Magnetic source magnetic resonance imaging (msMRI) is an fMRI technique that has been under development for direct detection of neuronal magnetic fields to map brain activity and has been shown to be experimentally detectable using conventional means, but there is debate on the detection of the msMRI signal since it can be only a 0.2% change. Detection of its temporal characteristics has yet to be reported and may strengthen the case for msMRI detection. The temporal characteristics of the detected msMRI signal were examined in this work, but it was found that the sensitivity of conventional analysis techniques are low within the context of msMRI, preventing consistent msMRI signal detection and analysis of its temporal characteristics. Examination of blood oxygen level dependent (BOLD) contrast contamination and application of mean-shift clustering (MSC) to fMRI analysis were performed to look into the possibility of improving the low sensitivity. fMRI analysis is commonly performed with cross correlation analysis (CCA) and techniques based on the General Linear Model (GLM), but both CCA and GLM techniques typically perform calculations on a per-voxel basis and do not consider relationships neighboring voxels may have. MSC is a technique to consider for this purpose and shows improved activation detection for both simulated and real BOLD fMRI data. To consider the issue of BOLD contamination, the hemodynamic response over time was examined using repeated median nerve stimulation. On average, the results show the BOLD signal is not detectable after the second fMRI run. The results are consistent with previous hemodynamic habituation effect studies with other types of stimulation, but they do not completely agree with findings of evoked potential studies. Overall, this work shows that the low detection sensitivity may be able to be addressed with the purpose of furthering msMRI research.

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This study was an attempt to replicate the positive results of a precognitive habituation (PH) experiment devised by Bem (2003). The procedure is based on the subliminal mere exposure (SME) design. In an SME procedure subjects are exposed to image-pairs in a preference task, after being exposed to one of those images (the target) subliminally. The target is preferred significantly more often due to the mere exposure effect. In the PH procedure the preference task precedes the exposure and images are of negative and erotic valence. It was hypothesized that due to exposure (in the future), subject preference will increase for negative and decrease for the erotic target images, especially for subjects classified erotically or negatively reactive (Bem, 2003). Also, that an overall (negative and erotic) effect would be shown. The results were not significantly above chance expectation for any of the hypotheses (50.0%; 47.2%, p = .149; 50.8%, p = .279).

Olfactory sensing is ubiquitous across animals and important for survival. Yet, its characteristics, mechanisms, and functions in humans remain not well understood. In this dissertation, I present four studies on human olfactory perception. Study I investigates the impact of short-term exposures to an odorant on long-term olfactory learning and habituation, while Study II examines human ability to localize smells; Study III probes visual-olfactory integration of object representations, and Study IV explores the role of olfaction in sensing nutrients. Several conclusions are drawn from these studies. First, brief intermittent exposures to even a barely detectable odorant lead to long-term incremental odorant-specific habituation. Second, humans localize smells based on gradient cues between the nostrils. Third, there is a within-hemispheric advantage in the integration of visual-olfactory object representations. Fourth, olfaction partakes in nutrient-sensing and facilitates the detection of food. Some broader implications of our findings are discussed.

Noise pollution can mask or distort bird songs, which inhibits mating success, predator detection, and parental response to begging calls. Road noise can cause lowered density and reproductive success in songbirds. I examined the impact of construction noise on reproductive success and territory selection of golden-cheeked warblers (Dendroica chrysoparia) at 3 sites: adjacent to road construction, adjacent to road-noise only, and a control with no noise or construction activity. I also examined birds' responses to experimental playback of construction noise to determine if warblers alter behavior in the presence of introduced road construction noise, if they have habituated to construction noise, and whether habituation is hindering their reproductive success. I used the Vickery reproductive index to evaluate productivity and automatic recording units to assess the levels of ambient noise in each site. From 2007-2009, productivity was stable in the road-noise only site and showed more annual variation in the construction and control sites; productivity was nearly identical in the latter 2 sites in 2008 and 2009. There was no significant difference in productive territory locations based on distance from road. Ambient noise was similar in the construction and roadnoise only sites but significantly different from the control. To examine habituation and territory placement, I (1) used construction noise playback to individual birds and evaluated occurrence of behavioral response as a function of distance from the roadway, and (2) established broadcast stations that simulate construction noise to determine impacts on territory selection. Of 88 surveys, 6 birds responded to construction noise playback. I conducted 18 control surveys and observed 1 behavioral response. All birds that responded were located greater than or equal to 140 m from the road. I established 3 broadcast stations per season in 2008 and 2009. In each year I placed broadcast units on the edges of randomly chosen territories identified during the previous field season. There was not a significant difference in mean territory shifts for broadcast and non-broadcast unit territories, and territory shifts did not show patterns in directionality or in reproductive success. Results suggest that construction noise does not appear to affect behavior or reproductive success of golden-cheeked warblers.

