A normative experimental study was undertaken to establish whether engaging in positive, negative, and neutral mental imagery affected the reaction rate of participants to positive, negative, and neutral word stimuli. The sample consisted of computer literate, English speaking participants with no history of clinical disorders. A total of 80 participants took part in the study, with 40 participants from either gender. The results of a factorial ANOVA indicated that the type of mental imagery engaged in had a significant effect on the rate at which participants responded to stimuli (p=.00023, F=8.4057), whilst the emotional valence of the stimuli did not have a significant effect (p=.30503, F=1.1877). However, the interaction between the type of mental imagery and the emotional valence of the stimuli was highly significant (p=.00794, F=3.4576), thereby indicating that engaging in positive or negative mental imagery did bias participants towards a faster reaction rate to positive or negative stimuli respectively. / M.A. (Psychology) / Psychology

Adolescent depression is a major public health problem, which is associated with educational problems, long-term psychiatric illness and suicide. One major source of stress during adolescence is peer rejection. In this thesis, I investigate the nature of the relationship between peer rejection and adolescent depression. In a review of longitudinal and experimental studies, I describe a bi-directional relationship between peer rejection and depressive symptoms. I then outline how genetic, cognitive and neural vulnerability may modify the effects of peer rejection on adolescent depression. Finally, I introduce five empirical chapters which test these hypotheses using different methodological approaches. The first study is a molecular genetic analysis of a sample of adolescents with and without a diagnosis of mood disorder. I report an interaction between diagnostic group, environmental stress (though not peer rejection specifically) and 5HTTLPR genotype on symptoms of anxiety, which supports the role of genetic factors in modifying the relationship between environmental stress and adolescent mood disorder. The second study is a behavioural study of negative attention biases in a typically developing sample of adolescents. I report a negative attention bias in adolescents with low (versus high) self-esteem. Although the data do not support a causal role for attention biases in adolescent depression, such biased cognitions could also moderate responses to peer rejection, maintaining affective symptoms. A final set of three fMRI datasets investigates how neural circuitry may influence depressed adolescents’ responses to peer rejection at three distinct stages: i) expectation of peer feedback, ii) the receipt of peer rejection, iii) emotion regulation of peer rejection. Data show distinct behavioural and neural differences between depressed patients and healthy controls during expectation and reappraisal of peer rejection, although heightened emotional reactivity immediately following the receipt of peer rejection did not differentiate behavioural or neural responses in adolescents with and without depression.

A normative experimental study was undertaken to establish whether engaging in positive, negative, and neutral mental imagery affected the reaction rate of participants to positive, negative, and neutral word stimuli. The sample consisted of computer literate, English speaking participants with no history of clinical disorders. A total of 80 participants took part in the study, with 40 participants from either gender. The results of a factorial ANOVA indicated that the type of mental imagery engaged in had a significant effect on the rate at which participants responded to stimuli (p=.00023, F=8.4057), whilst the emotional valence of the stimuli did not have a significant effect (p=.30503, F=1.1877). However, the interaction between the type of mental imagery and the emotional valence of the stimuli was highly significant (p=.00794, F=3.4576), thereby indicating that engaging in positive or negative mental imagery did bias participants towards a faster reaction rate to positive or negative stimuli respectively. / M. A. (Psychology) / Psychology

