Two-matrix orthogonal rotation procedures

Examples are presented in which it is either desirable or necessary to transform two sets of orthogonal axes to simple structure positions by means of the same transformation matrix. A solution is then outlined which represents a two-matrix extension of the general orthomax orthogonal rotation criterion. In certain circumstances, oblique two-matrix solutions are possible using the procedure outlined and the Harris-Kaiser [1964] logic. Finally, an illustrative example is presented in which the preceding technique is applied in the context of an inter-battery factor analysis.The work reported herein was supported by Grant S72-1886 from the Canada Council. The author acknowledges the helpful contributions of Nancy Reid and Lawrence Ward to parts of this paper.     

Behavioral momentum: the effects of the temporal separation of rates of reinforcement.

In Part 1 of the experiment, rats responded under a variable-interval (VI) 30-s schedule and a VI 120-s schedule, with each in effect for a block of consecutive sessions. That is, the two VI schedules were presented in successive conditions. In Part 2 the VI schedules alternated each day, and in Part 3 the schedules alternated within the session as a multiple schedule. For half of the rats in Parts 1 and 2, the VI schedule alternated every few minutes within the session with a stimulus that signaled extinction. For each part, once response rates had stabilized, resistance to change was measured by prefeeding and extinction. When the schedules were examined in successive conditions (Part 1), resistance to extinction was greater under the VI 120-s schedule of reinforcement than under the VI 30-s schedule, but no consistent differences in resistance to prefeeding were observed between the two VI schedules. When the VI schedules alternated each day (Part 2), resistance to extinction was greater under the VI 120-s schedule. However, no consistent differences in resistance to prefeeding were observed between the VI schedules without extinction in Group A, but resistance to prefeeding was greater under the VI 30-s schedule for rats with the added extinction component in Group B. When the VI schedules alternated within the session as a multiple schedule (Part 3), resistance to extinction and resistance to prefeeding were greater under the VI 30-s schedule. The data suggest that different rates of reinforcement, and their accompanying discriminative stimuli, must be compared within the same session (or at least on alternate days) to produce data consistent with the behavioral momentum model.     

Estimation of interhemispheric dynamics from simple unimanual reaction time to extrafoveal stimuli

This essay reviews research on interhemispheric transfer time derived from simple unimanual reaction time to hemitachistoscopically presented visual stimuli. Part 1 reviews major theoretical themes including (a) the significance of the eccentricity effect on interhemispheric transfer time in the context of proposed underlying neurohistological constraints; (b) the significance of gender differences in interhemispheric transfer time and findings in dyslexics and left-handers in the context of a fetal brain testosterone model; and (c) the significance of complexity effects on interhemispheric transfer time in a context of dynamic vs. hard-wired concepts of the underlying interhemispheric communication systems. Part 2 consists of a meta-analysis of 49 published behavioral experiments, in view of drawing a portrait of the best set of experimental conditions apt to produce salient, reliable, and statistically significant measures of interhemispheric transfer time, namely (a) index rather than thumb response, (b) low rather than high target luminance, (c) short rather than prolonged target display, and (d) very eccentric rather than near-foveal stimulus location. Part 3 proposes a theoretical model of interhemispheric transfer time, postulating the measurable existence of fast and slow interhemispheric channels. The proposed mechanism's evolutionary adaptive value, the neurophysiological evidence in its support, and favorable functional evidence from studies of callosotomized patients are then presented followed by proposals for critical experimental tests of the model.     

Assessing empirical research in bioethics

Empirical research can aid ethical reflection in bioethics by identifying issues, by seeing how they are currently resolved, and by assessing the consequences of these current resolutions. This potential can be misused when the ethical issues in question are fundamentally non-consequentialist or when they are consequentialist but the empirical research fails to address the important consequences. An example of the former problem is some recent studies about bad consequences resulting from commercialized living kidney donor programs. These consequences could be avoided, but the crucial non-consequentialist ethical issues about exploitation and commercialization would still remain. Examples of the latter problem are provided by recent studies of the allocation of ICU beds and of physician deception, where important consequences were not adequately studied.     

Behavior systems and reinforcement: an integrative approach.

Most traditional conceptions of reinforcement are based on a simple causal model in which responding is strengthened by the presentation of a reinforcer. I argue that reinforcement is better viewed as the outcome of constraint of a functioning causal system comprised of multiple interrelated causal sequences, complex linkages between causes and effects, and a set of initial conditions. Using a simplified system conception of the reinforcement situation, I review the similarities and drawbacks of traditional reinforcement models and analyze the recent contributions of cognitive, regulatory, and ecological approaches. Finally, I show how the concept of behavior systems can begin to incorporate both traditional and recent conceptions of reinforcement in an integrative approach.     

The Logic Of Reliable And Efficient Inquiry

Journal of Philosophical Logic - This paper pursues a thorough-going instrumentalist, or means-ends, approach to the theory of inductive inference. I consider three epistemic aims: convergence to a...     

Religion and Science Conversation: A Case Illustration

The March 1999 issue of Zygon provides a case illustration of a religion-and-science conversation. The three responses to the issues raised by The Humanizing Brain represent a spectrum ranging from skepticism to affirmation. Each is examined in turn. Next, we present a constructive set of guidelines beginning with the recognition that interdisciplinary talk requires stretching disciplinary language into metaphor and analogy. We conclude with a methodology emphasizing empiricism and wholism.     

Storytellers and Scenario Spinners: Some Reflections on Religion and Science in Light of a Pragmatic, Evolutionary Theory of Knowledge

Asserting that both scientists and religious thinkers are involved in telling stories about the past and spinning scenarios about the future, I first compare and contrast the purposes of scientific and religious storytelling. Then, in light of some recent work on brain and language evolution, I offer a possible story about how humans might have become storytellers. Finally, I discuss how religious stories might be evaluated pragmatically and even scientifically by developing Lakatosian-type research programs.     

Predictive coding explains binocular rivalry: an epistemological review

Binocular rivalry occurs when the eyes are presented with different stimuli and subjective perception alternates between them. Though recent years have seen a number of models of this phenomenon, the mechanisms behind binocular rivalry are still debated and we still lack a principled understanding of why a cognitive system such as the brain should exhibit this striking kind of behaviour. Furthermore, psychophysical and neurophysiological (single cell and imaging) studies of rivalry are not unequivocal and have proven difficult to reconcile within one framework. This review takes an epistemological approach to rivalry that considers the brain as engaged in probabilistic unconscious perceptual inference about the causes of its sensory input. We describe a simple empirical Bayesian framework, implemented with predictive coding, which seems capable of explaining binocular rivalry and reconciling many findings. The core of the explanation is that selection of one stimulus, and subsequent alternation between stimuli in rivalry occur when: (i) there is no single model or hypothesis about the causes in the environment that enjoys both high likelihood and high prior probability and (ii) when one stimulus dominates, the bottom-up, driving signal for that stimulus is explained away while, crucially, the bottom-up signal for the suppressed stimulus is not, and remains as an unexplained but explainable prediction error signal. This induces instability in perceptual dynamics that can give rise to perceptual transitions or alternations during rivalry.