The current study examined the psychological effects of recurring earthquake aftershocks in the city of Christchurch, New Zealand, which began in September 2010. Although it has been identified that exposure to ongoing adverse events such as continuing terrorist attacks generally leads to the development of increasing symptomology over time, differences in perceived controllability and blame between man-made and natural adverse events may contribute to differences in symptom trajectories. Residents of two Christchurch suburbs differentially affected by the earthquakes (N = 128) were assessed on measures of acute stress disorder, generalised anxiety, and depression, at two time points approximately 4-5 months apart, in order to determine whether symptoms intensified or declined over time in the face of ongoing aftershocks. At time 1, clinically significant levels of acute stress were identified in both suburbs, whereas clinical elevations in depression and anxiety were only evident in the most affected suburb. By time 2, both suburbs had fallen below the clinical range on all three symptom types, identifying a pattern of habituation to the aftershocks. Acute stress symptoms at time 2 were the most highly associated with the aftershocks, compared to symptoms of generalised anxiety and depression which were identified by participant reports to be more likely associated with other earthquake-related factors, such as insurance troubles and less frequent socialisation. The finding that exposure to ongoing earthquake aftershocks leads to a decline in symptoms over time may have important implications for the assessment of traumatic stress-related disorders, and provision of services following natural, as compared to man-made, adverse events.

Computer dialogs communicate important security messages, but their excessive use has produced habituation: a strong tendency by computer users to ignore security dialogs. Unlike physical warnings, whose design and use is regulated by law and based on years of research, computer security dialogs are often designed in an arbitrary manner. We need scientific solutions to produce dialogs that users will heed and understand. Currently, we lack an understanding of the factors that drive users’ attention to security dialogs, and how to counteract habituation. Studying computer security behavior is difficult because a) users are more likely to expose themselves to risk in a lab experiment than in daily life, b) the size of observed effects is usually very small, which makes it necessary to collect many observations, and c) it is complex to balance research interests and the ethical duty not to harm. My thesis makes two contributions: a novel methodology to study behavioral responses to security dialogs in a realistic, ethical way with high levels of ecological validity, and a novel technique to increase and retain attention to security dialogs, even in the presence of habituation.

Eight experiments tested priming in short-term memory as a model for latent inhibition and habituation. The model postulates that the two phenomena result from reduced processing when a representation of the target stimulus is already active (primed) in short-term memory at the time of its presentation. Priming is assumed to depend on the integrity of an association formed between the contextual stimuli and the conditional stimulus (CS) during exposure. Using a procedure that should have overshadowed the context, Experiment 1 found that latent inhibition and habituation were nevertheless maintained when a second CS of either equal or shorter duration overlapped with the target during exposure. Experiment 2 found no support for the priming of a configural stimulus when simultaneous compounds were preexposed. Experiment 3 ruled out sensitization and/or pseudoconditioning as an alternative explanation of latent inhibition. Experiments 4, 5 and 6 showed that sensory preconditioning as well as habituation and latent inhibition were obtained with compound exposure, providing evidence that the added CS was indeed processed along with the target. In Experiment 7, sequential pairings produced as much latent inhibition as compounds but less sensory preconditioning. Experiment 8 showed that retardation of conditioned inhibition was not attenuated by compound exposure. These results are interpreted as consistent with a correlational approach to classical conditioning.

Thesis (M.S.)--University of Wisconsin--Madison, 1982. / Typescript. Includes bibliographical references (leaves 133-144).

Thesis (M.A.)--University of British Columbia, 2003. / Includes bibliographical references (leaves 154-170).