Prospective Graduate Students / Postdocs
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Rebecca Todd
Associate Professor
Research Classification
Research Interests
cognition
Emotional learning (associative learning of reward and punishment)
Human Cognition and Emotion
Human Neurocognitive processes underlying all of the above
Learning and Memory
Motivation, Emotions and Rewards
Motivationally and affectively biased attention and memory
Relevant Thesis-Based Degree Programs
Affiliations to Research Centres, Institutes & Clusters
Research Options
I am available and interested in collaborations (e.g. clusters, grants).
I am interested in and conduct interdisciplinary research.
I am interested in working with undergraduate students on research projects.
Research Methodology
My lab uses computer-based behavioural measures, as well as psychophysiological, eye tracking, EEG, and functional brain imaging measures.
Great Supervisor Week Mentions
Each year graduate students are encouraged to give kudos to their supervisors through social media and our website as part of #GreatSupervisorWeek. Below are students who mentioned this supervisor since the initiative was started in 2017.
Every day in @BecketTodd’s lab feels like coming home. I am 101% sure I speak for all of her students. Always grateful for my #GreatSupervisor. You deserve all the [ice cream] and [bears] in the world. #UBC
Graduate Student Supervision
Doctoral Student Supervision
Dissertations completed in 2010 or later are listed below. Please note that there is a 6-12 month delay to add the latest dissertations.
Reward sensitivity and emotionally biased cognition in depression (2023)
For this dissertation, I examined anticipatory reward sensitivity, facial emotion judgment, and self-referential processing in major depressive and bipolar spectrum disorders (MDD and BSD) during a major depressive episode (MDE). I also examined whether these cognitive-affective processes predicted trajectories of response to repetitive transcranial magnetic stimulation (rTMS) for treatment-resistant depression (TRD) and/or changed from pre-treatment to post treatment. In Chapter 1, I begin by conceptualizing the constructs of interest and reviewing previous research relevant to MDD and BSD as well as rTMS for TRD. I subsequently introduce my research questions and hypotheses. In Chapter 2, I report a study examining differences in the cognitive-affective processes of interest between acutely depressed individuals with MDD and BSD, as well as non-psychiatric control participants (NCs). I show that individuals with MDD exhibited blunted anticipatory reward sensitivity and attributed fewer positive traits to themselves compared to individuals with BSD and NCs. Participants with BSD also self-attributed fewer positive traits than NCs. Individuals with MDD and BSD attributed more negative traits to themselves and had greater negative self-referential memory bias than NCs. Thus, anticipatory reward sensitivity and self-attribution of positive traits may be higher in BSD than MDD, and self-attribution of negative traits and negative self-referential memory bias appear higher in both disorders, compared to NCs. Chapter 3 is a study examining the roles of reward sensitivity, facial emotion judgment, and self-referential processing in response to rTMS for TRD. I found that anticipatory reward sensitivity and the number of negative traits participants self-attributed at baseline were significantly associated with overall depressive and suicidality symptoms, from baseline to three months post treatment. Furthermore, participants self-attributed a higher number of positive traits and a lower number of negative traits, and had lower negative self-referential memory bias, at one-week post rTMS compared to baseline. The findings suggest baseline reward sensitivity and negative self-referential processing may be risk factors for higher depressive symptoms and suicidality during and after rTMS. Additionally, rTMS may help address negatively biased self-referential processing. In Chapter 4, I conclude with a final summary and discussion of this research, including limitations and future directions.
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Individual differences in development and representation of novel affective associations (2019)
Emotionally arousing events are typically better remembered than mundane ones, in part because emotionally relevant aspects of our environment are prioritized in attention. Such biased attentional tuning is itself the result of associative processes through which we learn affective and motivational relevance of cues. While such affective biases in cognition can be highly adaptive, extreme biases to specific categories of aversive or rewarding stimuli can be symptomatic of psychopathology. That raises the question which factors contribute to individual differences in development of affective biases via emotional learning processes and how emotional associations come to be represented in the brain. More specifically, the present thesis aimed to investigate the role of individual differences in the norepinephrine and stress system in emotional learning processes. In Study I, I demonstrated that a common genetic variation putatively influencing norepinephrine availability is associated with subjective perception of ambiguous stimuli as more rewarding. Moreover, change in affective bias was mediated by acute stress. Thus, in the first study I established that individual differences in the locus coeruleus-norepinephrine (LC-NE) and stress system play a role in affective perception and the flexibility of the underlying subjective biases. In Study II and III, I found that acute stress affects both classical and operant conditioning and that the direction of those effects depends on the timing of the stressor relative to the learning experience. Study IV aimed to investigate the neural representation of the development of novel affective associations using functional magnetic resonance imaging (fMRI). By means of representational similarity analysis (RSA) - a multivariate approach to analyzing neuroimaging data - the study revealed that conditioned stimuli reactivate the representational pattern elicited by the unconditioned stimuli. I further observed that it is specifically the hedonic response to the unconditioned stimulus that is being reproduced by the conditioned stimulus. Together these studies demonstrate a role for the norepinephrine and stress system in reward-based learning as well as providing new information of neural mechanisms underlying emotional learning. This research provides insight into individual differences in emotional learning processes that can underlie formation of affective biases.
