This thesis discusses the philosophical positions that have arisen out of the research with cerebral commissurotomy patients. Following this discussion we develop and defend a position of our own. The first chapter discusses the operation and the postoperative tests that were conducted. Evidence is set out that makes it prima facie plausible that these patients have two minds. This evidence is basically evidence that the two hemispheres are not capable of pooling their informational content in special situations. Evidence for this non integration is found in all the senses except taste. This chapter also discusses hemispheric specialization, language in the minor hemisphere and the cuing mechanisms of the split hemispheres. The second chapter is devoted to Puccetti and Bogen who argue that normal humans have two minds. Their evidence for this comes from the evidence for two minds in the cerebral commissurotomy patients. Puccetti argues that if two minds were not present to start with, a simple operation would not elicit two minds from one. Puccetti also discusses tests on normal humans that are to support his position. These arguments are discussed and rejected. The third chapter discusses additional evidence for only one mind in normal humans. Puccetti's arguments are not only inadequate in that they do not prove their point but they ignore a great deal of evidence that there is only one mind in normal humans. This evidence comes from interference that two different tasks cause for each other. There is also evidence that the two hemispheres work together on one task and that their specialization is complimentary, resulting in functional dependence, rather than being duplicative. The fourth chapter is devoted to Eccles' attempt to reduce the minor hemisphere to an unconscious, computer like entity. He argues from what he calls, 'the unity of consciousness' and on epistomological grounds concerning evidence for a mind other than one's own. The argument from the unity of consciousness, however, begs the question and his epistomological considerations leave him in grave danger of solipsism. Chapter five discusses Dewitt's attempt to mediate between Eccles and Puccetti. Dewitt believes that Puccetti is right in asserting that these patients have two minds. On the other hand he is impressed with Eccles theory that the lack of language in the minor hemisphere causes a great disparity between the minor hemisphere and the major hemisphere. He therefore concludes that the patients have two minds, one of which does not qualify for personhood. Dewitt, however, has gravely underestimated the ability of the minor hemisphere. It has more language capacity than he believes and gives every evidence of being a person. It is also questionable whether or not language is a necessary condition for the self-awareness that goes with personhood. Chapter six looks at Robinson's attempts to undermine the two mind interpretation of the evidence. He does this mainly by trying to find tiimilar counter examples that resist a two mind interpretation. His program fails due to the dissimilarity of the counter examples and the cerebral commissurotomy results. Chapter seven considers Nagel's contention that the patients have an uncountable number of minds. Nagel does not believe that there is a strange uncountable number of minds that these patients actually have. Instead he believes that it is impossible to say how many minds they do have because we do not know how to count them. Nagel reasons that we have good evidence to believe that the patients have one mine and good evidence that they have two. Since both cannot be true we do not know what to say about these patients. Nagel believes that the above considerations make it difficult for us to understand these patients' mental lives. We agree with Nagel that there are times when it is difficult if not impossible to say how many minds the commissurotomy patient has. We disagree that this is always the case. Our problem with counting is not, however, a failure to understand something about the patients' mental lives, but is due to a counting problem when two hemispheres are only partially integrated. We agree with a suggestion from Nagel that an unusual connection between the hemispheres does not settle the question of how many minds the patient might be said to have. The hemispheres do seem to be able to integrate or pool their information using sophisticated muing mechanisms. Our position is that the patients usually have one mind that integrates the two hemispheres of the brain by cuing. The testing situations, however, interfere with this cuing and thereby cause a temporary, partial nonintegration between the hemispheres. During this time we, therefore do not know how many minds the patient can be said to have. / Arts, Faculty of / Philosophy, Department of / Graduate

No description available.

The purpose of this study was to examine language organization in the brain by using a series of three tasks concurrent with event-related potentials (ERPs) to investigate both hemispheric differences and interhemispheric reactions. Overall, the findings from this study support a relative rather than absolute hemispheric specialization for language processing. Despite an overall RVF (LH) advantage, both hemispheres were capable of performing the tasks and benefited from semantic priming.

