[Show abstract][Hide abstract] ABSTRACT: Bipedal gaits have been classified on the basis of the group symmetry of the minimal network of identical differential equations (alias cells) required to model them. Primary bipedal gaits (e.g., walk, run) are characterized by dihedral symmetry, whereas secondary bipedal gaits (e.g., gallop-walk, gallop-run) are characterized by a lower, cyclic symmetry. This fact has been used in tests of human odometry (e.g., Turvey et al. in P Roy Soc Lond B Biol 276:4309–4314, 2009, J Exp Psychol Hum Percept Perform 38:1014–1025, 2012). Results suggest that when distance is measured and reported by gaits from the same symmetry class, primary and secondary gaits are comparable. Switching symmetry classes at report compresses (primary to secondary) or inflates (sec-ondary to primary) measured distance, with the compression and inflation equal in magnitude. The present research (a) extends these findings from overground locomotion to tread-mill locomotion and (b) assesses a dynamics of sequentially coupled measure and report phases, with relative velocity as an order parameter, or equilibrium state, and difference in symmetry class as an imperfection parameter, or detuning, of those dynamics. The results suggest that the symmetries and dynamics of distance measurement by the human odometer are the same whether the odometer is in motion relative to a stationary ground or stationary relative to a moving ground.
[Show abstract][Hide abstract] ABSTRACT: Research on dynamic touching of a rod attached at its center point to the shoulders (1st vertebra) has shown that with voluntary wielding—by means of axial rotations, flexions-extensions, and lateral bending of the trunk—participants can selectively perceive the whole rod length and a partial rod length (e.g., leftward segment) with comparable precision to wielding by hand (Palatinus, Carello & Turvey, 2011). The present research addressed whether this haptic ability is preserved in quiet standing, when postural control is limited to center of pressure (COP) fluctuations at the mm/ms scale and, if so, whether the intentions (“perceive partial”, “perceive whole”) are distinguishable within the fluctuations. The participants provided significantly distinct, appropriately scaled, whole and partial estimates of three rod-lengths (72, 96 and 120 cm) with three mass manipulations (no mass, 150 g mass rightward, and 150 g mass leftward, of attachment point). The COP displacement time series were subjected to multifractal, detrended, fluctuation analysis. The resultant spectrum of fractal scaling exponents for gradually different-sized fluctuations revealed that the intention to perceive partial length elicited larger fractal scaling exponents for progressively smaller fluctuations. Our results indicate that the significant mechanical variables for haptically perceiving object extent are available in the small scale of normal body sway and that these seemingly “passive” movements reflect the intention of the perceiver.
Journal of Experimental Psychology Human Perception & Performance 05/2014; · 3.11 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: ABSTRACT For any given animal, the sources of mechanical disturbances inducing tissue deformation define environment from the perspective of the animal's haptic perceptual system. The system's achievements include perceiving the body, attachments to the body, and the surfaces and substances adjacent to the body. Among the perceptual systems, it stands alone in having no defined medium. There is no articulated functional equivalent to air and water, the media that make possible the energy transmissions and diffusions underpinning the other perceptual systems. To identify the haptic system's medium the authors focus on connective tissue and the conjunction of muscular, connective tissue net, and skeletal (MCS) as the body's proper characterization. The challenge is a biophysical formulation of MCS as a continuum that, similar to air and water, is homogeneous and isotropic. The authors hypothesized a multifractal tensegrity (MFT) with the shape and stability of the constituents of each scale, from individual cell to whole body, derivative of continuous tension and discontinuous compression. Each component tensegrity of MFT is an adjustive-receptive unit, and the array of tensions in MFT is information about MCS. The authors extend the MFT hypothesis to body-brain linkages, and to limb perception phenomena attendant to amputation, vibration, anesthesia, neuropathy, and microgravity.
Journal of Motor Behavior 01/2014; 46(3):143-87. · 1.04 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: "Quiet standing" is standing without intended movement. To the naked eye, a person "quiet standing" on a rigid surface of support is stationary. In the laboratory quiet standing is indexed by behavior (at the millimeter scale) of the center of pressure (COP), the point location of the vertical ground reaction force vector (GRF). We asked whether quiet standing is lateralized and whether the COP dynamics of the right and left legs differ. In answer, we reexamined a previous quiet standing experiment (Kinsella-Shaw et al. in J Mot Behav 38:251-264, 2006) that used dual, side-by-side, force plates to investigate effects of age and embedding environment. All participants, old (M age = 72.2 ± 4.90 years) and young (M age = 22.8 ± 0.83 years), were right handed and right footed. Cross-recurrence quantification of the anterior-posterior and mediolateral coordinates of each COP revealed that, independent of age, and with no right GRF bias, right-leg coordination was (1) more dynamically stable and less noisy than left-leg coordination and (2) more responsive to changes in degree of visible structure. The results are considered in the context of theories of laterality inclusive of lateralized differences in postural dynamics.
