Relations between the physiology of attention and the physiology of consciousness

Summary Consciousness, analyzed as a neurological system like any other, has four functions. The first is planning and setting up behavioral plans or schemata in advance of their execution in behavior. This function requires an internal record of the schema with its subordinate parts and of the current status of its execution. The second function is execution, which requires giving a priority to each schema and executing the one with the highest priority. The third is directing two kinds of attention: outside-in attention changes priorities as a result of demands from the environment; inside-out attention directs behavior toward particular aspects of the environment on the basis of the needs of the current schema. Fourth is retrieving long-term episodic memories, which can be used only in planning, executing, and attention. Aspects of these functions can be seen in neurophysiology, especially in frontal and temporal lobes. Psychophysical analysis of visual functions shows that most information processing proceeds without consciousness.     

On the tunnel effect

The experiments described in this paper consist of presenting observers with two similar objects in successive movement in the same plane but of which the end of the first and the beginning of the second are hidden by a screen (tunnel). Under proper experimental conditions the impression received is one of continuous and uniform movement by a single object passing behind the screen.

The hidden phase of this movement assumes all of the characteristics of true, visible movement for its entire extent, and any lengthening of the duration of the invisible phase gives the impression of a momentary halt behind the screen at a definite point. A modification of the position or of the relative orientation of the visible portions of the trajectory influences the apparent form of its invisible portion. This form can be made to assume the aspects of complicated curves which are sketched and described by different observers with remarkable consistency.

All these phenomena are dependent upon the objctive conditions: the speed of the objects while they are visible, the length of the tunnel, the duration of the invisible phase, the relative position of the visible portions of the trajectory; and they vary systematically with these conditions. As one or other of these conditions is varied, the impression of continuity may give way to one of a simple succession of independent movements.

It is thought that the absence of sensory qualities justifies the use of the term “amodal data” to describe the way in which the hidden movement phase makes itself known to the observer. These “amodal data” form the bridge between the modal phases and become an integral part of the total sensory experience. These properties are determined by the nature of the complex system of excitations in the same way as those of the modal phases and one can thus consider this amodal aspect of the combined experience as a truly perceptual phenomenon.     

The psychology and physiology of temperament: pragmatism in context

This paper traces William James's famous "temperament thesis" according to which the philosophical stance that individuals take depends on their "temperaments." It seeks to understand James's conception of temperament by locating James within a set of contemporary investigations that linked the sources of mental, and even higher, intellectual processes to the physiological and organic constitution of the individual. The paper argues that James understood temperament along the reflex-arc model and discusses the implications of that physiological account of temperament for James's overall conception of philosophy.     

Chaos in physiology

A bird’s eye view of the role of nontrivial dynamical phenomena in physiological systems is presented. Many levels in the physiological hierarchy are affected. It appears that physiology has a particularly high affinity to chaos. The old central place of physiology in the circle of sciences can perhaps be regained if the two disciplines join resources. Even physics may turn out to be dependent on the chaotic micro dynamics of the brain.     

The physiology of willpower: linking blood glucose to self-control.

Past research indicates that self-control relies on some sort of limited energy source. This review suggests that blood glucose is one important part of the energy source of self-control. Acts of self-control deplete relatively large amounts of glucose. Self-control failures are more likely when glucose is low or cannot be mobilized effectively to the brain (i.e., when insulin is low or insensitive). Restoring glucose to a sufficient level typically improves self-control. Numerous self-control behaviors fit this pattern, including controlling attention, regulating emotions, quitting smoking, coping with stress, resisting impulsivity, and refraining from criminal and aggressive behavior. Alcohol reduces glucose throughout the brain and body and likewise impairs many forms of self-control. Furthermore, self-control failure is most likely during times of the day when glucose is used least effectively. Self-control thus appears highly susceptible to glucose. Self-control benefits numerous social and interpersonal processes. Glucose might therefore be related to a broad range of social behavior.     

The influence of calibration method and eye physiology on eyetracking data quality

Recording eye movement data with high quality is often a prerequisite for producing valid and replicable results and for drawing well-founded conclusions about the oculomotor system. Today, many aspects of data quality are often informally discussed among researchers but are very seldom measured, quantified, and reported. Here we systematically investigated how the calibration method, aspects of participants’ eye physiologies, the influences of recording time and gaze direction, and the experience of operators affect the quality of data recorded with a common tower-mounted, video-based eyetracker. We quantified accuracy, precision, and the amount of valid data, and found an increase in data quality when the participant indicated that he or she was looking at a calibration target, as compared to leaving this decision to the operator or the eyetracker software. Moreover, our results provide statistical evidence of how factors such as glasses, contact lenses, eye color, eyelashes, and mascara influence data quality. This method and the results provide eye movement researchers with an understanding of what is required to record high-quality data, as well as providing manufacturers with the knowledge to build better eyetrackers.     

The Duchenne smile: emotional expression and brain physiology. II

Facial expression, EEG, and self-report of subjective emotional experience were recorded while subjects individually watched both pleasant and unpleasant films. Smiling in which the muscle that orbits the eye is active in addition to the muscle that pulls the lip corners up (the Duchenne smile) was compared with other smiling in which the muscle orbiting the eye was not active. As predicted, the Duchenne smile was related to enjoyment in terms of occurring more often during the pleasant than the unpleasant films, in measures of cerebral asymmetry, and in relation to subjective reports of positive emotions, and other smiling was not.     

