Research master thesis | Psychology (research) (MSc)
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Poverty in the UK has increased, particularly after the Covid-19 pandemic. To prevent people from falling into a poverty trap, it is important to understand how financial scarcity affects financial...Show morePoverty in the UK has increased, particularly after the Covid-19 pandemic. To prevent people from falling into a poverty trap, it is important to understand how financial scarcity affects financial decisions involving risks. This topic lacks consensus in the literature with some authors arguing for a tendency towards more risk-taking, while others arguing for more risk aversion. This study posits that the risk tendency is influenced by frames of gains and losses. More specifically, financial scarcity leads to more risky choices in the domain of losses (H1), whereas it leads to less risky choices in the domain of gains (H2). People in financial scarcity tend to experience negative affect that impacts their cognitive systems, leading to more reliance on System 1 thinking, which exacerbates biases, such as the reflection effect. To test the hypotheses an online survey was conducted and 200 participants from the UK were recruited via Prolific Academic. The participants were divided into two groups for the manipulation of financial scarcity using the household task. Half of the participants were in the debts condition (financial scarcity), whereas the other half were not (control). Subsequently, all participants were presented with six risky choices, where they had to choose one of two options (one risky, the other conservative) framed in both gains and losses and three combinations of probabilities. Results from a Generalized Mixed Model showed that the cognitive bias associated with the reflection effect was found to be equally present in everyone and was more pronounced for more extreme probabilities (e.g., 10%/90% and 20%/80%), but not for moderate probabilities (e.g., 40%/60%). Thus, the expected interaction between debts and frames was not confirmed. It is suggested that future studies use an intuitive decision-making manipulation with more extreme probabilities (e.g., 1%/99%), consider a field risk manipulation, an incentivized lottery and the same expected value within and between probabilities at the lottery.Show less
Research master thesis | Psychology (research) (MSc)
closed access
Within negotiations individuals differ in their motivation to reach certain outcomes over others (outcome orientation). These differences may exaggerate as asymmetrical power dynamics impose...Show moreWithin negotiations individuals differ in their motivation to reach certain outcomes over others (outcome orientation). These differences may exaggerate as asymmetrical power dynamics impose disadvantageous conditions for some individuals within a group. As such restrictions may limit an individual’s ability to realise its interest in certain outcomes, individuals may evoke compensatory mechanisms to alleviate these disadvantages. Building on previous studies (Van Tol & Steinel, 2019), we propose that creative cognitions (e.g., flexibility or originality) may qualify as such potential compensatory mechanism. Consequently, we predict that the effect of individual outcome orientation in relation to an asymmetrical dispersion of power within groups may motivate compensatory engagements in creative behaviours that aim to alleviate the effects of disadvantageous situational constraints. To this end, 150 participants took part in a three-person fictious face-to-face online study. Participants were randomly assigned to either a powerful, powerless, or equal power condition, whilst further differentiations ensured individualistic and collectivistic outcome orientations. Upon reading the instructions, participants completed both a flexibility and an originality task. Results of a 2 (social motive: pro-social vs. pro-self) x 3 (relative power: powerless vs. equal power vs. powerful) ANOVA, as well as a 2 (social motive: pro-social vs. pro-self) x 3 (relative power: powerless vs. equal power vs. powerful) ANCOVA (with individual knowledge about cooking as covariate) revealed non-significant interaction effects for both flexible (ANOVA) and original (ANCOVA) compensation. Across the possible combinations of powerless and powerful, and pro-social and pro-self, participants did not differ in their creativity scores, disconfirming our hypotheses. As these null findings stand in direct contradiction to previous literature, the need for further investigation of creative cognitions in negotiations is highlighted.Show less
Research master thesis | Psychology (research) (MSc)
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Previous studies have highlighted the role of perspective giving in improving intergroup attitudes, particularly among disadvantaged groups. Building on this research, in the current study I...Show morePrevious studies have highlighted the role of perspective giving in improving intergroup attitudes, particularly among disadvantaged groups. Building on this research, in the current study I investigated how the content of perspective giving, focused on issues of inequality or harmony between groups, influences disadvantaged group members’ motivations for collective actions towards social change. I specifically examined this within the context of Cyprus focusing on the Turkish-speaking Cypriot minority (N = 161) in relation to the Greek-speaking Cypriot majority, using a vignette experimental approach. As hypothesized, I found that participants who focused on inequalities with the advantaged outgroup reported greater support for social change, collective action intentions, and change motivation compared to those who focused on commonalities with the outgroup. However, the expected interaction with perspective giving was not found, as it did not make a difference whether the participants gave their perspective to a member of the advantaged outgroup or did not. These findings contribute to our understanding of the complexities of intergroup dynamics and extend on the possible effects of perspective giving on collective action intentions.Show less
