Biomedical subjects

M T Turvey

Publications and source records attributed to M T Turvey.

At least 73 records · Page 4Linked to original sources

PubMed1995

Effects of association, frequency, and stimulus quality on naming words in the presence or absence of pseudowords.

According to classical dual-route theory, effects of associative priming and frequency on the naming of printed words arise from lexical access and should be weak or absent when word names are assembled prelexically. Assembled naming would be more likely in a shallow orthography, especially in the presence of nonwords. This hypothesis was examined with the shallow Serbo-Croatian orthography. Interactions between association, frequency, and stimulus quality were also examined in both Serbo-Croatian and English. Contrary to classical dual-route theory, both lexical effects were found for naming words in Serbo-Croatian, with or without nonwords. Neither interaction was significant in Serbo-Croatian and only association x quality was significant in English. Discussion focused on (a) the claim that lexical effects on naming in a shallow orthography constitute prima facie evidence against either prelexical phonology or the orthographic depth hypothesis, and (b) the possible factorization of frequency and active associative knowledge in naming words.

Adolescent↗

PubMed1995

Does perceived size depend on perceived distance? An argument from extended haptic perception.

Two experiments were directed at the comparison between two perspectives on the perception of size achieved by probing the gap between two occluded distal surfaces by means of a hand-held rod. One perspective was the classical size-distance invariance hypothesis developed for the problem of visual size perception with a central role for perceived distance; the other was the hypothesis that the extended haptic perception of gap size is specific to a physical invariant lambda of the dynamics of probing. Experiment 1 examined the relation between hepatically perceived gap size and haptically perceived gap distance. No causal connection between the two was found, and all the variance in perceived size was accounted for by lambda. Experiment 2 manipulated the rotational inertia of the probe. Its effect was different for the two perceptions of size and distance, underscoring their independence. The indifference of perceived size to perceived distance was discussed in reference to identifying invariants for both the haptic and the visual perception of size at a distance.

Adult↗

PubMed1994

Phase-entrainment dynamics of visually coupled rhythmic movements.

Do interlimb rhythmic coordinations between individuals exhibit the same relations among the same observable quantities as interlimb rhythmic coordination within an individual? The 1:1 frequency locking between the limbs of two people was investigated using a paradigm in which each person oscillated a hand-held pendulum, achieving and maintaining the mutual entrainment through vision. The intended coordination was antiphase, phi = pi, and the difference between the uncoupled eigen-frequencies, delta omega, was manipulated through differences in the lengths of the two pendulums. The mean phase relation and its variance for visually coupled coordinations differing in delta omega were predicted by an order parameter equation developed by Haken et al. (1985) and Schöner et al. (1986) for the relative phase of correlated movements of limb segments. Specifically, the experiment revealed that: (1) the deviation of phi from pi increased with increasing deviation of delta omega from 0; and (2) fluctuations in phi increased with increasing deviation of delta omega from 0. With deviations of delta omega from 0, new peaks were added at higher harmonics in phi's power spectrum. These results were in agreement with previous research on the stable states of interlimb coordination within a person, mediated by mechanoreceptive rather than photoreceptive mechanisms. Additionally, they were in agreement with previous research on phase transitions in interlimb coordination which have been shown to conform to the same order parameter dynamics whether the coupling be mechanoreceptively or photoreceptively based. It was suggested that phase entrainment in biological movement systems may abide by dynamical principles that are indifferent to the details of the coupling.

Adult↗

PubMed1994

Eigenvalues of the inertia tensor and exteroception by the "muscular sense".

Muscle spindles and Golgi tendon organs constitute the receptor foundation to the "muscle sense." Muscle sensitivity has long been assumed relevant to the non-visual perception of the positions and motions of the body's segments and of the properties of hand-held objects. Dynamic touch is the label given to the particular kind of tactile exteroperception that involves a non-spatial input from muscles and tendons. When a hand-held object is wielded, hefted, carried and so on, the hand movements, together with the physical properties of the object, produce torques and angular motions that change in time with the movement. There is, however, an unchanging quantity that relates the variable torques and angular motions, namely, the object's inertia for rotation about a fixed point in the wrist. Our research revealed that the non-visual perception of the length of a wielded object by dynamic touch is a function of muscular sensitivity to the principal moments or eigenvalues of the inertia tensor. Across four experiments, variations in object length were accompanied by variations in width, spatial and material heterogeneity, the relation of the tensorial components to mass, and geometric shape. Subjects had no foreknowledge of the variations in object dimensions. Perceived lengths of occluded objects were reported by adjusting a visible marker so that its position corresponded to the position of the felt end of the object. In each experiment, perceived length was closely related to actual length and uniquely constrained by the major and minor eigenvalues of the inertia tensor. The present results, in conjunction with previous research, suggest that the inertia tensor provides the domains for two sets of functions realized by the "muscular sense," one consisting of the principal moments of inertia or eigenvalues, which map on to perceived object magnitudes (e.g. length, weight), and one consisting of the principal directions or eigenvectors, which map on to perceived relations between hand and object (e.g. position of grasp). The significance of information-perception specificity over cognitive mechanisms is underlined and perspectives on dynamic touch and its underlying muscular sensitivity, including a general tensorial analysis, are discussed.

