published_or_final_version / abstract / toc / Psychology / Master / Master of Philosophy

No description available.

No description available.

No description available.

A forced-choice reaction time (RT) task was used to examine the relations between covert orienting (shifts of visual attention independent of eye movement) and filtering (the inhibition of processing of irrelevant stimuli) components of attention in persons with Down syndrome (n = 17) and children of average intelligence (n = 17) matched for mental age (MA), (MA = approximately 5 years). Conditions varied with regard to presence or absence of distractors, and the validity (valid, invalid, or neutral) of location cues. RT/p(correct) scores of both groups were longer in distractor-present conditions and in conditions when the location cue provided incorrect information (invalid cue). In addition, RT/p(correct) scores of both groups were longer when it was necessary to simultaneously search for a target and filter out irrelevant information, than when each of these attention demanding tasks was utilized separately. However, there were no differences in performance between persons with Down syndrome and MA matched children of average intelligence. This evidence is used to challenge the notion of an overall deficit in selective attention abilities in persons with Down syndrome as compared to MA matched children of average intelligence. Findings are also discussed in terms of their support for a capacity sharing relationship between covert orienting and filtering.

This thesis investigates the relationship between consciousness, attention, and experience in the periphery of the visual field. I argue that there are some visual experiences that lack content in the sense of lacking accuracy conditions and also in stronger senses. I define subjective space as the manifold constituted by the various factors that modulate awareness of an object including attention, eccentricity, eccentricity-relative spacing, and so on. The subjective periphery is that area of subjective space in which no objects or properties are experienced. It is subjectively peripheral experiences that lack content. In part my argument depends on claims about phenomenal experience. I establish these by considering a variety of introspective and experimental phenomena related to attention and conscious awareness and extracting a set of data that are neutral with respect to the theories that might explain them. I pursue an argument to the best explanation, refuting three popular explanations and championing my own. The first is that endorsed by Dennett (1991) and Noë (2004). They each claim that our experience of phenomenal character in the subjective periphery is an illusion (or a defeasible illusion). The second explanation, endorsed by Block (2007), is that there is phenomenal experience and content in the periphery but no cognitive awareness of it; thus, reports and other indicators of content fail. The third explanation is that there are indeterminate or general contents in the subjective periphery. This is the representationalist’s explanation. The fourth explanation, my explanation, is that there are in fact experiences that do not present objects or properties at locations in the subjective periphery, and that consequently lack content. I argue that this is the best explanation of the data since the others either fail to account for all the neutral data, can be shown to be false for independent reasons, or both. I also defend a number of distinct conclusions that nevertheless strengthen the main line of argument. For example, I consider the view that all attention is conscious, which helps to salvage the reliability of introspection as a method of investigating attention and experience.

No description available.

No description available.

No description available.

No description available.