stimuli have been widely demonstrated in individuals with posttraumatic stress disorder (PTSD). However, the majority of these studies used methods not suited to differentiating difficulty disengaging attention from threatening stimuli (interference) from facilitated detection of threat. In the current study, a visual search task (VST) with a lexical decision component was used to differentiate between attentional interference and facilitation. Forty-six sexual assault survivors with High PTSD or Low PTSD symptoms completed the VST with three types of stimuli (trauma-related, general threat-related, and semantically-related neutral words), to examine the specificity of attentional biases associated with PTSD symptoms. High PTSD participants showed increased interference to trauma-related words relative to Low PTSD participants. Furthermore, the increased attentional interference in High PTSD participants was specific to trauma-related stimuli. No evidence was found for facilitated detection of threatening stimuli in PTSD. These results provide additional support for attentional biases in PTSD relating to attentional interference with trauma-related cues rather than facilitated detection of threat. The implications for this pattern of results are discussed in relation to anxiety disorders that are characterized by rumination and/or intrusions (e.g., PTSD, GAD) rather than those more circumscribed to fight or flight response (e.g., phobias).