Real-world perception of emotion results from the integration of multiple cues, most notably facial expression and affective prosody. The use of incongruent emotional stimuli presents an opportunity to study the interaction between sensory modalities. Thirty-seven participants were exposed to audio-visual stimuli (Robins & Schultz, 2004) including angry, fearful, happy, and neutral presentations. Eighty stimuli contain matching emotions and 240 contain incongruent emotional cues. Matching emotions elicited a significant number of correct responses for all four emotions. Sign tests indicated that for most incongruent conditions, participants demonstrated a bias towards the visual modality. Despite these findings, specific incongruent conditions did show evidence of blending. Future research should explore an evolutionary model of facial expression as a means for behavioral adaptation and the possibility of an “emotional McGurk effect” in particular combinations of emotions.

<p>Schizophrenia is a psychiatric disorder characterized by social dysfunction. People with schizophrenia misinterpret social information and it is suggested that this difficulty may result from visual processing deficits. As faces are one of the most important sources of social information it is hypothesized that people suffering from the disorder have impairments in the visual face processing system. It is unclear which mechanism of the face processing system is impaired but two types of deficits are most often proposed: a deficit in face perception in general (i.e., processing of facial features as such) and a deficit in facial emotion processing (i.e., recognition of emotional facial expressions). Due to the contradictory evidence from behavioural, electrophysiological as well as neuroimaging studies offering support for the involvement of one or the other deficit in schizophrenia it is early to make any conclusive statements as to the nature and level of impairment. Further studies are needed for a better understanding of the key mechanism and abnormalities underlying social dysfunction in schizophrenia.</p>

Past research demonstrates that fearful faces lead to an increase in temporal and a decrease in spatial gap detection, an effect proposed to be caused by a flow of input to the magnocellular pathways from the amygdala to the visual system (Bocanegra & Zeelenberg, 2009). The amygdala is also active for positive and arousing stimuli, including happy faces. The current study extends past research by presenting happy facial cues just before a gap detection task. Facial stimuli (i.e., happy/neutral faces) were presented in the periphery of the receptive field and quickly followed by a Landolt circle. Half of the participants were asked to detect a temporal gap and half a spatial gap. Response accuracy of gap detection was measured using signal detection theory. Consistent with past research on fearful faces, positive expressions were expected to facilitate temporal gap detection but not spatial gap detection when happy faces were used as cues in gap detection tasks. The current study found no difference in spatial or temporal gap detection given the emotional cue that preceded gap detection on each trial. Positive emotion did not appear to have the same impact as fear on the amygdala and visual areas involving attention.

