This thesis describes a dissimilarity-based classification tool, the δ-machine, which gives an alternative way of statistical modeling compared to the conventional ones that directly use predictor... Show moreThis thesis describes a dissimilarity-based classification tool, the δ-machine, which gives an alternative way of statistical modeling compared to the conventional ones that directly use predictor variables. We use the symbol δ, because it is commonly used as a symbol for dissimilarities in multidimensional scaling.In this thesis, we discuss the properties of the δ-machine, and extend the δ-machine from handling continuous predictor variables only to handle different types of predictor variables, including continuous, ordinal, nominal, and binary predictor variables via the two tailored dissimilarity functions. Furthermore, we study the classification performance of the δ-machine in high dimensional data. We propose a Majorization-Minimization algorithm to interpolate new data points coherently into previously constructed classical multidimensional scaling (CMDS) configurations, and use the proposed algorithm in the δ-machine in high dimensional data scenario, where CMDS is applied to reduce the original high dimensional predictor variables. In order to make predictions for new data points, therefore, needs to interpolate them into the constructed CMDS.The δ-machine shows promising predictive performance in general and is able to find informative exemplars/prototypes, which bring extra insights of data. The informative exemplars could be used in the further study. Show less
This thesis investigated the development of emotional functioning in 2-to-6-year-old children with and without autism. Whereas autistic children experienced more challenges in the emotional domain,... Show moreThis thesis investigated the development of emotional functioning in 2-to-6-year-old children with and without autism. Whereas autistic children experienced more challenges in the emotional domain, their emotional abilities improved with age, and developed in similar ways as observed in non-autistic children. On the one hand, this thesis showed that autistic children might deal with emotions in a different way, and they might experience various difficulties when communicating emotions with non-autistic people. One the other hand, it is important to note that the difficulties could be bidirectional. As stated by the “double empathy problem”, non-autistic people may experience the same difficulties when communicating with autistic people. This could be a meaningful direction for future research, investigating emotional communication as a two-way interaction rather than focusing only on how people with autism react to people without autism. Furthermore, this thesis showed that autistic children had the potential to learn and to develop in the emotional domain. Again, this points to the importance of investigating how to create an inclusive social environment, which is not only nurturing for children without autism, but can also benefit the development of children with autism and with other special needs. Show less
This PhD project revealed that the female hormonal status – including OC use – and stress vulnerability – as defined by the MR-haplotype – have practical implications in experimental psychological... Show moreThis PhD project revealed that the female hormonal status – including OC use – and stress vulnerability – as defined by the MR-haplotype – have practical implications in experimental psychological research. Furthermore, incorporation of these variables in models of emotional information processing may be of help in understanding and treating mood disorders in women. Namely, even small biases may affect information processing and may contribute to the resilience or proneness to mood-disorders.Our research was among the first to show that the genetic makeup of healthy women may play a role in the influence of the female hormonal status on emotional information processing. Healthy female MR-haplotype 1/3 carriers may be more prone to distress, and may also be more sensitive to (pharmacological) changes which may counteract or sustain their vulnerability. Consistently, we observed subtle markers of depressogenic side-effects of OC only in MR-haplotype 1/3 carriers. Our findings regarding the MR-haplotypes 2 carriers are generally in line with earlier observations. We observed that MR-haplotype 2 carriers – especially homozygotes – are the less susceptible, more optimistic and more rational individuals, also in ‘unstressed’ conditions. However, stress-related psychopathology is very heterogeneous by nature and proteins from multiple genes are likely to interact in the stress-susceptibility phenotype. Last but not least, we should not ignore that the increased vulnerability of women to mood disorders is the result of a plethora of biological, psychological and sociological factors.OC-users had lower affect variability and reduced sensitivity to interpersonal emotional cues. This may be experienced as either a stabilizing or a blunting effect of OC, perhaps depending on the individual’s appraisal. The lower depression scores of OC-users in our longitudinal study suggests a protective effect of monophasic OC on symptoms of reproductive depression. Future studies should investigate (former) OC-users in larger cohorts including novel users, satisfied users and ‘brand-switchers’ in order to control for the survivor effect. Show less
This dissertation covered several relevant cycles of placebo research with the main aim to optimize placebo effects in medical contexts. Firstly, a literature review described how the immune system... Show moreThis dissertation covered several relevant cycles of placebo research with the main aim to optimize placebo effects in medical contexts. Firstly, a literature review described how the immune system can be impacted by placebo effects and their underlying learning theories. In the following chapter, these learning theories were integrated to form an optimal research design by means of pharmacological conditioning to fit a specific patient group: children with juvenile idiopathic arthritis. Secondly, this dissertation focused on developing placebo information strategies to harness placebo beliefs and educate persons about the relevancy of placebo effects in practice. These insights are valuable because treatment expectations can have a positive or negative effect on treatment outcomes. Finally, insights from placebo learning theories and placebo information strategies were combined in an integrative experimental research design. This research design employed a more ethical form of placebo use because participants were made aware of placebos, called open-label placebos. In this last study we demonstrated that open-label placebo analgesia can be induced by combining learning theories and placebo information strategies. Altogether, this dissertation provided insights in learning mechanisms, communication strategies, and research paradigms that involve the optimization of placebo effects in medical context. Show less