Negatively biased interpretation has been hypothesized as an important factor in the aetiology and maintenance of depression. Recently developed cognitive bias modification paradigms, intending to change these biases towards a more optimistic interpretation tendency (CBM-I), seem to offer new promising implications for cognitive therapy innovation. Surprisingly, the increasing interest in the modifiability of interpretation bias is contrasted by a severe lack of methodological and measurement development studies. A review of current research revealed 1) a severe lack of psychometrically evaluated measures for depressionrelated interpretation bias and its modification, 2) inconsistent findings for the existence of depression-related interpretation bias depending on the (direct or indirect) assessment paradigm, 3) a demand for profound knowledge about the underlying work mechanisms and best ingredients for CBM-I procedures, and 4) a lack of measures and CBM-I training materials in the German language. With these considerations in mind, the objectives of this dissertation were 1) to develop and evaluate an internally consistent and valid measure for the assessment of depression-related interpretation bias and its modification, 2) to validate an indirect priming task to assess interpretation bias and to further examine the interrelations of four different direct and indirect assessment paradigms, 3) to evaluate a new and more active CBM-I variant and test its effectiveness in comparison with guided CBM-I and a control group, and 4) to provide valid test and CBM-I training materials in German. The aim of study 1 was to develop and evaluate a pragmatic assessment instrument, consisting of a 30-item questionnaire (long version) and two 15-item parallel short versions (A and B). Items were generated as ambiguous sentences, reflecting three relevant content areas based on Beck’s cognitive triad (Beck et al., 1979). All three versions of the instrument were found to be structurally stable, internally consistent and valid. In line with Beck’s cognitive triad (Beck et al., 1979) in depression, confirmatory factor analyses determined a three factor solution (self, experiences, future). Significant correlations were found between all scales and depressive mood. The two short versions represent the same underlying constructs, share identical psychometric properties and possess high parallel-test reliability. The study was the first to evaluate and confirm the factorial validity as well as the parallel-test reliability, and therefore suitability to measure modification of interpretation bias measure in the context of depressed mood. The aim of study 2 was to evaluate an indirect affective priming task using homophones as ambiguous material and to compare this task to three different already established interpretation bias paradigms, namely an ambiguous scenarios test, a scrambled sentences test under cognitive load, as well as a homophone paradigm. No empirical support for mood-related interpretation bias was found for the newly developed affective priming task as well as the homophone task, which both did not differentiate between dysphoric and non-dysphoric individuals. The ambiguous scenarios test and the scrambled sentences test under cognitive load were shown to be internally consistent and valid instruments that were also highly intercorrelated. These findings emphasize the challenge to create valid ambiguous test stimuli for the measure of depression-related interpretation bias as well as the inequality of different assessment paradigms. Study 2 was the first study to examine the relatedness of four different direct and indirect assessment paradigms for the measure of depression-related interpretation bias in one sample. The aim of study 3 was to compare the efficacy of CBM-I requiring participants to imagine standardized positive resolutions to a novel, more active training version that required participants to generate the positive interpretations themselves. Participants were randomly allocated to (1) standardized CBM-I, (2) self-generation CBM-I or (3) a control group. Outcome measures included self-report mood measures and a depression-related interpretation bias measure. Both positive training variants significantly increased the tendency to interpret fresh ambiguous material in an optimistic manner. However, only the standardized imagery CBM-I paradigm positively influenced mood. Study 3 successfully evaluated a new CBM-I variant, gained insights about the role of self-generation and added further support to the potential therapeutic significance of imagery-based cognitive bias modification strategies. Altogether, this