Spiders at the cocktail party: an ancestral threat that surmounts inattentional blindness

When the WRENCH turns a few heads: Expectation and semantic relatedness in inattentional blindness

Semantic relatedness and expectation were investigated in inattentional blindness-failure to perceive an unexpected object in plain sight when attention is engaged elsewhere. Participants named primary-task pictures and ignored distractor pictures. Four trials preceded a 'critical' trial where an unexpected six-letter-word appeared at fixation, simultaneously with the pictures. In Experiment 1, we found robust effects for both in-lab and on-line-Zoom methodology. More participants reported the unexpected word semantically-related to the primary-task pictures than a semantically-unrelated word. In Experiment 2, expectations were violated, by changing the semantic category of the primary-task pictures. More participants reported the unexpected word semantically-related to the unexpected picture category than a semantically-unrelated word. When attentional resources are consumed by a task, a violation to task expectations is not enough to reorient attention to an unexpected word. Attention reorients to what is meaningful to the task, and what is meaningful is updated in light of unexpected information.

Terrorism as Coalitional Predation: Explaining Definitional Ambiguities and Precautionary Responses

Terrorism continues to be an enigmatic and contested concept, lacking a universally accepted definition despite extensive scholarly debate. Lay intuitions, however, demonstrate a notable convergence in identifying acts as "terrorism" when specific situational features are present, such as indiscriminate violence and out-group perpetration. These features elicit predictable and robust precautionary responses, raising the question: Is there a unified and parsimonious explanation for these phenomena? It is hypothesized that a situational template exists in the human mind, the coalitional predation template (CPT), which evolved not to detect modern-day terrorism, per se, but to identify and respond to situations of predatory coalitional conflict. The paper examines the potential cues and mechanisms that constitute the psychological systems activated by such threats, suggesting that matching the input cues of the CPT triggers well-documented precautionary responses to terrorism. However, this cue-based system may not align neatly with contemporary threats, leading to disproportionate responses to some threats while underestimating others. The model also posits that interpretations of violence can vary due to incomplete cues and the social position of the evaluator, leading to public disagreements and inconsistencies in defining terrorism. Consequently, arriving at an unambiguous and widely accepted definition of terrorism may not be possible. The model presented may account for a range of phenomena, including the inclination towards attributing mental illness to particular violent incidents and the uncanny surface similarities between terrorism and war crimes. The findings have significant implications for both the theoretical understanding of terrorism and practical policy responses.

No evidence of attentional prioritization for threatening targets in visual search

Throughout human evolutionary history, snakes have been associated with danger and threat. Research has shown that snakes are prioritized by our attentional system, despite many of us rarely encountering them in our daily lives. We conducted two high-powered, pre-registered experiments (total N = 224) manipulating target prevalence to understand this heightened prioritization of threatening targets. Target prevalence refers to the proportion of trials wherein a target is presented; reductions in prevalence consistently reduce the likelihood that targets will be found. We reasoned that snake targets in visual search should experience weaker effects of low target prevalence compared to non-threatening targets (rabbits) because they should be prioritized by searchers despite appearing rarely. In both experiments, we found evidence of classic prevalence effects but (contrasting prior work) we also found that search for threatening targets was slower and less accurate than for nonthreatening targets. This surprising result is possibly due to methodological issues common in prior studies, including comparatively smaller sample sizes, fewer trials, and a tendency to exclusively examine conditions of relatively high prevalence. Our findings call into question accounts of threat prioritization and suggest that prior attention findings may be constrained to a narrow range of circumstances.

Attentional, emotional, and behavioral response toward spiders, scorpions, crabs, and snakes provides no evidence for generalized fear between spiders and scorpions

Spiders are among the animals evoking the highest fear and disgust and such a complex response might have been formed throughout human evolution. Ironically, most spiders do not present a serious threat, so the evolutionary explanation remains questionable. We suggest that other chelicerates, such as scorpions, have been potentially important in the formation and fixation of the spider-like category. In this eye-tracking study, we focused on the attentional, behavioral, and emotional response to images of spiders, scorpions, snakes, and crabs used as task-irrelevant distractors. Results show that spider-fearful subjects were selectively distracted by images of spiders and crabs. Interestingly, these stimuli were not rated as eliciting high fear contrary to the other animals. We hypothesize that spider-fearful participants might have mistaken crabs for spiders based on their shared physical characteristics. In contrast, subjects with no fear of spiders were the most distracted by snakes and scorpions which supports the view that scorpions as well as snakes are prioritized evolutionary relevant stimuli. We also found that the reaction time increased systematically with increasing subjective fear of spiders only when using spiders (and crabs to some extent) but not snakes and scorpions as distractors. The maximal pupil response covered not only the attentional and cognitive response but was also tightly correlated with the fear ratings of the picture stimuli. However, participants' fear of spiders did not affect individual reactions to scorpions measured by the maximal pupil response. We conclude that scorpions are evolutionary fear-relevant stimuli, however, the generalization between scorpions and spiders was not supported in spider-fearful participants. This result might be important for a better understanding of the evolution of spider phobia.