Research master thesis | Psychology (research) (MSc)
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Adolescents with ADHD partake in risk-taking behavior (RTB), such as risky driving or unsafe sex, more often than their peers. Because RTB is strongly related to risk perception and RTB takes place...Show moreAdolescents with ADHD partake in risk-taking behavior (RTB), such as risky driving or unsafe sex, more often than their peers. Because RTB is strongly related to risk perception and RTB takes place in a group of peers, it is important to gain a better understanding of risk perception in a social context. First, this study investigated whether adolescents with ADHD are more susceptible to 1) peer influence only and 2) peer influence and presence on a behavioral level. Further, we examined the neural responses to these two social manipulations. We examined whether peer attachment acted as a buffer against susceptibility. Finally, we adopted a continuous approach of ADHD and examined the link between inattention symptoms and hyperactivity-impulsivity symptoms and susceptibility to peer influence and presence. Adolescent boys (ages 13-23) with ADHD (n = 46) and without ADHD (n = 57) performed a risk rating task with a behavioral part and an fMRI-scanner part. The scanner part included highly believable virtual peer influence and peer presence manipulations. For our fMRI analyses we selected regions of interest that are implicated in the social brain (TPJ and dmPFC), the reward processing network (VS, Insula and vmPFC), and the cognitive control network (dlPFC). All adolescents showed equal susceptibility to peer influence only. Similarly, all adolescents showed a higher susceptibility to peer influence and presence. We found no effects on susceptibility of clinical diagnosis, inattention or hyperactivity-impulsivity symptoms or peer attachment. Our fMRI results showed effects in the TPJ. First, peer influence only elicited less activation in the bilateral TPJ for adolescents with ADHD. Second, activity in the left TPJ elicited by peer influence and presence was stronger for adolescents with weaker peer attachment. Together, these findings indicate that peer influence and presence may partly cause increased RTB in adolescence. However, increased RTB in adolescents with ADHD cannot be explained by increased susceptibility peer influence and presence. These findings provide an opportunity to decrease excessive RTB through increasing resistance to peer influence and presence in interventions for adolescents in general.Show less
Research master thesis | Psychology (research) (MSc)
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Novelty can be defined as a motivationally and attentionally salient learning signal. Past research has found benefits of novelty to include increased plasticity and enhanced memory encoding....Show moreNovelty can be defined as a motivationally and attentionally salient learning signal. Past research has found benefits of novelty to include increased plasticity and enhanced memory encoding. Briefly exposing subjects to a novel stimulus or environment in place of an expected threat has also been shown to enhance the extinction process following fear conditioning in both rodents and humans. This is important, as the treatment for trauma-based disorders such as post-traumatic stress disorder (PTSD) has only been demonstrated effective for up to 66% of those affected and a dysfunction in the fear extinction process appears central in the development and continuation of such disorders. The current study explored whether replacing a fear-inducing stimulus with a novel visual stimulus resulted in more effective fear extinction, as quantified using both subjective and objective parameters, namely subjective arousal, and pupil dilation. In addition, a condition with olfactory novelty was included to explore the effects of contextual novelty on preventing the reinstatement of the conditioned fear 24 hours following fear conditioning. The study successfully established fear conditioning using threatening visual stimuli in a classical conditioning paradigm. However, there was no support for novelty-enhanced fear extinction, nor for the benefit of olfactory novelty on the retention of fear extinction 24 hours post-extinction. Rather, an increase in pupil dilation in the context of a novel olfactory environment was found especially in conditions where a fear-inducing unconditioned stimulus had been paired with a novel replacement stimulus, possibly suggesting a contextual novelty-induced fear reinstatement effect.Show less
Research master thesis | Psychology (research) (MSc)
