‘What was I thinking ?!?’ – No matter age, intelligence or social status, we all experience moments like these. Perhaps it is walking into a room and forgetting what you went there to do or maybe failing to add sugar to your coffee due to an interruption. Regardless, even though many of our daily activities are accomplished through routines that require very little conscious effort, errors of attention or slips of action do occur. This collection of studies was designed with three main questions in mind: 1) can action slips be induced in a laboratory-based task (Slip Induction Task; SIT), 2) how well do currently established theories of action slips explain the errors that are induced within the SIT, and 3) what insight can be gained about preventing such errors? The first experiment was developed to replicate previous findings regarding the effectiveness of the SIT, as well as to determine the extent to which SIT performance correlates with other measures of attention failure. The study discussed in Chapter 3 expands on those results by investigating the effects of healthy aging on slip induction and finds that while older adults were better able to avoid action slips, they appear to sacrifice speed for accurate performance. The goal of the subsequent study was to determine whether young adult participants would also enjoy increased accuracy if they completed the task at a slower pace. Finally, the study discussed in Chapter 5 looks at whether changing the goal of the SIT would alter participants’ ability to inhibit unexpected cue information.

The updating process, which consists of building mental models and adapting them to the changes occurring in the environment, is impaired in neglect patients. A simple rock-paper-scissors experiment was conducted in our lab to examine updating impairments in neglect patients. The results of this experiment demonstrate a significant difference between the performance of healthy and brain damaged participants. While healthy controls did not show any difficulty learning the computer’s strategy, right brain damaged patients failed to learn the computer’s strategy. A computational modeling approach is employed to help us better understand the reason behind this difference and thus learn more about the updating process in healthy people and its impairment in right brain damaged patients. Broadly, we hope to learn more about the nature of the updating process, in general. Also the hope is that knowing what must be changed in the model to “brain-damage” it can shed light on the updating deficit in right brain damaged patients. To do so I adapted a pattern detection method named “ELPH” to a reinforcement-learning human decision making model called “RELPH”. This model is capable of capturing the behavior of both healthy and right brain damaged participants in our task according to our defined measures. Indeed, this thesis is an effort to discuss the possible differences among these groups employing this computational model.

