Emotional experiences are more likely to be remembered than more neutral, mundane ones. In young adults, negative information may be particularly memorable. Yet, an interesting change seems to happen in aging: As adults grow older, they may start remembering positive information more often than negative information. This positive memory bias in aging is commonly observed and is often explained in terms of changing time perspectives and motivation across the lifespan (i.e., Socioemotional Selectivity Theory; Carstensen, Isaacowitz, & Charles, 1999). However, few studies have considered the basic interactions between memory and emotion that could influence this positivity bias. In this thesis, I examine whether certain factors partially independent of aging (i.e., semantic relatedness and distinctiveness, Study 1; mood, Studies 2-4), might influence the presence and magnitude of the positivity bias in memory. In Study 1, I explore the cognitive mechanisms required to produce the positivity bias and apply what is learned in this paper to investigate, in Studies 2-4, whether differences in mood could explain why the positivity bias occurs. In all studies, memory is measured using immediate free recall of positive, negative, and neutral pictures. In Study 1, I manipulate item interrelatedness (i.e., the extent of relatedness among pictures of a same category) and relative distinctiveness (i.e., the processing of a picture category at the same time as or in isolation from the others) to show that older adults’ emotional memory can be entirely explained by these two factors. The distinctive processing of positive pictures relative to other pictures is necessary for producing a positivity bias in older adults, which completely disappears when the distinctive processing of positive pictures is removed. Therefore, in subsequent studies I encourage the distinctive processing of items to increase the likelihood of observing a positivity bias and its possible interaction with mood. In Study 2, I test whether differences in mood predict differences in emotional memory bias in young and older adults using a video mood induction technique validated in a separate pilot study. In Studies 3 and 4, I further test the effect of mood on the positivity bias beyond any age-specific factors, by examining young adults only. This serves to reduce the likelihood of confounds that might exist between age groups (i.e., related to neurocognitive changes or decline), in order to study the true effects of mood on the positivity bias. In Study 3, I use a written priming task to experimentally manipulate mood and time perspective in young adults. In Study 4, I compare differences in naturally occurring moods and emotional memory in two separate young adult samples: university students and non-students. The experimental mood manipulations have minimal influence on the presence of a negativity bias in young adults (Studies 2 and 3), and influence to a small extent the memory advantage of positive over neutral material in older adults (Study 2). Non-student young adults show a similar preferential memory for positive material that is different from what is observed in university students, but this is not easily attributed to differences in mood (Study 4). In light of these results, I argue that the positivity effect in aging memory reflects a temporary contextual advantage for positive information that is not permanent or irreversible. Rather, it seems to depend in varying degrees on the context of study (i.e., relatedness and distinctiveness), mood, and the young-adult reference group. This has implications for how future research defines and studies the positivity effect in aging.

Despite an increase in interventions targeted at lowering the rate of HIV/AIDS among college students, the rate of HIV/AIDS infections has not decreased. The purpose of this study was to identify factors (i.e., HIV-sexual knowledge, self-positivity bias, peer norms, acculturation, perceived risk of HIV, HIV-related stigma, and condom use) that may affect condom use among college students who live in an area where the prevalence of HIV is relatively high. The current study utilized a sexually active sample (N=397) of diverse college students (predominantly African American and White) in an urban setting to examine the relationships. Path analysis was used to explore hypotheses. Results indicated that students who endorsed higher levels of self-positivity bias were more likely than other students to report not using condoms the last time they had sex and to perceive themselves at less risk of HIV/AIDS infection. In addition, students who reported unsupportive peer norms regarding safe sex practices perceived themselves at a higher risk of HIV/AIDS. With respect to gender differences, females reported more stigma towards individuals with HIV/AIDS than males, and males reported more perceived risk of HIV/AIDS than females. Lastly, African American college students perceived themselves to be at greater risk of contracting HIV/AIDS than other students and minority students endorsed greater stigma towards individuals with HIV/AIDS than White students. Results emphasize the need for college HIV/AIDS interventions to target peer norms and personal bias as well as cultural and gender differences that might impact condom use.