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The processing of cartoony and photorealistic faces (2019)
Cartoony faces are everywhere, from texting apps to children’s cartoons. Cartoony faces are also often used in cognitive research contexts, where they are used to stand in as simplified photographic faces for their ease of manipulation and creation. This presents an often unspoken assumption: that a cartoony face is analogous to a photographic face in how it will be responded to, understood, and processed by the brain. Over 8 experiments, my dissertation aims to better understand how cartoony faces are similar to photographic faces, and where they differ. In the first two experiments, I found that there was no evidence that people see themselves in simple cartoony faces, as had been suggested in the past, and also that participants associated their photographs more with themselves than drawings of themselves. In Experiments 3 and 4, I found that, as faces become more cartoonized, they become easier to discriminate expressions on as well, and that such changes to ‘cartoonization’ is also represented by changes in neural processing. In Experiments 5 and 6, I found further evidence that cartoony imagery was easier to process than photographic imagery, as measured by the amount of attention – i.e., eye-gaze – that was necessary to respond to cartoony imagery vs. photorealistic imagery. I also found evidence that entirely cartoony displays were more likely to be viewed as congruent when relating symbols to faces compared to mixed media displays. Finally, in Experiments 7 and 8, I found that novel, unknown expressions could be learned easily on both photographic faces as well as cartoony faces, although there was no habituation to cartoony faces while there was to photographic faces. My research demonstrates that cartoony imagery is easier to process compared to photorealistic imagery, and that the extent of this has never fully been described. My research also demonstrates several examples of how cartoony faces show different patterns of allocated attention and different patterns of elicited ERPs compared to photorealistic images.
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Master's Student Supervision
Theses completed in 2010 or later are listed below. Please note that there is a 6-12 month delay to add the latest theses.
Parsing out anticipatory and consummatory reward underlying anhedonia in mood disorders (2023)
Anhedonia presents in various psychiatric disorders and is a core symptom of depression. It involves disruptions in temporally and anatomically distinct subcomponents of reward processing, including reward anticipation and consumption. Studies using electroencephalography (EEG) to examine both anticipatory and consummatory reward processing components are limited, and study paradigms that incorporate psychological constructs like decision-making and reinforcement learning often overlap and confound the electrophysiological markers that are unique to anticipatory and consummatory reward processing. This study aims to validate an EEG-based Monetary Incentive Delay (MID) paradigm in a college population to examine relevant anticipatory and consummatory reward-related event-related potentials (ERPs), P3 and stimulus-preceding negativity (SPN), during different stages of reward processing. We found that the paradigm successfully elicited reward-related ERPs. Cue-P3 amplitudes and latency were modulated by reward magnitudes, however, no significant effect of reward magnitudes and valence was found on SPN and Feedback-P3, respectively. The paradigm was adjusted following the initial study to eliminate potential interfering visual effects from the cue and feedback stimuli. Additional data were collected in a new group of participants, and we found similar results, but without the confounding potentials. The paradigm also incorporated behavioural measurements of reward anticipation and consumption, and higher anticipatory and consummatory ratings and shortened response time towards the target stimuli were elicited as reward magnitudes increased. We concluded that the validated MID paradigm allows for a precise examination of reward-related ERPs, especially at early anticipation stage, and offers a valuable tool for investigating reward processing and related symptoms in clinical populations. Future studies should consider recruiting larger and more diverse samples besides college populations to investigate symptoms of anhedonia and reward processing in clinical populations.
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Gender moderates the relationship between mood disorder symptoms and effortful avoidance performance (2022)
We must often decide how much effort to exert to avoid undesirable outcomes or obtain rewards, or whether to withhold action altogether. In depression and anxiety, levels of avoidance tend to be excessive and reward-seeking is reduced. Furthermore, the cost of effort deployment to avoid aversive outcomes or obtain reward may be overweighed with higher depressive symptoms. Understanding how such dimensional behaviours in mood disorder symptoms arise is hampered by outstanding questions about the links between motivated action and inhibition and depressive symptoms, and whether these differ with comorbid anxiety. Furthermore, gender differences are present in the incidence and manifestation of depression and anxiety, but the impact of these gender differences on avoidance and reward-seeking behaviours has not yet been characterized. Here, a reverse-translated task from animal studies was used to examine the relationship between negative affect and performance on effortful active and inhibitory avoidance (Study 1) and reward seeking (Study 2), and whether these effects are moderated by gender. Undergraduates and paid online workers (NAvoid = 545, NReward = 310; NFemale = 368, NMale = 450, MAge = 22.58, RangeAge = 17-62) were assessed on the Beck Depression Inventory (BDI-II) and the Beck Anxiety Inventory (BAI) and performed an instructed online avoidance or reward-seeking task. Participants had to make multiple presses on active trials and withhold presses on inhibitory trials to avoid an unpleasant sound (Study 1) or obtain points towards a monetary reward (Study 2). On active trials, physical effort (number of key presses) was increased on a progressive ratio schedule every 20 trials. Overall, men deployed more effort than women in both avoidance and reward-seeking, and anxiety symptoms were negatively associated with active reward-seeking accuracy regardless of gender. Gender moderated the relationship between anxiety symptoms and inhibitory avoidance, such that women with higher anxiety showed reduced inhibitory avoidance accuracy. Anxiety symptoms interacted with depressive symptom levels in active avoidance only. Our results illuminate gender differences in the relationship between mood disorder symptoms and the motivation to actively and effortfully respond to obtain positive and avoid negative outcomes.