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While the traditional bystander effect literature suggested that the presence of bystanders leads to less help provided to the victims, recent studies that focused on dangerous incidents provided...Show moreWhile the traditional bystander effect literature suggested that the presence of bystanders leads to less help provided to the victims, recent studies that focused on dangerous incidents provided evidence for decreased or even reversed bystander effect in the presence of bystanders. Although previous research proposed that the heightened arousal experienced by bystanders during dangerous incidents with in-group victims leads to increased assistance, empirical evidence supporting this claim remains limited and difficult to be studied with self-report measurements. This study addresses these limitations by employing the biopsychological model of challenge and threat (BPS-CT) to examine empirically the physiological reactions of bystanders. Participants were exposed to vignettes describing dangerous and non-dangerous incidents involving in-group and out-group victims, while their cardiovascular activity and blood pressure were measured. The presence of bystanders was found to have a marginal impact on reducing threat among bystanders, irrespective of the incident's severity. Moreover, in dangerous incidents, the presence of other bystanders and a shared in-group identity with the victim heightened participants' sense of challenge. The findings align with previous meta-analytic evidence, highlighting that bystanders are more likely to intervene in dangerous situations. The results are discussed and possible implications are proposed for designing intervention programs aimed at increasing bystander intervention rates.Show less
Research master thesis | Psychology (research) (MSc)
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This study investigated the impact of parental verbal threat (vs. safety) information regarding a stranger on a child’s subjective and behavioral fear responses towards that stranger. As a...Show moreThis study investigated the impact of parental verbal threat (vs. safety) information regarding a stranger on a child’s subjective and behavioral fear responses towards that stranger. As a manipulation, parents were instructed to provide their children (N=79), aged 10-14 years, with standardized verbal threat or safety information about two strangers in the lab. Then, children engaged in a social interaction task with the two strangers (blind to their condition) separately, while child behavioral avoidance was recorded. Following the task, children reported fear beliefs for each stranger. Also, parents completed a self-report questionnaire on social anxiety symptoms. Children reported more fear beliefs for the stranger paired with the threat information, but no significant difference was found in observed avoidance. In addition, verbal threat information did not have a stronger influence on children’s observed avoidance in case of higher reported fear beliefs. Similarly, high parental social anxiety symptoms did not moderate the impact of verbal threat information on the child’s cognitive or behavioural fear indices. However, they did have a significant influence on behavioural avoidance, regardless of verbal information. Overall, this study shows a causal effect of verbal threat messages provided by parents only on child subjective fear and highlightsthe need for further research on the verbal transmission of childhood social fears in the context of family, by examining these processes in various social situations, age groups, and fear indices.Show less
Research master thesis | Psychology (research) (MSc)
open access
Human decision-making in the context of value-based learning considerably deviates from the premise to always maximise short-term reward. This sort of behavioural variability has been attributed to...Show moreHuman decision-making in the context of value-based learning considerably deviates from the premise to always maximise short-term reward. This sort of behavioural variability has been attributed to exploration during the choice process and has been linked to the locus coeruleusnoradrenaline (LC-NA) system. A recent computational account implementing a “noisy” reinforcement learning (RL) model provides evidence that computational imprecision during the learning process contributes to behavioural variability in decision-making as well. In the present study, the role of the LC-NA system in modulating learning imprecision has been investigated, using a multi-modal approach including the newly developed noisy RL model, a double-blind pharmacological manipulation, and EEG. The responses of thirty participants in a decision-making task were investigated during two experimental sessions in which either atomoxetine, a NA reuptake inhibitor, or placebo was administered, and the model fit of the noisy RL model was tested against the classical RL model without learning imprecision parameter. Contrary to our expectations, we did not find evidence for a modulatory role of the LC-NA system of learning imprecision. However, in line with our expectations, increased NA levels did not impact exploratory behaviour either. Crucially, the noisy RL model outperformed the classical RL model assuming exact learning and learning imprecision led to a significant number of non-maximising decisions contributing to behaviour variability. Moreover, the exploratory EEG analyses on potential underlying mechanisms of learning imprecision suggest learning noise to emerge broadly during feedback processing, rather than within a certain time window. The current study provides further evidence for the importance of computational imprecision during value-based learning.Show less
