Psychology (Functional Area: Brain, Behaviour & Cognitive Sciences)

Permanent URI for this collectionhttps://hdl.handle.net/10315/28606

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Access status: Open Access ,
Intra- And Extra-Dimensional Learning in the Common Marmoset
(2025-11-11) Alvi, Marium Humaira; Ma, Liya
Cognitive flexibility is the brain’s ability to suppress the current strategy in favour of a better alternative when the context changes. Impaired cognitive flexibility is a transdiagnostic deficit in several neuropsychiatric disorders. How the primate brain supports this process is not well understood. We trained 4 marmosets on a novel intra- and extra-dimensional shifting (IEDS) task involving 2 dimensions: shape and colour. They were pre-trained on each of the 6 features (3 shapes and 3 colours) separately, which were then combined into compound stimuli. Marmosets were required to select the compound stimulus with the target feature (e.g. red). After reaching criterion (8/10 correct), the target feature shifted within or across dimensions. Next, we implemented a feature reinforcement learning model, and found that the estimated learning rate, choice determinism and attentional parameters for marmosets fell within the range typically observed in healthy humans, underscoring translational value.
Access status: Open Access ,
Initial Implicit Changes in Adaptation as a Function of Different Perturbations
(2025-11-11) Nabaee-Tabriz, Zacchary; Henriques, Denise Y. P.
Implicit motor adaptation allows us to maintain accurate movements under changing conditions. This process, driven by sensory prediction errors (SPE), mismatches between predicted and observed sensory-motor outcomes, corrects motor commands unconsciously. This study examined the extent to which initial implicit adaptation is sensitive to error magnitude and whether it reflects the behaviour observed in prolonged exposure contexts. We employed a single-trial learning (STL) paradigm within a classical visuomotor adaptation task. Participants reached to dot and arc targets while experiencing single rotated-cursor trials (1°-90°), isolating trial-by-trial changes in motor outputs, along with a long-exposure block involving a 20° rotation to test STL predictability in prolonged contexts. Results suggest initial implicit adaptation follows a saturating response pattern with increasing error magnitude while model-derived predictions tracked reasonably with long-exposure performance. Our findings reveal key features of early implicit adaptation and highlight STL as a promising tool for examining implicit adaptation in varying contexts.
Access status: Open Access ,
The Contribution Of Monocular And Binocular Depth Cues To Size Discrimination Of 3D Objects
(2025-11-11) Gunasekera, Iroshini Udayangi; Wilcox, Laurie
The study of perceived size has often been linked to distance, with the role of depth cues, motion and interaction receiving less attention. Here, we evaluated the contribution of depth cues to perceived size during passive viewing and active interaction with 3D shapes in virtual reality. In Experiment 1, observers’ precision was similar in both passive and active conditions, and across modality. In Experiment 2, we increased shape complexity and added an object motion condition to make the task more difficult. Results revealed that precision was high under binocular viewing in both conditions and but significantly reduced in the monocular active condition. Movement data indicated that observers moved laterally to obtain depth from motion parallax in the monocular active condition, but this strategy did not improve precision. These findings underscore the importance of binocular depth information in perceiving 3D object size, even when motion or interaction could theoretically enhance size judgements.
Access status: Open Access ,
Scrambled Narratives and Changes in Memory Composition Over Time
(2025-11-11) Fisher, William McQuigge; Bellana, Buddhika
Event memories consist of both episodic and schematic contributions. Typically, episodic details are more susceptible to forgetting than schematic details, resulting in memories becoming less episodic and more schematic over time. This thesis presents a novel paradigm to efficiently quantify changes in episodic and schematic contributions to retrieval over time. Participants (N = 201) read a short story with the order of events randomly scrambled. After a delay (Immediate, 24-hour, 48-hour, 72-hour, 1-week), participants performed a temporal order memory test. Over longer delays, we found that participants’ memory for the scrambled story became increasingly dissimilar to the scrambled order that was originally studied (i.e., less episodic). Instead, participants’ memory increasingly resembled the never-presented coherent version of the story (i.e., more schematic). These results suggest that recall increasingly relies on prior knowledge, rendering incoherent memories more coherent with time.