Adult↗

PubMed1994

Lexical involvement in naming does not contravene prelexical phonology: comment on Sebastián-Gallés (1991).

N. Sebastián-Gallés (1991) showed lexical involvement in naming Spanish. Her results were purported to be a failure to substantiate claims for prelexical phonology that characterize Serbo-Croatian. Summaries of several experimental demonstrations of lexical involvement in naming Serbo-Croatian are used to show that such results are only interpretable consistently in a model that assumes prelexical phonology. The lexicon is accessed through assembled phonology, but assembled and lexical phonology interact in resolving a unique pronunciation when several pronunciations are assembled and in assigning stress, which is not assembled. The authors argue that lexical access need not be different in different orthographies but that the weights on connections between orthographic and phonological substructures established through covariant learning will distinguish orthographies in the rate and degree of phonological involvement in word recognition.

Croatia↗

PubMed1994

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 Iij's eigenvalues in perceiving the magnitudes of objects and Iij's eigenvectors in perceiving hand-object relations (e.g., position of grasp).

Adult↗

PubMed1994

Visual lexical access is initially phonological: 1. Evidence from associative priming by words, homophones, and pseudohomophones.

In 9 experiments, a target word (e.g., frog) was named following an associate (TOAD), or a word (e.g., TOWED) or nonword (e.g., TODE) homophonic with the associate. At brief (e.g., 50 ms) stimulus onset asynchronies (SOAs), the 3 primes produced equal associative priming. At a long SOA (250 ms), priming by TOAD was matched by TODE but not by TOWED. Equal priming at brief SOAs by the 3 primes and no priming by orthographic controls (TOLD, TORD) suggests that lexical access is initially phonological. TOWED priming less than TODE at SOA = 250 ms suggests that phonologically activated representations whose input orthography does not match the addressed spelling (available only for words) are eventually suppressed. Phonological constraints on lexical access precede and set the stage for orthographic constraints.

Adult↗

PubMed1994

Visual lexical access is initially phonological: 2. Evidence from phonological priming by homophones and pseudohomophones.

Seven experiments were conducted that examined phonological and orthographic priming of naming using three- and four-field masking procedures with prolonged targets. Experiments 1-3 found significant phonological priming by homophones (TOWED-toad) that was independent of prime identifiability and prime-target stimulus onset asynchrony (SOA; 30, 60, or 250 ms). Subsequent experiments found significant phonological priming by pseudohomophones (TODE-toad) that was similarly independent of prime identifiability and SOA. Collectively, the limited effects of orthographic control primes (TOLD-toad, TODS-toad) and the pronounced and orthographically independent effects of phonological primes suggest (a) a leading role in visual word perception for a fast-acting, automatic, assembled phonology, and (b) a phonological basis, rather than an abstract graphemic basis, for the processing equivalency of letter variations.

Analysis of Variance↗

PubMed1994

Phonological codes are early sources of constraint in visual semantic categorization.

Two experiments were directed at early phonological activation in the semantic categorization task. In Experiment 1, briefly exposed targets homophonic to category exemplars (ROWS for the category A FLOWER), and their graphemic controls (ROBS), were judged for category membership with and without a backward pattern mask. False positives were greater for ROWS than ROBS to the same degree under both unmasked and masked conditions. In Experiment 2, false positives were examined in the semantic categorization task under backward dichoptic masking by pseudowords that were, in turn, masked monoptically by a pattern mask. Briefly exposed homophones (e.g., WEAK), masked by a phonologically similar pseudoword ("feek"), a graphemic control ("felk"), or an unrelated pseudoword ("furt"), were categorized as category exemplars (A UNIT OF TIME). The difference in false positives was significant for WEAK-feek versus WEAK-furt, but not for WEAK-felk versus WEAK-furt. It was suggested that the persistence of the homophonic effects under the pattern masking of Experiment 1 and their amplification under the phonological masking of Experiment 2 were because phonological codes cohere rapidly and provide, thereby, immediately available constraints on semantic processing.

