Todd Handy

Professor

Relevant Degree Programs

 

Graduate Student Supervision

Doctoral Student Supervision (Jan 2008 - Mar 2019)
The spatial and temporal dynamics of self-relevance of attention for objects (2017)

Ownership is a powerful mechanism for influencing attention. Objects that are owned by the self receive more attention and are more likely to be remembered than equivalent objects that are owned by another person. The most common explanation for this ownership effect is self- referencing/self-relevance: the act of associating an object with the self such that it is personally relevant to the self. What remained unknown is how the ownership-attention relationship functions when the scope of the self is expanded to include the influences of the body and the continuity (or lack thereof) of self-relevance over time. Over three studies, my dissertation aims to contextualize the attentional effects of ownership within these broader dimensions. In the first study, I found that the presence of the body could moderate the classic effect of ownership but that this moderation depends on the body’s ability to directly manipulate the contents of its environment. In the second study, I found that ownership might operate as a form of affective salience, altering attentional prioritization and, in turn, temporal perception. In the third study, I found that objects that cease to be self-owned still receive greater attentional resources than objects that are not initially self-owned, suggesting that the effects of self-relevance are robust to subsequent changes in ownership. My research demonstrates that the effects of ownership on attention may rely on multiple aspects of self, including embodiment and motivational significance. Importantly, one critical element that emerges from these studies is that of an active or agentic self that is distinguishable from more object-based aspects of self. Collectively, these findings suggest that a deeper understanding of ownership effects on attention necessitates a deeper understanding of the self.

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The neurocognitive consequences of the wandering mind : a mechanistic account of sensory-motor decoupling (2014)

One unique characteristic of humans is our ability to mind wander – a state in which we engage in thoughts that are not directly tied to sensations from our surrounding environment. The Executive Function Model of mind wandering proposed the decoupling of our executive resources from the external environment is what facilitates the maintenance of these internal trains of thoughts. Accordingly, my dissertation aims to characterize how our neurocognitive processing of external stimuli waxes and wanes as our minds wander away from the task-at-hand. I present three sets of studies in this dissertation, each examining one specific aspect of neurocognitive engagement with the external environment, namely affective processing, behavioral performance monitoring, and attentional processing. Consistent with the Executive Function Model, my research indicates all three types of neurocognitive processing were attenuated during mind wandering episodes. This suggests mind wandering appears to disengage executive resources from our environment and direct them to inner streams of thoughts via this wide-ranging neurocognitive attenuation. One exception to this global pattern of attenuation of external processing is the detection of external stimuli that deviates from our expectations. Taken together, these observations suggest our ability to transiently decouple our thoughts from the external environment is integral to normal human neurocognitive functioning. A deeper understanding of this phenomenon may therefore inform strategies for regulating this mental experience so as to maximize their utility, and minimize their detrimental effects on our daily functioning and well-being.

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Imaired attentional processing as a risk factor for falls in older adults (2013)

No abstract available.

Attentional and cognitive consequences of migraine visual cortical hyperexcitability (2012)

People with migraine have hyperexcitable visual cortical response to normal visual inputs between attacks. Given that our attentional and perceptual processing can be influenced by our sensory experience, we might expect migraine visual cortical hyperexcitability to have a forward cascade of effects on cognitive processing. With this in mind, this dissertation explored the functional consequences of migraine hyperexcitable visual cortices on attentional and cognitive processing between headache attacks. To begin with, given that top-down attentional control signals can affect excitability of sensory response in visual cortex, Chapter 2 assessed if this normal modulation is affected in migraineurs. Using a probabilistic spatial orienting task while measuring ERPs to attended vs. unattended foveal and parafoveal stimuli, Chapter 2 revealed that migraineurs manifest heightened sensory responses of to-be-ignored visual stimuli. Next, Chapter 3 examined the behavioral impact of hyperexcitability of migraine visual cortex in terms of its effect on bottom-up attentional processing, in this case reflexive attentional orienting. Using three behavioral spatial attention paradigms, this chapter provided evidence of heightened reflexive visual-spatial orienting specific to sudden-onset peripheral events. Lastly, Chapter 4 assessed post-spatial-selection consequences of visual cortical hyperexcitability in migraineurs. Participants viewed unfamiliar commercial logos in the context of a target identification task while brain responses were recorded via ERPs. Following this task, participants individually identified those logos that they most liked or disliked. The results of this chapter suggested that migraineurs were not only evaluating environmental stimuli more than controls over time, but also not adequately hedonically categorizing it for quick allocation of attention. Collectively, the research presented in this dissertation suggests that migraineurs have anomalies specifically pointing to increased allocation of attention to extraneous environmental stimuli. The final concluding chapter briefly recaps each research chapter and then critically examines the impact of these findings in the context of four outstanding questions exposed by this research. Specifically, are top-down attentional control signals in migraineurs intact? How might anomalies found in this dissertation be a result of or independent from known sensory cortical abnormalities? How do the findings fit with the migraineur experience? Finally, what are the real-world clinical implications for migraineurs?