Access status: Open Access ,
Using Tools as Cues for Motor Adaptation in Virtual Reality
(2025-11-11) King, Andrew Michael; Henriques, Denise Y. P.
Humans are highly skilled at switching between tools, even when they demand opposing motor actions. This thesis investigates how people acquire and maintain distinct tool-specific motor memories by examining the cues that enable dual adaptation to conflicting sensorimotor demands. Using a visuomotor adaptation paradigm in immersive virtual reality (VR), we tested whether visual or movement-related tool features support separate internal models for opposing perturbations. Participants performed a shooting task with altered visual feedback, where each tool was associated with an opposing visuomotor rotation. Across three groups, tools differed only in colour (Colour Control), in shape but not movement direction (Motor Congruent), or both (Motor Incongruent). A single adaptation control group was also included. Only the Motor Incongruent group demonstrated robust dual adaptation and aftereffects, comparable to single tool learning. These findings suggest movement-specific features play a critical role in the formation of distinct internal models during tool learning.
Access status: Open Access ,
Investigating Local and Configural Shape Processing with Steady-State Visual Evoked Potentials
(2025-11-11) Samet, Shaya Steven; Kohler, Peter J.
Object recognition relies on shape, comprised of both local and configural shape information. Local shape information involves elements such as line curvature and edge angles confined to specific regions and perceived independently, while configural shape information arises from the spatial arrangement of local shape features. Previous research suggests that humans primarily use edges and contours for object recognition and are sensitive to disruptions in configural shape. However, it remains unclear how the human visual system separately encodes local and configural shape information, and whether distinct neural mechanisms underlie these processes. We presented stimuli manipulating local and configural shape information independently to participants while recording EEG responses using a Steady-State Visual Evoked Potentials paradigm. Our results reveal that object recognition depends on two mechanisms: one more transient that is sensitive to local shape localized in occipital regions, and one sustained and sensitive to configural shape manipulations localized in right temporal cortex.
Access status: Open Access ,
Attitudes and Perceptions Towards Snakes: Informing Conservation Education
(2025-11-11) Webber, Lauren Samantha; MacDonald, Suzanne
Public aversion to snakes poses a challenge to conservation efforts. This study explored how sociodemographic factors, emotional responses, and personal experiences influence attitudes toward snakes and willingness to engage in conservation education programs. A quantitative survey of 369 Canadian adults assessed emotional, experiential, and demographic predictors using validated and adapted measures. Regression analyses revealed that age, gender, religiosity, pet ownership, and direct experience significantly predicted attitudes. Fear and disgust emerged as distinct but overlapping predictors, with disgust exerting a stronger negative effect on conservation willingness. Participants with more positive attitudes were significantly more likely to express interest in education programs, especially live encounters. Findings suggest that tailored educational strategies addressing both emotional and demographic factors may enhance public support for snake conservation. This research contributes to the design of more effective conservation programs by identifying key predictors of public engagement and attitude change.
Access status: Open Access ,
The Effect of Healthy Aging on the Perception- Action Dissociation
(2025-11-11) Tassone, Felicia; Freud, Erez
The two visual pathways hypothesis posits distinct brain systems for vision-for-perception and vision-for-action. While this dissociation is well-established in younger adults, its integrity in healthy aging remains unclear. To address this, younger (n = 25, range: 18–25 years) and older adults (n = 25, range: 60–95 years) completed estimation and grasping tasks in two experiments. In Experiment 1, two rectangular objects with varying lengths (40 mm and 42 mm) were placed on the “far” and “close” surfaces of a Ponzo illusion board. Despite age-related changes in grasping kinematics, the perception–action dissociation persisted: the illusion influenced estimation, while grasping showed a reversed effect. Experiment 2 tested whether this reversal was due to surface size by removing illusory cues and varying only the background surface size (“big” versus “small”). While estimation was unaffected, surface size modulated grasping in both groups, with a stronger effect in older adults. These findings indicate that the perception–action dissociation is preserved in aging, but older adults rely more on contextual cues during action, potentially reflecting compensatory mechanisms to maintain visuomotor performance in daily life.
