Neutral Faces Research Articles

Impairment of unconscious emotional processing after unilateral medial temporal structure resection

The role of the amygdala in unconscious emotional processing remains a topic of debate. Past lesion studies have indicated that amygdala damage leads to impaired electrodermal activity in response to subliminally presented emotional stimuli. However, electrodermal activity can reflect both emotional and nonemotional processes. To provide behavioral evidence highlighting the critical role of the amygdala in unconscious emotional processing, we examined patients (n = 16) who had undergone unilateral resection of medial temporal lobe structures, including the amygdala. We utilized the subliminal affective priming paradigm in conjunction with unilateral visual presentation. Fearful or happy dynamic facial expressions were presented in unilateral visual fields for 30 ms, serving as negative or positive primes. Subsequently, neutral target faces were displayed, and participants were tasked with rating the valence of these targets. Positive primes, compared to negative ones, enhanced valence ratings of the target to a greater extent when they stimulated the intact hemisphere (i.e., were presented in the contralateral visual field of the intact hemisphere) than when they stimulated the resected hemisphere (i.e., were presented in the contralateral visual field of the resected hemisphere). These results suggest that the amygdala is causally involved in unconscious emotional processing.

Anatomical variants of acne differ in their impact on social perception.

Acne negatively affects quality of life, however quality-of-life scores poorly correlate with disease severity scores. Previous research demonstrated existence of facial areas in which skin lesions have greater impact on gaze patterns. Therefore, we hypothesized that anatomical variants of acne may be perceived differently. The aim was to investigate effect of anatomical variants of acne on natural gaze patterns and resulting impact on social perception of acne patients. We tracked eye movements of participants viewing neutral and emotional faces with acne. Images were rated for acne-related visual disturbance, and emotional faces were rated for valence intensity. Respondents of an online survey were asked to rate their perception of pictured individuals' personality traits. All faces with acne were perceived as less attractive and received poorer personality judgements with mid-facial acne presenting smallest deviation from healthy faces. T-zone and mixed acne exhibited the least significant difference in respondents gaze behaviour pattern from each other. In addition, there was no significant difference in respondents' grading of acne visual disturbance or ratings for attractiveness, success and trustworthiness. U-zone adult female acne was rated as the most visually disturbing and received the lowest scores for attractiveness. Happy faces with adult female acne were rated as less happy compared to other acne variants and clear-skin faces. Anatomic variants of acne have a distinct impact on gaze patterns and social perception. Adult female acne has the strongest negative effect on recognition of positive emotions in affected individuals, attractiveness ratings and forming social impressions. If perioral acne lesions are absent, frontal lesions determine impact of acne on social perception irrespective of the presence of mid-facial lesions. This perceptive hierarchy should be taken into consideration while deciding treatment goals in acne patients, prioritizing achieving remission in perioral and frontal area.

Attentional processing of preserved face and scrambled face distractors in preschool children with autism spectrum condition

ABSTRACT The current study investigated attentional processing of preserved neutral face and scrambled neutral face distractors at both involuntary and voluntary orienting levels in children with and without autism spectrum condition (ASC). The findings suggest similar influences of face configuration on reflexive orienting in both groups but reveal group differences in voluntary disengagement from face-related distractors. The ASC group exhibited difficulties in disengaging from the central neutral faces, and the TD group showed longer latencies for scrambled faces. These group differences suggest inefficiency in adopting a global face processing strategy at the voluntary attentional level in ASC. We discuss how the observed effects might impact upon the development of social communication skills in ASC.

Still face in pet dogs (Canis familiaris).

Dogs are able to cooperate in reciprocal exchange with humans but little is known about the extent of these abilities (Range & Virányi, 2015). In the Still Face paradigm, infants reply to a sudden nonreciprocal facial expression with gaze aversion and an increase in re-engagement and distress behaviors (E. Tronick et al., 1978). We directly adapted this method; the dog's owner talked to the dog, then abruptly switched to a still, neutral face, maintaining eye contact. In Study 1 (N = 20), we found that dogs showed a significant decrease in the amount of looking at the owner in the Still Face phase, paralleling the results found in gaze aversion in infants, and they performed fewer pawing and vocalizations toward the person in the Still Face phase. In Study 2 (N = 60), we included one condition of continuous physical contact, and one condition that was a direct replication of the initial study without physical contact. Similar to human infants, we found a significant decrease in looking from the Interaction phase to the Still Face phase. However, in contrast to human infants, re-engagement and stress behaviors were higher in the Interaction phase than the Still Face phase. Looking and re-engagement behaviors differed based on the condition, with a smaller difference between phases in the Petting condition. These results suggest that dogs are capable of perceiving these small changes in human affect. However, unlike human infants, dogs seem to have greater expectations about physical interactions than verbal interactions, as they reacted more strongly to an Interaction phase without physical contact than the Still Face. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Sustained looking at faces at 5months of age is associated with socio-communicative skills in the second year of life.

