Engagement with angry faces during attentional bias modification: Insights from the N2pc

<p>Healthy individuals show an attentional bias toward threat, and this bias is exaggerated in anxious individuals. Recent studies have shown that training anxious individuals to attend to neutral information can reduce their threat bias and anxiety levels. This training is called attentional bias modification (ABM). However, despite the large literature on ABM, it is still unclear how ABM achieves its effects. Two mechanisms – facilitated engagement with threat, and delayed disengagement from threat – are thought to be involved in the threat bias. In this thesis, I investigated the effects of ABM on engagement with angry faces. First, in Experiment 1 I developed an ABM task to train healthy individuals to attend to either angry or neutral faces. Participants completed a dot-probe task in which they saw two faces – one angry and one neutral – followed by a target that appeared more often in the location of either the angry or neutral face (depending on their respective training condition). Experiment 1 was successful at inducing a bias. Next, Experiment 2 used this task to investigate the effects of ABM on event-related potentials before, during, and after training. The N2pc component, which provides a measure of attentional engagement, was used to investigate changes in engagement with angry and neutral faces as a function of training. Consistent with previous studies, there was an overall N2pc for the angry face, indicating that participants were engaging their attention with the angry face. However, the N2pc was not affected by training, even though participants were moving their eyes in the training-congruent direction during training, indicating sensitivity to the training contingency. These results suggest that ABM does not affect attentional engagement with threat stimuli. Rather, it is likely that an improved ability to disengage attention from threat stimuli underlies ABM’s training effects.</p>

Engagement with angry faces during attentional bias modification: Insights from the N2pc

<p>Healthy individuals show an attentional bias toward threat, and this bias is exaggerated in anxious individuals. Recent studies have shown that training anxious individuals to attend to neutral information can reduce their threat bias and anxiety levels. This training is called attentional bias modification (ABM). However, despite the large literature on ABM, it is still unclear how ABM achieves its effects. Two mechanisms – facilitated engagement with threat, and delayed disengagement from threat – are thought to be involved in the threat bias. In this thesis, I investigated the effects of ABM on engagement with angry faces. First, in Experiment 1 I developed an ABM task to train healthy individuals to attend to either angry or neutral faces. Participants completed a dot-probe task in which they saw two faces – one angry and one neutral – followed by a target that appeared more often in the location of either the angry or neutral face (depending on their respective training condition). Experiment 1 was successful at inducing a bias. Next, Experiment 2 used this task to investigate the effects of ABM on event-related potentials before, during, and after training. The N2pc component, which provides a measure of attentional engagement, was used to investigate changes in engagement with angry and neutral faces as a function of training. Consistent with previous studies, there was an overall N2pc for the angry face, indicating that participants were engaging their attention with the angry face. However, the N2pc was not affected by training, even though participants were moving their eyes in the training-congruent direction during training, indicating sensitivity to the training contingency. These results suggest that ABM does not affect attentional engagement with threat stimuli. Rather, it is likely that an improved ability to disengage attention from threat stimuli underlies ABM’s training effects.</p>

Saccadic eye movements are deployed faster for salient facial stimuli, but are relatively indifferent to their emotional content

The present study explores the threat bias for fearful facial expressions using saccadic latency as the response mode, with a particular focus on the role of low-level facial information, including spatial frequency, physical contrast, and apparent, perceived contrast. In a simple localisation task, participants were presented with spatially-filtered versions of neutral, fearful, angry and happy faces. Faces were either composed of naturally-occurring, expression-related differences in contrast, normalised for RMS contrast, or normalised for their apparent, perceived contrast. Together, findings show that saccadic responses are not biased toward fearful expressions compared to neutral, angry or happy counterparts, regardless of their spatial frequency content. Saccadic response times are, however, significantly influenced by the physical contrast of facial stimuli, and the extent to which these are preserved or normalised at the physical (RMS matched) and psychophysical (perceptually matched) level. We discuss the implications of findings for the threat bias literature, and the extent to which image processing can be expected to influence behavioural responses to socially-relevant facial stimuli.

Hydrocortisone as an adjunct to brief cognitive-behavioural therapy for specific fear: Endocrine and cognitive biomarkers as predictors of symptom improvement

Background: Glucocorticoid (GC) administration prior to exposure-based cognitive-behavioural therapy (CBT) has emerged as a promising approach to facilitate treatment outcome in anxiety disorders. Further components relevant for improved CBT efficacy include raised endogenous GCs and reductions in information-processing biases to threat. Aims: To investigate hydrocortisone as an adjunct to CBT for spider fear and the modulating role of threat bias change and endogenous short-term and long-term GCs for treatment response. Methods: Spider-fearful individuals were randomized to receiving either 20 mg of hydrocortisone ( n = 17) or placebo ( n = 16) one hour prior to single-session predominantly computerised exposure-based CBT. Spider fear was assessed using self-report and behavioural approach measures at baseline, 1-day and 1-month follow-up. Threat processing was assessed at baseline and 1-day follow-up. Cortisol and cortisone were analysed from hair and saliva samples at baseline. Results/outcomes: Self-report, behavioural and threat processing indices improved following CBT. Hydrocortisone augmentation resulted in greater improvement of self-report spider fear and stronger increase in speed when approaching a spider, but not on threat bias. Neither threat bias nor endogenous GCs predicted symptom change, and no interactive effects with hydrocortisone emerged. Preliminary evidence indicated higher hair cortisone as predictor of a stronger threat bias reduction. Conclusions/interpretation: Our data extend earlier findings by suggesting that GC administration boosts the success of exposure therapy for specific fear even with a low-level therapist involvement. Future studies corroborating our result of a predictive hair GC relationship with threat bias change in larger clinical samples are needed.