Research master thesis | Psychology (research) (MSc)
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Posttraumatic stress disorder (PTSD) and dissociative symptoms often co-occur. Yet, the symptom interrelations between PTSD and dissociation have not been disentangled. The timing and type of...Show morePosttraumatic stress disorder (PTSD) and dissociative symptoms often co-occur. Yet, the symptom interrelations between PTSD and dissociation have not been disentangled. The timing and type of traumatic events have been suggested to play crucial roles in the comorbidity between PTSD and dissociative symptoms. Therefore, partial correlations between PTSD, dissociative symptoms, and adverse childhood maltreatment (ACE) were investigated in two regularized partial correlation networks. Online self-report responses from participants (N = 495) of an overarching study on domestic violence were used. Symptoms and maltreatment types were assessed with the Post-Traumatic Stress Disorder Checklist DSM-5, the Dissociation Experience Scale-II, and the Childhood Trauma Questionnaire-Short Form. The first network analysis included nine nodes (four PTSD symptoms, three dissociation symptoms, two assumed confounders). The second analysis additionally considered five ACE types. The network exploration revealed few and weak connections between PTSD and dissociation. Regardless of the bridge strength, absorption/imagination and hyperarousal showed to be hubs linking PTSD and dissociative symptoms. Adding ACE barely changed the bridges between PTSD and dissociative symptoms. Amnesia appeared to be a hub for connecting dissociative symptoms to ACE. Emotional abuse was the only maltreatment type connected to the PTSD symptoms. These preliminary findings suggest that PTSD and dissociation are largely independent constructs and hint towards separate diagnostic entities. The study was limited by the sample’s subclinical symptoms and maltreatment scores. This limitation may also be partly responsible for the poorly connected network. Prospective studies with clinical samples are needed to further investigate the interplay between PTSD, dissociation, and ACE.Show less
Research master thesis | Psychology (research) (MSc)
under embargo until 2025-08-31
2025-08-31T00:00:00Z
Background: An innovative approach to improving poor psychological outcomes in breast cancer patients undergoing chemotherapy is via clinician-patient communication strategies such as educating...Show moreBackground: An innovative approach to improving poor psychological outcomes in breast cancer patients undergoing chemotherapy is via clinician-patient communication strategies such as educating patients about the nocebo effect (i.e., nocebo information) and using reassurance of non-abandonment (i.e., clinician-expressed empathy). Research suggests that nocebo information may improve some outcomes in non-cancer settings, but its effectiveness on psychological outcomes in cancer settings remains uncertain. Clinician-expressed empathy has repeatedly been shown to improve short-term psychological outcomes in cancer patients, although the long-term effects require further investigation. Moreover, potential interaction effects between nocebo information and clinician-expressed empathy observed in non-cancer settings warrant exploration in cancer care. Objective: To investigate the distinct and combined effects of nocebo information and clinician-expressed empathy on breast cancer patients’ psychological outcomes (main outcome: state anxiety) over time and at short term when undergoing chemotherapy. Methods: In this 2x2 clinical proof-of-principle randomized controlled trial, female breast cancer patients undergoing chemotherapy for the first time viewed 1 out of 4 role-played information videos, wherein the levels of nocebo information (present vs. absent) and empathy (present vs. absent) were varied. Using stepwise multilevel analyses and two-way analyses of variance, we investigated the videos’ effects on participants’ psychological outcomes over time and at short term. Results: Among the 19 participants, over time, nocebo information showed trends (p > .05) to improve state anxiety but worsen self-efficacy and distress, and empathy showed trends to worsen state anxiety, self-efficacy, as well as distress. When combined, nocebo information and empathy significantly and largely worsened self-efficacy (β = -3.21; p = .009). At short term, both nocebo information and empathy showed trends (p > .05) to worsen feelings of satisfaction and trust. Conclusion: Although these unexpected and mixed findings are preliminary, they highlight the need to fully understand the potential benefits and risks associated with clinician-patient communication strategies in cancer care.Show less
Research master thesis | Psychology (research) (MSc)
under embargo until 2024-08-31
2024-08-31T00:00:00Z
