Fearful Expressions Research Articles

Acute sleep disruption reduces fear memories in male and female mice.

Sleep problems are a prominent feature of mental health conditions including post-traumatic stress disorder (PTSD). Despite its potential importance, the role of sleep in the development of and/or recovery from trauma-related illnesses is not understood. Interestingly, there are reports that sleep disruption immediately after a traumatic experience can reduce fear memories, an effect that could be utilized therapeutically in humans. While the mechanisms of this effect are not completely understood, one possible explanation for these findings is that immediate sleep disruption interferes with consolidation of fear memories, rendering them weaker and more sensitive to intervention. Here, we allowed fear-conditioned mice to sleep immediately after fear conditioning during a time frame (18 h) that includes and extends beyond periods typically associated with memory consolidation before subjecting them to 6-h of sleep disruption. Mice exposed to this delayed regimen showed dramatic reductions in fear during tests conducted immediately after sleep disruption, as well as 24 h later. This sleep disruption regimen also increased levels of mRNA encoding brain-derived neurotrophic factor (BDNF), a molecule implicated in neuroplasticity, in the basolateral amygdala (BLA), a brain area implicated in fear and its extinction. These findings raise the possibility that the effects of our delayed sleep disruption regimen are not due to disruption of memory consolidation, but instead are caused by BDNF-mediated neuroadaptations within the BLA that actively suppress expression of fear. Treatments that safely reduce expression of fear memories would have considerable therapeutic potential in the treatment of conditions triggered by trauma.

Cocaine diminishes consolidation of cued fear memory in female rats through interactions with ventral hippocampal D2 receptors

In addition to cocaine's addictive properties, cocaine use may lead to heightened risk-taking behavior. The disruptive effects of cocaine on aversive memory formation may underlie this behavior. The present study investigated the effects of cocaine on fear memory using a cued fear conditioning paradigm in female Sprague Dawley rats, and further determined the role of D2 receptors in modulating the effect of cocaine on cued fear expression. Animals received six evenly spaced shocks preceded by a tone. The following day, rats were returned to the fear chamber where tones, but no shocks, were delivered. In Experiment 1, separate or concurrent administrations of cocaine (15 mg/kg; i.p.) and the D2 receptor antagonist eticlopride (0.1 mg/kg; i.p.) were given immediately after conditioning trials. It was determined that cocaine administration during the consolidation period diminished the expression of cued fear during the subsequent test day. Concurrent eticlopride administration attenuated this effect, indicating the involvement of D2 receptors in the deleterious effects of cocaine on fear memory consolidation. In Experiment 2, eticlopride (0.05 μg) was infused directly into the ventral hippocampus (VH) after fear conditioning and before cocaine administration. Cocaine continued to disrupt consolidation of cued and contextual fear memory, and concurrent intra-VH eticlopride blocked this effect, thereby demonstrating that VH D2 receptors mediate cocaine-induced impairment of fear memory consolidation. Overall, the present study provides evidence that acute cocaine administration impairs aversive memory formation and establishes a potential circuit through which cocaine induces its detrimental effects on fear memory consolidation.

Predictability modulates the early neural coding of spatially unattended fearful faces

In this study, we assessed whether predictability affected the early processing of facial expressions. To achieve this, we measured lateralised early- and mid-latency event-related potentials associated with visual processing. Twenty-two participants were shown pairs of bilaterally presented fearful, happy, angry, or scrambled faces. Participants were required to identify angry faces on a spatially attended side whilst ignoring happy, fearful, and scrambled faces. Each block began with the word HAPPY or FEARFUL which informed participants the probability at which these faces would appear. Attention effects were found for the lateralised P1, suggesting that emotions do not modulate the P1 differentially, nor do predictions relating to emotions. Pairwise comparisons demonstrated that, when spatially unattended, unpredicted fearful faces produced larger lateralised N170 amplitudes compared to predicted fearful faces and unpredicted happy faces. Finally, attention towards faces increased lateralised EPN amplitudes, as did both fearful expressions and low predictability. Thus, we demonstrate that the N170 and EPN are sensitive to top-down predictions relating to facial expressions and that low predictability appears to specifically affect the early encoding of fearful faces when unattended, possibly to initiate attentional capture.

Do Children with High Callous-Unemotional Traits Have Attentional Deficits to Emotional Stimuli? Evidence from a Multi-Method and Multi-Informant Study.

