The pupils of the eyes reflexively constrict in light and dilate in dark to optimize retinal illumination. Non-visual cognitive factors, like attention, arousal, decision-making, etc., also influence pupillary light response. During passive viewing, the eccentricity of a stimulus modulates the pupillary aperture size driven by spatially weighted corneal flux density, which is the product of luminance and the area of the stimulus. Whether the scope of attention also influences PLR remains unclear. In this study, we contrasted the pupil dynamics between (...) diffused and focused attentional conditions during decision-making, while the global CFD remained the same in the two conditions. A population of 20 healthy humans participated in a pair of forced choice tasks. They distributed attention to the peripheral decision cue in one task, and concentrated at the center in the other to select the target from four alternatives for gaze orientation. The location of this cue did not influence participants’ reaction time. However, the magnitude of constriction was significantly less in the task that warranted attention to be deployed at the center than on the periphery. We observed similar pupil dynamics when participants either elicited or canceled a saccadic eye movement, which ruled out pre-saccadic obligatory attentional orientation contributing to PLR. We further addressed how the location of attentional deployment might have influenced PLR. We simulated a biomechanical model of PLR with visual stimulation of different strengths as inputs corresponding to the two attentional conditions. In this homeomorphic model, the computational characteristic of each element was derived from the physiological and/or mechanical properties of the corresponding biological element. The simulation of this model successfully mimicked the observed data. In contrast to common belief that the global ambient luminosity drives pupillary response, the results of our study suggest that the effective CFD determined via the luminance multiplied by the size of the stimulus at the location of deployed attention in the visual space is critical for the magnitude of pupillary constriction. (shrink)

Neural substrates of fatigue in traumatic brain injury are not well understood despite the considerable burden of fatigue on return to productivity. Fatigue is associated with diminishing performance under conditions of high cognitive demand, sense of effort, or need for motivation, all of which are associated with cognitive control brain network integrity. We hypothesize that the pathophysiology of TBI results in damage to diffuse cognitive control networks, disrupting coordination of moment-to-moment monitoring, prediction, and regulation of behavior. We investigate the cingulo-opercular (...) and frontoparietal networks, which are engaged to sustain attention for task and maintain performance. A total of 61 individuals with mild TBI and 42 orthopedic control subjects participated in functional MRI during performance of a constant effort task requiring altering the amount of effort utilized to manually squeeze a pneumostatic bulb across six 30-s trials. Network-based statistics assessed within-network organization and fluctuation with task manipulations by group. Results demonstrate small group differences in network organization, but considerable group differences in the evolution of task-related modulation of connectivity. The mild TBI group demonstrated elevated CO connectivity throughout the task with little variation in effort level or time on task, while CO connectivity diminished over time in controls. Several interregional CO connections were predictive of fatigue in the TBI group. In contrast, FP connectivity fluctuated with task manipulations and predicted fatigue in the controls, but connectivity fluctuations were delayed in the mild traumatic brain injury group and did not relate to fatigue. Thus, the mTBI group’s hyper-connectivity of the CO irrespective of task demands, along with hypo-connectivity and delayed peak connectivity of the FP, may allow for attainment of task goals, but also contributes to fatigue. Findings are discussed in relation to performance monitoring of prediction error that relies on internal cues from sensorimotor feedback during task performance. Delay or inability to detect and respond to prediction errors in TBI, particularly evident in bilateral insula-temporal CO connectivity, corresponds to day-to-day fatigue and fatigue during task performance. (shrink)

In his 1993 Nicod Lectures, Jerry Fodor proposed a solution to a certain version of the problem of‘inscrutability of reference’, which problem poses a challenge to a certain naturalistic, computational approach to cognition which Fodor has favoured. The problem is that purely informational accounts of an agent's mental contents cannot discriminate meanings finely enough. Fodor proposes a strategy of solution which appeals to the inferential dispositions of agents to discriminate contents more finely. After a brief exposition of the problem and (...) Fodor's bid for solution, I employ three counterexamples to argue that Fodor's proposal cannot succeed. (shrink)

The traditional conception of knowledge is justified, true belief. If one looks at a modern textbook on epistemology, the great bulk of questions with which it deals are to do with personal knowledge, as embodied in beliefs and the proper experiences that someone ought to have had in order to have the right (or justification) to know. I intend to argue that due to the explosive growth of knowledge whose domain is “outside the head”, this conception has outlived its relevance. (...) -/- On the other hand, Karl Popper’s (1934) Falsificationism, with its emphasis on the objective character of knowledge, is not only a sounder, but also a more appropriate theory of knowledge for understanding the nature and growth of civilization. Later, Popper (1945) generalized this approach to obtain critical rationalism, in which all claims to knowledge, whether scientific or otherwise, are understood as objective solutions to objective problems and can be evaluated by other non-observational - types of criticism. I will first argue that Popper’s methodology is quite suited to the view that knowledge is an objective autonomous product and then adduce his theory of world 3, an ontology that neatly wraps up various considerations. World 3 is the domain of abstract products of the human mind that now have a life of their own, outside of human heads: theories, arguments, problems, plans, etc. I then adduce some other arguments for the autonomous quality of knowledge. (shrink)

Argues that the planetary crisis, which has been produced by modernity, demands a postmodern politics.