A dichotic listening task was used to investigate the lateralization of sarcasm processing. Thirty-nine right-handed students were asked to identify which ear heard sarcastic and sincere phrases. Prosody and discourse context were simultaneously manipulated. For some trials, participants heard only the short prosodic phrases, while on other trials participants heard short vignettes prior to the phrases, which provided a context that primed either literal (sincere) or non-literal (sarcastic) interpretation. Contrary to Voyer et al. (2008), there were no differences in accuracy between the two hemispheres. However, when discourse context and prosody did not match, there was a significant right hemisphere advantage for sarcasm recognition and a left hemisphere advantage for the recognition of sincere utterances. / Department of Psychological Science

The purpose of this study was to examine and compare inferential abilities on a reading comprehension task in two groups of adults who had suffered cerebrovascular accidents (CVA). Sixteen subjects with a CVA to the right hemisphere of the brain were compared to an equal number of left hemisphere damaged subjects. Subjects were selected after they had demonstrated an adequate level of functioning on the Short Porch Index of Communicative Ability (SPICA), a test which measures communicative efficiency, to perform the tasks required in this study. All subjects were administered the revised version of the Nelson Reading Skills Test (NRST). On the NRST, test questions can be grouped into three categories representing literal, translational and high levels of inference. Subjects were presented five reading paragraphs. They were asked to answer thirty-three questions pertaining to the reading material by pointing to the correct answer out of four choices. Subjects were allowed to refer back to the paragraphs when trying to answer the questions. Results revealed total NRST performance to be significantly better for RBD subjects. RBD subjects also performed significantly better than LBD subjects on translational inference items. The research data did not reflect the expected error pattern with most errors on questions requiring high inferential abilities followed by translational items and fewest errors on literal inferences for either group of subjects.

No description available.

Thesis (Ph. D.)--University of Chicago, Dept. of Psychology, 2001. / Includes bibliographical references. Also available on the Internet.

Normal Language requires the integration of formal, conceptual, and pragmatic knowledge. It appears to involve the analytic processing of the left hemisphere and the holistic processing of the right. To study hemisphere involvement in language processing, patients with unilateral right or left hemisphere lesions and a matched neurologically normal control group were tested on their ability to perceive stress and intonation contrasts in words and phrases of varying length. The results suggest that both hemispheres are involved in normal language processing, each in a qualitatively different way. Whereas the left hemisphere appears to work from the bottom up, analyzing information sequentially and arriving at the overall pattern, the right hemisphere works from the top down, beginning with the overall pattern and working to fill in the details. Moreover, the importance of each hemisphere's participation may change in response to different grammatical and contexual variables.

Considering that the nature of the input is one of the most important variables in determining how the brain will process information, findings from tachistoscopic studies aimed at assessing hemispheric specializations are examined in terms of the characteristics of the incoming information either available or required for processing. The basic features of the tachistoscopic technique are analyzed, and a framework for further investigation is suggested along with a reinterpretation of existing evidence. In a subsequent series of four experiments, several assumptions and interpretations made earlier are empirically tested. In a second series of three experiments, hemispheric asymmetries are examined with respect to the properties of the visual system and its capacity to extract information in terms of the spatial-frequency spectral components of a stimulus. Methodological and theoretical implications of the results are discussed, and an account of cerebral specialization suggesting a hemispheric sensitivity to different aspects of the same information is proposed.

Many athletes and spectators believe that experiencing and controlling psychological momentum is a critical component to achieving success in sport (Perreault, Vallerand, Montgomery, & Provencher, 1998; Stanimirovic & Hanrahan, 2004). Despite this, little is known regarding why some individuals perceive momentum differently than others. This study was designed to determine if optimistic thinking has a relationship with psychological momentum perceptions. Female Division I NCAA volleyball players (N = 68) completed the Life Orientation Test – Revised (Scheier, Carver, & Bridges, 1994), the Sport Attributional Style Scale - Short (Hanrahan & Grove, 1990b), and a psychological momentum survey. The results indicated that attributional style constructs intentionality and globality were significant predictors of psychological momentum perceptions. Also, participants had greater disagreement regarding the momentum value of early and late points in a set than those in between. Neither dispositional optimism nor sport-specific optimistic attributional style were correlated with psychological momentum perceptions. Future attempts to measure psychological momentum perceptions should consider a mixed methods approach along with more ecologically valid assessment protocols. / Department of Psychological Science