Callous-unemotional (CU) traits in children and adolescents are linked to severe and persistent antisocial behavior. Based on past empirical research, several theoretical models have suggested that CU traits may be partly explained by difficulties in correctly identifying others' emotional states as well as their reduced attention to others' eyes, which could be important for both causal theory and treatment. This study tested the relationships among CU traits, emotion recognition of facial expressions and visual behavior in a sample of 52 boys referred to a clinic for conduct problems (Mage = 10.29years; SD = 2.06). We conducted a multi-method and multi-informant assessment of CU traits through the Child Problematic Traits Inventory (CPTI), the Inventory of Callous-Unemotional (ICU), and the Clinical Assessment of Prosocial Emotions-Version 1.1 (CAPE). The primary goal of the study was to compare the utility of these methods for forming subgroups of youth that differ in their emotional processing abilities. An emotion recognition task assessed recognition accuracy (percentage of mistakes) and absolute dwell time on the eyes or mouth region for each emotion. Results from repeated measures ANOVAs revealed that low and high CU groups did not differ in emotion recognition accuracy, irrespective of the method of assessing CU traits. However, the high CU group showed reduced attention to the eyes of fearful and sad facial expressions (using the CPTI) or to all emotions (using the CAPE). The high CU group also showed a general increasein attention to the mouth area, but only when assessed by the CAPE. These findings provide evidence to support abnormalities in how those elevated on CU traits process emotional stimuli, especially when assessed by a clinical interview, which could guide appropriate assessment and more successful interventions for this group of youth.

Translational approaches to the neurobiological study of conditional discrimination and inhibition: Implications for psychiatric disease.

There is a growing number of studies investigating discriminatory fear conditioning and conditioned inhibition of fear to assess safety learning, in addition to extinction of cued fear. Despite all of these paradigms resulting in a reduction in fear expression, there are nuanced differences among them, which could be mediated through distinct behavioral and neural mechanisms. These differences could impact how we approach potential treatment options in clinical disorders with dysregulated fear responses. The objective of this review is to give an overview of the conditional discrimination and inhibition findings reported in both animal models and human neuropsychiatric disorders. Both behavioral and neural findings are reviewed among human and rodent studies that include conditional fear discrimination via conditional stimuli with and without reinforcement (CS+ vs. CS-, respectively) and/or conditional inhibition of fear through assessment of the fear response to a compound CS-/CS+ cue versus CS+. There are several parallels across species in behavioral fear expression as well as neural circuits promoting fear reduction in response to a CS- and/or CS-/CS+ compound cue. Continued and increased efforts to compare similar behavioral fear inhibition paradigms across species are needed to make breakthrough advances in our understanding and treatment approaches to individuals with fear disorders. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Ceftriaxone Inhibits Conditioned Fear and Compulsive-like Repetitive Marble Digging without Central Nervous System Side Effects Typical of Diazepam-A Study on DBA2/J Mice and a High-5HT Subline of Wistar-Zagreb 5HT Rats.

Background: Ceftriaxone upregulates GLT1 glutamate transporter in the brain and may have anti-CFC and anti-OCD effects. Methods: Twenty WZ-5HT rats were used to investigate the effects of ceftriaxone on obsessive-compulsive (OCD)-like behaviour in the marble-burying (MB) test, freezing behaviour in contextual fear conditioning (CFC) and expression of GLT1 protein in the hippocampus or amygdala using immunoblots. Fifteen DBA/2J mice were used in the MB test. We also compared diazepam with ceftriaxone in open-field, beam-walking, and wire-hanging tests on 47 DBA/2J mice. Ceftriaxone (200 mg/kg) and saline were applied intraperitoneally, once daily for 7 (rats) or 5 (mice) consecutive days. A single dose of diazepam (1.5-3.0 mg/kg) or saline was injected 30 min before the behavioural tests. Results: Ceftriaxone significantly diminished OCD-like behaviour (↓ number of marbles buried) and freezing behaviour in CFC context session (↑ latencies, ↓ total duration, ↓ duration over four 2 min periods of the session) but increased GLT1 protein expression in the amygdala and hippocampus of rats. Diazepam induced sedation, ataxia and myorelaxation in mice. Ceftriaxone did not have these side effects. Conclusions: The results of this study confirm the anti-CFC and anti-OCD effects of ceftriaxone, which did not produce the unwanted effects typical of diazepam.