Access status: Open Access ,
Naturalistic Visuomotor Behaviours Reveal Reduced Handedness Lateralization In Autism
(2025-11-11) Fewster, Emily Claire; Freud, Erez
Autistic individuals often exhibit differences in perceptual and visuomotor functioning, potentially reflecting reduced cortical specialization. The current study investigates how handedness, a robust marker of cerebral lateralization, is modulated in autistic and non-autistic right-handed adults (n=27 per group) using a naturalistic LEGO® model-building task. Participants recreated five models from blocks placed on a standardized tabletop, enabling detailed analysis of real-world visuomotor behaviour. Autistic participants showed a lower proportion of right-hand grasps and more balanced cross-body reaches, indicating reduced lateralization. They also preferred blocks closer to their hands, suggesting larger safety margins in 3D space use. Movement trajectory analyses revealed more idiosyncratic action sequences and slower completion times compared to non-autistic participants, reflecting reduced motor efficiency. These findings demonstrate reduced specialization of hand use in autism, which may contribute to challenges and differences in visuomotor control.
Access status: Open Access ,
Concussion Recovery and Skilled Performance in Working-Aged Adults: Sex Differences in the Neural Correlates of Persisting Symptoms After Concussion
(2025-11-11) Bumra, Kiran Kaur; Sergio, Lauren E.
Cognitive-motor integration (CMI) refers to the ability to follow rules that guide perception and action. Following a concussion, CMI neural networks are often disrupted, impairing complex movement. We previously identified links between white matter integrity and visuomotor performance in working-age adults with persistent post-concussion symptoms (PPCS). We investigated the impact of sex, age, and CMI processes on visuomotor performance in PPCS. Forty-two adults (47.5 ± 9.87 years; 25 females, 17 males) completed a direct hand-to-target task and an indirect CMI task (plane-change and feedback reversal). Symptom severity, dizziness, cortical volumes and thickness, and resting-state functional connectivity (RSFC) were assessed. Females demonstrated slower CMI task performance, reduced cortical volume (left cuneus and superior frontal), thinner cortex (left precuneus), greater RPQ-3 symptom severity, and lower RSFC across multiple brain networks. Regression showed female sex and older age predicted poorer CMI performance. Findings highlight sex- and age-related neural factors underlying post-concussion motor deficits.
Access status: Open Access ,
Taking into Account Self-Motion in Depth While Assessing External Motion in Depth
(2025-11-11) Pandey, Anita; Harris, Laurence
During sideways movement of an observer, optic flow parsing – in which an object’s speed is extracted from all the other movement present in the scene – has been shown to be incomplete, with an overestimation of self-motion and an underestimation of object speed, especially when target and observer move in opposite directions (Jörges & Harris, 2022). Here I assess the efficiency of optic flow parsing for an object moving in depth while the observer is also moving either towards or away from the object. Participants were asked to compare the speed of a sphere moving towards or away from them relative to a ball moving sideways either while they were stationary or during visually simulated self-motion. The data showed flow parsing in depth to be incomplete. Curiously, the underestimation of object speed was largely irrespective of whether the ball and the observer moved in the same or opposite directions. These findings may be accounted for by a Bayesian model that includes a “Regression to the Mean Speed” prior.
