Hypothesis Of Functional Equivalence Research Articles

Inequivalent and uncorrelated response priming in motor imagery and execution.

Theoretical considerations on motor imagery and motor execution have long been dominated by the functional equivalence view. Previous empirical works comparing these two modes of actions, however, have largely relied on subjective judgments on the imagery process, which may be exposed to various biases. The current study aims to re-examine the commonality and distinguishable aspects of motor imagery and execution via a response repetition paradigm. This framework aims to offer an alternative approach devoid of self-reporting, opening the opportunity for less subjective evaluation of the disparities and correlations between motor imagery and motor execution. Participants performed manual speeded-choice on prime-probe pairs in each trial under three conditions distinguished by the modes of response on the prime: mere observation (Perceptual), imagining response (Imagery), and actual responses (Execution). Responses to the following probe were all actual execution of button press. While Experiment 1 compared the basic repetition effects in the three prime conditions, Experiment 2 extended the prime duration to enhance the quality of MI and monitored electromyography (EMG) for excluding prime imagery with muscle activities to enhance specificity of the underlying mechanism. In Experiment 1, there was no significant repetition effect after mere observation. However, significant repetition effects were observed in both imagery and execution conditions, respectively, which were also significantly correlated. In Experiment 2, trials with excessive EMG activities were excluded before further statistical analysis. A consistent repetition effect pattern in both Imagery and Execution but not the Perception condition. Now the correlation between Imagery and Execution conditions were not significant. Findings from the current study provide a novel application of a classical paradigm, aiming to minimize the subjectivity inherent in imagery assessments while examining the relationship between motor imagery and motor execution. By highlighting differences and the absence of correlation in repetition effects, the study challenges the functional equivalence hypothesis of imagery and execution. Motor representations of imagery and execution, when measured without subjective judgments, appear to be more distinguishable than traditionally thought. Future studies may examine the neural underpinnings of the response repetition paradigm to further elucidating the common and separable aspects of these two modes of action.

The Relationship Between Internal Motor Imagery and Motor Inhibition in School-Aged Children: A Cross-Sectional Study

Functional equivalence hypothesis and motor-cognitive model both posit that motor imagery performance involves inhibition of overt physical movement and thus engages control processes. As motor inhibition in internal motor imagery has been fairly well studied in adults, the present study aimed to investigate the correlation between internal motor imagery and motor inhibition in children. A total of 73 children (7-year-olds: 23, 9-year-olds: 27, and 11-year-olds: 23) participated the study. Motor inhibition was assessed with a stop-signal task, and motor imagery abilities were measured with a hand laterality judgment task and an alphanumeric rotation task, respectively. Overall, for all age groups, response time in both motor imagery tasks increased with rotation angles. Moreover, all children’s response times in both tasks decreased with age, their accuracy increased with age, and their motor inhibition efficiency increased with age. We found a significant difference between 7-year-olds and 9-year-olds in the hand laterality judgment task, suggesting that the involvement of motor inhibition in internal motor imagery might change with age. Our results reveal the underlying processes of internal motor imagery development, and furthermore, provide practical implications for movement rehabilitation of children.

SIGNIFICANCE OF MORPHOPHONOLOGICAL ELEMENTS IN THE PROCESS OF WORD FORMATION

The article considers the role of morphophonological elements such as stress, alternation of phonemes in the choice of suffixes in the deminutative word formation, and the nature of the relationship between them. It is traditionally believed that Russian word formation is agglutinative, since the affix dominates, and the stress and alternation of phonemes are subordinate to it. The Russian language is fusional in the typological characteristics, as fusional characteristics that manifest themselves in alternation of phonemes, alternation of stress, declension, conjugation and derivation, define the typological features of the Russian language. Therefore, the article suggest that Russian word formation is also fusional. Fusion is expressed in the fact that the morphological characteristics of the deriving word predict the choice of suffixes, which are variants within the same paradigm of allomorphs of the word-forming affix. The research showed that stress, phoneme alternation and suffix are functionally equal, since suffix can also specify the stress and the alternant of the derived word. Consequently, the alternation of allomorphs of suffixes, as well as alternations in a word stem, including the rules for choosing allomorphs, is not an object of word-formation analysis, but relate to morphophonology. Thus, the hypothesis of functional equivalence of stress, phoneme alternation, and affix alternation is confirmed in the description of word formation of masculine diminutives with suffixes -ик, -ок (-ек), -ушек (-юшк, -ишек), -анёк (-енёк), as shown in the suffix allomorph selection table.