Oxytocin receptor control social information about fear expression of others in mice

The social functions of oxytocin are diverse, and the specific aspects of information processing involved in emotional contagion remain unclear. We compared some fear-related behaviors among oxytocin receptor knockout mice and oxytocin-receptor-reduced mice with that of wild-type mice. In the observational fear assay, which reflects fear emotional contagion, mice that observed other individuals receiving electric shocks exhibited vicarious freezing. Mice with reduced or knockout oxytocin receptor expression showed reduced vicarious freezing. In the emotional discrimination assay, which reflects the ability to perceive others’ emotional cues, we compared approach and scent-sniffing behaviors toward fear and emotionally neutral individuals. While wild-type mice were able to detect the fear emotion of others, mice with reduced or knocked-out oxytocin receptors showed reduced discrimination ability. In the fear behavior assays, which do not present social cues, we did not find these differences in oxytocin receptor expression in the brain. These findings indicate that oxytocin plays a role in emotional contagion by perceiving the emotions of others.

Modulation of the somatosensory blink reflex under fear

ObjectiveThis study evaluated the isolated and combined effects of fear and PPS paradigms on SBR. MethodThe prospective study was conducted with healthy participants. After stimulation of the right median nerve at the wrist, bilateral recordings were randomized under the following conditions: First experiment (with the right hand on the chair armrest): i. baseline recordings, ii. while watching fearful facial expressions from the Karolinska Emotional Faces battery (fear), iii. post-watching (post-fear), iv. while watching neutral facial expressions from the same battery (neutral), v. Immediately after viewing (post-neutral). Second experiment (right hand 2 cm away from the right eye, PPS): i. reference condition (PPS), ii. while watching fearful facial expressions (PPS-fear), iii. while watching neutral facial expressions (PPS-neutral). In each condition, SBR latency, area, duration, and amplitudes were measured and compared between conditions. ResultsWe included 16 participants. SBR could be recorded in 11 (mean age:30.7 ± 5.2, F/M:5/6). First experiment: SBR amplitude was significantly reduced in fear condition (p = 0.008), and SBR area was reduced considerably in fear and post-fear conditions (p = 0.004) compared to the baseline. Second experiment: The SBR area was higher in the PPS (p = 0.009) compared to the baseline and even higher in the fearPPS compared to the PPS (p = 0.038). In neutral or PPS-neutral conditions, the area of the SBR did not change significantly. ConclusionFear suppressed SBR, but fear increased SBR when a threat stimulus was present. The findings were unrelated to habituation or attention, indicating cortical-amygdala-bulbar connections.

A prefrontal-habenular circuitry regulates social fear behaviour.

The medial prefrontal cortex (mPFC) has been implicated in the pathophysiology of social impairments including social fear. However, the precise subcortical partners that mediate mPFC dysfunction on social fear behaviour have not been identified. Employing a social fear conditioning paradigm, we induced robust social fear in mice and found that the lateral habenula (LHb) neurons and LHb-projecting mPFC neurons are synchronously activated during social fear expression. Moreover, optogenetic inhibition of the mPFC-LHb projection significantly reduced social fear responses. Importantly, consistent with animal studies, we observed an elevated prefrontal-habenular functional connectivity in subclinical individuals with higher social anxiety characterized by heightened social fear. These results unravel a crucial role of the prefrontal-habenular circuitry in social fear regulation and suggest that this pathway could serve as a potential target for the treatment of social fear symptom often observed in many psychiatric disorders.

Reading language of the eyes in female depression.

Aberrations in non-verbal social cognition have been reported to coincide with major depressive disorder. Yet little is known about the role of the eyes. To fill this gap, the present study explores whether and, if so, how reading language of the eyes is altered in depression. For this purpose, patients and person-by-person matched typically developing individuals were administered the Emotions in Masked Faces task and Reading the Mind in the Eyes Test, modified, both of which contained a comparable amount of visual information available. For achieving group homogeneity, we set a focus on females as major depressive disorder displays a gender-specific profile. The findings show that facial masks selectively affect inferring emotions: recognition of sadness and anger are more heavily compromised in major depressive disorder as compared with typically developing controls, whereas the recognition of fear, happiness, and neutral expressions remains unhindered. Disgust, the forgotten emotion of psychiatry, is the least recognizable emotion in both groups. On the Reading the Mind in the Eyes Test patients exhibit lower accuracy on positive expressions than their typically developing peers, but do not differ on negative items. In both depressive and typically developing individuals, the ability to recognize emotions behind a mask and performance on the Reading the Mind in the Eyes Test are linked to each other in processing speed, but not recognition accuracy. The outcome provides a blueprint for understanding the complexities of reading language of the eyes within and beyond the COVID-19 pandemic.