Memory and concentration problems are frequently reported long after experiencing a mild traumatic brain injury (mild TBI), though conflict with null findings of deficits on standard neuropsychological tests. Experimental research shows that these inconsistencies are, in part, due to the simplicity of neuropsychological tests. As well, past research suggests that when neuropsychological deficits are occasionally detected within this population, they could be influenced by diagnosis threat: an expectation bias for impaired performance when individuals are merely informed that cognitive problems may be experienced following a mild TBI. The main goal of this thesis was to specify the long-term cognitive effects of mild TBI, with the prediction that, while cognitive complaints may be over-reported due to diagnosis threat, significant deficits can be detected using sensitive measures in experimental paradigms. Experiment 1 sought to document whether diagnosis threat influenced self-report of everyday attention and memory problems and neuropsychological task performance in individuals with a remote history of mild TBI. We found that undergraduate students with a mild TBI were significantly more likely to report having attention and memory failures in their daily lives when exposed to diagnosis threat, compared to undergraduate students not exposed to diagnosis threat. These findings call into question the efficacy of using of self-report measures to identify long-term cognitive deficits following a mild TBI. In an attempt to further specify persistent significant cognitive deficits, we designed two different experimental paradigms that uniquely manipulated the demand place on executive processes, as past research suggested deficits emerge only when tasks require considerable cognitive resources. In Experiment 2a, we manipulated processing load on a visual working memory task, across two conditions, while also limiting the potential effect of diagnosis threat. While self-report and neuropsychological measures of attention and memory did not differentiate the groups, the mild TBI group took significantly longer to accurately detect repeated targets on our working memory task. Accuracy was comparable in the low-load condition and, unexpectedly, mild TBI performance surpassed that of controls in the high-load condition. Temporal analysis of target identification suggested a strategy difference between groups: mild TBI participants made a significantly greater number of accurate responses following the target’s offset, and significantly fewer erroneous distracter responses prior to target onset, compared to controls. In Experiment 2b we also examined whether manipulating executive processing demands would differentiate mild TBI from controls, this time on a routine action task that required participants to learn a sequence of hand movements to targets. While not significant, we found a trend such that mild TBI participants were slower to respond on trials with a large executive demand compared controls, while no differences were found on trials with relatively low executive requirements. Results from Experiments 2a and 2b provide stronger evidence for mild TBI-related slowing during a working memory task with an executive component compared to a skilled action task that also had an executive component, but placed minimal demand on memory. To more precisely identify the brain basis of this cognitive slowing, in Experiment 3 we administered a visual n-back task in which we systematically increased working memory demands from 0- to 3-item loads. We found that, compared to controls, mild TBI participants showed a reduction in P300 amplitude, conceptualized as an index of available cognitive resources for stimulus classification. While no late stage response differences were found between groups, P300 amplitude was negatively correlated with response times at higher loads in both control and mild TBI participants. Findings suggest that high functioning young adults who sustained a mild TBI in their remote past, have a reduced amount, or inefficient recruitment of, cognitive resources for target detection; a potential mechanism underlying mild TBI-related response slowing on tasks that place a heavy demand on processing resources. Similar to the effects of mild TBI, aging is also known to negatively impact cognition. In Experiment 4, we examined whether TBI-related deficits persist into older adulthood, and compound the negative effect of aging on cognition. We administered the same working memory task as in Experiment 2a, along with a variety of neuropsychological tests in order to investigate the effect of a TBI sustained an average of 50 years in the past. While no group differences emerged on our experimental working memory task, older adults with a history of 1 or 2 TBIs performed significantly worse than non head-injured older adults only on neuropsychological measures of attention that had an executive component. Such results suggest that a remote TBI sustained early in life further compounds normal age-related cognitive decline. Together, these experiments help specify the measures that best detect long lasting cognitive changes following TBI. Particularly, our findings provide a potential explanation for why long-term cognitive deficits are difficult to identify in the young mild TBI population: the majority of neuropsychological tests are insensitive to minor changes in information processing speed and, as a result, the execution of slowing strategies to maintain accuracy may go undetected. Our findings also demonstrate the importance of investigating longer-term effects of TBI, as they may be chronic and impact cognitive task performance in old age, amplifying normal age-related cognitive deficits.

In our pilot study investigating Texas Hold ‘em poker, we found that players bluffing (with a losing hand) elicits a similar physiological arousal response (as measured by skin conductance levels) to those in a position of strength and poised to win. Since arousal has been suggested to be a reinforcing factor in problematic gambling behaviour, we sought to replicate the findings of our pilot study in the current investigation. We aimed to extend our previous findings further by: isolating truthful betting (strong betting) to disambiguate deception when players are in positions of strength (i.e. trapping), measuring subjective excitement levels and risk assessments, investigating the physiological arousal responses following wins versus losses, and finally, exploring group differences (i.e. problem gambling status, experience levels). 71 participants played 20 naturalistic rounds of Texas Hold ‘em poker for monetary rewards. We were able to replicate our previous findings that bluffing triggers a physiological arousal (as measured by skin conductance responses) similar to truthful strong betting. Trapping was also found to elicit a skin conductance response similar to both bluffing and strong betting. Measures of subjective excitement revealed a pattern that converged with physiological data. Furthermore, wins were found to be more arousing than losses. Finally, our exploratory analysis of group differences (i.e. problem gambling status, experience) proved to be an insignificant factor with all measures. We conclude that the effect of bluffing on physiological arousal is so powerful that it pervades all participants; which is problematic due to its risky nature and potential to be self-triggered. With its ever increasing popularity and availability, more research on Texas Hold ‘em poker is warranted for treatment implications.