This thesis investigated the processing of emotional stimuli by the visual system, and how the processing of emotions interacts with visual awareness. Emotions have been given ‘special’ status by some previous research, with evidence that the processing of emotions may be relatively independent of striate cortex, and less affected by disruption to awareness than processing of emotionally neutral images. Yet the extent to which emotions are ‘special’ remains questionable. This thesis focused on the processing of emotional stimuli when activity in V1 was disrupted using transcranial magnetic stimulation (TMS), and whether emotional properties of stimuli can be reliably discriminated, or affect subsequent responses, when visibility is low. Two of the experiments reported in this thesis disrupted activity in V1 using TMS, Experiment 1 with single pulses in an online design, and Experiment 2 with theta burst stimulation in an offline design. Experiment 1 found that a single pulse of TMS 70-130 ms following a presentation of a body posture image disrupted processing of neutral but not emotional postures in an area of the visual field that corresponded to the disruption. Experiment 2 did not find any convincing evidence of disruption to processing of neutral or emotional faces. From Experiment 1 it would appear that emotional body posture images were relatively unaffected by TMS, and appeared to be robust to disruption to V1. Experiment 2 did not add to this as there was no evidence of disruption in any condition. Experiments 3 and 4 used visual masking to disrupt awareness of emotional and neutral faces. Both experiments used a varying interval between the face and the mask stimuli to systematically vary the visibility of the faces. Overall, the shortest SOA produced the lowest level of visibility, and this level of visibility was arguably outside awareness. In Experiment 3, participants’ ability to discriminate properties of emotional faces under low visibility conditions was greater than their ability to discriminate the orientation of the face. This was despite the orientation discrimination being much easier at higher levels of visibility. Experiment 4 used a gender discrimination task, with emotion providing a redundant cue to the decision (present half of the time). Despite showing a strong linear masking function for the neutral faces, there was no evidence of any emotion advantage. Overall, Experiment 3 gave some evidence of an emotion advantage under low visibility conditions, but this effect was fairly small and not replicated in Experiment 4. Finally, Experiments 5-8 used low visibility emotional faces to prime responses to subsequent emotional faces (Experiments 5 and 6) or words (Experiments 7 and 8). In Experiments 5, 7 and 8 there was some evidence of emotional priming effects, although these effects varied considerably across the different designs used. There was evidence for meaningful processing of the emotional prime faces, but this processing only led to small and variable effects on subsequent responses. In summary, this thesis found some evidence that the processing of emotional stimuli was relatively robust to disruption in V1 with TMS. Attempts to find evidence for robust processing of emotional stimuli when disrupted with backwards masking was less successful, with at best mixed results from discrimination tasks and priming experiments. Whether emotional stimuli are processed by a separate route(s) in the brain is still very much open to debate, but the findings of this thesis offers small and inconsistent evidence for a brain network for processing emotions that is relatively independent of V1 and visual awareness. The network and nature of brain structures involved in the processing of subliminal and low visibility processing of emotions remains somewhat elusive.

Few studies have explored emotion processing abilities in children following Acquired Brain Injury (ABI). This study develops previous research in this area by exploring emotion processing skills in children with focal ABI, using eye tracking technology. It was hypothesised that children with focal ABI would demonstrate impaired emotion recognition abilities relative to a control group and that, similar to adult eye tracking studies, they would show an atypical pattern of eye moments when viewing faces. Sixteen participants with focal ABI (10-16 years) and 27 healthy controls (10-16 years) completed one novel and one adapted visual emotion processing task, presented using a T120 Tobii eye-tracker. The eye-tracker measured eye-movement fixations in three areas of interest (AOIs; eyes, nose, mouth), as participants viewed the stimuli. Emotion perception accuracy was recorded. All participants from the ABI group also completed neuropsychological assessment of their immediate visual memory, visual attention, visuospatial abilities, and everyday executive function. The results of the study showed no significant difference in accuracy between the ABI and control groups. However, on average children with ABI appeared slightly less accurate than the control group in both emotion recognition tasks. Within-subjects analysis revealed no effect of lesion location and laterality or age at lesion onset upon emotion recognition accuracy. Eye tracking analysis showed that children within the ABI group presented with an atypical pattern of eye movements relative to the control group, demonstrating significantly greater fixation times within the eye region, when viewing disgusted, fearful angry and happy faces. The ABI group also showed reduced mean percentage fixation duration within the nose and mouth regions, relative to controls. Furthermore, it was observed that the ABI group took longer on average to give an accurate response to sad, disgusted, happy and surprised faces and this difference reached statistical significance for the accurate recognition of happy and surprised faces. It is suggested that the atypical fixation patterns noted within the ABI group, may represent a difficulty with dividing visual attention rapidly across the whole of the face. This slowing may have an impact upon functioning in everyday social situations, where rapid processing and appraisal of emotion is thought to be particularly important. It is therefore suggested that eye tracking technology may be a valuable method for the identification of subtle difficulties in facial emotion processing, following focal ABI in childhood, and may also have an application in the rehabilitation of these difficulties in future.