Prior studies have shown ambiguous results concerning the question if and how cognitive performance and neurophysiological markers change under the influence of weightlessness. Additional research...Show morePrior studies have shown ambiguous results concerning the question if and how cognitive performance and neurophysiological markers change under the influence of weightlessness. Additional research is necessary to confirm effects and shed light on experimental and interindividual differences and those related to various mechanisms underlying cognitive processes. This study aimed to assess the influence of microgravity on the neurocognitive marker P3 during parabolic flight. METHODS: Participants were trained to perform a brain-computer interface (BCI) task, which included a visual oddball paradigm task. Nine participants performed this task during parabolic flight. Statistic analyses assessed the amplitude and latency of the P3 event-related potential (ERP). RESULTS: Results revealed no significant differences for P3 Amplitude nor Latency in the 0G condition versus the 1G condition. The amplitude for oddball stimuli was significantly higher than the amplitude for standard stimuli in both 1G and 0G. CONCLUSION: There needs to be greater consensus and understanding concerning the effects of microgravity on cognitive performance and ERPs. The data presented here does not verify that short bouts of microgravity could enhance nor diminish neuro-behavioral performance. It does confirm that the visual-based oddball paradigm is feasible in microgravity conditions.Show less
Research master thesis | Psychology (research) (MSc)
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In PTSD research, script-driven imagery procedures are used to induce fear expression in traumatized participants but no consensus on a standard script for research has been established yet. This...Show moreIn PTSD research, script-driven imagery procedures are used to induce fear expression in traumatized participants but no consensus on a standard script for research has been established yet. This study fills a research gap by being the first to directly compare two contemporary imagery script procedures to evaluate their feasibility. We hypothesized an audio-scripted imagery procedure to lead to higher fear expression (heart rate, skin conductance, subjective distress) than an imagery-only script. A moderating effect of the vividness of the stressful memory on fear expression was also hypothesized. In a between-subjects design, participants (N = 37) were sorted into two conditions and were interviewed regarding a stressful life experience. Fear expression was measured during baseline and imagery. Contrary to expectations, both procedures led to a similar increase in fear expression. Crucially, the audio-scripted imagery procedure might be especially effective for participants with a high baseline vividness of the stressful memory which has implications for future PTSD research. Upcoming studies should investigate changes to the script procedures to facilitate comparison between scripts and further explore the effect of script procedures on high-vividness participants.Show less
Research master thesis | Psychology (research) (MSc)
closed access
Introduction: Selective serotonin reuptake inhibitors (SSRI’s) are an effective treatment for many depressed patients, but their disadvantages include a wide range of side effects and a delayed...Show moreIntroduction: Selective serotonin reuptake inhibitors (SSRI’s) are an effective treatment for many depressed patients, but their disadvantages include a wide range of side effects and a delayed treatment response. In contrast, subanesthetic doses of ketamine show acute antidepressant effects. Previous functional connectivity findings implicate the ventromedial prefrontal cortex (vmPFC) and posterior cingulate cortex (PCC), key areas of the default mode network (DMN), in ketamine’s acute antidepressant effect. In addition, psilocybin has also shown acute antidepressant effects with a potential role for the claustrum, an area functionally connected to the DMN. However, pharmacological fMRI findings concerning acute antidepressant drug action may be moderated by the decision to include or exclude a controversial preprocessing step called global signal regression (GSR). In this study, we investigated ketamine’s acute effects on functional connectivity patterns in the brain in order to probe the underlying mechanism of its acute antidepressant effects. Hypotheses: Ketamine acutely decreases functional connectivity between the vmPFC and PCC and between the DMN and claustrum. In addition, these findings will not be affected by the decision to include or exclude GSR. Method: Twenty volunteers were administered ketamine as well as a placebo on separate days in a randomized, double-blind, crossover design. We acquired resting-state functional magnetic resonance imaging (fMRI) data before, during and immediately after the acute phase of administration. Results: No differences in functional connectivity patterns were found between ketamine and placebo. These results were unaffected by the inclusion or exclusion of GSR. Conclusion: It remains unclear which changes in functional connectivity occur in the acute phase of ketamine administration. Future research should investigate the influence of GSR on fMRI findings.Show less
Research master thesis | Psychology (research) (MSc)