Central amygdala CRF+ neurons promote heightened threat reactivity following early life adversity in mice

Failure to appropriately predict and titrate reactivity to threat is a core feature of fear and anxiety-related disorders and is common following early life adversity (ELA). A population of neurons in the lateral central amygdala (CeAL) expressing corticotropin releasing factor (CRF) have been proposed to be key in processing threat of different intensities to mediate active fear expression. Here, we use in vivo fiber photometry to show that ELA results in sex-specific changes in the activity of CeAL CRF+ neurons, yielding divergent mechanisms underlying the augmented startle in ELA mice, a translationally relevant behavior indicative of heightened threat reactivity and hypervigilance. Further, chemogenic inhibition of CeAL CRF+ neurons selectively diminishes startle and produces a long-lasting suppression of threat reactivity. These findings identify a mechanism for sex-differences in susceptibility for anxiety following ELA and have broad implications for understanding the neural circuitry that encodes and gates the behavioral expression of fear.

“The oncologist told me”: Reported speech as a patients’ resource to volunteer concerns in oncological visits

Based on the “patient centered approach”, growing emphasis within policies has been put on patients' active participation in medical encounters. Consistently, research has investigated patients' initiatives during medical visits in a wide array of settings and specialties. Among these, oncological care constitutes a setting where patient participation is particularly crucial as well as challenging. However, previous studies in this setting have focused mainly on doctors' interactional work, with few works exploring patients' expressions of fears, uncertainties, and hopes. The present study contributes to this underexplored line of inquiry by showing how oncological patients take the initiative and make relevant their concerns through reported speech (RS). Based on a corpus of 106 video-recorded oncological visits collected in Italy and adopting conversation analysis, the article shows how patients use RS to volunteer some information they have previously been told by other, non-present physicians. Through RS, patients cautiously make relevant specific aspects of their case that have not been addressed in the ongoing interaction and appear to constitute a concern for them (e.g., presence of metastases, treatment side effects, hospitalization length). In response, the physician addresses the patient's concern, either by confirming the reported information or by distancing themselves from it, thus providing their opinion on the matter.

Social interaction-induced fear memory reduction: exploring the influence of dopamine and oxytocin receptors on memory updating

It has been well established that a consolidated memory can be updated during the plastic state induced by reactivation. This updating process opens the possibility to modify maladaptive memory. In the present study, we evaluated whether fear memory could be updated to less-aversive level by incorporating hedonic information during reactivation. Thus, male rats were fear conditioned and, during retrieval, a female was presented as a social rewarding stimulus. We found that memory reactivation with a female (but not a male) reduces fear expression within-session and in the test, without presenting reinstatement or spontaneous recovery. Interestingly, this intervention impaired extinction. Finally, we demonstrated that this emotional remodeling to eliminate fear expression requires the activation of dopamine and oxytocin receptors during retrieval. Hence, these results shed new lights on the memory updating process and suggests that the exposure to natural rewarding information such as a female during retrieval reduces a previously consolidated fear memory.

Approach-avoidance tendencies in proactive and reactive aggression.

Aggressive behaviors have been related to approach/avoidance tendencies. In our current study, we investigated whether approach/avoidance tendencies for angry versus fearful emotional expressions were differentially predictive of children's reactive and proactive aggression. A total of 116 children (58 girls, Mage = 10.90, standard deviation SDage = 0.98) completed an approach/avoidance task (AAT) and a stimulus-response compatibility task (SRCT), both measuring the extent to which they tended to approach or avoid angry and fearful facial expressions relative to neutral facial expressions. Children also completed a self-report scale of reactive and proactive aggression. Although none of the approach/avoidance tendency scores correlated significantly with either of the aggression scores, stronger approach tendencies for angry faces and stronger avoidance tendencies for fearful faces in the AAT predicted more reactive aggression. Similar yet nonsignificant results were found for proactive aggression, but no effects were replicated in the SRCT. Our results thus invite the conclusion that reactive aggression is characterized by a tendency to approach angry faces and a tendency to avoid fearful faces. However, the poor discrimination between both types of aggression as well as the lack of convergence between the results of our two measures of approach/avoidance tendencies indicates that further research is needed to establish the role of approach/avoidance tendencies for emotional faces as markers for childhood aggression.