Efficiently processing information from faces in infancy is foundational for nonverbal communication. We studied individual differences in 5-month-old infants' (N=517) sustained attention to faces and preference for emotional faces. We assessed the contribution of genetic and environmental influences to individual differences in these gaze behaviors, and the association between these traits and other concurrent and later phenotypes. We found an association between the mean duration of looking at a face (before looking away from it) at 5months and socio-communicative abilities at 14months (β=0.17, 95% CI: 0.08; 0.26, p<0.001). Sustained attention to faces predicted socio-communicative abilities over and above variance captured by mean fixation duration. We also found a statistically significant but weak tendency to prefer looking at smiling faces (relative to neutral faces), but no indication that variability in this behavior was explained by genetic effects. Moderate heritability was found for sustained attention to faces (A=0.23, CI: 0.06; 0.38), while shared environmental influences were non-significant for both phenotypes. These findings suggest that sustained looking at individual faces before looking away is a developmentally significant 'social attention' phenotype in infancy, characterized by moderate heritability and a specific relation to later socio-communicative abilities.

Unveiling why race does not affect the mask effect on attractiveness: but gender and expression do

Studies show that surgical face masks can have both positive and negative effects on attractiveness. Race has been implicated as a moderator of the size of this mask effect. Here, the moderating effects of expression, race and gender are explored. The mask effect was more positive for males than for females, for neutral faces than for smiling faces, and there were differences between the races. Further, the effect of unmasked attractiveness was partialled out for each image, which removed the race effects, but the gender and expression effects remained. It is suggested that racial differences previously observed in the mask effects are a consequence of differences in attractiveness of the faces sampled from those races. Re-analysis of previous research that showed race effects also demonstrates how they are better explained as attractiveness effects rather than race effects. This explanation can provide order to the different findings observed across the literature.

Subjectively salient faces differ from emotional faces: ERP evidence

The self-face is processed differently than emotional faces. A question arises whether other highly familiar and subjectively significant non-self faces (e.g. partner’s face) are also differentiated from emotional faces. The aim of this event-related potential (ERP) study was to investigate the neural correlates of personally-relevant faces (the self and a close-other’s) as well as emotionally positive (happy) and neutral faces. Participants were tasked with the simple detection of faces. Amplitudes of N170 were more negative in the right than in the left hemisphere and were not modulated by type of face. A similar pattern of N2 and P3 results for the self-face and close-other’s face was observed: they were associated with decreased N2 and increased P3 relative to happy and neutral faces. However, the self-face was preferentially processed also when compared to a close-other’s face as revealed by lower N2 and higher P3 amplitudes. Nonparametric cluster-based permutation tests showed an analogous pattern of results: significant clusters for the self-face compared with all other faces (close-other’s, happy, neutral) and for close-other’s face compared to happy and neutral faces. In summary, the self-face prioritization was observed, as indicated by significant differences between one’s own face and all other faces. Crucially, both types of personally-relevant faces differed from happy faces. These findings point to the pivotal role of subjective evaluation of the saliency factor.

Functional brain responses to emotional faces after three to five weeks of intake of escitalopram in healthy individuals: a double-blind, placebo-controlled randomised study