Spider vs. guns: expectancy and attention biases to phylogenetic threat do not extend to ontogenetic threat

Introduction

Attention bias plays an important role in specific fears and phobias. Previous studies revealed that a-priori expectancies affect attention toward neutral stimuli but not threatening stimuli. The aim of the current study was to test whether this selective influence of expectancies on attention is specific to phylogenetic threat (i.e., spiders) or whether it can be generalized to ontogenetic threat (i.e., guns). Correspondingly, we directly compared expectancy effects on attentional allocation to phylogenetically vs. ontogenetically threatening stimuli.

Method

Expectancies were manipulated by presenting a cue indicating the likelihood of the appearance of a deviant picture in a visual search array. The array included eight distractors and one neutral (phone/bird) or threatening (gun/spider) deviant picture. In a comprehensive design, we examined the effects of stimulus type (phylogenetic/ontogenetic) and visual background (white and sterile/complex and ecological). Individual differences such as intolerance of uncertainty and spider fear were also measured.

Results

Results showed that attention bias toward spiders does not extend to threatening ontogenetic stimuli (i.e., guns). Our previous findings on attention bias toward spiders were replicated and a small to medium positive correlation was found between reaction time to bird targets and pre-existing fear of spider levels. Cues were used to detect threatening as well as neutral targets on both background types, except for spider targets on a complex background, replicating previous results. A small to medium positive correlation was also found between fear of spiders and intolerance of uncertainty.

Discussion

Together, these results suggest that expectancy and attentional processes may differ between ontogenetic and phylogenetic threat. Importantly, the effects of expectancy on attentional allocation depend on an interaction between the type of threat (ontogenetic/phylogenetic), visual factors, and individual differences.

Negative emotion-conditioned prepulse induces the attentional enhancement of prepulse inhibition in humans

Prepulse inhibition (PPI) is a reduction of the acoustic startle reflex (ASR) when the startling stimulus is preceded by a weaker and non-startling stimulus (i.e., prepulse). Previous studies have revealed that PPI can be top-down modulated by selective attention to the fear-conditioned prepulse in animals. However, few researchers have tested this assumption in humans. Thus, in this study, the negative emotional-conditioned prepulse (CS+) was used to explore whether it could improve participants' attention, and further improve the PPI. The results showed that the CS+ prepulse increased the PPI only in females, PPI produced by CS+ prepulse was larger in females than in males, and the perceptual spatial attention further improved the PPI in both females and males. The results suggested that the PPI was affected by emotional, perceptual spatial attention, and sex. These findings highlight an additional method to measure top-down attentional regulation of PPI in humans. Which may offer a useful route to enhance the diagnosis of affective disorders, such as anxiety, depression, and post-traumatic stress disorder.

Detecting valence from unidentified images: A link between familiarity and positivity in recognition without identification

Research using the Recognition Without Identification paradigm (Cleary & Greene, 2000, Journal of Experimental Psychology: Learning, Memory, and Cognition, 26[4], 1063-1069; Peynircioǧlu, 1990, Journal of Memory and Language, 29, 493-500) has found that participants can discriminate between old and new stimuli even when the stimuli are obscured to a degree that they are unidentifiable. This methodology has been adapted in the past by using heavily obscured threatening and nonthreatening images and asking participants to try to identify each image followed by a familiarity rating of the image. Past results showed that threatening images that were not able to be identified were rated as more familiar than nonthreatening images that were not able to be identified (Cleary et al., 2013, Memory & Cognition, 41, 989-999). The current study used a similar methodology to explore the possibility that a sense of familiarity can serve to guide our attention toward potential threats in the environment. However, contrary to earlier results, we found that positive images were rated as more familiar than negative images. This pattern was found with both identified and unidentified images and was replicated across five experiments. The current findings are consistent with the view that feelings of positivity and familiarity are closely linked (e.g., de Vries et al., 2010, Psychological Science, 21[3], 321-328; Garcia-Marques et al., 2004, Personality and Social Psychology Bulletin, 30, 585-593; Monin, 2003, Journal of Personality and Social Psychology, 85[6], 1035-1048).

Animate monitoring is not uniform: implications for the animate monitoring hypothesis

The animate monitoring hypothesis (AMH) purports that humans evolved specialized mechanisms that prioritize attention to animates over inanimates. Importantly, the hypothesis emphasizes that any animate-an entity that can move on its own-should take priority in attention. While many experiments have found general support for this hypothesis, there have yet been no systematic investigations into whether the type of animate matters for animate monitoring. In the present research we addressed this issue across three experiments. In Experiment 1, participants (N = 53) searched for an animate or inanimate entity in a search task, and the animate was either a mammal or a non-mammal (e.g., bird, reptile, insect). Mammals were found significantly faster than inanimates, replicating the basic AMH finding. However, they were also found significantly faster than non-mammals, who were not found faster than inanimates. Two additional experiments were conducted to probe for differences among types of non-mammals using an inattentional blindness task. Experiment 2 (N = 171) compared detection of mammals, insects, and inanimates, and Experiment 3 (N = 174) compared birds and herpetofauna (reptiles and amphibians). In Experiment 2, mammals were spontaneously detected at significantly higher rates than insects, who were detected at only slightly higher rates than the inanimates. Furthermore, when participants did not consciously identify the target, they nonetheless could correctly guess the higher level category of the target (living vs. nonliving thing) for the mammals and the inanimates, but could not do so for the insects. We also found in Experiment 3 that reptiles and birds were spontaneously detected at rates similar to the mammals, but like insects they were not identified as living things at rates greater than chance when they were not consciously detected. These results do not support a strong claim that all animates are prioritized in attention, but they do call for a more nuanced view. As such, they open a new window into the nature of animate monitoring, which have implications for theories of its origin.

