‘The similes of the Sun, Line, and Cave in the Republic remain a reproach to Platonic scholarship because there is no agreement about them, though they are meant to illustrate.’ So wrote A.S. Ferguson in 1934, and so he could write to-day. Four decades have produced at least twenty more substantial contributions to the debate, but no agreement. I shall not attempt to arbitrate between existing interpretations, nor shall I offer an account of the ‘simile of light’ as a whole. (...) I shall confine my attention to a single point: the significance of the shadows in the cave, and of the objects which cast them. The suggestion I shall make seems an obvious one, but I have not found it in the literature. I hope to show at least that it deserves serious consideration. (shrink)

In a recent article, C. H. Kahn addresses an ‘old scholarly myth’, namely the idea that Book I of the Republic began life as an earlier, independent dialogue and was subsequently adapted to serve as a prelude to the much longer work that we know. The case for this hypothesis rests both on stylometric considerations and on the many ‘Socratic’ features that Book I, unlike the rest of the Republic, shares with Plato's earlier works. Having disposed of the positive arguments (...) in favour of the ‘myth’, Kahn turns to the contrary—and in his view overwhelming—evidence that Book I was composed from the start as an integral part of the longer Republic. He catalogues 12 passages in Book I, accounting for roughly half its length, whose full significance will, he argues, only emerge if they are seen as instances of prolepsis, deliberate anticipations of what is to come in later books. (shrink)

At the beginning of Book II of the Republic, Glaucon and Adeimantus ask Socrates to tell them what it is to be just or unjust, and why a man should be the former. Socrates suggests in reply that they consider first what it is for a polis to be just or unjust—a polis is bigger than an individual, he says, so its justice should be more readily visible. Now if we were to view in imagination a polis coming into existence, (...) he goes on, we should see also its justice and injustice coming into existence, and this might help us to discover what these qualities are. (shrink)

Implicit processes almost certainly preceded explicit processes in our evolutionary history, so they are likely to be more resistant to disruption according to the principles of evolutionary biology [Reber, A. S. . The cognitive unconscious: An evolutionary perspective. Consciousness and Cognition, 1, 93–133.]. Previous work . Knowledge, nerves and know-how: The role of explicit versus implicit knowledge in the breakdown of a complex motor skill under pressure. British Journal of Psychology, 83, 343–358.]) has shown that implicitly learned motor skills remain (...) stable under psychological pressure and concurrent cognitive demands, and recently [Poolton, J. M., Masters, R. S. W., & Maxwell, J. P. . Passing thoughts on the evolutionary stability of implicit motor behaviour: Performance retention under physiological fatigue. Consciousness and Cognition, 16, 456–468.] showed that they also remain stable under conditions of anaerobic fatigue that would have significantly challenged the survival skills of our ancestors. Here we examine the stability of an implicitly learned motor skill under fatigue conditions that primarily tax a different physiological system , but which have equally strong evolutionary connotations. Participants acquired a throwing task by means of an errorless learning method or an errorful method. Motor performance in the errorless condition, but not the errorful condition, remained stable following an exhaustive VO2 max. running test. Our findings replicate and extend the work of Poolton et al., providing further support for Reber’s evolutionary distinction between implicit and explicit processes. (shrink)

§1. The origins of recursion theory. In dedicating a book to Steve Kleene, I referred to him as the person who made recursion theory into a theory. Recursion theory was begun by Kleene's teacher at Princeton, Alonzo Church, who first defined the class of recursive functions; first maintained that this class was the class of computable functions ; and first used this fact to solve negatively some classical problems on the existence of algorithms. However, it was Kleene who, in his (...) thesis and in his subsequent attempts to convince himself of Church's Thesis, developed a general theory of the behavior of the recursive functions. He continued to develop this theory and extend it to new situations throughout his mathematical career. Indeed, all of the research which he did had a close relationship to recursive functions.Church's Thesis arose in an accidental way. In his investigations of a system of logic which he had invented, Church became interested in a class of functions which he called the λ-definable functions. Initially, Church knew that the successor function and the addition function were λ-definable, but not much else. During 1932, Kleene gradually showed1 that this class of functions was quite extensive; and these results became an important part of his thesis 1935a. (shrink)

Forty‐nine subjects judged the relevancy of sentence parts of a word problem (the Allsports problem). Patterns of subjects' judgments suggest three problem‐solving heuristics: a SETS heuristic, a TIME heuristic, and a QUESTION heuristic. Presentation of the question before the problem tends to suppress SETS and TIME heuristics. A computer program (ATTEND) is presented to simulate subjects' behavior on the Allsports problem. The program is context‐sensitive in that it can change a relevance judgment upon the acquisition of further information. Averaged subject (...) judgments and ATTEND judgments agree for 87% of the items. (shrink)