Short-term intake of selective serotonin reuptake inhibitors (SSRIs) modulates threat-related amygdala responses in healthy individuals. However, how SSRI intake over a clinically relevant time period modulates threat-related amygdala responses is less clear. In a semi-randomised, double-blind, placebo-controlled study of 64 healthy individuals (SSRI n = 32, placebo n = 32), we examined the effect of 3–5 weeks of SSRI escitalopram (20 mg daily) on brain response to angry, fearful and neutral faces using BOLD fMRI. Data was analysed using a whole-brain region-wise approach extracting standardised effects (i.e., Cohen’s D). The study was conducted at the Copenhagen University Hospital. A priori, we hypothesised that SSRI would attenuate amygdala responses to angry and fearful faces but not to neutral ones. Whether SSRI modulates correlations between amygdala responses to emotional faces and negative mood states was also explored. Compared to placebo, 3–5 weeks of SSRI intake did not significantly affect the amygdala response to angry, fearful, or neutral faces (|Cohen’s D|< 0.2, PFWER = 1). Whole-brain, region-wise analyses revealed significant differences in frontal (|Cohen’s D|< 0.6, PFWER < .01) and occipital regions (|Cohen’s D|< 0.5, PFWER < .01). SSRI did not modulate correlations between amygdala responses to emotional faces and negative mood states. Our findings indicate that a 3–5 week SSRI intake impacts cortical responses to emotional stimuli, an effect possibly involved in SSRI’s therapeutic efficacy.Trial registration Clinical Trials NCT04239339.

Facial emotion recognition in individuals with mild cognitive impairment: An exploratory study.

Understanding facial emotions is fundamental to interact in social environments and modify behavior accordingly. Neurodegenerative processes can progressively transform affective responses and affect social competence. This exploratory study examined the neurocognitive correlates of face recognition, in individuals with two mild cognitive impairment (MCI) etiologies (prodromal to dementia - MCI, or consequent to Parkinson's disease - PD-MCI). Performance on the identification and memorization of neutral and emotional facial expressions was assessed in 31 individuals with MCI, 26 with PD-MCI, and 30 healthy controls (HC). Individuals with MCI exhibited selective impairment in recognizing faces expressing fear, along with difficulties in remembering both neutral and emotional faces. Conversely, individuals with PD-MCI showed no differences compared with the HC in either emotion recognition or memory. In MCI, no significant association emerged between the memory for facial expressions and cognitive difficulties. In PD-MCI, regression analyses showed significant associations with higher-level cognitive functions in the emotional memory task, suggesting the presence of compensatory mechanisms. In a subset of participants, voxel-based morphometry revealed that the performance on emotional tasks correlated with regional changes in gray matter volume. The performance in the matching of negative expressions was predicted by volumetric changes in brain areas engaged in face and emotional processing, in particular increased volume in thalamic nuclei and atrophy in the right parietal cortex. Future studies should leverage on neuroimaging data to determine whether differences in emotional recognition are mediated by pathology-specific atrophic patterns.

The effect of reward expectation on working memory of emotional faces under different levels of cognitive load: an ERP study.

Using event-related potentials (ERPs), this study examined the impact of reward expectations on working memory of emotional faces under different levels of cognitive load in a task combining the N-back paradigm and the reward expectation paradigm. The experiment involved presenting high- or low-reward cues followed by an N-back task for emotional faces with different loads. The accuracy results showed that under a high task load, both reward and emotion effects were significantly observed. However, these effects disappeared under a low task load. Analysis of the ERP data revealed that the early P2 and VPP components exhibited greater responses to fearful faces than to neutral faces. In the later stages, the P3 and LPP components showed greater reactions to high rewards than to low rewards. Additionally, the P2 component was found to be modulated by task load in relation to rewards, the EPN component demonstrated task load modulation with respect to emotions, and the N170 component showed an interaction effect between rewards and emotions. These findings imply that load regulates the reward effect and the emotional superiority effect in the process of working memory for emotional faces. In the cognitive processing of working memory, motivation and emotion jointly influence processing. Emotional factors have a greater impact in the early stage of processing, while motivation factors have a greater impact in the late stage of processing.

Keeping distance or getting closer: How others' emotions shape approach-avoidance postural behaviors and preferred interpersonal distance.

Understanding the influence of emotions on social interactions is important for a global understanding of the dynamics of human behavior. In this study, we investigated the interplay between emotions, spontaneous approach or avoidance tendencies, and the regulation of interpersonal distance. Fifty-seven healthy adults participated in a three-part experiment involving exposure to approaching or withdrawing emotional faces (neutral, happy, sad, fearful, disgusted, angry). The sequence began with an initial computerized stop-distance task, followed by a postural task in which participants' approach or avoidance tendencies were quantified via center of pressure (CoP-Y) displacements on a force platform, and concluded with a final computerized stop-distance task. Our findings revealed a gradient in postural responses, with the most forward CoP-Y displacements for neutral and happy faces, indicative of approach tendencies. These were followed by lesser forward displacements for sad and fearful faces, and most pronounced backward displacements for disgusted and angry faces, indicating avoidance. Furthermore, we observed modulations in participants' preferred interpersonal distance based on emotional cues, with neutral and happy faces associated with shorter distances, and disgusted and angry faces linked to larger distances. Despite these similar results, no direct correlation was found between CoP-Y and preferred interpersonal distance, underscoring a dissociation between spontaneous and voluntary social behaviors. These results contribute to a better understanding of how emotional expressions shape social interactions and underscore the importance of considering emotional cues, postural action tendencies, and interpersonal distance in facilitating successful social interactions.