The results described in this thesis support the strong empirical evidence for the effectiveness of CBT-Ef for patients with an eating disorder and a BMI>17.5. When compared to TAU, we found... Show moreThe results described in this thesis support the strong empirical evidence for the effectiveness of CBT-Ef for patients with an eating disorder and a BMI>17.5. When compared to TAU, we found comparable effects on eating disorder psychopathology, however CBT-Ef is superior in enhancing self-esteem with significantly fewer sessions and within a shorter time. We found no support for the hypothesis that more severe self-esteem problems, higher levels of perfectionism, or more interpersonal problems would obstruct long-term improvement and would therefore need extra attention in an extended protocol. A broader use of CBT-Ef in clinical practice could result in more efficient and accessible treatment for patients with an eating disorder. In another study we found COMET to be effective in enhancing self-esteem in patients with an eating disorder. Since we did not find the predictive value of low self-esteem in CBT-E treatment outcome, we suggest to integrate COMET in an eating disorder treatment only when low self-esteem is pronounced and interferes with making progress. Show less
The aim of the current dissertation was to examine the psychological, neurological and behavioral impact of different types of traumatic (A1) and stressful (non-A1) life events, including a focus... Show moreThe aim of the current dissertation was to examine the psychological, neurological and behavioral impact of different types of traumatic (A1) and stressful (non-A1) life events, including a focus on the impact of childhood maltreatment. The role of brain structure (hippocampal volume) and function (neural correlates of emotional face processing and social rejection) in intergenerational transmission of child abuse versus neglect was investigated using a multi-generational family study design. Show less
In this thesis, I investigated the behavioral and neural processes involved in self-concept development in adolescence within the context of future-oriented educational decision-making. The studies... Show moreIn this thesis, I investigated the behavioral and neural processes involved in self-concept development in adolescence within the context of future-oriented educational decision-making. The studies presented in this thesis all highlight that self-concept is a multifaceted and complex construct that not only develops in interaction with the social environment, but can also have an impact on someone’s future environment. For example, results from chapter 2 indicated that the social environment, expressed in the outcomes of social comparisons, can affect the positivity of the self to a different extent across multiple domains and different stages of adolescence. Chapter 3 showed how adolescents’ academic self-concept can influence their motivation to stay committed to goals important for their future educational environment, whereas chapter 4 illustrated differences in self-esteem and self-concept clarity in individuals who differed in their experienced problems with choosing this future educational environment. Finally, chapter 5 demonstrated that in late adolescence, sensitivity to outside influences can be used to stimulate self-concept development through training which can ultimately help adolescents in their educational decision-making and adjustment in higher education. Together, these studies provide a comprehensive view on self-concept development in adolescence that takes place within a broader social, and educational context. Show less
This thesis consists of three empirical chapters that investigate elements of human social behavior, adherence to and violations of social norms, and the computational and neurological... Show moreThis thesis consists of three empirical chapters that investigate elements of human social behavior, adherence to and violations of social norms, and the computational and neurological underpinnings thereof. I focus on three behavioral paradigms in particular – the attacker-defender contest, the trust game, and the ultimatum game – which model asymmetrical conflicts, generosity and reciprocity, and norms of fairness, respectively. Ultimately, each chapter acts as a building block contributing a different perspective to the study of human sociality. Using economic games, computational models based on the principle of utility, and model-based neuroimaging, my research contributes to the scientific endeavor working to crack the “elaborate and secret code that is written nowhere, known by none, and understood by all” (Sapir, 1927, p.137) Show less
This dissertation examines the relations between two ethnic groups in Kosovo who have lived segregated since the Kosovo War (1998-1999), Kosovar Albanians and Kosovar Serbs. The main research... Show moreThis dissertation examines the relations between two ethnic groups in Kosovo who have lived segregated since the Kosovo War (1998-1999), Kosovar Albanians and Kosovar Serbs. The main research question I examined is how contact between the segregated Kosovar Albanian majority and Kosovar Serb minority can be stimulated. Across five studies, I investigated the role of social identity complexity and inclusiveness, as well as distinctiveness threat in the willingness of Albanians and Serbs in Kosovo to interact. Overall, the findings reveal that the generation of Kosovars who grew up after the war have a very limited intention to invest in a peaceful and inclusive society. Using a social identity approach, I outline several social psychological barriers that play a role here, ranging from negative interethnic relations and reluctance to form relationships with Kosovars belonging to other ethnic groups, to difficulties in integrating one’s ethnic identity (Albanian or Serbian) into a new national Kosovar identity that is still in development since the country gained independence in 2008. The dissertation also discusses the importance and the prospects of fostering more inclusive social identities among Kosovar Albanians and Kosovar Serbs to live together in peace as they develop the new nation of Kosovo. Show less