Le port du masque affecte l'identification des expressions faciales émotionnelles, surtout chez les personnes âgées

Younger adults have difficulties identifying emotional facial expressions from faces covered by face masks. It is important to evaluate how face mask wearing might specifically impact older people, because they have lower emotion identification performance than younger adults, even without face masks. We compared performance of 62young and 38older adults in an online task of emotional facial expression identification using masked or unmasked pictures of faces with fear, happiness, anger, surprise, and neutral expression, from different viewpoints. Face masks affected performance in both age groups, but more so in older adults, specifically for negative emotions (anger, fear), in favour of the saliency hypothesis as an explanation for the positive advantage. Additionally, face masks more affected emotion recognition on profile than on three-quarter or full-face views. Our results encourage using clearer and full-face expressions when dealing with older people while wearing face masks.

The impact of chronic fluoxetine treatment in adolescence or adulthood on context fear memory and perineuronal nets.

Selective serotonin reuptake inhibitors, such as fluoxetine (Prozac), are commonly prescribed pharmacotherapies for anxiety. Fluoxetine may be a useful adjunct because it can reduce the expression of learned fear in adult rodents. This effect is associated with altered expression of perineuronal nets (PNNs) in the amygdala and hippocampus, two brain regions that regulate fear. However, it is unknown whether fluoxetine has similar effects in adolescents. Here, we investigated the effect of fluoxetine exposure during adolescence or adulthood on context fear memory and PNNs in the basolateral amygdala (BLA), the CA1 subregion of the hippocampus, and the medial prefrontal cortex in rats. Fluoxetine impaired context fear memory in adults but not in adolescents. Further, fluoxetine increased the number of parvalbumin (PV)-expressing neurons surrounded by a PNN in the BLA and CA1, but not in the medial prefrontal cortex, at both ages. Contrary to previous reports, fluoxetine did not shift the percentage of PNNs toward non-PV cells in either the BLA or CA1 in the adults, or adolescents. These findings demonstrate that fluoxetine differentially affects fear memory in adolescent and adult rats but does not appear to have age-specific effects on PNNs.

Threat-dependent scaling of prelimbic dynamics to enhance fear representation

Promptly identifying threatening stimuli is crucial for survival. Freezing is a natural behavior displayed by rodents toward potential or actual threats. Although it is known that the prelimbic cortex (PL) is involved in both risk evaluation and in fear and anxiety-like behavior expression, here we explored whether PL neuronal activity can dynamically represent different internal states of the same behavioral output (i.e., freezing). We found that freezing can always be decoded from PL activity at a population level. However, the sudden presentation of a fearful stimulus quickly reshaped the PL to a new neuronal activity state, an effect not observed in other cortical or subcortical regions examined. This shift changed PL freezing representation and is necessary for fear memory expression. Our data reveal the unique role of the PL in detecting threats and internally adjusting to distinguish between different freezing-related states in both unconditioned and conditioned fear representations.

The effects of fear of COVID-19 among Spanish healthcare professionals in three years after the pandemic onset via validation of the FCV-19S: a prospective study

