The aim of this thesis is to investigate the effect of parafoveal information on central word processing. This topic impacts on two controversial areas of research: the allocation of attention during reading, and letter processing during word recognition. Researchers into the role of attention during reading are split into two camps, with some believing that attention is allocated serially to consecutive words and others that it is spread across multiple words in parallel. This debate has been informed by the results of recent experiments that test a key prediction of the parallel processing theory that parafoveal and foveal processing occur concurrently. However, there is a gap in the literature for tightly-controlled experiments to further test this prediction. In contrast, the study of the processing that letters undergo during word recognition has a long history, with many researchers concluding that letter identity is processed only conjointly with letter ‘slot’ position within a word, known as ‘slot-based’ coding. However, recent innovative studies have demonstrated that more word priming is produced from prime letter strings containing letter transpositions than from primes containing letter substitutions, although this work has not been extended to parafoveal letter prime presentations. This thesis will also discuss the neglected subject of how research into these separate topics of text reading and isolated word recognition can be integrated via parafoveal processing. It presents six experiments designed to investigate how our responses to a central word are affected by varying its relationship with simultaneously presented parafoveal information. Experiment 1 introduced the Flanking Letters Lexical Decision task in which a lexical decision was made to words flanked by bigrams either orthographically related or unrelated to the response word; the results indicated that there is parafoveal orthographic priming but did not support the ‘slot-based’ coding theory as letter order was unimportant. Experiments 2-4 involved eye-tracking of participants who read sentences containing a boundary change that allowed the presentation of an orthographically related word in parafoveal vision. Experiment 2 demonstrated that an orthographically related word at position n+1 reduces first-pass fixations on word n, indicating parallel processing of these words. Experiment 4 replicated this result, and also showed that altering the letter identity of word n+1 reduced orthographic priming whereas altering letter order did not, indicating that slot-based coding of letters does not occur during reading. However, Experiment 3 found that an orthographically related word presented at position n-1 did not prime word n, signifying the influence of reading direction on parafoveal processing. Experiment 5 investigated whether the parallel processing that words undergo during text reading conditions our representations of isolated words; lexical decision times to words flanked by bigrams that formed plausible or implausible contexts did not differ. Lastly, one possible cause of the reading disorder dyslexia is under- or over- processing of parafoveal information. Experiment 6 therefore replicated Experiment 1 including a sample of dyslexia sufferers but found no interaction between reading ability and parafoveal processing. Overall, the results of this thesis lead to the conclusion that there is extensive processing of parafoveal information during both reading (indicating parallel processing) and word recognition (contraindicating slot-based coding), and that underpinning both our reading and word recognition processes is the flexibility of our information-gathering mechanisms.

No description available.

The BRB consists of both capillary endothelial cells (REC) and retinal pigment epithelial cells (RPE). Both cell types have been suggested as potential activators of circulating T cells. In this study, an <I>in vitro</I> model using cultured rat REC and syngeneic T cells was developed. Furthermore RPE and for the purpose of comparative studies, AEC were also successfully cultured. It was demonstrated that activation of T lymphocyte LFA-1 is a critical event governing the adhesion of T cells to RPE and REC as IFN-γ induced up-regulation of RPE and REC ICAM-1 expression did not increase binding of resting T lymphocytes. The enhanced adhesion of activated lymphocytes (but not resting lymphocytes) to normal and IFN-γ treated RPE and REC was inhibited by LFA-1 mAb and to a lesser extent by ICAM-1 mAb but not OX34 (CD2). Treatment of lymphocytes with the anti-VLA-4 mAb resulted in differential effects on binding to AEC and REC. MAb to VLA-4 significantly blocked enhanced adhesion of activated T cells to AEC but not to REC. The results also demonstrated that VLA-4 mAb significantly inhibited unactivated T cell binding to IFNγ+TNFα+LPS stimulated AEC but not REC, suggesting that VLA-4 may also function in an activation-independent manner. It was shown that activation of T cells can enhance their migratory activity across cultured REC monolayers. Migration was decreased by both adhesion receptor-dependent mechanisms i.e., mAb to LFA-1 (but not ICAM-1) and adhesion receptor-independent mechanisms by means of PGE<SUB>2</SUB>. The results of this thesis have shown that activation of LFA-1 is required for functioning of the LFA-1/ICAM-1-mediated lymphocyte adhesion and migration. In addition to the role of adhesion molecules, inflammatory mediator PGE<SUB>2</SUB>, but not NO<SUP>o</SUP>, was found to be important in regulation of T cell adhesion and migration across REC.