Do Spiders Ride on the Fear of Scorpions? A Cross-Cultural Eye Tracking Study

Deep fear of spiders is common in many countries, yet its origin remains unexplained. In this study, we tested a hypothesis based on recent studies suggesting that fear of spiders might stem from a generalized fear of chelicerates or fear of scorpions. To this end, we conducted an eye tracking experiment using a spontaneous gaze preference paradigm, with spiders and scorpions (previously neglected but crucial stimuli) as threatening stimuli and grasshoppers as control stimuli. In total, 67 participants from Somaliland and 67 participants from the Czech Republic were recruited and presented with a sequence of paired images. Both Somali and Czech people looked longer (total duration of the gaze) and more often (number of fixations) on the threatening stimuli (spiders and scorpions) when presented with a control (grasshopper). When both threatening stimuli were presented together, Somali participants focused significantly more on the scorpion, whereas in Czech participants, the effect was less pronounced, and in Czech women it was not significant. This supports the hypothesis that fear of spiders originated as a generalized fear of scorpions. Moreover, the importance of spiders as fear-eliciting stimuli may be enhanced in the absence of scorpions in the environment.

Fear, disgust, hate: negative emotions evoked by animals in ancient literature

Ancient literature contains thoughts, observations and opinions about animals causing fear, disgust or hate that can be of great interest to scientists researching the problem of phobias, fears and anxieties in history. So in this article, it is argued that we can go as far back as ancient times in the research on the history of animal phobias (or, speaking more generally, in research on the entire spectrum of negative emotions evoked by animals in individuals or in entire social groups or societies). In that period, the phenomenon was observed and described in an anecdotal form, and attempts to establish the causes of this phenomenon were undertaken. This article discusses these early ideas about phobias, fears and anxieties related to animals.

Surprising Threats Accelerate Conscious Perception

The folk psychological notion that "we see what we expect to see" is supported by evidence that we become consciously aware of visual stimuli that match our prior expectations more quickly than stimuli that violate our expectations. Similarly, "we see what we want to see," such that more biologically-relevant stimuli are also prioritised for conscious perception. How, then, is perception shaped by biologically-relevant stimuli that we did not expect? Here, we conducted two experiments using breaking continuous flash suppression (bCFS) to investigate how prior expectations modulated response times to neutral and fearful faces. In both experiments, we found that prior expectations for neutral faces hastened responses, whereas the opposite was true for fearful faces. This interaction between emotional expression and prior expectations was driven predominantly by participants with higher trait anxiety. Electroencephalography (EEG) data collected in Experiment 2 revealed an interaction evident in the earliest stages of sensory encoding, suggesting prediction errors expedite sensory encoding of fearful faces. These findings support a survival hypothesis, where biologically-relevant fearful stimuli are prioritised for conscious access even more so when unexpected, especially for people with high trait anxiety.

The effects of task-irrelevant threatening stimuli on orienting- and executive attentional processes under cognitive load

Human visual attention is biased to rapidly detect threats in the environment so that our nervous system can initiate quick reactions. The processes underlying threat detection (and how they operate under cognitive load), however, are still poorly understood. Thus, we sought to test the impact of task-irrelevant threatening stimuli on the salience network and executive control of attention during low and high cognitive load. Participants were exposed to neutral or threatening pictures (with moderate and high arousal levels) as task-irrelevant distractors in near (parafoveal) and far (peripheral) positions while searching for numbers in ascending order in a matrix array. We measured reaction times and recorded eye-movements. Our results showed that task-irrelevant distractors primarily influenced behavioural measures during high cognitive load. The distracting effect of threatening images with moderate arousal level slowed reaction times for finding the first number. However, this slowing was offset by high arousal threatening stimuli, leading to overall shorter search times. Eye-tracking measures showed that participants fixated threatening pictures more later and for shorter durations compared to neutral images. Together, our results indicate a complex relationship between threats and attention that results not in a unitary bias but in a sequence of effects that unfold over time.

