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Browsing by Author "Troup, Lucy J., advisor"

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    Attentional biases and time course of emotion processing in depression
    (Colorado State University. Libraries, 2014) Bastidas, Stephanie P., author; Troup, Lucy J., advisor; Henry, Kimberly L., committee member; Draper, Bruce A., committee member
    Depressive mood is associated with differential patterns in emotion processing, but it is unclear which stages of processing differ in depressed individuals. The current study explored the nature of biases in early vs. late components of attention. Experiment 1 examined attention biases in orienting to and disengaging from positive and negative emotional stimuli behaviorally. Depressed participants presented greater overall biases than controls in the dot-discrimination but not in the dot-detection task. Positive and negative affect were associated with greater orienting bias and reduced disengaging bias for happy faces in the detection task and smaller bias for happy faces and greater for sad faces in the discrimination task. Experiment 2 explored differences in the time course of emotion processing, with focus on early P3 component differences during implicit and explicit processing. Results showed greater P3 for happy than neutral trials over midline frontal electrodes and the opposite pattern over parietal electrodes in depressed but not control participants during implicit processing. P3 was slower in depressed than controls during explicit processing over lateral sites. Midline electrodes showed slower P3 for happy than neutral during implicit processing and for sad than neutral during explicit, independent of group. Results suggest the presence of attentional biases in depressed individuals independent of emotion. These biases might be better reflected during intentional than incidental emotion processing. Future study is needed to fully understand the relationship of emotion processing for different degrees of depressive symptoms, emotions, and with regard to other modalities of intention in emotion processing.
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    Effects of in-group bias on face recognition using minimal group procedures
    (Colorado State University. Libraries, 2014) Nguyen, Maia T., author; Troup, Lucy J., advisor; Draper, Bruce, committee member; Rhodes, Matthew G., committee member
    The current series of experiments examined the effects of social categorization on face recognition. The use of minimal group procedures was expected to enhance recognition for in-group members compared to out-group members. In Experiment 1, participants were assigned to 1 of 3 conditions: name study--participants studied a list of 16 names associated with their in-group [red or green], numerical estimation--participants were randomly divided into 2 groups [red or green] after estimating the number of dots in a series of 10 images, and the control condition. This was followed by a study phase in which participants were presented with a total of 32 female and male Caucasian faces on red or green backgrounds. A final recognition test was given following a filler task. Experiment 2 had two of the previously used conditions, name study and control. Faces were presented on red and green backgrounds during test--with old faces presented on the same background as seen at study. Experiment 3 presented a subset of stimuli used in Experiment 2 with a longer presentation time (10 seconds). Findings suggest only moderate difference in response bias between experimental and control groups overall in Experiments 2 and 3. Moderate differences in hits, false alarms, and d' were also found in Experiment 3 between experimental conditions. Group membership did not elicit significant effects on measures of accuracy, reaction time, and confidence ratings.
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    Event-related potentials for the implicit and explicit processing of emotional facial expressions as basic level- and subordinate level-stimulus categories
    (Colorado State University. Libraries, 2014) Nomi, Jason S., author; Troup, Lucy J., advisor; Davalos, Deana, advisor; Kraiger, Kurt, committee member; Draper, Bruce A., committee member
    The two dominant models in face perception propose independent mechanisms are responsible for initial face perception (discriminating a face from an object), identity recognition (recognizing a specific face) and emotional expression perception (processing of an expression). However, Bruce and Young (1986) propose a linear model where identity recognition and expression perception operate in a parallel manner after initial face perception while Haxby, Hoffman and Gobbini (2000) propose an interactive model where all three mechanisms interact with each other within a non-linear core system. Event related potentials (ERPs) demonstrate that initial face perception is reflected by the temporal occipital P1 and N170 while identity recognition is reflected by the anterior N250. Some studies have found an expression influence on the P1 and N170 while other studies have not, providing mixed support for either model. The current study examined how facilitation of basic level and subordinate level category processing of emotional expressions may have influenced the results of previous studies. Research in stimulus category processing demonstrates that faces are typically processed at the subordinate level (e.g. my friend "Joe" as opposed to the basic level of "face") while objects are processed at the basic level (e.g. car but not the subordinate level of "Nissan Sentra"). However, there has been little research exploring how the processing of expressions may be influenced by category processing. Happy, neutral and sad expressions were presented in isolation for Experiment 1 to facilitate processing of expressions on the basic level (faces are all unfamiliar with the most basic changes being only in expression) while the same expressions were presented alongside cars, houses and butterflies in Experiment 2 to facilitate subordinate processing (basic level: faces vs. objects; subordinate level: happy, neutral and sad expressions and cars, houses and butterflies). Experiment 1 found P1 and N170 modulations by happy, neutral and sad expressions that were not influenced by implicit or explicit processing condition with no such modulations in Experiment 2. Additionally, there were early modulations of ERPs related to expression in both experiments in the 30-80ms range with explicit processing mediating face and object differences found in the 30-80ms range for Experiment 2. The results of the current study support the Haxby, Hoffman, and Gobbini model where expression perception mechanisms can modulate early ERP components reflecting initial face perception and also show that this modulation depends on the presence or absence of comparison object stimuli. When comparison stimuli were not present (Experiment 1), expressions processed as a basic level stimulus category mainly influenced ERPs in the 140-400ms time range reflecting enhanced processing of the specific expression. When comparison object stimuli were present (Experiment 2), expressions processed as a subordinate stimulus category mainly influenced ERPs in the 30-140ms time range reflecting quicker categorization due to the presence of object stimuli rather than processing of the specific emotional expression.
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    Residual effects of cannabis on attention toward and awareness of emotional facial expressions: event-related potential studies
    (Colorado State University. Libraries, 2018) Torrence, Robert D., author; Rojas, Donald C., advisor; Troup, Lucy J., advisor; Nerger, Janice, committee member; Burzynska, Agnieszka, committee member
    Cannabis use has increased since legalization in various states within the United States of America. Although much of the research on the neurological and psychological effects of cannabis has been on non-human animals, the current research suggests that it can have anxiolytic effects but also decrease some cognitive functioning (e.g. memory, emotional processing, etc.). Individuals with high anxiety has been suggested to have increased attentional bias towards threat-related stimuli. The purpose of the current two studies was to examine the residual effects cannabis has on attentional bias towards and awareness of emotional facial expressions. Both experiments used event-related potential (ERP) to measure brain activity related to attentional processing. Experiment 1 used a dot-probe task with fearful and neutral facial expression to examine attentional bias. The second experiment used a backward masking paradigm to restrict awareness of facial expressions (i.e. fearful, happy, and neutral). The results indicated that cannabis use was associated with differences in attentional processing. Specifically, experiment 1 suggested cannabis users had reduced attentional bias towards fearful facial expressions as compared to non-users. The results from experiment 2 suggested an opposite effect, cannabis users had increased processing of emotional facial expressions. An explanation of the difference in results is the cannabis users in experiment 1 used less frequently than users in experiment 2. The results of both studies suggested cannabis use has an inverse relationship with anxiety related attentional processing of emotional expressions.