No description available.

When you want to pick up an object, it is usually a simple matter to reach out to its location, and accurately pick it up. Almost every action in such a sequence is guided and checked by vision, with eye movements usually preceding motor actions (Hayhoe & Ballard, 2005; Hayhoe, Shrivastava, Mruczek, & Pelz, 2003). However, most research in this area has been concerned about the sequence of movements in complex “everyday” tasks like making tea or tool use. Less emphasis has been placed on the object itself and where on it the eye and hand movements land, and how gaze behaviour is different when generating a perceptual response to that same object. For those studies that have, very basic geometric shapes have been used such as rectangles, crosses and triangles. In everyday life, however, there are a range of problems that must be computed that go beyond such simple objects. Objects typically have complex contours, different textures or surface properties, and variations in their centre of mass. Accordingly, the primary goals in conducting this research were three fold: (1) To provide a deeper understanding of the function of gaze in perception and action when interacting with simple and complex objects (Experiments 1a, 1b, 1c); (2) To examine how gaze and grasp behaviours are influenced when you dissociate important features of an object such as the COM and the horizontal centre of the block (Experiments 2a, 2c); and (3) To explore whether perceptual biases will influence grasp and gaze behaviours (Experiment 2b). The results from the current series of studies showed the influence of action (i.e., the potential to act) on perception in terms of where we look on an object, and vice versa, the influence of perceptual biases on action output (i.e. grasp locations). In addition, grasp locations were found to be less sensitive to COM changes than previously suggested (for example see Kleinholdermann, Brenner, Franz, & Smeets, 2007), whereas fixation locations were drawn towards the ‘visual’ COM of objects, as shown in other perceptual studies (for example see He & Kowler, 1991; Kowler & Blaser, 1995; McGowan, Kowler, Sharma, & Chubb, 1998; Melcher & Kowler, 1999; Vishwanath & Kowler, 2003, 2004; Vishwanath, Kowler, & Feldman, 2000), even when a motor response was required. The implications of these results in terms of vision for Perception and vision for Action are discussed.

The primary focus of this research was to examine that portion of the model for psychotherapy developed by John Grinder and Richard Bandler in their 1976 book, The Structure of Magic II, concerned with internal representational systems. Specifically, the study was designed to investigate the relationship between reflexive eye movement patterns, verbalizations, and individual self-report as measures of representational systems. This comparison was made to determine if the three variables would demonstrate significant agreement as predictors of internal representational systems.Students in undergraduate psychology courses in two different departments of a large midwestern university were solicited as subjects for this research. One hundred and twenty-eight individuals participated in the study. Those individuals who participated represented various age groups and academic majors. In this study subjects served as their own controls.Four hypotheses were formulated to investigate the probability of various combinations of eye movements, verbalizations, and individual self-reports as predictors of respresentational systems. The author developed nine stimulus cues for subject response. Six cues required no verbal response and were used for eye movement rating only. The remaining three cues were responded to verbally and provided both eye movement and verbalization ratings. Each subject was individually rated on eye movements and verbalizations by different raters. A frequency count procedure was utilized in rating each individual's eye movements and verbalizations. The most frequently occurring system was classified as the primary representational system for each of these variables. At the completion of the study, each individual provided information on his or her primary representational system through use of a short questionnaire developed by the author. The representational system rated as number one on the self-report questionnaire was classified as the primary representational system for individual self-report. The results of all ratings were classified as either visual, kinesthetic, or auditory and then compared on the variables.Statistical analyses were carried out to determine if there was significant agreement (p<.05) between the variables. Analysis of the results indicated one significant finding. The most reliable means of determining representational systems in this study was through a combination of observing eye movements and listening to the predicate system most frequently used in the verbalizations of an individual. This method was more reliable than observing eye movements and obtaining an individual's self-report; or listening to the most frequently used predicate system and obtaining an individual's self-report; or observing eye movements, listening for the most frequently used predicate system, and obtaining an individual's self-report. The combination of observing eye movements and listening for the most frequently used predicate system was statistically significant. All other combinations mentioned failed to reach statistical significance.