Specificity of spiders among fear- and disgust-eliciting arthropods: Spiders are special, but phobics not so much

To investigate a specificity of spiders as a prototypical fear- and disgust-eliciting stimuli, we conducted an online experiment. The respondents rated images of 25 spiders, 12 non-spider chelicerates, and 10 other arthropods on a fear and disgust 7-point scale. The evaluation of 968 Central European respondents confirmed the specificity of spiders among fear- and disgust-eliciting arthropods and supported the notion of spiders as a cognitive category. We delineated this category as covering extant spider species as well as some other chelicerates bearing a physical resemblance to spiders, mainly whip spiders and camel spiders. We suggested calling this category the spider-like cognitive category. We discussed evolutionary roots of the spider-like category and concluded that its roots should be sought in fear, with disgust being secondary of the two emotions. We suggested other chelicerates, e.g., scorpions, might have been important in formation and fixation of the spider-like category. Further, we investigated an effect of respondent's sensitivity to a specific fear of spiders on evaluation of the stimuli. We found that suspected phobic respondents were in their rating nearly identical to those with only high fear of spiders and similar to those with only moderate fear of spiders. We concluded that results based on healthy respondents with elevated fear should also be considered relevant for arachnophobia research.

What Makes Spiders Frightening and Disgusting to People?

The quality of human-animal interactions may crucially influence conservation efforts. Unfortunately, and despite their important roles in the functioning of the ecosystem, some animals are considered notoriously unpopular. Using the forced-choice paradigm, we investigated which cues humans perceive as frightening and disgusting in spiders, one of the most unpleasant animals in the world. The research was carried out with a representative sample of N = 1,015 Slovak adults. We found that perceived fear and disgust of spiders were triggered predominantly by enlarged chelicerae, enlarged abdomen, and the presence of body hair. Longer legs were associated with perceived fear as well; however, the presence of two eyes did not produce any statistical significance in terms of fear. We hope that further research in this field, where additional cues can be manipulated (e.g., color and number of legs), will improve conservation efforts by using an improved reputation of spiders in the eyes of the general public.

Super-natural fears

Supernatural fears, although common, are not as well-understood as natural fears and phobias (e.g., social, blood, and animal phobias) which are prepared by evolution, such that they are easily acquired through direct experience and relatively immune to cognitive mediation. In contrast, supernatural fears do not involve direct experience but seem to be related to sensory or cognitive biases in the interpretation of stimuli as well as culturally driven cognitions and beliefs. In this multidisciplinary synthesis and collaborative review, we claim that supernatural beliefs are "super natural." That is, they occur spontaneously and are easy to acquire, possibly because such beliefs rest on intuitive concepts such as mind-body dualism and animism, and may inspire fear in believers as well as non-believers. As suggested by psychological and neuroscientific evidence, they tap into an evolutionarily prepared fear of potential impending dangers or unknown objects and have their roots in "prepared fears" as well as "cognitively prepared beliefs," making fear of supernatural agents a fruitful research avenue for social, anthropological, and psychological inquires.

Threat-relevant stimuli cannot be better detected by preschoolers in an inattentional blindness task

Detecting the unexpected threat-relevant stimuli plays a vital role in preschoolers' daily life safety, but a few studies have investigated how preschoolers process this kind of stimuli. We applied a classical inattentional blindness task (designed by Mack and Rock Inattentional blindness. MIT Press, 1998) to explore whether threat-relevant stimuli could be better detected in an inattentional condition and whether the age and the fluid intelligence could predict the incidence of the detection. With the involvement of two hundred and thirty-nine preschoolers (aged from 4 to 6 years), we found that it was not more likely for preschoolers to detect the threat-relevant stimuli (Knife and Snake) compared with the non-threat-relevant stimuli (Spoon and Snail). The age difference of detection only occurred in the divided attentional condition, but not in the inattentional condition. Moreover, the group of 5-year-old preschoolers with higher fluid intelligence scores was more likely to detect the unexpected stimuli, but the prediction was not powerful. These findings demonstrate that the threat-superiority effect on IB does not occur on preschoolers and the individual difference of preschoolers' IB is unstable. This study enriches the cognition of young children's attentional bias to threat-relevant stimuli, and has certain significance to understand the essence of children's attentional process.

The Dynamic and Fragile Nature of Eyewitness Memory Formation: Considering Stress and Attention

Eyewitnesses are often susceptible to recollection failures and memory distortions. These failures and distortions are influenced by several factors. The present review will discuss two such important factors, attention failures and stress. We argue that acute stress, often experienced by eyewitnesses and victims of crimes, directly influences attentional processes, which likely has downstream consequences for memory. Attentional failures may result in individuals missing something unusual or important in a complex visual field. Amongst eyewitnesses, this can lead to individuals missing details, even unusual or important central details, regarding the crime. Surprisingly, few studies have investigated attentional failures in eyewitness scenarios, and none have investigated the relationship between stress, attention, and witness memory. This review will discuss the impact of attentional failures, mainly those resulting from inattentional blindness, in applied contexts in order to bridge to eyewitness scenarios. In addition, we will integrate the applied literature on attentional failures with literature that examines the influences of arousal and stress on attention. We will conclude by presenting how future research may tease apart the independent contributions of arousal and stress on attentional failures and successes and how this research may inform understanding of eyewitness reliability.