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Attentional biases by induced microvalence in novel objects: an emphasis on the role of experience (2020)
How do each of us come to view the world uniquely? An emerging theory of microvalence proposes that subtle feelings of reward and punishment derived from individualized experiences with basic everyday objects help determine how we later attend and behave towards them. These objects that are part of our more mundane experiences are thought to be given attentional priority similar to objects that evoke stronger emotional responses. However, this relationship between preferences guided by daily experience and attention has not been tested. I introduced a novel paradigm to induce microvalences by simulating real life experience paired with an interocular suppression technique (bCFS) to explore its role in attention. Consistent with the theory of microvalence, affective ratings indicated that our novel shapes possessed pre-existing affective properties by which they are evaluated, giving rise to preferences. Unexpectedly, we observed a unifying effect of experience, blurring perceived differences between novel shapes, thus collapsing initial preferences (feelings of like or dislike). Results showed, however, that microvalences were not prioritized in attention. Our findings place emphasis on the role of experience in shifting automatic preferences to create unbiased representations of the world.
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Associations of bipolar traits with reward and threat sensitivity and conditioning (2018)
Bipolar Spectrum Disorders (BSDs) affect 1% of the population and cause significant interpersonal, occupational, and health challenges. Identifying cognitive, affective, and behavioural factors that influence BSD symptoms and related behaviours, consistent with a dimensional approach to psychopathology, may help improve our understanding and treatment of these disorders. Reward and threat sensitivity and learning, for example, are cognitive processes that may be dimensionally related to BSD risk, onset, and course. However, studies exploring reward and threat sensitivity and learning as a function of continuously measured bipolar traits, as opposed to categorical diagnoses or acute symptoms, have mostly employed self-report measures of sensitivity and overlooked classical conditioning. Thus, in this investigation, I explored how bipolar traits in two university student samples related to reward and threat sensitivity and conditioning measured using laboratory tasks. In Study 1, I found that higher self-reported lifetime hypomanic and depressive symptoms significantly predicted sensitivity to incentive reward and a stronger classically conditioned response to a threat-related cue, respectively. In Study 2, I addressed these questions in a larger sample of participants based on three higher-order bipolar traits as predictors of sensitivity and conditioning, variables extracted from measures of lower-order BSD-related traits using principal components analysis. Participants with higher scores for Factor 1, characterized by impulsiveness, low self-control, and low achievement, demonstrated significantly weaker classically conditioned responses to reward- and threat-related cues. Higher Factor 2 scores, indicating greater vulnerability to emotion dysregulation and negative affective responses to stress, significantly predicted greater sensitivity to threat. Finally, higher scores for Factor 3, reflecting a tendency to pursue and engage in stimulating experiences despite potential risks, significantly predicted greater sensitivity to incentive reward and lower susceptibility to forming classically conditioned responses to threat-related cues. These results indicate that bipolar traits may be meaningfully associated with patterns of reward and threat sensitivity and conditioning, associations which may have important implications for predicting and altering maladaptive levels of bipolar traits.
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The influence of appetitive and aversive stimuli on subjective temporal acuity (2017)
Anecdotal reports that time “flies by” or “slows down” during emotional events are supported by evidence that the motivational relevance of stimuli influences subsequent duration judgments. Yet it is unknown whether the subjective quality of events as they unfold is altered by motivational relevance. In a novel paradigm, we measured the subjective experience of moment-to-moment visual perception. Participants judged the temporal smoothness of high-approach positive (desserts), negative (e.g. bodily mutilation), and neutral images (commonplace scenes) as they faded to black. Results revealed approach-motivated blurring (AMB), such that positive stimuli were judged as smoother and negative stimuli as choppier relative to neutral stimuli. Participant ratings of approach-motivation predicted perceived fade smoothness after controlling for low-level stimulus features. Electrophysiological data indicated AMB modulated relatively rapid perceptual activation. Results indicate that stimulus value influences subjective temporal perceptual acuity, with approach-motivating stimuli eliciting perception of a “blurred” frame rate characteristic of speeded motion.
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Current Students & Alumni
This is a small sample of students and/or alumni that have been supervised by this researcher. It is not meant as a comprehensive list.
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