The effect of working memory load on selective attention to emotional faces for social anxiety individuals.

Research has confirmed that individuals with social anxiety (SA) show an attentional bias towards threat-related stimuli. However, the extent to which this attentional bias depends on top-down cognitive control processes remains controversial. The present study investigated the effect of working memory (WM) load on selective attention to emotional faces in both high social anxiety (HSA) and low social anxiety (LSA) groups by manipulating WM load through the inclusion of forward counting in multiples of two (low load) or backward counting in multiples of seven (high load) within a modified flanker task. In the flanker task, emotional faces (angry, happy, or neutral faces) were used as targets and distractors. A total of 70 participants (34 HSA participants; 36 LSA participants) completed the flanker task in the laboratory. The results showed that the HSA individuals performed worse when responding to angry targets. Relative to LSA individuals, HSA individuals showed interference from angry distractors in the flanker task, resulting in significantly lower accuracy in identifying angry targets compared to happy targets. These results were unaffected by the manipulation of WM load. The findings imply HSA individuals have impaired attentional control, and that their threat-related attentional bias relies more on the bottom-up automatic attentional process.

Emotions related to threatening events are mainly linked to the right hemisphere.

A recent meta-analysis of functional neuroimaging contrasts between emotional and neutral face processing has shown that the processing of facial emotions can be better classified according to threat detection than emotional valence, with the authors suggesting that their data are inconsistent with both the right-hemisphere and valence models of emotional laterality. I report empirical and theoretical data indicating that facial expressions are better classified according to threat detection than to the distinction between positive and negative emotions. I challenge, however, the claim that laterality effects provide little support to the right-hemisphere model of emotional laterality. This claim contrasts with neuropsychological and psychophysiological investigations that have shown that the right hemisphere has a graded prevalence for emotions provoked by threatening events. A reanalysis of data obtained in the target study suggests that the reported data are not necessarily inconsistent with a model assuming a graded, right-hemisphere dominance for emotions. I present a model of hemispheric asymmetries that could be consistent with the assumption that the right hemisphere's dominance for emotions may mainly be concerned with threatening events.

Combining electrodermal activity analysis and dynamic causal modeling to investigate the visual-odor multimodal integration during face perception

Objective. This study presents a novel methodological approach for incorporating information related to the peripheral sympathetic response into the investigation of neural dynamics. Particularly, we explore how hedonic contextual olfactory stimuli influence the processing of neutral faces in terms of sympathetic response, event-related potentials and effective connectivity analysis. The objective is to investigate how the emotional valence of odors influences the cortical connectivity underlying face processing and the role of face-induced sympathetic arousal in this visual-olfactory multimodal integration. Approach. To this aim, we combine electrodermal activity (EDA) analysis and dynamic causal modeling to examine changes in cortico-cortical interactions. Results. The results reveal that stimuli arising sympathetic EDA responses are associated with a more negative N170 amplitude, which may be a marker of heightened arousal in response to faces. Hedonic odors, on the other hand, lead to a more negative N1 component and a reduced the vertex positive potential when they are unpleasant or pleasant. Concerning connectivity, unpleasant odors strengthen the forward connection from the inferior temporal gyrus (ITG) to the middle temporal gyrus, which is involved in processing changeable facial features. Conversely, the occurrence of sympathetic responses after a stimulus is correlated with an inhibition of this same connection and an enhancement of the backward connection from ITG to the fusiform face gyrus. Significance. These findings suggest that unpleasant odors may enhance the interpretation of emotional expressions and mental states, while faces capable of eliciting sympathetic arousal prioritize identity processing.

(Micro)saccade-related potentials during face recognition: A study combining EEG, eye-tracking, and deconvolution modeling.