Decades of research have demonstrated that people sometimes provide self-evaluations that emphasize their most flattering qualities. Different theoretical accounts have been offered to explain the mechanisms underlying positively-biased self-evaluation. Some researchers theorize that positively-biased self-evaluations arise from a self-protection motivation because positivity biases increase in situations of heightened self-esteem threat. Alternative views question whether self-protection motivation is a necessary or even dominant source of positivity bias by demonstrating that positively-biased self-evaluations occur even when threat is not heightened, and that a general judgment approach leads to positivity biases in some domains but also to negativity biases in other domains. One reason for this gap in knowledge is that behavioral measures are limited in their ability to resolve whether the processes underlying positively-biased self-evaluation are the same or different depending on contextual motivators. Neuroimaging methods are well suited to examine whether different mechanisms underlie similar behaviors, specifically similar positively-biased responses in different contexts. The four studies presented here explore the neural mechanisms of positively-biased self-evaluation by first identifying a core set of neural regions associated with positivity bias (Study 1A and 1sB), examining whether a heightened self-protection motivation changes the engagement of those neural systems (Study 2), and specifying the precise mechanisms supported by those regions (Study 3). Studies 1A and 1B revealed evidence for a neural system comprised of medial and lateral orbitofrontal cortex (OFC) and, to a lesser extent dorsal anterior cingulate (dACC) that was modulated by positivity bias. Study 2 found that a heightened self-protection motivation changes the engagement of medial OFC in positively-biased self-evaluation. Finally, Study 3 found evidence that medial OFC may support a common mechanism in positively-biased judgment that is implemented differently as a function of the motivational context. Taken together, these studies represent a first step toward developing a neural model of positively-biased self-evaluation. The findings provide some preliminary evidence that positivity biases may represent distinct processes in different motivational contexts. This dissertation sets the stage for future work to examine how specific positively-biased cognitive mechanisms may be supported by specific neural systems and computations as a function of motivational contexts. / text

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The aims of the present thesis were two fold. The first aim was to investigate the relationship between self-referential and emotional processing. The second aim was to investigate the extent to which self-referential processing is altered as a function of mood. In order to address these two aims, a variety of behavioural and physiological measures were recorded and a new methodology was employed in the following experimental chapters. The aim of experiment one was to investigate how non-dysphoric and dysphoric individuals evaluate the emotional valence and self-referential content of word stimuli at a behavioural level. A self-positivity bias was identified in non-dysphoric individuals, positive words were rated as self-referential and negative words were rated as non-self-referential. Compared to non-dysphoric individuals, dysphoric individualsâ evaluations of self-reference but not emotional valence were altered. Event-related potentials (ERPs) were employed in experiment two to investigate self-referential processing at a neural level. A two stage model of processing was identified in which, an evaluation of emotional valence was found to occur prior to an interaction between self-reference and emotional valence. A self-positivity bias was identified in the ERP component known as the N400. ERP waves were more negative going to self negative and non-self-positive words when compared to self-positive and non-self-negative words. This bias was explained in terms of the semantic mismatch hypothesis. The aim of experiment three was to investigate how the neural processing of self-referential and emotional information is altered as a function of mood. Differences between nondysphoric and dysphoric individuals were identified during the early stages of ii processing in an emotion task. Between group differences were identified during the later stages of processing in a self-reference task, around 400 ms. Skin conductance and heart rate were employed in experiment four to examine autonomic responses during self-referential and emotional processing in healthy individuals. Both decision-making tasks were found to elicit similar physiological responses. These findings were taken to suggest that a large component of self-referential processing involves the processing of emotional information. Finally, the aim of experiment five was to investigate if person-referent processing was altered during the experience of a negative mood. The behavioural and neural responses of non-dysphoric and dysphoric individuals were compared across self-referent and other-referent decision-making tasks. Between group differences were specific to the self-reference task at the behavioural level. However, group differences were identified in both the self-referent and other-referent tasks at the neural level. The results provide partial support for the hypothesis that negative mood is associated with specific impairments in self-referential processing. Overall the results of the present thesis illustrate that the processing of emotional information plays a large role in self-referential decision-making. Furthermore, the N400 was found be involved in this type of decision-making at the semantic level. Negative mood was associated with greater changes in self-referential processing than in other forms of emotional or person-referent processing. In the final chapter, a two stage model is proposed to account for self-referential processing. The implications of this model are discussed in terms of two macro-cognitive theories, interacting cognitive subsystems (ICS) and SPAARs. Finally, the limitations and future directions for developing this line of research are outlined.

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