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Master's Student Supervision (2010-2017)
An unforgettable apple : attention and memory for forbidden objects (2013)

Are we humans drawn to the forbidden? From jumbo-sized soft drinks to illicit substances, the influence of prohibited ownership on subsequent demand has made this question a pressing one. We know that objects we ourselves own have a heightened psychological saliency, relative to comparable objects that are owned by others, but do these kinds of effects extend from self-owned to "forbidden" objects? To address this question I developed a modified version of the Turk shopping paradigm in which “purchased” items were assigned to various recipients. Participants sorted everyday objects labeled as self-owned, other-owned, and either forbidden to oneself (Experiment 1) or forbidden to everyone (Experiment 2). Subsequent surprise recognition memory tests revealed forbidden objects with high (Experiment 1) but not low self-relevance (Experiment 2) were recognized as well as self-owned objects and better than other-owned objects. In a third and final experiment I used event-related potentials (ERPs) to determine whether self-owned and self-forbidden objects, which showed a common memory advantage, are in fact treated the same at a neurocognitive-affective level. I found that both object types were associated with enhanced cognitive analysis, relative to other-owned objects, as measured by the P300 ERP component. However, I also found that self-forbidden objects uniquely triggered an enhanced response preceding the P300, in an ERP component (the N2) sensitive to more rapid, affect-related processing. Our findings thus suggest that while self-forbidden objects share a common cognitive signature with self-owned objects, they are unique in being identified more quickly at a neurocognitive level.

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The effects of music playing on cognitive task performance (2011)

Numerous music cognition studies have demonstrated the cognitive benefits of both long-term and short-term musical training. Whereas a great number of these studies deal with the short-term benefits for the music listener or the longer term benefits for the novice or accomplished musician, our study examines the short-term effects of music playing for the advanced performer. For our pretest-posttest design, we recruited advanced classically/score-based trained pianists. The participants started by completing a creative exercise (alternative uses task) or detail-oriented exercise (proofreading task). They then performed a piano piece for ten minutes. The performances were followed by completion of the second cognitive task (whichever task they were not given in the pretest condition). No significant pretest-posttest differences in creativity were reported. However, we found that participants performed significantly worse in the posttest detail-oriented task. Our results suggest that performance in tasks involving attention to detail—specifically, a proofreading task involving the visual detection of errors — may be hindered immediately following a short period of score-based music playing when the piece is already familiar to the performer.

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Slow fluctuations in attentional control of sensory cortex (2010)

Top-down control of visual sensory cortex has long been tied to the orienting of visual spatial attention on a rapid, moment-to-moment basis. Here we examined whether sensory responses in visual cortex are also modulated by natural and comparatively slower fluctuations in whether or not one is paying attention to the task at hand. Participants performed a simple visual discrimination task at fixation as the event-related potentials (ERPs) to task-irrelevant probes in the upper visual periphery were recorded. At random intervals, participants were stopped and asked to report on their attentional state at the time of stoppage––either "on-task" or "off-task." ERPs to the probes immediately preceding these subjective reports were then examined as a function of whether attention was in an "on-task" vs. "off-task" state. We found that sensory-evoked responses to the probes were significantly attenuated during "off-task" relative to "on- task" states, as measured by the visual P1 ERP component. In two additional experiments we replicated this effect while (1) finding that "off-task" sensory attenuation extends to the auditory domain, as measured by the auditory N1 ERP component, and (2) eliminating state-dependent shifts in general arousal as a possible explanation for the effects. Collectively, our findings suggest that sensory gain control in cortex is yoked to the natural ebb and flow in how much attention we pay to the current task over time.

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Recent Tri-Agency Grants

The following is a selection of grants for which the faculty member was principal investigator or co-investigator. Currently, the list only covers Canadian Tri-Agency grants from years 2013/14-2016/17 and excludes grants from any other agencies.

  • Exploring the cognitive underpinnings of hoarding - Canadian Institutes of Health Research (CIHR) - Transitional Operating Grant (2015/2016)
  • Reshaping the path of mild cognitive impairment by refining exercise prescription: understanding training type and exploring mechanisms - Canadian Institutes of Health Research (CIHR) - Transitional Operating Grant (2015/2016)
  • The cognitive neuroscience of selective attention in dynamic behavioral and psychological contexts - Natural Sciences and Engineering Research Council of Canada (NSERC) - Discovery Grants Program - Individual (2014/2015)
  • Gaining insight to brain-behaviour relationships: developing a neuroepidemiology study using the canadian longitudinal study on aging - Canadian Institutes of Health Research (CIHR) - Planning Grant - Priority Announcement (2013/2014)
  • Interhemispheric contributions to neuroplasticity and motor learning after stroke - Canadian Institutes of Health Research (CIHR) - Operating Grant (2013/2014)
  • Visual attention and its role in visuomotor processing - Natural Sciences and Engineering Research Council of Canada (NSERC) - Discovery Grants Program - Individual (2013/2014)

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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