AbstractDespite being validated in different populations to assess fear of COVID-19, the Fear of COVID-19 Scale (FCV-19S) has scatter validations in healthcare professionals, often with several limitations, especially in Spanish-speaking professionals. Our research aims to extend previous studies by: (i) using a large sample of Spanish nurses and physicians; (ii) incorporating longitudinal data; and (iii) using a covariance-based SEM methodology to test different factor structures. 686 Spanish healthcare professionals (M = 42.7 years; 80.5% women; 76.7% nurses) participated in 2021 (Time 1), of whom, 216 were reassessed one year later (Time 2). The results (S-Bχ2 = 69.134, df = 13, p < 0.001, CFI = 0.974, and SRMR ≤ 0.031) supported a two-factor structure with a factor of somatic reactions and another of emotional expressions of fear of COVID-19. The FCV-19S evidenced strong factorial measurement invariance regarding gender, professional category, age and professional experience and also showed significantly higher levels of fear of COVID-19 in women, nurses, and professionals under 40 years old. The internal consistency was high for the somatic factor (ω = 0.86; α = 0.85), the emotional factor (ω = 0.82; α = 0.82) and the overall scale (α = 0.89). The scale showed good convergent, divergent, and incremental validity with respect to psychological symptomatology, perceived health, burnout, and worry about contagion. Finally, the FCV-19S showed criterion validity regarding generalized anxiety disorder, burnout, and the risk of leaving the profession. The FCV-19S evidenced excellent psychometric properties in Spanish healthcare professionals and was predictive of different health outcomes one year after administration. Study implications and limitations are also discussed.

Mating-induced release of oxytocin in the mouse lateral septum: Implications for social fear extinction

In mammals, some physiological conditions are associated with the high brain oxytocin (OXT) system activity. These include lactation in females and mating in males and females, both of which have been linked to reduced stress responsiveness and anxiolysis. Also, in a murine model of social fear conditioning (SFC), enhanced brain OXT signaling in lactating mice, specifically in the lateral septum (LS), was reported to underlie reduced social fear expression. Here, we studied the effects of mating in male mice on anxiety-related behaviour, social (and cued) fear expression and its extinction, and the activity of OXT neurons reflected by cFos expression and OXT release in the LS and amygdala. We further focused on the involvement of brain OXT in the mating-induced facilitation of social fear extinction. We could confirm the anxiolytic effect of mating in male mice irrespective of the occurrence of ejaculation. Further, we found that only successful mating resulting in ejaculation (Ej+) facilitated social fear extinction, whereas mating without ejaculation (Ej-) did not. In contrast, mating did not affect cues fear expression. Using the cellular activity markers cFos and pErk, we further identified the ventral LS (vLS) as a potential region participating in the effect of ejaculation on social fear extinction. In support, microdialysis experiments revealed a rise in OXT release within the LS, but not the amygdala, during mating. Finally, infusion of an OXT receptor antagonist into the LS before mating or into the lateral ventricle (icv) after mating demonstrated a significant role of brain OXT receptor-mediated signaling in the mating-induced facilitation of social fear extinction.

Promoting pedestrian safety in Bangladesh: Identifying factors for drivers’ yielding behavior at designated crossings using behavior change theories

Objective In Bangladesh, drivers’ failure to yield to pedestrians at designated crossings poses a significant safety risk and discourages their use of such crossings. The use of behavior change theories could be more appropriate in such complex situations where the interdependent behaviors of drivers and pedestrians interact. While many studies have identified factors that affect drivers’ yielding behavior in the literature, fewer efforts have been made to apply behavior change theories in exploring and validating these factors, and to reach a consensus among competing road users. This study is among the first to utilize behavior change theories in Bangladesh to identify pedestrians’ safety factors that could promote drivers’ yielding behavior, upon which a consensus between drivers and pedestrians could be established. Methods A self-reported attitudinal survey was administered to 202 drivers on two highways in Bangladesh with a questionnaire using the capability, opportunity, motivation, and behavior (COM-B) model for the comprehensive coverage of behavior change theories. The focus group interviews were also conducted with 40 pedestrians and 19 drivers who have experience with four crossing sites on the selected highways. The collected data were analyzed using a regression model to identify significant factors influencing the drivers’ yielding behavior. These factors were then justified using a deductive thematic coding framework based on behavior change theories. Results The regression model explained the variance in drivers’ yielding by 45.1% with eight factors. The model found seven positive significant contributory factors in the drivers’ yielding that could promote pedestrian safety. Of them, the motivation factors were avoiding random crossing by pedestrians, vulnerable groups, assertiveness, and facial fear expressions; and the opportunity factors were traffic signs or advanced yield lines, crossing in groups at specific times, and enforcement. Conclusions The study’s findings have practical implications for policymakers, highway designers, and other stakeholders involved in promoting pedestrian safety by acknowledging their stake in making any decision that might impact them. Highway designers can use the thematic coding framework to recommend any contributory factors involved, where competing drivers’ unwillingness to yield is the primary threat to pedestrians’ safety.