Does hunger promote the detection of foods? The effect of value on inattentional blindness

Although human perception has evolved into a potent and efficient system, we still fall prey to astonishing failures of awareness as we miss an unexpected object in our direct view when our attention is engaged elsewhere (inattentional blindness). While specific types of value of the unexpected object have been identified to modulate the likelihood of this failure of awareness, it is not clear whether the effect of value on inattentional blindness can be generalized. We hypothesized that the combination of hunger and food-stimuli might increase a more general type of value so that food stimuli have a higher probability to be noticed by hungry participants than by satiated participants. In total, 240 participants were assigned towards a hungry (16 h of fasting) or satiated (no fasting) manipulation and performed afterward a static inattentional blindness task. However, we did not find any effect of value on inattentional blindness based on hunger and food stimuli. We speculate that different underlying mechanisms are involved for different types of value and that value manipulations need to be strong enough to ensure certain value strengths.

Preferential snake detection in a simulated ecological experiment

OBJECTIVES

According to Isbell's snake detection theory (SDT), the need to rapidly detect and thus avoid snakes had a major impact on the evolution of the primate visual system, and thus the origin and evolution of the primate lineage, as expansion of the visual sense is a key characteristic of primates. The SDT rests on the assumption that there are both cortical (conscious) and subcortical (unconscious) brain structures and pathways that are responsible for rapid visual detection of and quick avoidance reactions to snakes. Behavioral evidence for the SDT primarily comes from visual search tasks and presentations of images on a computer screen; our aim was to evaluate the SDT under more ecologically valid circumstances.

MATERIALS AND METHODS

We asked participants to take a virtual hike in which a realistic model of a snake, rabbit, or bottle had been placed on the trail. Subjects were instructed simply to imagine themselves as the hiker while watching the video. We measured heart rate and skin conductance reactions while the participants viewed the video. After the video, the participants were shown pictures of the three stimuli and asked if they had seen any of them.

RESULTS

We found that snakes were detected more often than rabbits or bottles, and that participants showed greater changes in heart rate and greater skin conductance responses in the snake condition than in the other two conditions, even when the participant did not report having seen the snake.

DISCUSSION

A critical component of the SDT is that primates must be able to quickly detect snakes even when their attention is directed elsewhere. Using a novel experimental context-a simulated hike-we assessed arousal and detection without directing participants to attend to any particular stimulus or event. Our data support the SDT by providing evidence of enhanced detection and autonomic arousal even in the absence of detection. Replication of these results using additional controls and experimental contexts will help refine our understanding of snake avoidance by primates.

The effect of emotional valence and age of faces on adults and children's inattentional blindness

Inattentional blindness (IB) refers to the nature of an individual being unaware of an unexpected stimulus when focusing on an attentional task. Investigation into IB provides an innovative approach for the research of attentional bias that is connected with an individual's immediate attentional capture. This study explored the effect of emotional valence and age of faces on the IB rates of children and adults. We employed a between-subject experimental design with a 2 (age of participants: child, adult) × 2 (age of face: child face, adult face) × 2 (emotional valence: positive, negative) method and used the classic IB task of cross judgment. The participants included 79 adults (54.63 ± 8.192 years old) and 78 children (10.62 ± 2.32 years old). The results showed that: (1) The IB rates of the two groups differed significantly. Children performed better than adults in detecting the faces appearing unexpectedly. (2) The effect of emotional valence only emerged on adult participants' IB. Adults were significantly more likely to detect the positive-emotional faces than the negative-emotional ones. (3) The age of a face was not a significant factor to predict participants' IB. Neither children nor adults showed a preference for the faces of a specific age (e.g., their own age). These findings revealed the distinct characteristics of attentional capture of children and adults when confronting unexpected facial stimuli.

Clarifying the effect of facial emotional expression on inattentional blindness

Conscious perception often fails when an object appears unexpectedly and our attention is focused elsewhere (inattentional blindness). While various factors have been identified as determinants of inattentional blindness, the influence of an unexpected object́s semantic value remains ambiguous. This is also true for the supposedly evolutionary meaning of faces; some studies found higher detection rates for faces while others did not or used control conditions that differed in physical aspects of the stimulus as well. In the proposed studies we aim to replicate and clarify the effect of the semantic value of faces on inattentional blindness in a controlled and systematic manner.

Negative emotions in the target speaker's voice enhance speech recognition under "cocktail-party" environments

Under a "cocktail-party" environment with simultaneous multiple talkers, recognition of target speech is effectively improved by a number of perceptually unmasking cues. It remains unclear whether emotions embedded in the target-speaker's voice can either improve speech perception alone or interact with other cues facilitating speech perception against a masker background. This study used two target-speaker voices with different emotional valences to examine whether recognition of target speech is modulated by the emotional valence when the target speech and the maskers were perceptually co-located or separated. The results showed that both the speech recognition against the masker background and the separation-induced unmasking effect were higher for the target speaker with a negatively emotional voice than for the target speaker with a positively emotional voice. Moreover, when the negative voice was fear conditioned, the target-speech recognition was further improved against speech informational masking. These results suggested that the emotionally vocal unmasking cue interacts significantly with the perceived spatial-separation unmasking cue, facilitating the unmasking effect against a masking background. Thus, emotional features embedded in the target-speaker's vocal timbre are also useful for unmasking the target speech in "cocktail-party" environments.