The following two studies examined the influence of spatial regularities on our ability to learn and predict frequencies and sequences of events. Research into statistical and sequence learning has demonstrated that we can learn the statistical properties of events and use this knowledge to make predictions about future events. Research has also demonstrated that redundant spatial features associated with events can influence our ability to respond to and discriminate between different stimuli. The goal of this thesis was to test whether redundant spatial features could influence our ability to notice non-spatial regularities in an environment. Using a computerized version of the children’s game ‘rock-paper-scissors’ (RPS), undergraduates were instructed to win as often as possible against a computer that played varying strategies. For each strategy, the computer’s plays were either presented with spatial regularity (i.e., ‘rock’ would always appear on the left of the screen, ‘paper’ in the middle, and ‘scissors’ on the right) or without spatial regularity (i.e., the items were equally likely to appear in any of the three screen locations). The results showed that, although irrelevant to the task itself, spatial regularities had a moderate influence when participants learned to exploit easy strategies, and a more pronounced influence when learning to exploit harder strategies. This research suggests that redundant spatial features can influence our ability to learn and represent distributions of events.

Experience of the built-environment is said to be dependent on visual perception and the physical properties of space. Scene and environmental preference research suggests that particular visual features greatly influence one’s response to their environment. Typically, environments which are informative and allow an individual to gain further knowledge about their surroundings are preferred. Although, such findings could be applied to the design process it is first necessary to develop a way in which to accurately and objectively describe the visual properties within an environment. Recently it has been proposed that isovist analysis could be employed to describe built-environments. In two experiments we examined whether or not isovist analysis can capture experience of real-world environments. In Experiment one we demonstrated that isovist analysis can be employed to describe experience of environment within a controlled, laboratory environment. In Experiment two we employed some of the methods of post-occupancy analysis to examine the robustness of the isovist approach and whether it would capture experience of a complex, real-world environment. The results of Experiment two suggest that isovist analysis could capture certain experiences, such as spaciousness, but failed to capture other responses. Regression analysis suggests that a large number of variables predicted experience, including previous experience with the building and the presence of other individuals. These findings suggest that experience of real-world, complex environments cannot be captured by the visual properties alone, but also highlight some of the other factors, such as presence of others and previous experiences may influence experience of built settings. Implications for the design processes are described.

The direction in which another is looking at triggers a spontaneous orienting of attention towards gaze direction in the viewer. However, whether the facial expression displayed by the gazing individual modulates this attention orienting is unclear. In this thesis, the modulation of gaze-oriented attention with facial expressions was explored in non-anxious individuals at the behavioral level and at the neural level using Event-Related Potentials (ERP). In the gaze-cueing paradigm used, a dynamic face cue averting gaze and expressing an emotion was presented, followed by a lateral, to-be-localized target. At the behavioral level, a faster response to targets appearing at the gazed-at location (congruent targets) than to targets appearing opposite to the gazed-at location (incongruent targets) was observed (Chapters 3-5). This so-called Gaze Orienting Effect (GOE) was enhanced with fearful, angry and surprised expressions relative to neutral and happy expressions and was driven by emotional differences in response speed to congruent targets (Chapters 3-5). These effects could not be attributed to better discrimination of those emotions when presented with an averted gaze (Chapter 2). These results confirm the impact of fear and surprise on gaze-oriented attention in non-anxious individuals and demonstrate, for the first time, a similar impact for angry expressions. All the emotions enhancing the GOE signal an evolutionary relevant stimulus in the periphery, are threat-related and carry a negative valence, which suggests that one of these attributes (or all combined) is driving the emotional modulation of gaze-oriented attention (surprise is treated like fear in the context of fearful expressions). In Chapter 4, the effect of the dynamic cue sequence on these GOE modulations was investigated. An emotional modulation of the GOE was found only when the gaze shift preceded the emotional expression, but not when the emotion was expressed before gaze shift or when expression and gaze shift were simultaneous. These results highlight the importance of using a sequence closer to real life situations (we usually orient attention before reacting to an object in the environment) in studying the modulation of the GOE with emotions. At the neural level, we investigated the ERPs associated with gaze-oriented attention at target presentation and at cue presentation (Chapters 3 and 5). Confirming previous reports, the amplitude of a target-triggered P1 ERP component was larger in the congruent than in the incongruent condition, reflecting enhanced processing of gaze-congruent targets. In addition, cue-triggered ERPs previously observed in response to arrow cues, were investigated. An Early Directing Attention Negativity (EDAN) and an Anterior Directing Attention Negativity (ADAN) were found, indexing respectively attention-orienting to the cued location and maintenance of attention at the cued location. This is the first study to report both EDAN and ADAN components in response to gaze cues. These results show clear markers of attention orienting by gaze at the neural level, during both cue and target processing. Neither EDAN nor ADAN was modulated by emotion. The congruency effect on P1 was enhanced for fearful, surprised and happy faces compared to neutral faces in Chapter 3 but no differences between the emotions were found in Chapter 5. Thus, the emotional modulation of the brain processes involved in gaze-oriented attention is very weak and protracted or occurs mainly between target onset and response to target. The relationships between participants’ autistic traits and their emotional modulation of gaze-oriented attention were also investigated. Results showed a negative correlation with the GOE to happy upright faces and with the P1 congruency effect, which suggests that individuals with more severe autistic traits are less sensitive to the impact of social emotions like joy. The implication of these results for attention orienting in general and for individuals with Autism Spectrum Disorder is discussed. Together, the findings reported in this thesis clarify the behavioral and neural processes involved in gaze oriented attention and its modulation by facial expression in addition to demonstrating a relationship between gaze oriented attention, its modulation with social emotions and autistic traits.