SIGNIFICANCE OF MORPHOPHONOLOGICAL ELEMENTS IN A NOMINAL WORD FORMATION AS A MANIFESTATION OF THE FUSION OF THE RUSSIAN LANGUAGE

The article considers the role of morphophonological elements such as stress, alternation of phonemes in the choice of suffixes in the diminutative word formation, and the nature of the relationships between them. It is traditionally believed that Russian word formation is agglutinative, since the affix dominates, and the stress and alternation of phonemes are subordinate to it. The Russian language is fusional in its typological characteristics, as fusional characteristics that manifest themselves in alternation of phonemes, alternation of stress, declension, conjugation and derivation, define the typological features of the Russian language. Therefore, the article suggests that Russian word formation is also fusional. Fusion is expressed in the fact that the morphological characteristics of the deriving word predict the choice of suffixes, which are variants within the same paradigm of allomorphs of the word-forming affixes. The research showed that stress, a phoneme alternation and a suffix are functionally equal, since the suffix can also specify the stress and the alternant of the derived word. Consequently, the alternation of allomorphs of suffixes, as well as alternations in a word stem, including the rules for choosing allomorphs, is not an object of word-formation analysis, but relate to morphophonology. Thus, the hypothesis of functional equivalence of a stress, a phoneme alternation, and an affix alternation is confirmed in the description of a word formation of masculine diminutives with suffixes �-ик�, �-ок� (�-ек�), �-ушек� (�-юшк�, �-ишек�), �-анёк� (�-енёк�) as shown in the suffix allomorph selection table.

Efectos de variar la dimensión del estímulo y la morfología de la respuesta sobre el aprendizaje de discriminación

The aim of this study was to explore the effect of varying the stimuli dimension or the response morphology on the discrimination learning. For a group of subjects, responding to the left lever after a fixed tone or responding to the right lever after a light were followed by water. For a second group, the arrangement was the same except that the light was replaced by an intermittent tone (Experiment 1). It was found that subjects trained with different stimuli dimension (tone vs. light) had a faster acquisition. In Experiment 2, for a group of subjects the first response to the left lever after presenting a fixed tone and pulling a chain after presenting an intermittent tone resulted in the delivery of water; whereas for a second group the conditions were the same except that instead of pulling the chain after the intermittent tone, subjects need to pressed the right lever to obtain water. Subjects trained with morphologically different responses (lever press vs. chain pulling) learned the task in fewer sessions than subjects trained with morphologically similar responses. As a whole, the results are discussed based on the differentiation between discriminated operants supporting the functional equivalence hypothesis.

Functional diversity of non-lethal effects, chemical camouflage, andvariation in fish avoidance in colonizing beetles.

Predators play an extremely important role in natural communities. In freshwater systems, fish can dominate sorting both at the colonization and post-colonization stage. Specifically, for many colonizing species, fish can have non-lethal, direct effects that exceed the lethal direct effects of predation. Functionally diverse fish species with a range of predatory capabilities have previously been observed to elicit functionally equivalent responses on oviposition in tree frogs. We tested this hypothesis of functional equivalence of non-lethal effects for four predatory fish species, using naturally colonizing populations of aquatic beetles. Among taxa other than mosquitoes, and with the exception of the chemically camouflaged pirate perch, Aphredoderus sayanus, we provide the first evidence of variation in colonization or oviposition responses to different fish species. Focusing on total abundance, Fundulus chrysotus, a gape-limited, surface-feeding fish, elicited unique responses among colonizing Hydrophilidae, with the exception of the smallest and most abundant taxa, Paracymus, while Dytiscidae responded similarly to all avoided fish. Neither family responded to A.sayanus. Analysis of species richness and multivariate characterization of the beetle assemblages for the four fish species and controls revealed additional variation among the three avoided species and confirmed that chemical camouflage in A.sayanus results in assemblages essentially identical to fishless controls. The origin of this variation in beetle responses to different fish is unknown, but may involve variation in cue sensitivity, different behavioral algorithms, or differential responses to species-specific fish cues. The identity of fish species occupying aquatic habitats is crucial to understanding community structure, as varying strengths of lethal and non-lethal effects, as well as their interaction, create complex landscapes of predator effects and challenge the notion of functional equivalence.