Experimental Brain Research 10/2013; · 2.22 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In prism adaptation experiments, the effect on throwing to a target is reduced (primary aftereffect is smaller) when the throwing condition with prisms removed (first test phase) is different from the throwing condition with prisms (the training phase). The missing adaptation, however, can be revealed through further testing (second test phase) in which the throwing condition during training is fully reinstated. We studied throwing underhand to a target flush with the floor. During training, participants wore left-shifting prism glasses while standing on the floor (Group 1) or on a balance board (Groups 2 and 3). Tests 1 and 2 following training involved the same underhand throwing. For Group 2, Test 1 was on the balance board and Test 2 on the ground; for Group 3, the order was reversed; and for Group 1, both tests were on the ground. The Group 3 Test 1 aftereffect was smaller, and the Test 2 aftereffect was larger than the respective tests for Groups 1 and 2, with the aftereffect sum the same for all three groups. A parallel was noted between prism adaptation and implicit memory: whether given training (study) conditions lead to better or poorer persistence of adaptation (memory performance) at test depends on the fit between the conditions at test relative to the conditions at training (study). In the general memory case, those conditions will involve nonobvious contributors to memory performance, analogous to the support for upright standing in the adaptation of the visual system to prismatic distortion investigated in the present research.
Experimental Brain Research 09/2013; · 2.22 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: What is the basis for the categorical distinctions evident in action? For some visually-guided activities it can be shown that categories of action are specified by criterial values of optical properties. In the more general case, the criterial optical properties should be scaled relative to dimensions of the acting animal. The analysis of the prey-catching behavior of praying mantids is used to exemplify the strategy for determining naturally defined boundaries on actions.
Journal of Motor Behavior 08/2013; 17(2):255-264. · 1.04 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: One commonly perceives whether a visible object will afford grasping with one hand or with both hands. In experiments in which differently sized objects of a fixed type are presented, the transition from using one of these manual modes to the other depends on the ratio of object size to hand span and on the presentation sequence, with size increasing versus decreasing. Conventional positive hysteresis (i.e., a larger transition ratio for the increasing sequence) can be accommodated by the order parameter dynamics that typify self-organizing systems (Lopresti-Goodman, Turvey, and Frank, Attention, Perception, & Psychophysics 73:1948-1965, 2011). Here we identified and addressed conditions of unconventional negative hysteresis (i.e., a larger transition ratio for the decreasing sequence). They suggest a second control parameter in the self-organization of affordance perception, one that is seemingly regulated by inhibitory dynamics occurring in the agent-task-environment system. Our experimental results and modeling extend the investigation of affordance perception within dynamical systems theory.
[Show abstract][Hide abstract] ABSTRACT: For skills that involve hitting a target, subsequent judgments of target size correlate with prior success in hitting that target. We used an archery context to examine the judgment-success relationship with varied target sizes in the absence of explicit knowledge of results. Competitive archers shot at targets 50 m away that varied in size among five diameters. Immediately after the arrow's release, its flight and landing were occluded and archers chose which of 18 miniature targets looked most like the distal target. Greater apparent size correlated with higher accuracy. In a second experiment, nonarchers merely aimed the bow (without an arrow) at varied targets. Apparent size was larger when the bow arm was stabilized than when it was not. Archery is seemingly an instance of affordance-based control: For an archer, the affordance of the target is the "hitableness" of its central regions, a property inclusive of his or her momentary, and perceptible, archery form. (PsycINFO Database Record (c) 2012 APA, all rights reserved).
Journal of Experimental Psychology Human Perception & Performance 06/2012; 38(5):1125-31. · 3.11 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We present an axiomatic derivation of a model proposed by Haken, Kelso, and Bunz (1985) that describes dynamical aspects of the rhythmic coordination between two limbs. Elaboration of this model has included a symmetry parameter that captures the coordination consequences of an inherent or imposed frequency difference between the limbs. We modified one of the axioms involved in the model derivation, a symmetry axiom, in order to incorporate a new symmetry parameter. This new parameter defines a shift between (a) the laboratory coordinate system, in which the behavior is observed, and (b) a second, postulated coordinate system. It is this second coordinate system, in which the relevant state dynamics is assumed to take place and in which the state dynamics evolves under the impact of an attractor. The state dynamics as described in the attractor coordinate system is then mapped by means of the new symmetry parameter to the laboratory coordinate system. We discuss analytically the bifurcation diagram of the model and determine main effects and interaction effects of manipulations related to the symmetry parameters and related to the mode of coordination (in-phase and anti-phase). The theoretical results are brought to bear on the challenging experimental observation that concurrent cognitive activity (counting, encoding, retrieving, sentence analysis) changes the location of the bimanual coordination attractor but not its strength. The theoretical results suggest that cognitive activity may have the effect it has because it shifts the attractor coordinate system relative to the laboratory coordinate system.
