Issued also as Thesis (Ph. D.)--Columbia University. / Bibliography: p. 53.

Thesis (Ph. D.)--University of Kansas, 1988. / Illustrations, v. 2 (leaves 273-382), not photocopied. Includes bibliographical references (leaves 255-271).

Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2003. / Includes bibliographical references (leaves 96-103). Also available in electronic version. Access restricted to campus users.

In the Critique of Pure Reason, Kant defends the mathematically deterministic world of physics by arguing that its essential features arise necessarily from innate forms of intuition and rules of understanding through combinatory acts of imagination. Knowing is active: it constructs the unity of nature by combining appearances in certain mandatory ways. What is mandated is that sensible awareness provide objects that conform to the structure of ostensive judgment: “This (S) is P.” Sensibility alone provides no such objects, so the imagination compensates by combining passing point-data into “pure” referents for the subject-position, predicate-position, and copula. The result is a cognitive encounter with a generic physical object whose characteristics—magnitude, substance, property, quality, and causality—are abstracted as the Kantian categories. Each characteristic is a product of “sensible synthesis” that has been “determined” by a “function of unity” in judgment. Understanding the possibility of such determination by judgment is the chief difficulty for any rehabilitative reconstruction of Kant’s theory. I will show that Kant conceives of figurative synthesis as an act of line-drawing, and of the functions of unity as rules for attending to this act. The subject-position refers to substance, identified as the objective time-continuum; the predicate-position, to quality, identified as the continuum of property values (constituting the second-order type named by the predicate concept). The upshot is that both positions refer to continuous magnitudes, related so that one (time-value) is the condition of the other (property-value). Kant’s theory of physically constructive grammar is thus equivalent to the analytic-geometric formalism at work in the practice of mathematical physics, which schematizes time and state as lines related by an algebraic formula. Kant theorizes the subject–predicate relation in ostensive judgment as an algebraic time–state function. When aimed towards sensibility, “S is P” functions as the algebraic relation “t → ƒ(t).” / text

Not available / text

The phenomenon of 'slowing down' in response to important cues in the operative field is proposed as a hallmark of expert surgical judgment. As part of a larger program of research, the purpose of this study was to explore a methodology for capturing 'slowing down' moments using a standardised task. Edited videos of 6 laparoscopic cholecystectomies were shown to 10 expert surgeons (>250 laparoscopic cholecystectomies completed). Participants were asked to think aloud while watching them as if observing each procedure in the operating room. Each session was audiotaped and transcribed. Many examples of 'slowing down' moments were identified in the transcripts, including several categories that were previously uncharacterised or undescribed. A subset of 'slowing down' moments was compared between participants. Many appeared to be inconsistent between expert surgeons, suggesting that with this methodology alone, formal teaching and assessment of the 'slowing down' phenomenon will be challenging.

The phenomenon of 'slowing down' in response to important cues in the operative field is proposed as a hallmark of expert surgical judgment. As part of a larger program of research, the purpose of this study was to explore a methodology for capturing 'slowing down' moments using a standardised task. Edited videos of 6 laparoscopic cholecystectomies were shown to 10 expert surgeons (>250 laparoscopic cholecystectomies completed). Participants were asked to think aloud while watching them as if observing each procedure in the operating room. Each session was audiotaped and transcribed. Many examples of 'slowing down' moments were identified in the transcripts, including several categories that were previously uncharacterised or undescribed. A subset of 'slowing down' moments was compared between participants. Many appeared to be inconsistent between expert surgeons, suggesting that with this methodology alone, formal teaching and assessment of the 'slowing down' phenomenon will be challenging.

Judgments of spatial relationships are often made when the object or observer are moving. Behaviourally, there is evidence that these ‘dynamic’ judgments of spatial extent differ from static judgments. Here I used three separate techniques for exploring dynamic judgments: first, a line bisection paradigm was employed to study ocular and pointing judgments of spatial extent while manipulating line length, position, speed, acceleration, and direction of scanning (Experiments 1-4); second, functional MRI (fMRI) was used to examine whether distinct brain regions were involved in dynamic versus static judgments of spatial extent (Exp 5); and finally, a mathematical and computational model of dynamic judgments was developed to provide a framework for interpreting the experimental results. In the behavioural experiments, substantial differences were seen between static and dynamic bisection, suggesting the two invoke different neural processes for computing spatial extent. Surprisingly, ocular and pointing judgments produced distinct bisection patterns that were uncorrelated, with pointing somewhat more impervious to manipulations such as scan direction and position than ocular bisections. However, a new experimental task for probing dynamic judgments (the ‘no line’ Experiment 4) found that scan direction can influence both hand behaviour. Functional MRI demonstrated that dynamic relative to static judgments produced activations in the cuneus and precuneus bilaterally, left cerebellum, and medial frontal gyrus, with reduced activation relative to static judgments observed in the supramarginal gyrus bilaterally. Dynamic bisections relative to a control condition produced activations in the right precuneus and left cerebellum, as well as in left superior parietal lobule, left middle temporal gyrus, and right precentral gyrus. It may be the case that velocity processing and temporal estimates are integrated primarily in the cuneus and precuneus bilaterally to produce estimates of spatial extent under dynamic scanning conditions. These results highlight the fact that dynamic judgments of spatial extent engage brain regions distinct from those employed to make static judgments, supporting the behavioural results that these are separate and distinct. Finally, a mathematical model was proposed for dynamic judgments of spatial extent, based on the idea that, rather than using an ‘all-or-none’ approach, spatial working memory actually takes about 100 ms to reach full representational strength for any given point in space. The model successfully explains many of the effects seen in the behavioural experiments including the effects of scan direction, velocity, line length, and position. In conjunction with the neuroimaging data, it also suggests why neglect patients may fail to show rightward bisection biases when making dynamic judgments of spatial extent. Overall, this work provides novel insights into how the brain executes dynamic judgments of spatial extent.

No description available.

No description available.