THE ATHLETES’ BODY SHAPES THE ATHLETES’ MIND – NEW PERSPECTIVES ON MENTAL ROTATION PERFORMANCE IN ATHLETES

Mentally rotating the image of an object is one fundamental cognitive ability in humans. Recent theoretical developments and empirical evidences highlight the potential role of the sensory-motor system, when analysing and understanding mental rotation. Therefore, the purpose of this study was to investigate the role of specific sensory-motor experience on mental rotation performance in gymnasts. N = 40 male gymnasts with either clockwise or anticlockwise rotation preference in a forward twisting layout salto performed a psychometric mental rotation test with either rotation-preference congruent or rotation-preference incongruent stimuli. Results revealed that choice reaction times differed clearly as a function of Angular Rotation between the stimuli figures. Gymnasts who preferred a clockwise rotation preference showed faster choice reaction times when the rotation direction of the reference figure was clockwise, and vice versa. The results clearly support the notion, that mental rotation performance varies as a function of sensory-motor system characteristics between different people. It is concluded, that sensory-motor experience in a particular sport may facilitate cognitive processing of experience-congruent stimuli. This may be advantageous for situations in which people are engaged in observing sport performance (i.e., judges, coaches). This conclusion could furthermore contribute to the training of athletes from sports such as sky-diving, scuba-diving, and climbing, where losses of spatial orientation can be life-threatening. Key words: functional equivalence hypothesis, gymnastics, rotation preference, sensory-motor experience.

Functional equivalence or behavioural matching? A critical reflection on 15 years of research using the PETTLEP model of motor imagery

Motor imagery, or the mental rehearsal of actions in the absence of physical movement, is an increasingly popular construct in fields such as neuroscience, cognitive psychology and sport psychology. Unfortunately, few models of motor imagery have been postulated to date. Nevertheless, based on the hypothesis of functional equivalence between imagery, perception and motor execution, Holmes and Collins in 2001 developed the PETTLEP model of motor imagery in an effort to provide evidence-based guidelines for imagery practice in sport psychology. Given recent advances in theoretical understanding of functional equivalence, however, it is important to provide a contemporary critical reflection on motor imagery research conducted using this model. The present article addresses this objective. We begin by explaining the background to the development of the PETTLEP model. Next, we evaluate key issues and findings in PETTLEP-inspired research. Finally, we offer suggestions for, and new directions in, research in this field.

Internet use increases the odds of using the public library

PurposeThe functional equivalence hypothesis suggests that a new communication medium will replace those activities that most closely perform the same functions for users as did the established media. There is scarce empirical evidence whether use of the internet displaces use of the public library. This survey aims to explore how the use of the internet is associated with the use of the public library for studying, work and business, everyday activities, and leisure activities. The author also studies which factors in addition to internet use predict the use of public libraries for these purposes.Design/methodology/approachThe data is based on a nationwide representative survey of the adult population in Finland aged 15‐79. The author used binary logistic regression analysis for modelling and predicting library use.FindingsThe results show that the use of the internet is positively associated with the use of public libraries. Those using the internet tend also to use the public library. Thus, the use of the internet does not replace the use of the public library, but merely complements it. It is found that the frequency of internet use and the number of books read are the strongest predictors of public library use.Originality/valueThis is the first study to show that the use of the internet for studying, work and business, everyday activities, and leisure activities is not replacing public library use for the same purposes, but merely complementing it.

Functional traits and their plasticity predict tropical trees regeneration niche even among species with intermediate light requirements

Summary Niche differentiation is a key issue in the current debate on community assembly mechanisms. In highly diverse moist tropical forests, tree species sensitivity to canopy openness is thought to be a major axis in niche differentiation. In the past, the syndrome of traits driving the demographic trade‐off involved in the niche‐based theory of coexistence has always been established among species situated at the two extremities of the shade‐tolerance gradient, even though most tropical tree species have intermediate light requirements. In addition, trait plasticity has seldom been linked to tropical tree species distribution along environmental gradients. This article examines covariations between leaf traits, whole‐plant traits and niche parameters among 14 tree species with intermediate light requirements in French Guiana and across a range of canopy openness. Each functional trait measured under field conditions was characterized by a median value and a degree of plasticity expressed under contrasting light regimes. Niche differentiation was characterized in terms of spatial light gradient. We first examined covariations between functional traits then explored to what degree the median value and plasticity in functional traits could predict light niche characteristics at the sapling stage and the ontogenetic change in light availability estimated by adult stature. Leaf mass per area (LMA) was positively correlated with leaf life span (LLS); species with higher LMA and higher LLS displayed lower diameter growth rates (GRs) and lower responsiveness to canopy gap at both whole‐plant and population levels. This proved that the relationships previously established over a broader range of species held true within the narrow range of the light requirements covered. Height GR plasticity accounted for 49% of the variation in light niche optimum. LMA plasticity, unlike LLS plasticity, was significantly correlated with light niche breadth and adult stature. Synthesis. This study demonstrates the relevance of considering the phenotypic plasticity in functional traits in community ecology, particularly for quantifying breadth of species distribution over environmental gradients. Our findings did not support Hubbell's hypothesis of functional equivalence and suggest that even a rather subtle variation in forest canopy disturbance promotes the coexistence of tropical tree species.

