Morphology in auditory lexical processing: Sensitivity to fine phonetic detail and insensitivity to suffix reduction

This dissertation investigates two seemingly contradictory properties of the speech perception system. On the one hand, listeners are extremely sensitive to the fine phonetic details in the speech signal. These subtle acoustic cues can reduce the temporal ambiguity between words that show initial segmental overlap, and can guide lexical activation. On the other hand, comprehension does not seem to be hampered at all by the drastic reductions that typically occur in casual speech. Complete segments, and sometimes even complete syllables, may be missing, but comprehension is seemingly unaffected. This thesis aims at elucidating how words are represented and accessed in the mental lexicon, by investigating these contradictory phenomena for the domain of morpholog

Effects of Complexity on Visuo-spatial Working Memory

Author version made available in accordance with the publisher's policy.Four experiments are reported in which the effect of complexity on short-term retention of visuo-spatial material was explored. The determinants of complexity can be separated into a quantitative factor, which sets an upper bound on complexity, and a structural factor, which reduces complexity. Variants of the Corsi blocks task were administered across the various experiments. Quantitative complexity was manipulated through the number of blocks on the board. Structural complexity was induced through the positioning of the blocks. Visuo-spatial span was found to be susceptible to both measures of complexity. Performance was inversely related to the number of blocks. Recall was also better when the blocks were positioned in a matrix than in a random fashion. Moreover, the effect of complexity was shown to be moderated by an interaction between structure and amount of information presented. These results demonstrate that complexity is an important characteristic of visuo-spatial working memory. This phenomenon may be used to further explore the properties of the visuo-spatial sketch pad, and advance its theoretical development

Complexity effects in visuo-spatial working memory: Implications for the role of long-term memory

Author version made available in accordance with the publisher's policy.Several studies have shown that the capacity of visuo-spatial working memory is limited by complexity. Using a variant of the Corsi blocks task, this paper investigated the effect of complexity of the to-be-remembered path on visuo-spatial memory span. Redundancy was determined by three Gestalt principles: symmetry, repetition and continuation. Experiment 1 revealed an effect of path complexity. The subsequent experiments explored whether the superiority for recall of structured over complex paths can be attributed solely to the operation of visuo-spatial working memory, or whether it also reflects the use of long-term knowledge. Experiment 2 demonstrated that the effect of complexity remained, even when the mechanisms for visuo-spatial coding were removed by a secondary visuo-spatial task. In Experiments 3 and 4 subjects were trained in the recall of complex paths. This led to the creation of long-term memory representations for these paths, as shown by an improvement in their span, and a concomitant lack of transfer to new paths. Finally, Experiment 5 showed that one prior repetition of a complex path was sufficient to produce specific and long-term learning effects. These results point to the involvement of long-term memory processes in the temporary retention of visuo-spatial material for which representations exist in long-term memory. They also suggest that the effect of complexity may provide a tractable technique for investigating the mechanisms underlying the limits of visuo-spatial short-term storage

Oxygen uptake kinetics in chronic heart failure : clinical and physiological aspects

Chronic heart failure (CHF) is a clinical syndrome characterized by exercise intolerance. Because resting indices of cardiac function and the level of perceived exercise intolerance correlate poorly with the exercise performance of these patients, exercise testing has become an important tool for the evaluation and monitoring of heart failure. Whereas the maximal aerobic capacity (peak VO2) has been shown to be a reliable indicator of the severity and prognosis of heart failure, submaximal exercise parameters may better reflect the ability to perform daily physical activities. Oxygen (O2) uptake kinetics describe the rate of change in oxygen uptake (VO2) during onset or recovery of exercise (O2 onset and recovery kinetics, respectively). Previous studies showed that, compared to healthy individuals, CHF patients have slower O2 onset and recovery kinetics, with the degree of the delay correlating with the functional impairment in these patients. However, it is not well established whether O2 uptake kinetics are sensitive to the effects of therapeutic interventions in CHF patients. Moreover, knowledge is lacking on the pathophysiological background of the delay in O2 uptake kinetics in CHF patients. This thesis addressed the following central questions: 1. Are O2 uptake kinetics useful in clinical practice to quantify and predict the effects of physical training in CHF patients? 2. What are the physiological determinants of O2 uptake kinetics in CHF patients

Approach bias for food cues in obese individuals

This study aimed to investigate the existence of an approach bias for food cues in obese individuals. A community sample of 56 obese women and 56 normal weight controls completed an approach–avoidance variant of the implicit association task. The obese participants were faster to respond to trials that paired food words with approach words, and trials that paired non-food words with avoid words, than the converse pairings, thus, demonstrating an approach bias for food. This bias was evident for both high caloric and low caloric food words, and was not attributable to a state of deprivation or feelings of hunger. By contrast, the normal weight controls did not show any such bias. The results are consistent with recent neurocognitive perspectives of obesity. At a practical level, approach biases for food may present a potential target for modifying (excessive) food intake

Hand-held dynamic visual noise reduces naturally occurring food cravings and craving-related consumption

Author version made available in accordance with the publisher's policy for non-mandated open access submission. Under Elsevier's copyright, non-mandated authors are permitted to make work available in an institutional repository.This study demonstrated the applicability of the well-established laboratory task, dynamic visual noise, as a technique for reducing naturally occurring food cravings and subsequent food intake. Dynamic visual noise was delivered on a hand-held computer device. Its effects were assessed within the context of a diary study. Over a 4-week period, 48 undergraduate women recorded their food cravings and consumption. Following a 2-week baseline, half the participants watched the dynamic visual noise display whenever they experienced a food craving. Compared to a control group, these participants reported less intense cravings. They were also less likely to eat following a craving and consequently consumed fewer total calories following craving. These findings hold promise for curbing unwanted food cravings and craving-driven consumption in real-world settings

Reaction to the LEXUS review in the LD&C Vol. 3, No. 2.

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