Access status: Open Access ,
A Multidimensional Perspective on Cognitive Functioning Across Sport Classifications in High-Performance Athletes
(2025-07-23) Camilleri, Carmel; Wojtowicz, Magdalena
This thesis presents a comprehensive investigation into the domain-general cognitive functioning of high-performance athletes, addressing inconsistencies in current assessment methods. The sample consisted of 188 athletes from the Canadian Sport Institute of Ontario from Team (n=94), Precision/Skill-dependent (n=56), and Speed-strength (n=28) sports. Athletes completed a battery of computerized neuropsychological tests. Study 1 examined multidimensional cognitive profiles. Athletes exhibited superior performance, with associations found between episodic memory, visuospatial working memory, attention/concentration, and verbal reasoning. Two latent factors—attention/executive function and short-term (working) emerged. Study 2 examined cognitive performance across sport type. Team sport athletes outperformed those in other sports on visual short-term (working) memory, response inhibition, visuospatial working memory, and working memory tasks. They also secured the highest proportion of high scores across increasing thresholds. Collectively, the current thesis provides a foundation for future research to advance athlete cognitive profiling to inform talent identification and development strategies.
Access status: Open Access ,
Atypical Relations Between Default, Dorsal Attention, and Frontoparietal Control Networks in Autism Spectrum Disorder
(2025-07-23) Hartman, Braxton Lorne; Stevens, Dale
Autism spectrum disorder (ASD) is a neurodevelopmental condition characterized by difficulties in social interaction and communication, and by restricted and repetitive behaviours. We used resting-state functional connectivity fMRI to investigate three intrinsic brain networks which subserve domains of behaviour known to be impacted in ASD; the antagonistic “default” and “dorsal attention” networks – which subserve internally and externally directed cognition, respectively – and the “frontoparietal control” network which flexibly couples with either default or dorsal attention networks in order to dynamically direct the locus of attention. Using a novel method to compare the hierarchical organization of networks between groups, we found atypical organization of the three networks in ASD, including a fractionation of the frontoparietal control network and attenuation of the anticorrelation between default and dorsal attention networks. These results suggest that ASD is associated with atypical hierarchical organization of large-scale intrinsic brain networks, potentially contributing to cognitive and behavioral symptoms.
Access status: Open Access ,
Neural Effects of Multisensory Dance Training in Parkinson's Disease: A Longitudinal Neuroimaging Case Study
(2025-07-23) Simon, Jenny Royze Daoang; DeSouza, Joseph FX
Dance is associated with a range of motor and non-motor benefits in people with Parkinson’s disease (PD) and recent evidence suggests that regular dance participation may delay progression of these symptoms. However, little is known about the neurobiological mechanisms of dance interventions in PD. This thesis aimed to explore potential neuroplastic changes in a 69-year-old male with mild PD participating in regular dance classes over 29 weeks. Functional MRI was performed at four timepoints (pre-training, 11 weeks, 18 weeks, 29 weeks), in which the participant imagined a dance choreography while listening to music. Neural activity was compared between dance-imagery and fixation blocks. Region of interest analysis revealed significant BOLD signal activation in the supplementary motor area, right and left superior temporal gyri and the right insula, with modulation observed over the training period. These results suggest the potential for dance to induce neuroplastic changes in people with PD.
Access status: Open Access ,
Comparing The Kinematics Of Grasping Vs. Placing In Humans
(2025-04-10) Por Davoody, Niousha; Crawford, John Douglas
While many studies have examined reach-to-grasp movements, the placement component remains less explored. Grasping and placing tasks share some common characteristics, such as precise localization and orientation of the hand, but differ in cognitive intent and sensory feedback, with grasping relying more on visual input and placing on somatosensory feedback relative to surroundings. This study employs a within-subjects 2x2x2 design, examining the effects of Task (grasp vs. place), Object Orientation (clockwise vs. counterclockwise), and Target Location (left vs. right) in right-handed participants performing in near-total darkness. Each participant completed 160 randomized trials across eight conditions, tracking hand and eye movements via an OptiTrack system and eye tracker. Results revealed significant main effects for Task, Location, and Orientation, along with notable interactions. Contrary to the hypothesis, placing tasks were faster than grasping tasks and exhibited higher orientation errors. This result contradicts the expectation that placement would require more precise alignment, suggesting that the simplified placement task used in this study may rely more on visual feedback, which was absent, compared to grasping. Movements toward the right showed faster velocities and fewer errors, reflecting hemispheric motor advantages, while clockwise orientations were associated with lower orientation errors compared to counterclockwise orientations. Interaction effects between Location and Orientation influenced certain variables, highlighting the role of spatial and alignment demands in motor control. These findings suggest that while grasping and placing tasks share overlapping motor control processes, they also engage distinct mechanisms under specific spatial conditions.