dissertation significantly contributed to the research field of depressionrelated interpretation bias by 1) filling a gap in measure development studies, 2) increasing the knowledge of the relatedness of different assessment paradigms, 3) increasing the knowledge about the working mechanisms and optimal ingredients of successful CBM-I, and 4) evaluating and providing assessment as well as CBM-I training materials for the German language context. / Ein negativer Interpretationsbias bezieht sich auf die Tendenz, mehrdeutige Reize (z.B. Situationen, Gesichtsausdrücke, Rückmeldung von anderen Personen) in einer pessimistischen Art und Weise zu interpretieren. Diese kognitive Verzerrung im Rahmen der Informationsverarbeitung wird als wichtiger Faktor für die Entstehung und Aufrechterhaltung von depressiven Störungen diskutiert. Insbesondere die Modifikation dieser Tendenz zu einem positiveren Interpretationsstil (Cognitive bias modification targeting interpretation; CBM-I) erweckte in den vergangenen Jahren großes Forschungsinteresse, da diese innovativen, computergestützten Techniken wirkungsvolle Behandlungsansätze für die Therapie von Depressionen bedeuten könnten. Nach aktuellem Forschungsstand besteht jedoch 1.) ein Mangel an hinreichend evaluierten Instrumenten für die Erhebung von depressionsbedingten Interpretationsverzerrungen und insbesondere deren Veränderbarkeit, 2.) eine inkonsistente Befundlage für die Existenz von depressionsbedingten Interpretationsverzerrungen in Abhängigkeit von der (direkten oder indirekten) Erhebungsmethode, 3.) ein Bedarf an genaueren Erkenntnissen über die zugrunde liegenden Wirkmechanismen und effektivsten Komponenten von CBM-I und 4.) ein Fehlen von CBM-I Materialien und Erhebungsmethoden in deutscher Sprache. Vor diesem Hintergrund wurden die Ziele dieser Dissertation formuliert, die neben einer kurzen Einführung in das Themengebiet und einer abschließenden Diskussion aus drei Studien besteht. Das Ziel der ersten Studie war die Entwicklung und Validierung eines pragmatischen Erhebungsinstrumentes zur Messung von depressionsbedingten Interpretationsverzerrungen, bestehend aus einem Fragebogen (Langfassung, 30 Items) und zwei Kurz- bzw. Parallelversionen (A und B, jeweils 15 Items). In den Items werden emotional mehrdeutig interpretierbare Szenarien beschrieben, deren Inhalte Beck‘s kognitive Triade (Beck et al., 1979) widerspiegeln. Den Ergebnissen zufolge können alle drei Versionen des Instruments als strukturell stabil, internal konsistent und valide bewertet werden. In Übereinstimmung mit der Theorie der kognitiven Triade (Beck et al., 1979) wurde mittels konfirmatorischer Faktorenanalyse eine Dreifaktorenlösung (Selbst, Erfahrungen, Zukunft) festgestellt. Signifikante Korrelationen wurden zwischen allen Skalenwerten und depressiver Symptomatik gefunden. Die beiden Parallelversionen weisen ähnliche psychometrische Eigenschaften sowie eine hohe Paralleltest-Konsistenz auf. Das Ziel der zweiten Studie war die Validierung eines indirekten, affektiven Priming- Verfahrens, in dem homophone Wörter als emotional zweideutige Stimuli eingesetzt wurden. Dieser Test wurde zusätzlich mit drei bereits etablierten Erhebungsparadigmen (Ambiguous Scenarios Test; Scrambled Sentences Test, Homophone-Test) verglichen. Hinsichtlich der Ergebnisse konnte keine empirische Unterstützung für den affektiven Priming-Test sowie für den Homophone-Test gefunden werden; beide Tests zeigten keinen Zusammenhang mit depressiven Symptomen. Der Ambiguous Scenarios Test und der Scrambled Sentences Test erwiesen sich als internal konsistent und valide und wiesen außerdem eine hohe Interkorrelation auf. Die Ergebnisse geben Aufschluss über die Vergleichbarkeit der unterschiedlichen Erhebungsparadigmen. Das Ziel der dritten Studie war die Entwicklung und Evaluation einer neuen, aktiveren CBM-I Variante, in der die Teilnehmer mittels eines computergestützten Trainings aufgefordert wurden, positive Interpretationen auf emotional mehrdeutige Szenarien eigenständig zu generieren. Die Ergebnisse der neuen CBM-I-Variante wurden mit den Ergebnissen einer herkömmlichen CBM-I-Variante (Standard-CBM-I) sowie den Ergebnissen einer Kontrollgruppe verglichen. Es zeigte sich, dass sowohl die neue CBM-I-Variante als auch Standard-CBM-I die Interpretationstendenz signifikant in eine positive Richtung verbesserten. Darüber hinaus konnte durch Standard-CBM-I eine stimmungsaufhellende Wirkung erzielt werden.