This article investigates the potential of fMRI to test assumptions about different components in models of complex cognitive tasks. If the components of a model can be associated with specific brain regions, one can make predictions for the temporal course of the BOLD response in these regions. An event‐locked procedure is described for dealing with temporal variability and bringing model runs and individual data trials into alignment. Statistical methods for testing the model are described that deal with the scan‐to‐scan correlations (...) in the errors of measurement of the BOLD signal. This approach is illustrated using a “sacrificial” ACT‐R model that involves mapping 6 modules onto 6 brain regions in an experiment from concerned with equation solving. The model's visual encoding predicted the BOLD response in the fusiform gyrus, its controlled retrieval predicted the BOLD response in the lateral inferior prefrontal cortex, and its subgoal setting predicted the BOLD response in the anterior cingulate cortex. On the other hand, its motor programming failed to predict anticipatory activation in the motor cortex, its representational changes failed to predicted the pattern of activity in the posterior parietal cortex, and its procedural component failed to predict an initial spike in caudate. The results illustrate the power of such data to direct the development of a theory of complex problem solving, both at the level of a specific task model as well as at the level of the cognitive architecture. (shrink)

This book explains the notational system NUSAP (Numeral, Unit, Spread, Assessment, Pedigree) and applies it to several examples from the environmental sciences.

There are currently two main philosophical theories of perception - Direct Realism and the Representative Theory. The former is supported by most contemporary philosophers, whereas the latter forms the groundwork for most scientific theories in this area. The paper describes a recent experiment involving retinal and cortical rivalry that provides strong empirical evidence that the Direct Realist theory is incorrect. There are of course a large number of related experiments on visual perception that would tend to lead us to the (...) same conclusion, but the experiment described in this paper does so in a singularly direct and straightforward manner. Often the most telling experiments are the simplest. (shrink)

BackgroundHospitalized older adults frequently have impaired cognition and must rely on surrogates to make major medical decisions. Ethical standards for surrogate decision making are well delineated, but little is known about what factors surrogates actually consider when making decisions.ObjectivesTo determine factors surrogate decision makers consider when making major medical decisions for hospitalized older adults, and whether or not they adhere to established ethical standards.DesignSemi-structured interview study of the experience and process of decision making.SettingA public safety-net hospital and a tertiary referral (...) hospital in a large city in the Midwest United States.ParticipantsThe study included 35 surrogates with a recent decision-making experience for an inpatient aged 65 or older.MeasurementsThe key factors that surrogates considered when making decisions. Interview transcripts were coded and analyzed using the grounded theory method of qualitative analysis.ResultsSurrogates considered patient-centered factors and surrogate-centered factors. Patient-centered factors included: respecting the patient’s input, using past knowledge of the patient to infer the patient’s wishes, and consider ing what is in the patient’s best interests. Some surrogates expressed a desire for more information about the patient’s prior wishes. Surrogate-centered factors included: surrogate’s wishes as a guide, surrogate’s religious beliefs and/or spirituality, surrogate’s interests, and family consensus.ConclusionOur study indicates that surrogate decision making is more complex than the standard ethical models, which are limited to considerations of the patient’s autonomy and beneficence. Because surrogates also imagine what they would want under the circumstances and consider their own needs and preferences, models of surrogate decision making must account for these additional considerations. Surrogates’ desire for more information about patients’ preferences suggests a need for greater advance care planning. (shrink)

A brain-computer interface is a rapidly evolving neurotechnology connecting the human brain with a computer. In its classic form, brain activity is recorded and used to control external devices like protheses or wheelchairs. Thus, BCI users act with the power of their thoughts. While the initial development has focused on medical uses of BCIs, non-medical applications have recently been gaining more attention, for example in automobiles, airplanes, and the entertainment context. However, the attitudes of the general public towards BCIs have (...) hardly been explored. Among the general population in Germany aged 18–65 years, a representative online survey with 20 items was conducted in summer 2018 and analysed by descriptive statistics. The survey assessed: affinity for technology; previous knowledge and experience concerning BCIs; the attitude towards ethical, social and legal implications of BCI use and demographic information. Our results indicate that BCIs are a unique and puzzling way of human–machine interaction. The findings reveal a positive view and high level of trust in BCIs on the one hand but on the other hand a wide range of ethical and anthropological concerns. Agency and responsibility were clearly attributed to the BCI user. The participants’ opinions were divided regarding the impact BCIs have on humankind. In summary, a high level of ambivalence regarding BCIs was found. We suggest better information of the public and the promotion of public deliberation about BCIs in order to ensure responsible development and application of this potentially disruptive technology. (shrink)

Three experiments explore the role of working memory in motor skill acquisition and performance. Traditional theories postulate that skill acquisition proceeds through stages of knowing, which are initially declarative but later procedural. The reported experiments challenge that view and support an independent, parallel processing model, which predicts that procedural and declarative knowledge can be acquired separately and that the former does not depend on the availability of working memory, whereas, the latter does. The behaviour of these two processes was manipulated (...) by providing or withholding visual (and auditory) appraisal of outcome feedback. Withholding feedback was predicted to inhibit the use of working memory to appraise success and, thus, prevent the formation of declarative knowledge without affecting the accumulation of procedural knowledge. While the first experiment failed to support these predictions, the second and third experiments demonstrated that procedural and declarative knowledge can be acquired independently. It is suggested that the availability of working memory is crucial to motor performance only when the learner has come to rely on its use. (shrink)