No description available.

No description available.

During traumatic events, individuals can experience dissociative symptoms related to changes in cognitively processing; these changes are suggested to impact on the development of posttraumatic stress disorder (PTSD) symptoms. Past literature has proposed two forms of peritraumatic dissociation (compartmentalisation and detachment), however little quantitative research has focussed on separately manipulating these experiences in order to further our understanding of their aetiology. The current study addressed this knowledge gap and additionally sought to understand the role of cognitive processing in the dissociation-intrusion relationship. Using an audio-only adaption of the trauma film paradigm, 60 participants were divided into three conditions and presented with different visual tasks - mirror staring, dot-staring or neutral images – that were hypothesised to induce the two forms of dissociation. Post-audio, a number of factors were assessed, including state dissociation, perceptual priming and conceptual priming, as well as intrusions over the following days. As hypothesised, participants in the dissociation conditions displayed an increase in perceptual priming compared the control conditions, and reported more severe intrusions. However, no differences were found in conceptual priming, in the overall number of intrusions between conditions, or in dissociative symptoms between the dissociation conditions. The current study utilised new techniques in the analysis of PTSD and its origins, and showed their potential in the experimental study of dissociation and analogue trauma techniques. The findings also contributed to the growing body of knowledge investigating the impact that dissociation and cognitive processing has on the aetiology of PTSD.

Soil salinity is a common abiotic stress for plants, that is having an increasing impact on international food production. A practical strategy to help mitigate the adverse effects of salinity stress on crop productivity is to increase salt tolerance of crop plants. It has been shown that exogenous application of L-proline and L-glutamate is capable of reducing the severity of salinity stress on seed germination and early seedling growth of brassica and cucumber, respectively. The main aim of the present study was to investigate the potential of all 20 common protein amino acids to alleviate salinity stress in lettuce (Lactuca sativa L., variety ‘Great Lakes’) during and immediately following germination. Sowing lettuce seeds in different concentrations of sodium chloride (NaCl) adversely affected germination and early seedling growth in a dose-dependent manner. After 48 hours of sowing lettuce seeds in 1 mM of any of the 20 exogenous amino acids in the absence of NaCl, it was found that the amino acids also inhibited seedling growth, particularly root elongation. However, in direct treatment experiments involving addition of seven amino acids singly (L-asparagine, L-isoleucine, L-leucine, L-proline, L-phenylalanine, L-tyrosine and L-valine) to an inhibitory concentration (60mM) of NaCl, it was found that lettuce seedling growth was protected from the salt stress. Additionally, seeds pre-treated for 8 hours before germination with L-arginine, L-glycine, L-histidine, L-methionine and L-phenylalanine, showed significant growth recovery after a further 40 hours growth exposed to 60mM NaCl. The measurements of cell size in root maturation zone and mitotic index at the root tip of lettuce seedlings after 48 hours from sowing seeds suggested that it might be possible that some amino acid treatments could affect cell elongation and / or cell division. However, further in-depth investigations are required and warranted to elucidate the mechanism(s) whereby exogenous amino acids could play a role in alleviation of salt stress in lettuce. It is concluded that several L-amino acids have the potential in pre-sowing seed treatment (seed priming technology) to enhance salt tolerance for crop stand establishment in soils with salinity issues.

Decades of priming research have revealed that environmental stimuli feed into our behaviours, often without any awareness of our using this information to guide our behaviour. This has been shown using plentiful stimuli across multiple contexts. One of the most socially rich stimuli in our environment is voice, and yet this has featured surprisingly little in behavioural research, particularly within social psychology. This thesis was written as a step towards addressing this gap, and it explores how voices might affect particular behaviours in different contexts. Three broad experiments, each with their own sub-experiments, investigated how voices, acting as proxies for social categories, could influence one's behaviour. In the first experiment, the responses to socially themed statements were influenced by the sex of the voice presenting those statements. Female voices primed more agreement to these statements than did male voices. In the second experiment, judgements of ambiguous stimuli and questions were also affected by voices, albeit in less clear ways. In the third experiment, the reaction times of participants were again affected by voices. Younger participants' reaction times were slower when listening to an older voice, and older participants' reaction times were faster when listening to an older voice. Across these three experiments, I found too that the presence of a voice led to task differences compared to when voice was absent. The combination of these experiments is, to my knowledge, the first to look at voice-based behavioural priming. How these results fit with selected existing theories, the potential to specify theories based on these results, and the possible practical applications of voice based priming are discussed.

No description available.