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Real-world natural behavior employs a range of frontal midline theta (FMθ)-related cognitive processes. Therefore, it is crucial to discover the natural behavioral correlated of fluctuations in FMθ...Show moreReal-world natural behavior employs a range of frontal midline theta (FMθ)-related cognitive processes. Therefore, it is crucial to discover the natural behavioral correlated of fluctuations in FMθ power. FMθ power has been investigated with a broad spectrum of behavioral tasks, each linked to a specific cognitive mechanism. However, the behavioral responses in those tasks cannot reflect natural behavior. This leaves a significant gap in our understanding of how these neuronal mechanisms translate into natural, complex, everyday behavior. This study bridges this gap through measuring the next-interval temporal dynamics of natural smartphone interactions. To quantify the complex real-world behavior, we are measured the next-interval temporal dynamics of natural smartphone interactions, using the recently introduced joint-interval distribution (JID). The JID represents the probability distribution of the occurrence of interaction interval k in conjunction with its next interval k+1. This method results in a 50x50 matrix where each pixel contains the probability of recorded interactions that occurred given a certain ITI (k) and consequent ITI (k+1). We measured simultaneous full-cap EEG and smartphone interactions during a one-hour session with 69 participants. The FMθ power and JID was calculated per two-minute bin per participant. We used robust regression of the two measures for each participant, and then applied a clustering method to account for multiple comparison. Four main findings emerge from the results: One, there are discernable behavioral correlates of fluctuations in FMθ power. Two, the fluctuations of FMθ power relate to specific temporal dynamics of natural smartphone behavior. Three, the behavioral correlates of fluctuations of FMθ power are more prominent in transitional than monotonous next-interval behavior. Four, there are individual differences in the behavioral correlates of FMθ power fluctuations. Overall, the results paints a multifaceted picture of the behavioral correlates of FMθ power, emphasizing both the complexity and the specificity of these relationships. The discovered natural behavioral correlates may extend existing theories on FMθ power’s role in cognition, specifically cognitive control, working and short-term memory, learning, performance, the DMN and adaptive motor control. Fluctuations in response times in cognitive assessment tasks may be transferable to the temporal dynamics of natural behavior. The discovery of the natural behavioral correlates of FMθ power fluctuations offer intriguing insights and new research opportunities.Show less
Research master thesis | Psychology (research) (MSc)
under embargo until 2024-08-01
2024-08-01T00:00:00Z
Causal beliefs about depression can shape patient behavior and treatment adherence and in the case of adolescent depression, causal beliefs of both depressed adolescents and their parents seem to...Show moreCausal beliefs about depression can shape patient behavior and treatment adherence and in the case of adolescent depression, causal beliefs of both depressed adolescents and their parents seem to be of equal importance. In this mixed-method study, we aimed to 1) qualitatively identify the causal beliefs of depression reported by clinically referred adolescents and their parents, and examine the discrepancies between mother-child and father-child pairs and to 2) quantitatively assess the relationship between these discrepancies and adolescent depression severity, and investigate whether this relationship was moderated by the adolescent’s attachment security with their parents. As part of the RE-PAIR project, a total of 34 adolescents, 34 mothers, and 26 fathers participated in interviews and completed questionnaires. The interview data was analyzed using thematic analysis in ATLAS.ti, and hierarchical regression analysis in SPSS was conducted to test the moderation hypothesis. The results revealed a total of 12 distinct causal beliefs, centered around relational issues, stressful family context, and inherent characteristics of the adolescent. We found high discrepancy levels (i.e. low agreement: 0-54%) between the reports of adolescents and their parents regarding these beliefs. However, these high discrepancies did not significantly relate to the severity of adolescent depression. While this study was the first to examine both adolescent and parental causal beliefs in a discrepancy-depression framework, further research is needed to understand the impact of discrepant perspectives on treatment outcomes and to explore the level of parental insight and understanding (e.g. good communication/ attachment security) for their adolescents’ perspective, despite differing views.Show less
Research master thesis | Psychology (research) (MSc)
closed access