Subjective ratings of fear are associated with frontal late positive potential asymmetry, but not with early brain activity over the occipital and centro-parietal cortices

The human frontal cortex is asymmetrically involved in motivational and affective processing. Several studies have shown that the left-frontal hemisphere is related to positive and approach-related affect, whereas the right-frontal hemisphere is related to negative and withdrawal-related affect. The present study aimed to investigate whether evolutionarily threatening stimuli modulate asymmetrical frontal activity. We examined hemispheric differences in frontal late positive potentials (f-LPP asymmetry) and frontal alpha power activation (frontal alpha asymmetry, FAA) in response to images depicting snakes, spiders, butterflies, and birds. Results showed that the late component of f-LPP asymmetry, but not FAA, was modulated by the category of stimuli. Specifically, threatening stimuli (snakes and spiders) evoked a relatively large late f-LPP over the right-frontal hemisphere than non-threatening stimuli (birds and butterflies). Moreover, this relatively great right-frontal activity was positively associated with the subjective ratings of fear. Importantly, the subjective ratings of fear were not associated with early brain activity over the occipital or centro-parietal cortices. These results suggest that late f-LPP asymmetry may reflect higher order affective processes, specifically the subjective appraisal of threatening stimuli and the subjective experience of fear, that are independent of the fast and automatic processing of evolutionarily significant and affectively arousing stimuli.

Loads of unconscious processing: The role of perceptual load in processing unattended stimuli during inattentional blindness

Inattentional blindness describes the failure to detect an unexpected but clearly visible object when our attention is engaged elsewhere. While the factors that determine the occurrence of inattentional blindness are already well understood, there is still a lot to learn about whether and how we process unexpected objects that go unnoticed. Only recently it was shown that although not consciously aware, characteristics of these stimuli can interfere with a primary task: Classification of to-be-attended stimuli was slower when the content of the task-irrelevant, undetected stimulus contradicted that of the attended, to-be-judged stimuli. According to Lavie’s perceptual load model, irrelevant stimuli are likely to reach awareness under conditions of low perceptual load, while they remain undetected under high load, as attentional resources are restricted to the content of focused attention. In the present study, we investigated the applicability of Lavie’s predictions for the processing of stimuli that remain unconscious due to inattentional blindness. In two experiments, we replicated that unconsciously processed stimuli can interfere with intended responses. Also, our manipulation of perceptual load did have an effect on primary task performance. However, against our hypothesis, these effects did not interact with each other. Thus, our results suggest that high perceptual load cannot prevent task-irrelevant stimuli that remain undetected from being processed to an extent that enables them to affect performance in a primary task.

Distance is relative: Inattentional blindness critically depends on the breadth of the attentional focus

Inattentional blindness - the phenomenon that we sometimes miss salient stimuli in our direct view when they appear unexpectedly and attention is focused on something else - is modulated by various parameters, including distance of the unexpected stimulus from the attentional focus. In two experiments, we expanded the existing literature on spatial factors influencing inattentional blindness as well as theories on the spatial distribution of attention. Noticing rates of unexpected objects were significantly higher when they appeared outside instead of inside the bounds of primary task stimuli. Thus, our results do neither support the account that spatial attention is tuned as a spotlight that includes relevant targets and everything in between nor an account of purely object-based attentional orientation. Instead, the results speak in favor of an inhibitory area between two attended targets. Experiment 2 replicated these surprising findings and additionally demonstrated that they were not confounded by task.

Ectoparasite defence in humans: relationships to pathogen avoidance and clinical implications

Currently, disgust is regarded as the main adaptation for defence against pathogens and parasites in humans. Disgust's motivational and behavioural features, including withdrawal, nausea, appetite suppression and the urge to vomit, defend effectively against ingesting or touching sources of pathogens. However, ectoparasites do not attack their hosts via ingestion, but rather actively attach themselves to the body surface. Accordingly, by itself, disgust offers limited defence against ectoparasites. We propose that, like non-human animals, humans have a distinct ectoparasite defence system that includes cutaneous sensory mechanisms, itch-generation mechanisms and grooming behaviours. The existence of adaptations for ectoparasite defence is supported by abundant evidence from non-human animals, as well as more recent evidence concerning human responses to ectoparasite cues. Several clinical disorders may be dysfunctions of the ectoparasite defence system, including some that are pathologies of grooming, such as skin picking and trichotillomania, and others, such as delusory parasitosis and trypophobia, which are pathologies of ectoparasite detection. We conclude that future research should explore both distinctions between, and overlap across, ectoparasite defence systems and pathogen avoidance systems, as doing so will not only illuminate proximate motivational systems, including disgust, but may also reveal important clinical and social consequences.This article is part of the Theo Murphy meeting issue 'Evolution of pathogen and parasite avoidance behaviours'.

