Jeffrey Kinsella-Shaw

Ecological mechanics: A physical geometry for intentional constraints

Abstract A proposal is made for a new discipline, ecological mechanics . This version of mechanics is complementary but not reducible to classical relativity, and quantum mechanics. Where traditional mechanics attempt causal analyses for all motions, ecological mechanics explicitly addresses the motions of living systems that exhibit goal-directedness. The shortcomings of the physical geometries underlying traditional mechanics are reviewed, and means are proposed for redressing their deficiencies for modeling the behaviors of intentional systems. This demands a new physical geometry that retains all the best features of the old ones but is extended to accommodate intentional acts. The new physical geometry combines a variant of Minkowskis space-time geometry with a (Cantorian) fractal geometry which reformulates Einsteins energy conversion law ( E = mc 2 ) and Plancks energy distribution law ( E = fh ) so that they apply, more realistically, to the scale of living systems. A new scaling technique called ecometrics , is introduced for accomplishing this feat. This approach assumes a symmetry operator which acts to ‘intentionalize’ causation and to ‘causalize’ intention so that perceptual information and action control processes are defined over a commensurate but dual measurement bases. The promise of ecological mechanics rests on the imputed discovery of a new conservation law which holds locally rather than absolutely. Empirical evidence is reviewed and graphically portrayed mathematical arguments are given that tend to support the hypothesis.

Inquiry into intentional systems I: Issues in ecological physics

SummaryThe role of intention in guiding the behavior of goal-directed systems is a problem that continues to challenge behavioral science. While it is generally agreed that intentional systems must be consistent with the laws of physics, there are many obvious differences between inanimate, physical systems and sentient, intentional systems. This suggests that there must be constraints over and above those of physics that govern goal-directed behavior. In this paper it is suggested that generic properties of self-organizing mechanisms may play a central role in the origin and evolution of intentional constraints. The properties of self-organizing systems are first introduced in the context of simple physical systems and then extended to a complex (biological) system. Whereas behavior of an inanimate physical system is lawfully determined by force fields, behavior of an animate biological system is lawfully specified by information fields. Biological systems are distinguished from simple physical systems in terms of their ubiquitous use of information fields as special (biological and psychological, social, etc.) boundary conditions on classical laws. Unlike classical constraints (boundary conditions), informational constraints can vary with time and state of the system. Because of the nonstationarity of the boundary conditions, the dynamic of the system can follow a complex trajectory that is organized by a set of spatially and temporally distributed equilibrium points or regions. It is suggested that this equilibrium set and the laws that govern its transformation define a minimal requirement for an intentional system. One of the benefits of such an approach is that it suggests a realist account for the origin of semantic predicates, thereby providing a basis for the development of a theory of symbolic dynamics. Therefore, the principles of self-organization provide a comprehensive basis for investigating intentional systems by suggesting how it is that intentions arise, and by providing a lawful basis for intentional behavior that reveals how organisms become and remain lawfully informed in the pursuit of their goals.

Role of the inertia tensor in haptically perceiving where an object is grasped.

When an object is held and wielded, a time-invariant quantity of the wielding dynamics is the inertia tensor Iij. Examination of Iij as a function of different locations at which a cylindrical object is grasped revealed that the off-diagonal components of Iij--the products of inertia--related most systematically to grip position. In 3 experiments, Ss wielded an occluded rod held at an intermediate point along its length and reproduced, with the other hand, the felt grip position on a visible rod. In Experiment 1, the wielded rods were homogeneous; in Experiments 2 and 3, weights were added on either side of the grasp, with different manners of grasp contrasted in Experiment 3. In all 3 experiments, perceived hand position was predicted by Iij. Discussion was focused on the role of Iijs eigenvalues in perceiving the magnitudes of objects and Iijs eigenvectors in perceiving hand-object relations (e.g., position of grasp).

Peripheral neuropathy and object length perception by effortful (dynamic) touch: a case study.