The purpose of this study was to determine the effect of priming on performance of a closed motor task (dart throwing). The priming task involved either reading or listening to one of three different sets of instructions explaining the mechanics of dart throwing: positive (emphasizing what to do or focus on), negative (emphasizing what not to do or focus on), and neutral. One hundred-twenty four participants were randomly assigned to 4 experimental groups (n = 21 for each) and 2 control groups (n = 20 for each) based on media (verbal or written) and direction (positive, negative, control) of script. Each participant completed a total of 6 blocks (3 dart-throws per block). In subsequent order, participants completed Blocks 1 and 2 (practice trials), the priming task, and then Blocks 3 through 6 (experimental trials).A 2 x 3 x 6 (Media x Direction x Block) ANOVA with repeated measures on the last factor found only a significant main effect for Block. However, tests of within-subject contrasts indicated a Block x Direction interaction from Block 1 to Block 2 and from Block 2 to Block 3, with the most dramatic change in performance seen in the group receiving the negative instructions. The results indicated that negative instruction can have an immediate negative impact on performance that is not seen with positive instruction. This negative impact can be overcome, however, if the performer is left alone to practice after receiving the negative instruction. This study has provided additional evidence that priming can influence motor responses. / School of Physical Education, Sport, and Exercise Science

Spatial neglect has mainly been described through its spatial deficits (such as attentional bias, disengagement deficit or exploratory motor behavior), but numerous other studies have reported non-spatial impairments in patients suffering from this disorder. In the present thesis, non-spatial deficits in neglect are hypothesized to form a core impairment, which can be summarized as a difficulty to learn and benefit from regularities in the environment. The different studies conducted and reported in the present thesis have converged to support this hypothesis that neglect patients have difficulty to interact with environmental statistics. The two first studies, which tested the visual modality (Chapters 2 and 3), have demonstrated that neglect patients have difficulties to become faster to respond to targets that appear successively at the same location (position priming). This difficulty is also more generic, as neglect patients do not learn that some things occur more often than others, such as for example that a target has a high probability to be repeated at a specific region. Those two studies have shown that neglect patients are impaired in position priming and statistical learning, which corresponds to difficulties benefiting from regularities presented in the visual domain. This difficulty may be explained by patients’ impairment in working memory or temporal processing. Several studies have reported the implication of those two mechanism in statistical learning: if patients tend to underestimate the time that a target is presented on the screen and have difficulties keeping in memory its precedent location, this translates into a difficulty to benefit from the repeats of the target position as well as a difficulty to benefit from transition probability. In order to verify if priming and statistical learning impairments were specific to the visual modality or if neglect patients present a multimodal difficulty to learn the transition probability in general, brain damaged patients were tested in the auditory domain (Chapter 5), with a paradigm that has shown statistical learning in infants. This study confirmed that for the auditory modality too, brain damaged patients are impaired in statistical learning. The different results of the studies reported in Chapters 2, 3, 4 and 5 converge to support the hypothesis that spatial neglect patients have difficulties benefiting from regularities of their environment. Nevertheless, this impairment is not irreversible, as it was demonstrated by a chronic neglect patient who was trained with three sessions distributed over three days (Chapter 2). Although having similar results to the other patients for the first session, this patients’ performance improved over the sessions to show a faster reaction time for the targets presented on the high probability region (his contralesional side). Therefore, priming and statistical learning investigated in this thesis are worth exploring further for their potential outcome in the rehabilitation domain.

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Recent research into hemispheric differences in sentence comprehension has produced a puzzling disparity between the results from behavioral studies on neurologically normal individuals and studies utilizing other methods such as electrophysiology, neuroimaging and the investigation of neuropsychological patients. The former approach tends to produce results that indicate a restriction of the right hemisphere (RH) to lower-level processing mechanisms that are comparatively less sensitive to context than the left hemisphere (LH), while the combined findings of the latter approaches suggest that not only is the RH capable of processing language at a higher level, it is particularly sensitive to contextual information and, furthermore, this may form part of the special role of the RH in language tasks. Accordingly, the present series of studies employed a normal-behavioral approach to further investigate the underlying processing mechanisms of the RH during sentence comprehension tasks. In each of the four experiments, right-handed adult participants completed a computer-based lexical decision task where reaction time and error rates were recorded. Stimuli were always centrally-presented, followed by a laterally-presented target word or non-word. In the first experiment, the sensitivity of the RH to message-level meaning was investigated by assessing whether it benefits from additional contextual information in sentences that was not the result of simple word-level associations. The remaining experiments aimed to examine several current models of RH language processing; specifically, they examined the applicability of the coarse-coding hypothesis (Beeman, 1993) and the integrative processing model (Federmeier, 2007) to RH sentence processing. The combined results of the four experiments lead to several conclusions. Firstly, this series of investigation consistently demonstrated that the RH does display a sensitivity to message-level processing that appears to be at least equivalent to that of the LH. This conclusion is uncommon in the normal-behavioral literature, but is consistent with evidence produced by other methodologies. Secondly, the coarse-coding hypothesis is insufficient in explaining RH language processing at the sentential level. Although there is considerable evidence in support of the coarse-coding model of RH processing of individual words, the findings of the present investigations do not support its applicability beyond this level. Thirdly, the integrative/predictive distinction between RH/LH language processing also appears to have limited applicability beyond sentence fragments and may instead be reflective of higher-level processing differences (e.g., wherein the RH may utilize a para-linguistic situation-model processing method whereas the LH may rely purely on a linguistic mechanism). Based on these conclusions, the present series of investigations appears to have resolved the inconsistent finding previously prominent in normal-behavioral literature and goes some way in determining the applicability of current models of RH language processing.