Journal of Mathematical Psychology 06/2012; 56(3):149–165. · 1.62 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Bipedal gaits have been classified on the basis of the group symmetry of the minimal network of identical differential equations (alias cells) required to model them. Primary gaits are characterized by dihedral symmetry, whereas secondary gaits are characterized by a lower, cyclic symmetry. This fact was used in a test of human odometry. Results suggest that when distance is measured and reported by gaits from the same symmetry class, primary and secondary gaits are comparable. Switching symmetry classes at report compresses (primary to secondary) or inflates (secondary to primary) measured distance, with the compression and inflation equal in magnitude. Lessons are drawn from modeling the dynamics of behaviors executed in parallel (e.g., interlimb coordination) to model the dynamics of human odometry, in which the behaviors are executed sequentially. The major observations are characterized in terms of a dynamics of sequentially coupled measure and report phases, with relative velocity as an order parameter, or equilibrium state, and difference in symmetry class as an imperfection parameter, or detuning, of that dynamic.
Journal of Experimental Psychology Human Perception & Performance 04/2012; 38(4):1014-25. · 3.11 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A nonword prime can sound like a target word or one of the target’s associates, and it can look like either without sounding
like either. These pseudohomophones and pseudohomographs can vary in the number of letters shared with the target or its associate.
In an associative priming experiment in which targets were named and prime duration was 125 msec within a mask-prime-mask-target
sequence, pseudohomophones primed and pseudohomographs did not, with the pseudoassociative priming being only weakly affected
by spelling differences. In three further experiments, prime homophony and homography were defined in respect to the target.
Prime durations were 125 and 21 msec within a maskprime-mask-target sequence and 57 msec vrithin a mask-prime-target sequence.
The superior priming by pseudohomophones was relatively insensitive to spelling. Results are discussed in terms of the phonological
coherence hypothesis and the roles for orthographic information implied by the hypothesis.
[Show abstract][Hide abstract] ABSTRACT: Reading a word may involve the spoken language in two ways: in the conversion of letters to phonemes according to the conventions of the language's writing system and the assimilation of phonemes according to the language's constraints on speaking. If so, then words that require assimilation when uttered would require a change in the phonemes produced by grapheme-phoneme conversion when read. In two experiments, each involving 40 fluent readers, we compared visual lexical decision on Korean orthographic forms that would require such a change (C stimuli) or not (NC stimuli). We found that NC words were accepted faster than C words, and C nonwords were rejected faster than NC nonwords. The results suggest that phoneme-to-phoneme transformations involved in uttering a word may also be involved in visually identifying the word.
Journal of Psycholinguistic Research 04/2012; · 0.59 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Gibson's (1966, 1979/1986) ecological approach to perception, action, and cognition is patently non-representational and non-computational. In the place of these commonly assumed neural endowments, ecological psychology seeks to expose the laws that underlie intelligent capabilities. It is argued that this is the goal for understanding the directed behavior of not just humans, not just animals, and not just the living. We argue that an approach to intelligence that is physically grounded is completely consistent with—and is even a natural consequence of—the central tenets of ecological psychology. We identify two dozen guidelines for seeking intelligence in first principles.
[Show abstract][Hide abstract] ABSTRACT: The effect of prism adaptation on movement is typically reduced when the movement at test (prisms off) differs on some dimension from the movement at training (prisms on). Some adaptation is latent, however, and only revealed through further testing in which the movement at training is fully reinstated. Applying a nonlinear attractor dynamic model (Frank, Blau, & Turvey, 2009) to available data (Blau, Stephen, Carello, & Turvey, 2009), we provide evidence for a causal link between the latent (or secondary) aftereffect and an additive force term that is known to account for symmetry breaking. The evidence is discussed in respect to the hypothesis that recalibration aftereffects reflect memory principles (encoding specificity, transfer-appropriate processing) oriented to time-translation invariance-when later testing conserves the conditions of earlier training. Forgetting or reduced adaptation effects follow from the loss of this invariance and are reversed by its reinstatement.
[Show abstract][Hide abstract] ABSTRACT: Humans and other animals can measure distances nonvisually by legged locomotion. Experiments typically employ an outbound measure (M) and an inbound report (R) phase. Previous research has found distance reproduction to be maximally accurate, when gait symmetry and speed of M and R are of like kind: Successful human odometry manifests at the level of the M-R system. In the present work, M was an experimenter-set distance produced by a blindfolded participant using a primary gait (walk, run). R was always by walk. Fast and slow versions of walk and run were adopted by participants, such that when M was fast R was slow, and vice versa. Distance was underestimated when M was slower than R and overestimated when M was faster than R. However, the pattern of participant-adopted velocities indicated that it was the instructions, not the speed as such, that yielded the pattern of results. The results are interpretable through a dynamical perspective and indicate speed is an imperfection parameter acting on the attractors of the M-R system.