Under natural viewing conditions, complex stimuli such as human faces are typically looked at several times in succession, implying that their recognition may unfold across multiple eye fixations. Although electrophysiological (EEG) experiments on face recognition typically prohibit eye movements, participants still execute frequent (micro)saccades on the face, each of which generates its own visuocortical response. This finding raises the question of whether the fixation-related potentials (FRPs) evoked by these tiny gaze shifts also contain psychologically valuable information about face processing. Here, we investigated this question by corecording EEG and eye movements in an experiment with emotional faces (happy, angry, neutral). Deconvolution modeling was used to separate the stimulus ERPs to face onset from the FRPs generated by subsequent microsaccades-induced refixations on the face. As expected, stimulus ERPs exhibited typical emotion effects, with a larger early posterior negativity (EPN) for happy/angry compared with neutral faces. Eye tracking confirmed that participants made small saccades in 98% of the trials, which were often aimed at the left eye of the stimulus face. However, while each saccade produced a strong response over visual areas, this response was unaffected by the face's emotional expression, both for the first and for subsequent (micro)saccades. This finding suggests that the face's affective content is rapidly evaluated after stimulus onset, leading to only a short-lived sensory enhancement by arousing stimuli that does not repeat itself during immediate refixations. Methodologically, our work demonstrates how eye tracking and deconvolution modeling can be used to extract several brain responses from each EEG trial, providing insights into neural processing at different latencies after stimulus onset.

Persistence of amygdala hyperactivity to subliminal negative emotion processing in the long-term course of depression

Biased emotion processing has been suggested to underlie the etiology and maintenance of depression. Neuroimaging studies have shown mood-congruent alterations in amygdala activity in patients with acute depression, even during early, automatic stages of emotion processing. However, due to a lack of prospective studies over periods longer than 8 weeks, it is unclear whether these neurofunctional abnormalities represent a persistent correlate of depression even in remission. In this prospective case-control study, we aimed to examine brain functional correlates of automatic emotion processing in the long-term course of depression. In a naturalistic design, n = 57 patients with acute major depressive disorder (MDD) and n = 37 healthy controls (HC) were assessed with functional magnetic resonance imaging (fMRI) at baseline and after 2 years. Patients were divided into two subgroups according to their course of illness during the study period (n = 37 relapse, n = 20 no-relapse). During fMRI, participants underwent an affective priming task that assessed emotion processing of subliminally presented sad and happy compared to neutral face stimuli. A group × time × condition (3 × 2 × 2) ANOVA was performed for the amygdala as region-of-interest (ROI). At baseline, there was a significant group × condition interaction, resulting from amygdala hyperactivity to sad primes in patients with MDD compared to HC, whereas no difference between groups emerged for happy primes. In both patient subgroups, amygdala hyperactivity to sad primes persisted after 2 years, regardless of relapse or remission at follow-up. The results suggest that amygdala hyperactivity during automatic processing of negative stimuli persists during remission and represents a trait rather than a state marker of depression. Enduring neurofunctional abnormalities may reflect a consequence of or a vulnerability to depression.

Looming Angry Faces: Preliminary Evidence of Differential Electrophysiological Dynamics for Filtered Stimuli via Low and High Spatial Frequencies.

Looming motion interacts with threatening emotional cues in the initial stages of visual processing. However, the underlying neural networks are unclear. The current study investigated if the interactive effect of threat elicited by angry and looming faces is favoured by rapid, magnocellular neural pathways and if exogenous or endogenous attention influences such processing. Here, EEG/ERP techniques were used to explore the early ERP responses to moving emotional faces filtered for high spatial frequencies (HSF) and low spatial frequencies (LSF). Experiment 1 applied a passive-viewing paradigm, presenting filtered angry and neutral faces in static, approaching, or receding motions on a depth-cued background. In the second experiment, broadband faces (BSF) were included, and endogenous attention was directed to the expression of faces. Our main results showed that regardless of attentional control, P1 was enhanced by BSF angry faces, but neither HSF nor LSF faces drove the effect of facial expressions. Such findings indicate that looming motion and threatening expressions are integrated rapidly at the P1 level but that this processing relies neither on LSF nor on HSF information in isolation. The N170 was enhanced for BSF angry faces regardless of attention but was enhanced for LSF angry faces during passive viewing. These results suggest the involvement of a neural pathway reliant on LSF information at the N170 level. Taken together with previous reports from the literature, this may indicate the involvement of multiple parallel neural pathways during early visual processing of approaching emotional faces.