Understanding the complex interactions between neurotransmitters and large-scale brain networks is crucial for unraveling the underlying neurochemical mechanisms of cognitive processes. Although...Show moreUnderstanding the complex interactions between neurotransmitters and large-scale brain networks is crucial for unraveling the underlying neurochemical mechanisms of cognitive processes. Although brain functions are modulated by a large number of neurotransmitters, one stands out for its key involvement in cognition: dopamine. This compound has been shown, although not consistently, to affect three of the main brain networks: the salience network (SN), the central executive network (CEN), and the default mode network (DMN). Specifically, an increase in dopamine has been often associated with an increase in intra SN-connectivity, resulting in a heightened negative coupling between the CEN and DMN. However, not only these results remain uncertain, but research in the field remains incomplete as until now, it has maintained a narrow focus. Thus, the present fMRI study aimed to expand on previous findings, by investigating the effects of dopamine on the SN, CEN and DMN during a working memory task. We recruited 30 healthy participants, all of which took part in two sessions, during which we manipulated their dopamine levels in the brain. To this end, in each session they received either a placebo or L-dopa, a precursor of dopamine known to increase the brain’s dopamine production and availability. During each session, participants underwent fMRI scanning, while performing a working memory task consisting of alternating working memory and rest blocks. Based on previous research, we hypothesized that dopamine would lead to a faster switch between the CEN and DMN when switching between working memory and rest blocks. In addition, we hypothesized that this faster switch would be driven by a higher intra SN connectivity. Results of paired permutation testing, as well as of a three-way ANOVA, revealed a lack of the expected dopamine-dependent changes. Dopamine did not significantly affect the switch between the CEN and DMN, nor it affected SN connectivity. These findings contradict previous literature, and call for further investigation of the dopaminergic modulation of these networks and their interactions.Show less
Research master thesis | Psychology (research) (MSc)
open access
Across clinical assessment tasks, a statistical model trained on the assessments of one person (a person’s model) has been shown to be more accurate than the person on which the model is based, the...Show moreAcross clinical assessment tasks, a statistical model trained on the assessments of one person (a person’s model) has been shown to be more accurate than the person on which the model is based, the Model-over-Person effect. Because the language that people use to express their state of mind is clinically meaningful, the objective of this study was to examine whether the Model-over-Person effect extends to language assessments as well as to identify conditions in which the effect occurs. The accuracy of the assessments of a person versus a person’s model was measured as their agreement with a reference standard (the mean assessment of multiple assessors) in two conditions: 1) the assessment of single words and 2) the assessment of texts. Artificial Intelligence based language assessments were employed to create the person’s model. No Model-over-Person effect occurred in the assessment of single words or all texts (N = 500 words/texts). A small Model-over-Person effect took place for all three assessors in the assessment of the longer texts (⩾ 50 words; dz = .39-.42; n = 23 texts). This effect be explained by the finding that a high amount of input data can make an assessment more prone to human error. Additionally, the relation between the accuracy and different assessment and language characteristics indicated that a person’s model could be more accurate in case of a low agreement among assessors and that the accuracy is not related to the confidence of the assessor in the assessment. The results show how computational language assessments can complement a person in accuracy and may support the use of computational language models as decision-support in clinical decision-making.Show less
Research master thesis | Psychology (research) (MSc)
closed access
Communication involves understanding the difference between our own perspective (visual perspective, beliefs, and knowledge) and that of an addressee. Previous research found that knowledge about a...Show moreCommunication involves understanding the difference between our own perspective (visual perspective, beliefs, and knowledge) and that of an addressee. Previous research found that knowledge about a speaker’s background (e.g., stereotypes, accent, etc.) affects online language processing in listeners. However, the role and automaticity of Theory of Mind (ToM) – the ability to attribute beliefs to someone - remains unclear. Typically, we expect individuals to speak according to their beliefs and perspectives. But what if their utterances mismatch with what we expect them to know? We designed a novel perspective-taking paradigm in a virtual environment, which manipulates an agent’s belief. We then recorded electroencephalographical data from participants, while they listened to the agent making statements either matching or mismatching their false or true beliefs. Specifically, we analyzed the N400: a component, which amplitude scales with the unexpectedness of a content word. We predicted that statements mismatching an agent’s true belief (e.g., seeing a car and saying “That’s a screwdriver”) would result in larger N400 components, compared to statements matching the true beliefs. We found strong evidence for this prediction. Further, we predicted that knowledge of an agent’s unawareness that the state of affairs has changed (i.e., a false belief) is considered when interpreting their statements. We found indirect evidence for this: statements matching their false beliefs do not elicit an N400. However, statements mismatching their false beliefs (e.g., agent says something they couldn’t have known) neither are marked by the N400. Results support ToM’s role in interpreting language.Show less