Journal of Motor Behavior 01/2012; 44(1):47-52. · 1.04 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Current research suggests that non-visual perception of the spatial orientation of body segments is tied to vectors representative of their mass moment distribution (v(mm)). Our question was whether the relative orientation of v(mm) of right and left hands (Δv(mm)=v(mm) left-v(mm) right) constitutes haptic information supporting bimanual coordination and, if so, how it contributes to coordination dynamics. Blindfolded participants coordinated the motions of a pair of cross-shaped, hand-held pendulums that were either symmetrically loaded (Δv(mm)=0) or asymmetrically loaded (Δv(mm)≠0). The sign and magnitude of Δv(mm), in particular of the first moment vector, systematically affected the pattern of coordination (indexed by mean relative phase ϕ), but not its stability. These results suggest that (1) Δv(mm) specifies a frame of reference about which coordination is organized; and (2) that the changes in pattern were a function of the experimentally induced biases in this perceptual frame of reference and not a function of a functional asymmetry akin to detuning. The implications of the findings to the understanding of perceptual regulation of interlimb coordination were discussed.
Human movement science 12/2011; · 2.15 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Dynamic touching is effortful touching. It entails deformation of muscles and fascia and activation of the embedded mechanoreceptors, as when an object is supported and moved by the body. It is realized as exploratory activities that can vary widely in spatial and temporal extents (a momentary heft, an extended walk). Research has revealed the potential of dynamic touching for obtaining non-visual information about the body (e.g. limb orientation), attachments to the body (e.g. an object's height and width) and the relation of the body both to attachments (e.g. hand's location on a grasped object) and surrounding surfaces (e.g. places and their distances). Invariants over the exploratory activity (e.g. moments of a wielded object's mass distribution) seem to ground this 'information about'. The conception of a haptic medium as a nested tensegrity structure has been proposed to express the obtained information realized by myofascia deformation, by its invariants and transformations. The tensegrity proposal rationalizes the relative indifference of dynamic touch to the site of mechanical contact (hand, foot, torso or probe) and the overtness of exploratory activity. It also provides a framework for dynamic touching's fractal nature, and the finding that its degree of fractality may matter to its accomplishments.
Philosophical Transactions of The Royal Society B Biological Sciences 11/2011; 366(1581):3123-32. · 6.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: On a daily basis, one perceives whether an object affords grasping with one hand or with both hands. In experiments in which differently sized objects of a fixed type have been presented, the transition from using one manual mode to the other has depended on both the ratio of object size to hand span and the presentation sequence-that is, size increasing versus decreasing. The transitions and their observed hysteresis (i.e., a transition ratio larger for the increasing sequence) can be accommodated by the order parameter dynamics typifying self-organizing systems. Here, we show that hysteresis magnitude depends on (a) the interaction between the attractors (one hand vs. two hands) and (b) the strength of the two-hands attractor. Through modeling and experimental results, we extend the investigation of affordance perception within dynamical-systems theory.
[Show abstract][Hide abstract] ABSTRACT: In each of three experiments, each subject in each condition received five successive short-term memory (STM) tests with phonemically similar consonant trigrams as the items to be remembered. The retention interval for tests 1–4 of all conditions in the three experiments was held constant at 16·5 sec. On test 5 the retention interval was varied across conditions with the three experiments exploring retention intervals in the range 1–21·5 sec. In all three experiments little, if any, forgetting was observed on test 1; in all three experiments proactive interference (PI) was observed to develop across tests. Analysis of the test 5 data indicated that the PI effect of prior test items upon the test 5 target item reached a maximum by 6·5 sec., with no further forgetting beyond this interval. The test 5 data also suggested a reminiscence effect at the longest retention interval of 21·5 sec. The implications of the data for a theory of PI in STM are discussed.
British Journal of Psychology. 04/2011; 61(4):467 - 472.
[Show abstract][Hide abstract] ABSTRACT: Cognitive science has always included multiple methodologies and theoretical commitments. The philosophy of cognitive science should embrace, or at least acknowledge, this diversity. Bechtel’s (2009a) proposed philosophy of cognitive science, however, applies only to representationalist and mechanist cognitive science, ignoring the substantial minority of dynamically oriented cognitive scientists. As an example of nonrepresentational, dynamical cognitive science, we describe strong anticipation as a model for circadian systems (Stepp & Turvey, 2009). We then propose a philosophy of science appropriate to nonrepresentational, dynamical cognitive science.