Childhood maltreatment increases risk for Posttraumatic Stress Disorder (PTSD). Maladaptive patterns of attention to threat-related stimuli warrant examination as possible contributing risk factors. It remains unclear whether persistent threat-processing biases are differentially apparent in adults who were maltreated as children and either did, or did not, develop later PTSD. The present study examined associations among attention bias, childhood maltreatment, and PTSD in adults. We hypothesized that attentional bias toward threat significantly mediates associations between childhood maltreatment and adult PTSD symptoms. 183 adults with and without childhood maltreatment histories participated in this study, which involved completion of a range of clinical measures; attention bias was measured by the Dot Probe task. We found that attention bias toward happy faces partially mediated the relationship between childhood maltreatment and PTSD avoidance and numbing symptoms. Childhood maltreatment, happy face attention bias, and perceived racially discriminative experiences all accounted for significant variance in PTSD symptoms.

Childhood maltreatment increases risk for Posttraumatic Stress Disorder (PTSD). Maladaptive patterns of attention to threat-related stimuli warrant examination as possible contributing risk factors. It remains unclear whether persistent threat-processing biases are differentially apparent in adults who were maltreated as children and either did, or did not, develop later PTSD. The present study examined associations among attention bias, childhood maltreatment, and PTSD in adults. We hypothesized that attentional bias toward threat significantly mediates associations between childhood maltreatment and adult PTSD symptoms. 183 adults with and without childhood maltreatment histories participated in this study, which involved completion of a range of clinical measures; attention bias was measured by the Dot Probe task. We found that attention bias toward happy faces partially mediated the relationship between childhood maltreatment and PTSD avoidance and numbing symptoms. Childhood maltreatment, happy face attention bias, and perceived racially discriminative experiences all accounted for significant variance in PTSD symptoms.

Early life stress (ELS) affects the developing brain and impacts capacity for self-regulation and risk for psychopathology. The high spatial resolution of functional magnetic resonance imaging (fMRI) confers an advantage for studying specific neural regions posited to link ELS with subsequent functioning. The first chapter in this dissertation reviews the literature establishing the feasibility and utility of fMRI research with infants and young children. This chapter examines methodological issues and outlines the potential for this technique to make unique contributions to understanding how ELS influences brain development. The next two chapters present results from a study that employed a functional activation paradigm and resting state functional connectivity MRI (rs-fcMRI) to examine associations between a common source of ELS, non-physical interparental conflict, and neural functioning during infancy. The functional activation paradigm focused on emotional tone of voice as a stimulus relevant to interparental conflict, which is likely salient to infants. Higher levels of interparental conflict (as reported by mothers) were associated with infants (6 to 12 months of age) showing greater reactivity to very angry versus neutral tone of voice in neural regions associated with processing and regulation of stress and emotion (hypothalamus and rostral anterior cingulate cortex). The rs-fcMRI analysis examined coordinated neural functioning in the absence of stimuli, focusing on the amygdala as a key region for understanding the impact of ELS and the posterior cingulate cortex as part of a group of regions that show higher levels of activity in the absence of stimuli (the default network). The results replicate previous work characterizing the default network in infants and provide novel evidence for the functional connectivity of the amydgala and amygdala subregions during infancy. Interparental conflict was associated with variation in the connectivity of both regions. Thus levels of interparental conflict were associated with neural reactivity to a stressor-relevant stimulus and with patterns of coordinated neural functioning in the absence of such stimuli. These results provide support for the utility of using fMRI with infants to examine early emerging associations between common forms of ELS and brain functioning. This dissertation includes previously published and co-authored material. / 2016-10-17