Access status: Open Access ,
Effects Of Tool Use And Perturbation During Motor Adaptation On Hand Localization In Immersive Virtual Reality
(2025-04-10) Khan, Maryum; Henriques, Denise
Our brain has a remarkable capacity for learning movements and adapting them to accomplish a motor goal. In many adaptation studies, participants move in a 2D plane while their hand is represented by a cursor. When visual feedback of hand position is misaligned, people can quickly compensate for this perturbation, show persistent reach aftereffects, and even misestimate the location of the unseen hand in the direction of previous visual training. However, it is unknown how well this generalizes to real-world settings or to the tools we use every day. Immersive virtual reality was used to test if end-effector shifts are also observed in more naturalistic virtual reality environments and if they extend to tools as end effectors. In the Hand Experiment, previous work from our lab was replicated where we found shifts in end-effector localization after adapting reach movements to a 30° and 60° visuomotor rotation of the hand, showing a similar magnitude of both shifts in where people indicate their perceived/felt hand and reach aftereffects following training to the perturbation in the VR environment. In the Pen Experiment, this paradigm was extended to investigate how well people can adapt when aiming with a common tool, like a pen, and whether the tool location is also recalibrated. The extent that the unseen location of hand-held tool, as well as the hand (in separate trials) recalibrates with adaptation was measured. Our results provide insight into the adaptative processes involved when learning to wield tools in more complicated, realistic environments.
Access status: Open Access ,
Sex-Related Differences In Visuomotor Skills, Cognition, And Emotionality Following Concussive Injury
(2025-04-10) Marks, CeAnn Alexia; Sergio, Lauren
Sex-related differences are commonly overlooked in most biomedical fields including concussion research. Much of the current concussion literature focuses on the analyses of males or a combined approach, lacking the separation of sexes for analytical purposes. Methods: Data were collected from 299 university athletes with varying concussion histories. Kinematic visuomotor measures and emotional symptoms were assessed through a basic visuomotor task and SCAT self-report measures. Results: Visuomotor performance varied substantially with concussion history and sex, with multiple concussions being linked to better performance. Emotionality results revealed females with 2 or more concussions have higher odds of being irritable, while 21-22-year-old females have lower odds of being nervous/anxious compared to their younger counterparts. No significant emotionality results were discovered for males. Conclusion: This study underscores distinctive recovery metrics between sexes in emotional and visuomotor domains following concussive injury. Findings suggest the need for tailored diagnostics and treatment for athletes following injury.
Access status: Open Access ,
Brain Responses To Symmetries In Naturalistic Novel Three-Dimensional Objects
(2025-04-10) Ragavaloo, Shenoa; Kohler, Peter
Human brains are sensitive to symmetry, especially vertical reflection, which is present in human faces and many other biological forms. However, symmetries in most visual scenes are rotated relative to the observer’s viewing location, failing to produce symmetry in the retinal image. We investigated the differences between perspective-distorted symmetry, and images that produce symmetry on the retina, and measured the association between responses to symmetry and autism spectrum disorder (ASD). We found that perspective-distorted symmetry with cues to 3D shape elicited responses, and both image-level and perspective distorted 3D symmetry elicited stronger responses than 2D symmetry. 3D image-level symmetry created stronger responses than 3D perspective-distorted symmetry. Lastly, there was no association between responses to symmetry and ASD. We conclude that symmetry processing occurs in the absence of a symmetry-related task, even for perspective-distorted symmetry. Additionally, there may not be any association between conditions that affect global processing and symmetry processing.