Dollars do not determine detection: Monetary value associated with unexpected objects does not affect the likelihood of inattentional blindness

Conscious perception often fails when an object appears unexpectedly and our attention is focused elsewhere (inattentional blindness). Although various factors have been identified that modulate the likelihood of this failure of awareness, it is not clear whether the monetary reward value associated with an object can affect whether or not this object is detected under conditions of inattention. We hypothesised that unexpectedly appearing objects that contain a feature linked to high value, as established via reward learning in a previous task, would subsequently be detected more frequently than objects containing a feature linked to low value. A total of 537 participants first learned the association between a perceptual feature (colour) and subsequent reward values (high, low, or none reward). Afterwards, participants were randomly assigned to a static (Experiment 1) or dynamic (Experiment 2) inattentional blindness task including an unexpected object associated with high, low, or none reward. However, no significant effect of the previously learned value on the subsequent likelihood of detection was observed. We speculate that artificial monetary value, which is known to affect attentional capture, is not strong enough to determine whether or not an object is consciously perceived.

What is so frightening about spiders? Self-rated and self-disclosed impact of different characteristics and associations with phobia symptoms

Spider phobia is a common and impairing mental disorder, yet little is known about what characteristics of spiders that spider phobic individuals find frightening. Using screening data from a clinical trial, we explored which characteristics that spider-fearful individuals (n = 194) rated as having the greatest impact on fear, used factor analysis to group specific characteristics, and explored linear associations with self-reported phobia symptoms. Second, a guided text-mining approach was used to extract the most common words in free-text responses to the question: "What is it about spiders that you find frightening?" Both analysis types suggested that movement-related characteristics of spiders were the most important, followed by appearance characteristics. There were, however, no linear associations with degree of phobia symptoms. Our findings reveal the importance of targeting movement-related fears in in-vivo exposure therapy for spider phobia and using realistically animated spider stimuli in computer-based experimental paradigms and clinical interventions such as Virtual Reality exposure therapy.

Do 5-Month-Old Infants Possess an Evolved Detection Mechanism for Snakes, Sharks, and Rodents?

The four experiments reported here used the preferential looking and habituation paradigms to examine whether 5-month-olds possess a perceptual template for snakes, sharks, and rodents. It was predicted that if infants possess such a template then they would attend preferentially to schematic images of these non-human animal stimuli relative to scrambled versions of the same stimuli. The results reveal that infants look longer at a schematic snake than at two scrambled versions of that image and generalize from real snakes to the schematic image. The experiments also demonstrate that 5-month-olds show no preferential looking for schematic sharks or schematic rodents relative to scrambled versions of those images. These data add to the growing support for the view that humans, like many non-human animals, possess an evolved fear mechanism for detecting threats that were recurrent across evolutionary time.

Cross-cultural variation in the development of folk ecological reasoning

Two studies examined children's reasoning about biological kinds in populations that vary in formal education and direct experience with the natural world, a Western (urban U.S.) and a Non-Western population (Tanna, Vanuatu). Study 1 examined children's concepts of ecological relatedness between species (N = 97, 5-13- year-olds). U.S. children provided more taxonomic explanations than Ni-Vanuatu children, who provided more ecological, physiological, and utility explanations than U.S. children. Ecological explanations were most common overall and more common among older than younger children across cultures. In Study 2, children (N=106, 6-11-year-olds) sorted pictures of natural kinds into groups. U.S. children were more likely than Ni-Vanuatu children to categorize a human as an animal and the tendency to group a human with other animals increased with age in the U.S. Despite substantial differences in cultural, educational, and ecological input, children in both populations privileged ecological reasoning. In contrast, taxonomic reasoning was more variable between populations, which may reflect differences in experience with formal education.

What's past is past: Neither perceptual preactivation nor prior motivational relevance decrease subsequent inattentional blindness

Inattentional blindness-the phenomenon that clearly visible, yet currently unexpected objects go unnoticed when our attention is focused elsewhere-is an ecologically valid failure of awareness. It is currently subject to debate whether previous events and experiences determine whether or not inattentional blindness occurs. Using a simple two-phase paradigm in the present study, we found that the likelihood of missing an unexpected object due to inattention did not change when its defining characteristic (its color) was perceptually preactivated (Experiment 1; N = 188). Likewise, noticing rates were not significantly reduced if the object's color was previously motivationally relevant during an unrelated detection task (Experiment 2; N = 184). These results corroborate and extend recent findings questioning the influence of previous experience on subsequent inattentional blindness. This has implications for possible countermeasures intended to thwart the potentially harmful effects of inattention.

Animacy increases second target reporting in a rapid serial visual presentation task

Attentional blink occurs when two target items, T1 and T2, are presented within brief moments of each other in a series of rapidly presented items and participants fail to report T2. The purpose of the present study was to examine the effect of characteristics of T2 on T2 reporting. Participants (N = 67) completed 4 blocks of 40 trials. Each trial consisted of 15 images, two of which were designated as T1 and T2. T2 was manipulated in three ways: animacy (animate or inanimate), threat (threatening or nonthreatening), and lag (200 ms or 400 ms after T1). The results indicated that more T2s were reported at the longer lag and that animate objects were reported more often than inanimate objects at both lags. Threat did not have a significant effect on T2 reporting although it interacted with lag: threatening objects were reported more frequently than nonthreatening objects at lag 2 but this trend reversed at lag 4. The results were consistent with the animate monitoring hypothesis, which claims that animate objects, because of their importance in ancestral environments, attract attention more easily than inanimate objects. Animate objects appear to capture attention more easily than inanimate objects as second targets in a rapid serial visual presentation task. This result is similar to animacy advantages reported with other attention tasks and with memory tasks.