THE MIND-BODY PROBLEM: A GUIDE TO THE CURRENT DEBATE (EDITED BY RICHARD WARNER AND TA D E U S Z SZUBKA) contains recent essays by the key players in the the field of the Mind-Body problem: Searle, Fodor, Problem Honderich, Nagel, McGinn, Stich, Rorty and others. But there are a few interesting exceptions, for example Edelman, Popper, Putnam and Dennett. Nevertheless, these thinkers do get a mention here and there, and nearly all the exciting topical issues are dealt with, including (...) externalism, functionalism, intentionality, Turing computational models, and the relationship between these philosophical problems and psychology. I am particularly struck by the tendency to engage in an evasive stratagem when it comes to stating the physicalist thesis. Instead of a clear definitive position about what kind of physical science would achieve the hoped-for reduction, what I found was variations on Lewis's claim that the reduction would be effected by a "unified body of scientific theories of the sort we now accept". Materialism used to be a clear doctrine: a clockwork Universe of impenetrable particles. But materialism transcended itself. First through Hobbes' and Leibniz's criticisms of Descartes, then Newton's demolition of the Cartesian idea that matter was essentially extension by introducing gravity (action at a distance) and then through the field theories of Faraday and Maxwell, and more recently through Einstein's work, which undermined the "substance" view of matter, something that remained permanent while other changes occurred. I contrast the perspectives of the Churchlands with those of Donald T. Campbell, Karl Popper and other evolutionary and emergentist views. -/- . (shrink)

Michel Haar supports the natural, but he fails to see that the drives behind technology— people's curiosity, exploration and desire to control—could not be more natural. They are, after all, part of our evolutionary heritage. As Konrad Lorenz, the famous ethologist, shows in Behind the Mirror. In his discussion of alienation, Haar also overlooks the work of Friedrich Hayek, the Nobel prizewinning economist, who explores the emergence of the extended society of worldwide markets in his book Fatal Conceit. Hayek predicts (...) that there will always be a tension between our instinctive need for the closeness and familiarity of the tribal-like grouping and the extended market. I contrast Haar also with the perspective of William Warren Bartley III in his book Unfathomed Knowledge, Unmeasured Wealth, in which a Bartley expounds a logical/epistemological argument to the effect that alienation of our products is insuperable. (shrink)

The myth of the framework, as Popper explains it, is the idea that a rational and fruitful discussion is impossible unless the participants share a common framework of basic assumptions or, at least, unless they have agreed on such a framework for the purposes of the discussion. Popper admits that understanding another mind or language max' be difficult, but if there is a desire to understand another person's aims and problems you can bridge the gap.

ROGER SCRUTON’s An Intelligent Person’s Guide to Philosophy takes a personal and provocative look at the subject—those abstract, but nevertheless practical, problems that concern anyone who has reflected on his or her life. Of special delight is his discussion of sex and music. I make some brief critical comments on this based on new economic approaches.

JOHN SEARLE is clear, challenging and profound, and his book The Mystery of Consciousness reflects its author. It offers an engaging debate between Searle and David Chalmers, Daniel Dennett, Roger Penrose and Israel Rosenfield. Searle also touches on the work of Gerald Edelman and Francis Crick. Yet Searle does not always hit the target. For example, he confuses giving an explanation with giving an ultimate explanation in criticising Edelman's reentry mapping.

A review of a book on Popper's encounter with Wittgenstein.

Review of Confessions of a Philosopher by Bryan Magee. Magee's heroes are those philosophers who did not lose their childhood wonder, but instead, cultivated it and tried to answer the big questions. His list includes Hume, Kant and Schopenhauer, and, this century, Heidegger, Popper, Russell and Wittgenstein. The villains are the philosophers who have tried to reduce philosophy to the linguistic analysis of questions without trying to answer them: Austin, Ryle and Strawson. Magee had the good fortune to have known (...) two of this century's greatest philosophers, Popper and Russell. (shrink)

Spanning forty years of Ray's career, these essays, for the first time collected in one volume, present the filmmaker's reflections on the art and craft of the cinematic medium and include his thoughts on sentimentalism, mass culture, ...

Examining one of the fundamental issues in cognitive psychology: How does our conscious experience come to be the way it is?