Right parietal lesions often lead to neglect, in which patients fail to attend to leftward stimuli. Recent models of neglect suggest that, in addition to attentional impairments, patients demonstrate impairments of spatial remapping and/or spatial working memory (SWM). Although spatial remapping could be considered a kind of spatial memory process itself (i.e., updating remembered locations based on anticipated saccade outcomes), the two processes operate on very different time scales (milliseconds versus seconds). In the present study, the influence of saccadic and spatial remapping on SWM was examined in healthy individuals. An initial control condition, in which participants had to respond to a probe stimulus (i.e., “is the probe in the location previously occupied by the target?”) following a 1500 ms delay, was contrasted with conditions in which the fixation point moved (left, right, up, or down) at the onset of the delay. In a second version of the task, participants made covert shifts of attention at delay onset requiring covert spatial, rather than saccadic, remapping. In both tasks SWM performance was best when no remapping was required. Decrements in SWM were largest overall in the spatial remapping task, whereas for both saccadic and spatial remapping, a consistent cost was observed for remapping the target array into right visual space. Results are discussed in terms of hemispheric biases in attention and differences in performance for peripersonal versus extrapersonal space.

In this dissertation, three experiments were conducted that examined the influence of task demands on manual asymmetries for the performance of reaching movements to tools. In all three experiments, the difference between the hands (in terms of preference for Experiment 1 and performance for Experiments 2 and 3) was studied in response to varying task demands for grasping movements to tools. In the first experiment, 82 right-handed and 60 left-handed university students performed reaching movements to tools and dowels at five positions within working space. Differences in the reaching patterns of the left and right hands to the tools and dowels were examined, as well as the effect of task demands (lift, use) and type of object (tool, dowel) on the reaching patterns. Dowels were used in order to examine if participants would treat a neutral object as if it were a tool in terms of their reaching patterns in working space. Results confirmed and extended prior research on the influence of task demands on reaching patterns within working space. Overall, there were more similarities in the general reaching patterns of left- and right-handed participants than differences. However key differences between the handedness groups emerged in the treatment of the dowel and the frequency of switches (reaching to lift the object with the non-preferred hand and transferring it to the preferred hand to use). Results also showed that tools enjoy a privileged association with the preferred hand, and that the intent of the movement has a very real goal on movement planning. The first experiment examined patterns of hand use across working space in response to differing task demands. In the next experiments performance differences between the hands in terms of movement planning and initiation were examined through the use of reaction time and movement time. In these experiments, reaction time represented the time from the presentation of a go signal to when the participant first lifted their hand, and movement time was the time between lifting the hand to lifting a tool off a sensor. Movement time represented the time to pick up the tool, and did not include the time to use the tool to perform a particular task and complete the reaching movement. In the second experiment, reaction time and movement time to tools placed at the midline position were examined under varying degrees of advance information using a precue paradigm. Three precue conditions were used which presented advance information on the hand to use to perform the movement (left or right) and/or the task (lift, use, or pantomime) to be performed: (1) both hand and task were cued in advance (Both precue); (2) task only was cued in advance (Task precue); and (3) neither hand nor task were cued in advance (No precue). Twenty-four right-handed university students performed reaching movements to tools under the three different precue conditions. The results of Experiment 2 showed that reaction time was sensitive to the amount of advance information presented in the precue. For reaction time manual asymmetries were observed in one condition only – a right hand advantage was present in the No precue condition. In contrast manual asymmetries in favor of the right hand were clearly observed with the movement time results. Experiment 2 was the first experiment reported in the literature to systematically examine reaction time for reaching and grasping movements to tools. In order to further explore these results, in Experiment 3 a fourth precue condition (in which the hand to be used was cued in advance; the Hand precue) was added to the precue paradigm used in Experiment 2. An additional variable called replacement time, which represented the time spent interacting with the tool, was also examined. Forty-two right-handed university students participated in Experiment 3. The results of Experiment 3 largely replicated the findings of Experiment 2, and indicated that both the amount and type of precue information had an effect on reaction time. The addition of the Hand precue condition suggested that having advance knowledge of the hand to be used to perform the task was of greater importance for movement planning than was advance knowledge of the task to be performed. Regarding the movement time results, Experiment 3 was one of the first experiments to show the influence of task demands on the magnitude of manual asymmetries. The lack of differences between the hands for the replacement time results also suggested that the initial execution of the movement (represented by movement time) was most sensitive to manual asymmetries. Overall, these experiments provided further insight into manual asymmetries for the performance of reaching movements, and illustrated how simple manipulations of task demands led to differences between the hands in measures of both preference and performance when interacting with tools.