The work within this thesis examined aspects of emotion processing among non-clinical females who varied in levels of eating-related psychopathology. Five studies employed a quantitative approach in order to assess potential deficits in both the control and experience of emotion. To examine the experience of emotion, Studies 1, 2 and 3 assessed the attentional processing of emotional stimuli in those with high and low levels of eating-related psychopathology. In Studies 1 and 2, specific components of attention bias including orientation, disengagement and avoidance were assessed in order to explore their role in contributing to disordered eating behaviour. Findings from these studies did not reveal any differences in attentional orienting between those with high and low levels of eating-related psychopathology. However, when primed with happy faces, those with high levels of disordered eating were significantly quicker than those with low levels to disengage from threat-relevant words. This finding could be interpreted in terms of emotional arousal with happy facial displays providing a protective function against subsequently presented stimuli. With regards to emotional avoidance, those with higher levels of eating-related psychopathology were more likely to avoid emotional displays relative to those with lower levels. In fact, a higher drive to achieve thinness was shown to predict a greater avoidance of both angry and happy facial expressions. Interestingly, depression, anxiety and alexithymia were all shown to impact upon attentional processing. In Study 3, the efficacy of attention training in reducing attentional biases towards threat in women with varying levels of disordered eating was examined. Importantly, a single session of attention training was found to be successful in modifying previously observed attentional biases towards threat. However, eating-related psychopathology was shown to have only a partial influence on participants attention processing. These findings suggest that the success of attention training may be independent of disordered eating. To examine the control of emotion within a non-clinical population, Study 4 utilised self-report questionnaires to explore associations between deficits in emotional functioning and severity of eating-related psychopathology. The data obtained from this questionnaire-based investigation are reported in a series of three short studies. Specifically, Study 4.1 of this chapter examined the relationship between difficulties in the regulation of emotion within eating-related psychopathology. Furthermore, Studies 4.2 and 4.3 set out to explore some of the factors which may influence emotion processing, such as pessimistic attitudes regarding emotional expression. Across all studies, the role of depression, anxiety and alexithymia as potential confounding factors was considered. Findings revealed a significant relationship between eating-related psychopathology and difficulties regulating emotion. Dysfunctional or negative attitudes towards the expression of emotion were also linked to a greater number of eating disorder-related concerns and behaviours. However, many of the associations between eating-related psychopathology and impaired emotional functioning were no longer apparent when depression, anxiety and alexithymia had been statistically accounted for. These findings not only support previous research, but highlight the importance of mood and alexithymia in contributing to the emotional deficits observed. Finally, Study 5 aimed to explore the potential consequences of inadequate emotion processing within eating-related psychopathology. Self-report measures were utilised to assess the frequency of eating-related intrusive thoughts in those with high levels of eating-related psychopathology. As predicted, those with greater levels of disordered eating reported experiencing a higher frequency of thoughts or intrusions relating to eating. This may point towards a failure to successfully process emotional experience in this group. Taken together, this body of work enhances the current understanding of the role of emotion processing in contributing to both the onset and maintenance of disordered eating. These findings also emphasise the key role of mood and alexithymia in influencing the relationship between emotional functioning and eating-related psychopathology. Therefore further research examining emotion processing within disordered eating must acknowledge the potential contribution of depression, anxiety and alexithymia. Furthermore, the present findings provide clear support for the development of a model of cognitive-emotion processing within eating-related psychopathology. The implications of these findings for both eating disorder treatment and prevention are discussed. Possible directions for future research are also identified.

Neurological abnormalities are associated with emotion processing deficits seen in children with neurodevelopmental disorders. Research suggests that inflammatory mechanisms can negatively impact brain structure and function and are thought to play a role in these processing atypicalities. Children with chromosome 22q11.2 deletion syndrome (22q11.2DS) exhibit emotion processing impairments and associated neural abnormalities. We investigated the roles of inflammatory factors and structural connectivity in relation to emotion processing deficits in 28 children with 22q11.2DS and 33 typically developing children (M = 11.12 years old; SD = 2.17). Results indicate poorer social skills and significantly lower emotion recognition scores in children with 22q11.2DS compared to controls. Additionally, children with 22q11.2DS had higher anisotropic diffusion in right amygdala to fusiform gyrus white matter pathways and lower serum IL-3 concentrations than their typically developing peers. Right amygdala to fusiform gyrus FA values partially mediated the relationship between 22q11.2DS and social skills, as well as the relationship between 22q11.2DS and emotion recognition accuracy. However, there was no indication that IL-3 mediated the relationship between diagnosis and abnormal connectivity. Future studies should employ longitudinal methods to characterize how these connectivity patterns influence social-emotional development as the child ages.