The unexpected killer: effects of stimulus threat and negative affectivity on inattentional blindness

Inattentional blindness (IB) occurs when observers fail to detect unexpected objects or events. Despite the adaptive importance of detecting unexpected threats, relatively little research has examined how stimulus threat influences IB. The current study was designed to explore the effects of stimulus threat on IB. Past research has also demonstrated that individuals with elevated negative affectivity have an attentional bias towards threat-related stimuli; therefore, the current study also examined whether state and trait levels of negative affectivity predicted IB for threat-related stimuli. One hundred and eleven participants (87 female, aged 17-40 years) completed an IB task that included both threat-related and neutral unexpected stimuli, while their eye movements were tracked. Participants were significantly more likely to detect the threatening stimulus (19%) than the neutral stimulus (11%) p  =  .035, odds ratio (OR)  =  4.0, 95% confidence interval OR [1.13, 14.17]. Neither state nor trait levels of negative affectivity were significantly associated with IB. These results suggest observers are more likely to detect threat-related unexpected objects, consistent with the threat superiority effect observed in other paradigms. However, most observers were blind to both unexpected stimuli, highlighting the profound influence of expectations and task demands on our ability to perceive even potentially urgent and life-threatening information.

Itsy Bitsy Spider…: Infants React with Increased Arousal to Spiders and Snakes

Attention biases have been reported for ancestral threats like spiders and snakes in infants, children, and adults. However, it is currently unclear whether these stimuli induce increased physiological arousal in infants. Here, 6-month-old infants were presented with pictures of spiders and flowers (Study 1, within-subjects), or snakes and fish (Study 1, within-subjects; Study 2, between-subjects). Infants' pupillary responses linked to activation of the noradrenergic system were measured. Infants reacted with increased pupillary dilation indicating arousal to spiders and snakes compared with flowers and fish. Results support the notion of an evolved preparedness for developing fear of these ancestral threats.

Subcortical Facilitation of Behavioral Responses to Threat

Behavioral responses to threat are critical to survival. Several cortical and subcortical brain regions respond selectively to threat. However, the relation of these neural responses and their underlying representations to behavior is unclear. We examined the contribution of lower-order subcortical representations to behavioral responses to threat in adult humans. In Experiments 1 and 2, participants viewed pairs of images presented to the same eye or to different eyes. We observed a monocular advantage, which indicates subcortical facilitation, for ancestral threats (snakes, spiders), but not for modern threats, positive images, or neutral images. In Experiment 3, we presented pairs of snakes or neutral images into the temporal or nasal hemifield. For snakes only, we observed a temporal hemifield advantage, which indicates facilitation by the retino-tectal subcortical pathway. These results advance the current understanding of processing of threat by adult humans by revealing the characteristics of behaviors driven by a lower-order neural mechanism that is specialized for the processing of ancestral threats. The results also contribute to ongoing debates concerning the biological generality of neural mechanisms for processing of complex, emotionally-relevant stimuli by providing evidence for conservation of lower-order neural mechanisms for processing of ancestral threats across both ontogeny and phylogeny.

Inattentional blindness for a gun during a simulated police vehicle stop

People often fail to notice unexpected objects and events when they are focusing attention on something else. Most studies of this “inattentional blindness” use unexpected objects that are irrelevant to the primary task and to the participant (e.g., gorillas in basketball games or colored shapes in computerized tracking tasks). Although a few studies have examined noticing rates for personally relevant or task-relevant unexpected objects, few have done so in a real-world context with objects that represent a direct threat to the participant. In this study, police academy trainees (n = 100) and experienced police officers (n = 75) engaged in a simulated vehicle traffic stop in which they approached a vehicle to issue a warning or citation for running a stop sign. The driver was either passive and cooperative or agitated and hostile when complying with the officer’s instructions. Overall, 58% of the trainees and 33% of the officers failed to notice a gun positioned in full view on the passenger dashboard. The driver’s style of interaction had little effect on noticing rates for either group. People can experience inattentional blindness for a potentially dangerous object in a naturalistic real-world context, even when noticing that object would change how they perform their primary task and even when their training focuses on awareness of potential threats.

The costs (or benefits) associated with attended objects do little to influence inattentional blindness

We sometimes fail to notice unexpected objects or events when our attention is directed elsewhere, a phenomenon called inattentional blindness. We explored whether unexpected objects that shared the color of consequential objects would be noticed more often. In three pre-registered experiments, participants played a custom video game in which they avoided both low- and high-cost missiles (Experiment 1 and 2) or tried to hit rewarding missiles while avoiding costly ones (Experiment 3). After participants had played the game for about 8min, an unexpected object moved across the screen. Although participants selectively avoided more costly missiles when playing, they were no more likely to notice an unexpected object when its color was associated with greater costs. Apparently, people are no more likely to notice unexpected objects that are associated with negative consequences. Future research should examine whether objects that are themselves consequential are noticed more frequently.