The spatial extents of hand-held objects can be perceived nonvisually by wielding them. This ability of effortful or dynamic touch to exploit the mass moments of an object to perceive its length was evaluated with a 40-years old right-handed woman with surgically treated Arnold-Chiari Type 1 Malformation and cervical syrinx. At the time of the experiment she presented with loss of discriminative touch in the left arm but no comparable sensory deficits in the right arm or the lower extremities. She could neither identify objects in her left hand nor tell that they were in the hand while manipulating them. She could, however, grasp an object tightly and wield it on request. In the experiment she wielded weighted rods of 45, 60, and 80cm length about the wrist. There were two main results. First, her nonvisual perception of rod length by the insensate left arm scaled systematically with rod moment of inertia. The scaling matched that of the intact right arm and the nondominant arm of haptically unimpaired controls tested with rods of similar dimensions. Second, her right arm was superior in accuracy and reliability than her insensate left arm and was equal to or better than the dominant arm of the control group on key measures of nonvisual length perception. The first result was evaluated in respect to the notions of numb touch and differences in the neural bases of discriminative and effortful touch. The second result was discussed in terms of contralateral cortical enhancement by deafferentation.

Reliability and validity of pendulum test measures of spasticity obtained with the Polhemus tracking system from patients with chronic stroke

BackgroundSpasticity is a common impairment accompanying stroke. Spasticity of the quadriceps femoris muscle can be quantified using the pendulum test. The measurement properties of pendular kinematics captured using a magnetic tracking system has not been studied among patients who have experienced a stroke. Therefore, this study describes the test-retest reliability and known groups and convergent validity of the pendulum test measures obtained with the Polhemus tracking system.MethodsEight patients with chronic stroke underwent pendulum tests with their affected and unaffected lower limbs, with and without the addition of a 2.2 kg cuff weight at the ankle, using the Polhemus magnetic tracking system. Also measured bilaterally were knee resting angles, Ashworth scores (grades 0–4) of quadriceps femoris muscles, patellar tendon (knee jerk) reflexes (grades 0–4), and isometric knee extension force.ResultsThree measures obtained from pendular traces of the affected side were reliable (intraclass correlation coefficient ≥ .844). Known groups validity was confirmed by demonstration of a significant difference in the measurements between sides. Convergent validity was supported by correlations ≥ .57 between pendulum test measures and other measures reflective of spasticity.ConclusionPendulum test measures obtained with the Polhemus tracking system from the affected side of patients with stroke have good test-retest reliability and both known groups and convergent validity.

Muscle-based perception: theory, research and implications for rehabilitation

INTRODUCAO: A percepcao muscular das propriedades espaciais dos membros restringe o padrao, periodo e magnitude das forcas exercidas durante a execucao de atividades motoras. A importância central da percepcao muscular, tanto para acoes rotineiras quanto para acoes especializadas, merece atencao da comunidade envolvida na area de reabilitacao, uma vez que alteracoes em suas funcoes podem estar relacionadas a importantes limitacoes funcionais. Nesta revisao, os autores apresentam um resumo da pesquisa que pode ser utilizada para guiar o desenvolvimento de ferramentas de avaliacao eficazes bem como programas de reabilitacao que sejam especificamente direcionados para estas disfuncoes. OBJETIVOS: Quatro pontos especificos foram incluidos: primeiro, a apresentacao da abordagem com base em informacoes relativas a percepcao muscular de acordo com as leis da fisica; segundo, a identificacao dos principios centrais determinantes da percepcao muscular que vem sendo revelada e apoiada por trabalhos empiricos; terceiro, um resumo dos relatos que investigaram e se os principios identificados poderiam ser generalizados para a percepcao muscular dos individuos com alteracoes motoras e sensitivas; e quarto, uma discussao preliminar sobre as implicacoes potenciais da pesquisa aqui apresentada, no tocante aos assuntos relacionados a reabilitacao.