Contrast normalisation masks natural expression-related differences and artificially enhances the perceived salience of fear expressions.

Fearful facial expressions tend to be more salient than other expressions. This threat bias is to some extent driven by simple low-level image properties, rather than the high-level emotion interpretation of stimuli. It might be expected therefore that different expressions will, on average, have different physical contrasts. However, studies tend to normalise stimuli for RMS contrast, potentially removing a naturally-occurring difference in salience. We assessed whether images of faces differ in both physical and apparent contrast across expressions. We measured physical RMS contrast and the Fourier amplitude spectra of 5 emotional expressions prior to contrast normalisation. We also measured expression-related differences in perceived contrast. Fear expressions have a steeper Fourier amplitude slope compared to neutral and angry expressions, and consistently significantly lower contrast compared to other faces. This effect is more pronounced at higher spatial frequencies. With the exception of stimuli containing only low spatial frequencies, fear expressions appeared higher in contrast than a physically matched reference. These findings suggest that contrast normalisation artificially boosts the perceived salience of fear expressions; an effect that may account for perceptual biases observed for spatially filtered fear expressions.

Contrast normalisation masks natural expression-related differences and artificially enhances the perceived salience of fear expressions.

Fearful facial expressions tend to be more salient than other expressions. This threat bias is to some extent driven by simple low-level image properties, rather than the high-level emotion interpretation of stimuli. It might be expected therefore that different expressions will, on average, have different physical contrasts. However, studies tend to normalise stimuli for contrast, potentially removing a naturally-occurring difference in salience. We assessed whether images of faces differ in both physical and apparent contrast across expressions. We measured physical contrast and the Fourier amplitude spectra of 5 emotional expressions prior to contrast normalisation. We also measured expression-related differences in perceived contrast. Fear expressions have a steeper Fourier amplitude slope compared to neutral and angry expressions, and consistently significantly lower contrast compared to other faces. This effect is more pronounced at higher spatial frequencies. With the exception of stimuli containing only low spatial frequencies, fear expressions appeared higher in contrast than a physically matched reference. These findings suggest that contrast normalisation artificially boosts the perceived salience of fear expressions; an effect that may account for perceptual biases observed for spatially filtered fear expressions.

0162 Mental Stress Compromises Human Sleep Through a Biological, Not Psychological, Pathway

Introduction The extent to which mental stress causes sleep disturbance is unknown as experimental studies of stress and sleep have yielded mixed results. Potential mechanisms linking stress to poor sleep are also poorly characterized. The current study aimed to 1) assess the impact of experimentally-induced mental stress on daytime sleep and 2) test candidate mechanisms including physiological and emotional stress reactivity, stress rumination, attentional threat bias, and insensitivity to future consequences. Methods Participants (N=30) were randomized to a control (n=14) or stress group (n=16). Both groups were given a 60-minute nap opportunity at midday (≈13:30). Prior to sleep, participants in the stress group completed a socially evaluative mental arithmetic stress task and were instructed that they would be required to give a brief speech upon awakening. Sleep was monitored with polysomnography and scored according to standard AASM criteria. Measures of heart rate (HR), blood pressure (BP) and self-reported stress were recorded during the stress task. Self-reported stress rumination was measured upon awakening. Attentional threat bias was measured using an emotional dot probe and performance on the Iowa Gambling Task quantified insensitivity to future consequences. Results Acute mental stress significantly increased HR and BP (all p&lt;.001, all Cohen’s d&gt;1.24) and participants reported significant increases in self-reported stress (p&lt;.001). The stress group exhibited longer sleep latency (p=.038, d=.82), shorter sleep duration (p=.044, d=.78), and worse sleep continuity (p=.045, d=.79). Subjective sleep quality was not different across groups (p=.39, d=.32). Of all candidate mechanisms, physiological reactivity was the only one significantly related to sleep measures. Greater HR reactivity predicted longer sleep latency (r=.37), shorter sleep duration (r=-.59), and worse sleep continuity (r=-.59). Conclusion Acute mental stress caused significant disturbances in a single episode of daytime sleep. The degree of disturbance was, to an extent, predicted by the amount of physiological reactivity to stress. Support This work was supported a Washington and Lee University Summer Lenfest Grant and the Summer Research Scholars Program.