Access status: Open Access ,
Role(s) Of Pannexin1A/B In The Physiology Of The Zebrafish Visual System
(2025-04-10) Houshangi-Tabrizi, Sarah; Zoidl, Georg R.
Panx1 proteins are glycosylated integral membrane channels with unique conduction properties, functioning as an ATP channel and non-selective ion channel in different physiological pathways. In zebrafish, the mammalian Panx1 ohnologues, Panx1a and Panx1b, have distinct tissue expression patterns. We previously demonstrated that in the retina, Panx1a is localized in the horizontal cell layer and the ON/OFF ganglion cell layer, while Panx1b protein is present in the horizontal cell layer, ganglion cell layer, and in the end-feet of the Muller glia astrocytes. Here we investigated the optic flow response in the Panx1a-/- and Panx1b-/- 6dpf larvae utilizing molecular, systems, and behavioral assays. The RNA-seq analysis revealed broad regulation of genes involved in axon guidance, retinal axon guidance, astrocytes, axons, dendrites, and synapse, confirmed by RT-qPCR in the 3dpf and 6dpf Panx1a-/- and Panx1b-/-. We demonstrate that Panx1a-/- and Panx1b-/- display an inability to make a leftward and rightward directional motion in low light contrast conditions when exposed to the left and right moving gratings. We also show how the strategic localization of Panx1a and Panx1b in the habenula region modulates visually guided behavior. Lastly, Panx1a-/- and Panx1b-/- demonstrate the inability to generate functional saccades and display ocular motor deficiencies linked to potential neurological disorders. These findings suggest that Panx1 modulates the axonal growth in axon guidance pathfinding and together are interconnected to the habenula region, leading to synaptic plasticity of the retinal neural circuitry, and regulating visually guided locomotion in the zebrafish larvae.
Access status: Open Access ,
Realism and Features Supporting Lightness Constancy in Virtual Scenes
(2025-04-10) Patel, Khushbu Yogeshbhai; Murray, Richard F.
Lighting and surface properties play an important role in visual perception. Our visual system decodes two-dimensional retinal images to discern potential three-dimensional scenes. A particular challenge in the context of achromatic lights and surfaces is lightness constancy — the ability to maintain a consistent perception of an object’s reflectance despite varying illumination conditions. Although humans are generally adept at maintaining lightness constancy, it is not perfect. This dissertation examines lightness constancy within both real-world and virtual environments, including flat-panel displays and virtual reality (VR). Chapter 2 evaluates lightness constancy through an asymmetric lightness matching task across a shadow boundary, using physical surfaces, a flat-panel display, and an immersive VR environment. While the VR condition exhibited realistic levels of lightness constancy, participants showed significantly lower levels of constancy in flat-panel display compared to the physical environment. Notably, participant variability was more pronounced in both virtual environments. In Chapter 3 the study extends to lightness matching across various 3D orientations using both physical surfaces and in VR. The findings reveal that lightness constancy is significantly weaker in VR compared to physical environments. Building on Chapter 3, Chapter 4 further evaluates lightness constancy using the same task, but incorporates more realistic and accurate rendering techniques, along with realistic materials, in VR. Contrary to expectations, the results show no notable improvement in lightness constancy, underscoring the persistent challenges in achieving realism for tasks evaluating lightness across 3D orientations in VR. Despite robust 3D shape, lighting, and depth cues available in VR, constancy is significantly worse in VR and our understanding of lightness perception fails to explain why. This discrepancy highlights a gap in our knowledge, pointing to potentially overlooked factors critical for accurate lightness perception, such as fine material details or subtle surface textures. In conclusion, the findings in this dissertation suggest that VR is a reasonable proxy for real-world scenarios in tasks when lightness is judged across a shadow boundary, but current technology falls short in replicating realistic lightness constancy when image luminance varies from one location to another due to differences in 3D orientation relative to a light source.

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