Emotional Face Processing in Autism Spectrum Condition: A Study of Attentional Orienting and Inhibitory Control.

A core feature of Autistic Spectrum Condition (ASC) is the presence of difficulties in social interactions. This can be explained by an atypical attentional processing of social information: individuals with ASC may show problems with orienting attention to socially relevant stimuli and/or inhibiting their attentional responses to irrelevant ones. To shed light on this issue, we examined attentional orienting and inhibitory control to emotional stimuli (angry, happy, and neutral faces).An antisaccade task (with both prosaccade and antisacade blocks) was applied to a final sample of 29 children with ASC and 27 children with typical development (TD).Whereas children with ASC committed more antisaccade errors when seeing angry faces than happy or neutral ones, TD children committed more antisaccade errors when encountering happy faces than neutral faces. Furthermore, latencies in the prosaccade and antisaccade blocks were longer in children with ASC and they were associated with the severity of ASC symptoms. Thus, children with ASC showed an impaired inhibitory control when angry faces were presented.This bias to negative high-arousal information is congruent with affective information-processing theories on ASC, suggesting that threatening stimuli induce an overwhelming response in ASC. Therapeutic strategies where train the shift attention to emotional stimuli (i.e. faces) may improve ASC symptomatology and their socials functioning.

Disrupted limbic-prefrontal effective connectivity in response to fearful faces in lifetime depression

BackgroundMultiple brain imaging studies of negative emotional bias in major depressive disorder (MDD) have used images of fearful facial expressions and focused on the amygdala and the prefrontal cortex. The results have, however, been inconsistent, potentially due to small sample sizes (typically N<50). It remains unclear if any alterations are a characteristic of current depression or of past experience of depression, and whether there are MDD-related changes in effective connectivity between the two brain regions. MethodsActivations and effective connectivity between the amygdala and dorsolateral prefrontal cortex (DLPFC) in response to fearful face stimuli were studied in a large population-based sample from Generation Scotland. Participants either had no history of MDD (N=664 in activation analyses, N=474 in connectivity analyses) or had a diagnosis of MDD during their lifetime (LMDD, N=290 in activation analyses, N=214 in connectivity analyses). The within-scanner task involved implicit facial emotion processing of neutral and fearful faces. ResultsCompared to controls, LMDD was associated with increased activations in left amygdala (PFWE=0.031,kE=4) and left DLPFC (PFWE=0.002,kE=33), increased mean bilateral amygdala activation (β=0.0715,P=0.0314), and increased inhibition from left amygdala to left DLPFC, all in response to fearful faces contrasted to baseline. Results did not appear to be attributable to depressive illness severity or antidepressant medication status at scan time. LimitationsMost studied participants had past rather than current depression, average severity of ongoing depression symptoms was low, and a substantial proportion of participants were receiving medication. The study was not longitudinal and the participants were only assessed a single time. ConclusionsLMDD is associated with hyperactivity of the amygdala and DLPFC, and with stronger amygdala to DLPFC inhibitory connectivity, all in response to fearful faces, unrelated to depression severity at scan time. These results help reduce inconsistency in past literature and suggest disruption of ‘bottom-up’ limbic-prefrontal effective connectivity in depression.

Extinction of negative conditioned stimulus valence in human fear conditioning

Fear conditioning is a common experimental paradigm for modelling the development, and exposure-based treatment, of anxiety disorders. Measures of fear such as threat-expectancy, physiological arousal, and fear ratings typically extinguish, however feared stimuli may still be evaluated negatively (i.e. retain negative valence). This systematic review provides the first investigation of the relationship between fear conditioning methodology and extinction of negative stimulus valence. Principal findings were that type of CS (conditioned stimulus) and the CS-US pairing (i.e. specific combination of CS and unconditioned stimulus) predicted extinction outcome. Extinction of absolute negative CS valence was always achieved with shape CSs; often achieved with low fear-relevant animals as CSs, and less frequently achieved with faces as CSs – particularly neutral faces paired with a shock US. Modified extinction procedures typically achieved the same outcome as standard extinction procedures, except for partially-reinforced extinction, which was less effective than standard extinction, and positive imagery training, which was more effective than standard extinction. Further studies are warranted to evaluate the influence of fear conditioning methodology on extinction of absolute negative CS valence.