Adult↗

PubMed1993

Constants underlying frequency changes in biological rhythmic movements.

When an animal increases or decreases the frequency of its limb motions, how should the transformation in timing be characterized? It has been hypothesized that the transformation is adiabatic, even though the biological conditions are nonconservative and non-rate-limited (Kugler and Turvey 1987). An adiabatic transformation requires that the rhythmic system's action (energy/frequency) and entropy production remain time-invariant throughout the transformation. The non-conservative adiabatic hypothesis was evaluated through an experiment on human rhythmic hand movements. On each trial, a subject began at a prescribed frequency and then, over a 30 s interval, increased (or decreased) the frequency continuously at will. For each subject, on each increasing and decreasing trial, cycle kinetic energy was a linear function of cycle frequency with a negative energy intercept. By the adiabatic hypothesis, the slope of the function defines the constant action and the intercept defines the constant dissipation - changes in cycle frequency incur no changes in energy dissipated per cycle. Slopes and intercepts were correlated suggesting a common basis for the two constants, and the variety of cycle amplitude-cycle duration relations were in agreement with the nonmonotonic, nonlinear space-time function predicted by the hypothesis. The possibilities of addressing aspects of the data through (a) muscle modeled as a continuum of Kelvin bodies with a continuous relaxation spectrum, and (b) various classes of autonomous differential equations, were discussed. Most importantly, the discussion focused on the puzzling independence of energy cost and speed exhibited by locomoting animals differing in morphology, physiology, size, and taxa. It was suggested that the independence may reflect a very general principle - adiabatic transformability of biological movement systems.

Adult↗

PubMed1993

Similar attentional, frequency, and associative effects for pseudohomophones and words.

Between the presentation and recall of 1 or 5 digits, Ss performed a secondary task of naming a visually presented letter string--a pseudohomophone (e.g., FOLE, HOAP) or its real-word counterpart (FOAL, HOPE). Memory load interacted with frequency (HOPE vs. FOAL, HOAP vs. FOLE) but not with lexicality (HOPE vs. HOAP, FOAL vs. FOLE). This outcome counters models in which nonwords are named by a slow (resource-expensive) process that assembles phonology and words are named by a fast (resource-inexpensive) process that accesses lexical phonology. When the associative priming-of-naming task was secondary to the memory task, pseudohomophone associative priming (HOAP-DESPAIR, FOLE-HORSE) equaled associative priming (HOPE-DESPAIR, FOAL-HORSE) and was affected in the same way by memory load. Assembled phonology seems to underlie the naming of both words and nonwords.

Adult↗

PubMed1993

Optical information about the severity of upcoming contacts.

The time derivative (tau) of the inverse of the relative rate of optical expansion (tau) may have critical values with potential implications for controlling activity. The present research addresses the particular hypothesis that tau < -0.5 specifies "unsafe" collision courses and tau > or = -0.5 specifies "safe" collision courses. Optical expansion patterns were simulated on a computer with -1.0 < or = tau < 0 and judged as suggesting a "hard" or "soft" collision. tau < -0.5 led to significantly different decisions from tau > or = -0.5, but the critical value of -0.5 was not perceived reliably as soft, a deviation possibly due to discretely approximating continuous functions. Additional experiments evaluated terminal rates of change and display duration and examined the effects of biasing the presented displays toward the soft or the hard end of the tau continuum. The results were consistent with the tau hypothesis.

Acceleration↗

PubMed1993

Coupling dynamics in interlimb coordination.

In 1:1 frequency locking, the interlimb phase difference phi is an order parameter quantifying the spatial-temporal organization of 2 rhythmic subsystems. Dynamical modeling and experimental analyses indicate that an intentional parameter phi psi (intended coordination mode, phi = 0 degrees or phi = 180 degrees) and 2 control parameters omega c (coupled frequency) and delta omega (difference between uncoupled eigen-frequencies) affect phi. An experiment was conducted on 1:1 frequency locking in which phi psi, omega c, and delta omega were manipulated using a paradigm in which a person swings hand-held pendulums. As delta omega deviated from 0, the observed phi deviated from the phi psi, indicating a displacement in the phi attractor point. The displacements were exaggerated by increasing omega c. The displacements were coordinated with a decrease in the stability of phi and with higher harmonics in power spectrum of phi. Implications of the results for modeling interlimb coordination are discussed.

Adult↗

PubMed1993

Haptically perceiving size at a distance.