Facial expressions play a fundamental role in social interactions, as demonstrated by our spontaneous inclination to mimic emotional expressions of others. In this thesis, I take a broad... Show moreFacial expressions play a fundamental role in social interactions, as demonstrated by our spontaneous inclination to mimic emotional expressions of others. In this thesis, I take a broad perspective and show that people mimic each other on many more levels than previously thought. Special attention is given to autonomic mimicry (synchrony in heart rate, skin conductance and pupil diameter), which is an underexplored area of research. In the first empirical chapter, I show that pupil mimicry activates social brain regions and when the pupils of interacting partners synchronously dilate, trust is promoted. In the subsequent real-life experiment, I demonstrate that synchrony in heart rate and skin conductance boost attraction between people on a date. In the remaining chapters, I manipulate mimicry with optical illusion and brain stimulation to provide evidence that autonomic and facial mimicry are controlled by distinct neurological pathways. Together, these findings implicate that the tendency to automatically mimic and physiologically align with others can result in emotional contagion – the tendency to ‘catch’ another person’s emotion, which in return encourages trust and affiliation. In sum, this research takes a fundamental step towards the understanding of the neurobehavioral pathways through which mimicry influence (pro)social behaviors. Show less
This dissertation reports about the construction and validation of the Apperception Test God Representations. First, results of a meta-analysis demonstrated that for adherents of monotheistic... Show moreThis dissertation reports about the construction and validation of the Apperception Test God Representations. First, results of a meta-analysis demonstrated that for adherents of monotheistic religions, their perceived and experienced relationship with the personal god they believe in, was associated with well-being and distress. Also, as was expected based on object-relations and attachment theory, God representations were associated with views of self and others and with neuroticism/optimism. However, these results were mostly based on self-report measures of God representations, which are thought to be susceptible to social desirability and doctrine effects. Many scholars believe that God representations are for an important part implicit. Because well-validated implicit God representation measures did not exist, this thesis project examined the validity of a newly developed measure. In a group of 74 Christian patients with personality disorders and a group of 71 Christian nonpatients, associations of implicitly measured God representations with implicitly and explicitly measured distress and object-relational and explicitly measured personality functioning were compared with associations of explicitly measured God representations with these variables. For patients, associations between changes in God representations and changes in distress and explicit object-relational functioning after psychotherapy were examined. Results predominantly corroborated the construct validity of the ATGR. Show less
The research presented in this dissertation was aimed at investigating the consequences of reward-oriented motivation (i.e., an inclination to strongly focus the entrepreneurship on pursuing... Show moreThe research presented in this dissertation was aimed at investigating the consequences of reward-oriented motivation (i.e., an inclination to strongly focus the entrepreneurship on pursuing rewards) and security-oriented motivation (i.e., an inclination to strongly focus the entrepreneurship on ensuring one’s survival and security) for business growth motivation among small-business owners. In addition, the research was aimed to examine the process through which reward-oriented motivation and security-oriented motivation relate to business growth motivation among small-business owners. The findings generally showed that relative to security-oriented motivation, reward-oriented motivation is positively predictive of business growth motivation among small business owners in a consistent manner. Furthermore, time perspective in the context of entrepreneurship, entrepreneurial-self-esteem, and perceived competence were found to be important variables in explaining the relationship between reward and security-oriented motivation and business growth motivation among small business owners. The findings in this dissertation highlight the importance of taking into account small business owners' motivation of engagement in entrepreneurship in efforts to assist small business owners to grow their businesses. Show less
The idea that perception is a direct reflection of the outer world has been challenged by the notion that information is integrated at all levels of processing, including perceptual levels. Affect... Show moreThe idea that perception is a direct reflection of the outer world has been challenged by the notion that information is integrated at all levels of processing, including perceptual levels. Affect has been suggested to be a powerful source of information. This thesis explored affective influences on auditory perception and processing and what such influences may imply about penetrability of perception. The presented studies found that listeners in a sad mood more frequently judged ambiguous pitch changes as going downwards than in a happy mood. Furthermore, auditory sensitivity in noise was related to the affective reactivity of the listener, but its relation with mood remained inconclusive and should be further explored. Finally, this thesis demonstrated that evaluative conditioning changed affective quality of sounds without changing low-level stimulus features, which future studies into auditory processing of affective sounds can utilize. Together the findings suggest that aspects of auditory perception are subject to affective influence. This is consistent with the notion that perceptual and non-perceptual information is integrated, allowing listeners to form percepts from often noisy, incomplete, or ambiguous auditory input. The findings provide a basis and stimulation to further investigate where in the brain and through which mechanisms this integration occurs. Show less