Haptic selective attention by foot and by hand

Nonvisual perceptions of a wielded objects spatial properties are based on the quantities expressing the objects mass distribution, quantities that are invariant during the wielding. The mechanoreceptors underlying the kind of haptic perception involved in wielding - referred to as effortful, kinesthetic, or dynamic touch - are those embedded in the muscles, tendons, and ligaments. The present experiments focus was the selectivity of this muscle-based form of haptic perception. For an occluded rod grasped by the hand at some intermediate position along its length, participants can attend to and report selectively the rods full length, its partial lengths (fore or aft of the hand), and the position of the grip. The present experiment evaluated whether participants could similarly attend selectively when wielding by foot. For a given rod attached to and wielded by foot or attached to (i.e. grasped) and wielded by hand, participants reported (by magnitude production) the rods whole length or fractional length leftward of the point of attachment. On measures of mean perceived length, accuracy, and reliability, the degree of differentiation of partial from full extent achieved by means of the foot matched that achieved by means of the hand. Despite their neural, anatomical, and experiential differences, the lower and upper limbs seem to abide by the same principles of selective muscle-based perception and seem to express this perceptual function with equal facility.

Deterministic and Stochastic Postural Processes: Effects of Task, Environment, and Age

ABSTRACT Upright standing is always environmentally embedded and typically co-occurs with another (suprapostural) activity. In the present study, the authors investigate how these facts affect postural dynamics in an experiment in which younger (M age = 20.23 years, SD = 2.02 years) and older (M age = 75.26 years, SD = 4.87 years) participants performed a task of detecting letters in text or maintaining gaze within a target while standing upright in a structured or nonstructured stationary environment. They extracted the coefficients of drift (indexing attractor strength) and diffusion (indexing noise strength) from the center of pressure (COP) time series in anteroposterior (AP) and mediolateral (ML) axes. COP standard deviation decreased with drift and increased with diffusion. The authors found that structure reduced AP diffusion for both groups and that letter detection reduced younger SD AP (primarily by diffusion decrease) and increased older SD ML (primarily by drift decrease). For older and younger participants, ML drift was lower during letter detection. Further, in older letter detection, larger visual contrast sensitivity was associated with larger ML drift and smaller SD ML, raising the hypotheses that ML sway helps information detection and reflects neurophysiological age.

Perceiving Action-Relevant Properties of Tools Through Dynamic Touch: Effects of Mass Distribution, Exploration Style, and Intention

At issue in the present series of experiments was the ability to prospectively perceive the action-relevant properties of hand-held tools by means of dynamic touch. In Experiment 1, participants judged object move-ability. In Experiment 2, participants judged how difficult an object would be to hold if held horizontally, and in Experiments 3 and 4, participants rated how fast objects could be rotated. In each experiment, the first and second moments of mass distribution of the objects were systematically varied. Manipulations of wielding speed and orientation during restricted exploration revealed perception to be constrained by (a) the moments of mass distribution of the hand-tool system, (b) the qualities of exploratory wielding movements, and (c) the intention to perceive each specific property. The results are considered in the context of the ecological theory of dynamic touch. Implications for accounts of the informational basis of dynamic touch and for the development of a theory of haptically perceiving the affordance properties of tools are discussed.

Interleg Coordination in Quiet Standing: Influence of Age and Visual Environment on Noise and Stability

ABSTRACT The authors reexamined reported effects of age, illumination, and stationary visible structure on the net center of pressure (COP) derived from dual, side-by-side force plates (J. Kinsella-Shaw, S. Harrison, C. Colon-Semenza, & M. Turvey, 2006) from the perspective of axial postural control. They questioned how left and right COP x (t), COP y (t), and vertically oriented ground reactive force, GRF z (t), coordinated during quiet standing. The Cross- recurrence Quantification (CRQ) revealed that coordination was primarily between fluctuations of similar direction, with coordination of left and right COP y (t) (anteroposterior fluctuations) dominant. CRQ also revealed that (a) illumination and structure affected the interlimb dynamics of older (M age = 72.2 ± 4.90 years) participants more than their younger (M age = 22.8 ± 0.83 years) counterparts, and (b) older participants exhibited greater interlimb entrainment (dynamical stability) in the presence of greater interlimb noise.