Psychopathy is a severe personality disorder associated with a range of affective, interpersonal, and behavioural abnormalities. Evidence suggests that psychopaths show marked deficits in processing emotional information, although it is unclear whether they also show more general deficits in error monitoring, attention allocation and response control. It is also unclear whether any variation in neurophysiological performance is also reflected in subclinical populations. In this thesis, event-related potentials (ERPs) were used to examine these issues and involved two separate samples. The first included incarcerated offenders with a range of scores on the Hare Psychopathy Checklist –Revised (PCL-R) and non-offender (staff) controls. The second included a large group of healthy undergraduate males with a full range on scores on the Self-Report Psychopathy Scale (SRP-III). Error monitoring was examined in both samples using a standard letter-flanker task and a modified version of the task in which faces with angry or fearful expressions were used instead of the usual letter stimuli. In general, psychopathy in both samples was associated with attenuated ERN amplitudes on the face flanker task only. Source modeling of the ERN indicated that, while the ERN is generally modeled as having a dipole in the ACC, the psychopath group showed no evidence of ACC activity in this region in conjunction with face-flanker errors. These data suggest that the affect-based neurophysiological deficits associated with psychopathy in the clinical range are observed in a graduated fashion among subclinical samples. Inhibitory control processes were also examined in the incarcerated group using the inhibitory N2 and anteriorized P3 as indices of inhibitory processes evident in correctly withholding prepotent response tendencies on a Go-NoGo task. Despite the common assumption that poor inhibitory control is a central aspect of psychopathy, there was no sign that those at higher levels of psychopathy showed any inhibitory control problems and they produced a robust NoGo N2 and P3. In fact, there were signs that the incarcerated offenders who were low on psychopathy were more likely to produce diminished inhibitory-related components. Finally, years of controversy regarding attention allocation deficits in psychopathy was addressed by collecting standard P3 components during a traditional visual oddball task in the university sample. Behavioural response and P3 amplitudes were unrelated to psychopathy. However, consistent with data from incarcerated samples, higher scores on psychopathy were associated with larger amplitude P2 and N5 responses to target relative to nontarget stimuli, again suggesting some continuity with respect to a distinct, although not necessarily deficient, attentional style at subclinical levels of psychopathy. In general, across these four data sets, the only clear evidence of impaired processing involved a reduced error-monitoring response during the face-flanker task when emotional stimuli formed the basis of the required discrimination and this reduced response was found to vary with the degree of psychopathy even within a subclinical range. These findings support a model of psychopathy involving limbic and paralimbic structures rather than a general reduction in neural function affecting error monitoring, attention allocation and response control.