Six experiments are reported on perceiving the sizes of gaps by probing with a hand-held rod. A collective parameter, lambda, is invariant over the time-varying dynamics of probing: lambda = sin(alpha/2)[1-(2a/b) + (a/p)] = sin(alpha/2) delta, where alpha is the angular excursion of the rod-plus-limb segment and a, b, and p are the distances, respectively, of the center of mass, point of contact, and the center of percussion from the axis of rotation. If perceived size is specific to lambda, then it should (a) be a single-valued function of lambda regardless of the muscles executing, and deformed by, the probing; (b) equal, underestimate, and overestimate actual size according to 2b/delta = 1, 2b/delta < 1, and 2b/delta > 1, respectively; and (c) change with actual size at a rate equal to (1/2b-a/b2 + a/2bp), the partial derivative of lambda with respect to size. The experimentally confirmed predictions are discussed in relation to hypotheses about the specificity of perception to information, and the tensorial nature of dynamic touch.

Adult↗

PubMed1993

Reduction in alphabet priming with delay and degradation.

Phonologically ambiguous Serbo-Croatian words are named more slowly than their phonologically unique partners. This difference is reduced by nonword primes containing consonants unique to one or the other alphabet. In 2 experiments we investigated the hypothesis that alphabet priming is the inhibition of unique and ambiguous letter units of one alphabet by the unique letter units of the other alphabet. In Experiment 1, ambiguous and unique words followed alphabet-specific nonwords at lags between 100 ms and 1,550 ms. The ambiguous-unique difference increased from 1 ms to 45 ms, consistent with a relaxing inhibitory process. In Experiment 2 we compared priming of ambiguous words with and without visual noise. Priming was less for noisy than for intact stimuli, as would be expected if noise slows processing and if the inhibition responsible for priming weakens further during the additional processing time.

Adolescent↗

PubMed1993

Further evidence for phonological constraints on visual lexical access: TOWED primes FROG.

If the phonological codes of visually presented words are assembled rapidly and automatically for use in lexical access, then words that sound alike should induce similar activity within the internal lexicon. TOWED is homophonous with TOAD, which is semantically related to FROG, and BEACH is homophonous with BEECH, which is semantically related to TREE. Stimuli such as these were used in priming-of-naming task, in which words homophonous with associates of the target words preceded the targets at an onset asynchrony of 100 msec. Relative to spelling controls (TROD, BENCH), the low-frequency TOWED and the high-frequency BEACH speeded up the naming of FROG and TREE, respectively, to the same degree. This result was discussed in relation to the accumulating evidence for the primacy of phonological constraints in visual lexical access.

Adult↗

PubMed1993

Tensorial basis to the constancy of perceived object extent over variations of dynamic touch.

Subjects wielded occluded rods, with or without attached masses, and reported the distances reachable with their distal tips. Experiments 1-3 compared wielding about the wrist, the elbow, and the shoulder. Experiments 4 and 5 compared free wielding, using the whole arm, with wielding only about the wrist. The two comparisons, respectively, were of spatial and temporal variations in the rod's rotational inertia. Perceived extent was found to be constant in both comparisons. This constancy was tied to the inertia tensor Iij defined about a point that remains a fixed distance from the object during wielding--an invariant of the spatially and temporally dependent patterning of mechanical energy impressed upon the tissues of the body. Discussion focused on the reciprocal action and perception capabilities of multisegmented limbs, the tensorial relations in the neurobiology of dynamic touch, and the strategy of understanding perceptual constancy through invariants.

Adult↗

PubMed1993

Commentary: development of perception-action systems and general principles of pattern formation.

Our commentary on this special issue devoted to Developmental Biodynamics: Brain, Body, and Behavior Connections is divided into 3 main sections. The first section is an overview of the individual contributions. 5 major themes are identified: (1) inappropriateness of computational treatments of development and the need for more biologically and physically relevant treatments; (2) significance of tailoring muscular to nonmuscular forces in developing movement coordination; (3) importance of spontaneous movements as exploratory and formative mechanisms; (4) influences of action capabilities on the development of perception capabilities, and vice versa; (5) applications of methods and techniques of nonlinear dynamics to developmental processes. In the second section, we provide a synopsis of current ways of thinking about prototypical developmental processes, namely, pattern formation and pattern differentiation, in various classes of physical and biological systems. It is suggested that efforts to understand the progressive formation and differentiation of patterns in terms of very general principles provide a valuable resource of concepts and methods for students of child development. In the third section, hypotheses about the development of perception-action systems are generated from juxtaposing the themes and conjectures of this special issue with general principles of pattern formation. The hypotheses suggest the possibility of a pattern formation or dynamics approach to child development as an alternative to the conventional approaches emphasizing maturation (nativist), specific learning experiences (empiricist), cognitive stages (Piagetian), and strategies of encoding and retrieval (information processing).

Child Development↗