No description available.

The correlation between the chemical stability and the microbiological activity of polymyxin B in phosphate buffer pH 6.0 and in proprietary eye drops was evaluated. High Performance Liquid Chromatography (HPLC) was used to quantify the amount of the main components in samples stored at 43,50,55 and 60°C for a period of 500 h. The data indicated that there are significant differences in chemical stability among the different proprietary eye drops. The accurate decomposition rate constants and shelf-lives (~o) at 4°C of two of the six formulated eye drops and the standard polymyxin B solution stored in glass containers at pH 6.0 were established. It was concluded that microbiological assay by agar diffusion was unsuitable for determining the activity of control polymyxin B in phosphate buffer and polymyxin B in eye drops. Killing time determinations for polymyxin B against cell suspensions of P. aeruginosa NCTC 6750 were consequently used. Thioglycollate broth containingp- aminobenzoic acid (PABA) 0.16 %w/v and magnesium sulphate 1 %w/v was used as an inactivating recovery medium. The effect of preservatives and of second antibacterials contained in the eye drops were tested individually and combined with polymyxin B. Thiomersal 0.001 %w/v, trimethoprim 0.02 %w/v and thiomersal 0.001 %w/v plus trimethoprim 0.02 %w/v did not have an effect on the activity of polymyxin B 2000 U/ml. Neomycin was an exception and at the concentrations in the range 0.0192 to 0.16 %w/v exhibited an antagonistic effect. Chemical interaction between polymyxin B and neomycin could not be detected and it was considered that the inhibitory effect of neomycin may be the result of competition between polymyxin B and neomycin for the same binding sites on the cell surface. Gentamicin is active against P. aeruginosa NCTC 6750 and at concentrations of 0.075 and 0.036 %w/v it exhibited an additive effect with polymyxin B 2000 U/ml against the test organism. The results obtained with the samples stored at 55°C for a period of 500 h demonstrated the critical effect of pH. At a pH of 6.0 microbiological activity and chemical stability appeared optimal. The chemical stability data of five eye drop samples correlated with microbiological activity data. Exceptions were polymyxin B in one eye drop sample and control polymyxin B. These extensively decomposed samples showed good antibacterial activity which appeared to result from the activity of decomposition products. Chemical stability data for standard polymyxin B solution at pH 6.0 also correlated to microbiological activity data over the temperature range of 92 - 115°C. The polymyxin B retained detectable microbiological activity when the amount of PB1 was greater than 20%. It is suggested that the decomposition products which occurred at these higher temperatures did not possess antibacterial activity.

The experiments studied the ability to perceive visual, events of a very simple kind: the appearance and disappearance of isolated dots in random dot patterns. The aim of the investigation was to explore the limits of this ability and clarify the relationship, between event perception and sensory storage. The first series of experiments studied the ability to detect the appearance and disappearance of single dots. Under appropriate conditions such changes can be detected in a pattern containing 1024 dots with 98% accuracy. This level of accuracy was largely maintained over manipulation of the number of dots in the pattern, pattern size and separation between dots. Performance was unaffected by whether pattern luminance was uniform or not. It is argued that to explain this performance the notion of sensory integration must be augmented by the concept of sensory differentiation. The ability to detect events was further investigated as a function of pattern complexity and ISI. The storage underlying event detection has a very high capacity and a short duration. The second series of experiments investigated the ability to perceive patterns of events. Letters defined by either appearances or disappearances were accurately identified; thus a pattern which was not visible was made visible by its disappearance. A measure of localization was obtained by requiring subjects to judge whether three events were aligned. It is concluded that both onset and offset of a pattern convey information about form but that acuity for events is poorer than for sustained stimuli. The possibility that event perception is achieved by integration at short stimulus durations was investigated by varying the durations of the patterns before and after the events. Little evidence for event perception by integration was found; increasing the durations of the patterns either improved performance or had little or no effect on it. The final experiment examined a conflict between the present results and studies of visual integration. The ability to perceive mixtures of appearances and disappearances was investigated and found to be poorer than the ability to process either type of event alone. The ability to detect and locate events is highly developed. This ability seems well adapted to the detection and perception of significant change in the natural environment. In contrast to the increasing scepticism concerning the function of sensory storage it is concluded that event perception is an important visual function in which sensory storage is clearly implicated.

No description available.