The physiology of attention: participation of cat striate cortex in behavioral choice

Summary In the awake, behaving cat, we have compared response of striate cortex neurons to informative and to noninformative stimuli. A cat pressed a pedal in response to a flashed pattern repeated every 10 s, receiving a reward if the press was within a 0.5–1.5-s post-stimulus window. There were three trial types: 50% of the trials had only the initial informative flash, 25% had an additional physically identical, but unrewarded, flash 500 ms after the first, and 25% had an unrewarded flash 3–5 s after the informative flash. Cats learned to respond only to the rewarded flashes. Neurons were divided into two categories: 27 neurons defined as primary showed an early burst of firing 30–70 ms after stimulus onset, and 17 did not. The distinction was arbitrary, since all cells were exposed to the same stimulus. For stimuli preceding a pedal press, stimulus-synchronized histograms of primary neurons had a smaller early burst and more firing before and after it. Response-synchronized histograms showed an abrupt decrease in firing shortly before the pedal press. The effects were stronger for primary cells in the stimulus-synchronized data and stronger for non-primary cells in the response-synchronized data.     

The effects of protective helmet use on physiology and cognition in young cricketers

Many studies have reported physiological and cognitive decrements following heat stress. Of particular concern in cricket are the possible negative effects of sustained protective helmet use, as this leads to an increase in heat‐related stress. Correct and rapid decision making, and focused attention are essential for efficient performance whilst batting, and it is possible that helmet usage could impair such processes. In a repeated‐measures, randomized crossover study, physiological, self‐report, and cognitive measures were taken from 16 teenage cricketers before and after moderately intense (batting) exercise. Participants underwent the assessments twice, once while wearing a standard protective helmet, and again, when not wearing a helmet (counterbalanced). While helmet use did not lead to significant physiological changes, wearing a helmet led to some cognitive impairments in attention, vigilance and reaction times. These preliminary findings could have significance for cognitively demanding sports (and perhaps military and industrial settings) in which participants perform cognitively demanding operations under conditions of physical exercise whilst wearing protective helmets. Additional factors of hydration, exercise duration, and helmet design are discussed. Copyright © 2004 John Wiley & Sons, Ltd.     

Decoding the language of the heart: Developing a physiology of inclusion

Constructs such as homeostasis and fight/flight have supported a scientific approach to physiology that has yielded a vast database of obvious heuristic value. Yet in spite of its value, these constructs have tended to create a mind-set that unwittingly supports what this article has labeled a “physiology of exclusion.” Reinforced by the philosophy of René Descartes, this perspective has led investigators to focus on isolated or separate animal organisms that are reflexively wired for self-preservation. It has created a mind-set in which both research investigators and the public at large tend to view the human body as either in a steady state of vigilance, maximally prepared for fight/flight, or in a state of quiescence. Assumptions of the solitary body, and solitary man wired to react for “self” preservation, has made it difficult to incorporate a growing body of evidence that indicates that social support and loving relationships are conducive to good health. It also has made it difficult for investigators to fully understand why human loneliness is a major cause of premature death. This article delineates these trends and offers a new construct, one that suggests that a “physiology of inclusion” be added to the prevailing view of a “physiology of exclusion.” Recent cardiovascular research is cited to help underscore the potential heuristic value of this new physiological construct.     

Carpal tunnel mechanics and its relevance to carpal tunnel syndrome

The carpal tunnel is an elaborate biomechanical structure whose pathomechanics plays an essential role in the development of carpal tunnel syndrome. The purpose of this article is to review the movement related biomechanics of the carpal tunnel together with its anatomical and morphological features, and to describe the pathomechanics and pathophysiology associated with carpal tunnel syndrome. Topics of discussion include biomechanics of the median nerve, flexor tendons, subsynovial tissue, transverse carpal ligament, carpal tunnel pressure, and morphological properties, as well as mechanisms for biomechanical improvement and physiological restoration. It is our hope that the biomechanical knowledge of the carpal tunnel will improve the understanding and management of carpal tunnel syndrome.     

Amodal causal capture in the tunnel effect

In addition to identifying individual objects in the world, the visual system must also characterize the relationships between objects, for instance when objects occlude one another or cause one another to move. Here we explored the relationship between perceived causality and occlusion. Can one perceive causality in an occluded location? In several experiments, observers judged whether a centrally presented event involved a single object passing behind an occluder, or one object causally launching another (out of view and behind the occluder). With no additional context, the centrally presented event was typically judged as a non-causal pass, even when the occluding and disoccluding objects were different colors--an illusion known as the 'tunnel effect' that results from spatiotemporal continuity. However, when a synchronized context event involved an unambiguous causal launch, participants perceived a causal launch behind the occluder. This percept of an occluded causal interaction could also be driven by grouping and synchrony cues in the absence of any explicitly causal interaction. These results reinforce the hypothesis that causality is an aspect of perception. It is among the interpretations of the world that are independently available to vision when resolving ambiguity, and that the visual system can 'fill in' amodally.