A phyletic perspective on the allometry of plant biomass‐partitioning patterns and functionally equivalent organ‐categories

Biomass-partitioning patterns influence the functioning of aquatic and terrestrial vegetation at all levels, ranging from individual growth and reproduction to the flow of mass and energy through entire communities. For this reason, leaf, stem and root dry biomass-partitioning patterns across taxonomically and ecologically diverse seed plants (spermatophytes) have been intensively investigated, both empirically and theoretically. By contrast, phyletically disparate plants (e.g. green and brown algal macrophytes, mosses and pteridophytes) have not been examined to determine whether the partitioning of their body parts into 'leaf', 'stem' and 'root' analogs accords with that of spermatophytes. In this review, the biomass-partitioning patterns of siphonous and brown algal macrophytes, mosses and pteridophytes were compared allometrically with those of spermatophytes and were shown to be largely in statistical accordance (thus lending support to the hypothesis that a single scaling relationship exists across eukaryotic photoautotrophs). This concordance is argued to support the hypothesis of functional equivalence across analogous, but developmentally different, body parts, a feature that permits the use of simpler biological model systems with which to derive analytical explanations for the biomass-partitioning patterns reported for more complex seed plants.

Neutral theory in community ecology and the hypothesis of functional equivalence

Probably no ecologist in the world with even a modicum of field experience would seriously question the existence of niche differences among competing species on the same trophic level. The real question, however, is how did these niche differences evolve, how are they maintained ecologically, and what niche differences, if any, matter to the assembly of ecological communities? By ecological community I refer to co-occurring assemblages of trophically similar species. By assembly I mean which species, having which niche traits, and how many species, co-occur in a given community. In my judgement, despite a long and rich tradition of research on these questions in community ecology (Chase & Leibold 2003), we are still far from having definitive answers. Several years ago, in an attempt to provide a fresh approach for tackling these questions, I introduced a formal neutral theory for ecology (Hubbell 1997, 2001). The traditional strategy has been to assume that ecological communities are inherently high-dimensional sensu Hutchinson’s (1957) niche hypervolume for each species, and then to build rather complex models from the outset, incorporating as many of the details of the growth and interactions of each and every species and with their physical environment as possible. Neutral theory, however, adopts a fundamentally different strategy, taking virtually the opposite tack. It begins with the simplest possible hypothesis one can think of – for example, the functional equivalence of species – and then adds complexity back into the theory only as absolutely required to obtain satisfactory agreement with the data. In this approach, one does not assume from the start that ecological communities are high-dimensional. Indeed, the fundamental question now becomes: What is the minimum necessary dimensionality of the theory required to characterize a given ecological community to a desired level of realism and precision? The hypothesis of functional equivalence is the cornerstone of neutral theory. It states that trophically similar species are, at least to a first approximation, demographically identical on a per capita basis in terms of their vital rates, of birth, death, dispersal – and even speciation. Elsewhere I have also used the term symmetry to describe such species (Hubbell 2005). Under the hypothesis of functional equivalence, species can still differ in a great many ways – including characters that enable taxonomists to recognize them as good species – so long as species do not differ in their per capita vital rates. All species in all trophically defined communities violate this assumption to some degree, but the question is, how good an approximation is it? In ecology, there are often multiple, sufficient explanations for the same phenomenon (Chave, Muller-Landau & Levin 2002; Purves & Pacala 2005), and this is especially true of approximate explanations. The strategy of neutral theory relies heavily on Occam’s Razor; but whether the assembly rules of ecological communities in nature obey this maxim – to always choose the most parsimonious explanation – is not yet clear. However, as Harte (2003) pointed out, one doesn’t necessarily discard theories just because they are just approximations. Physicists still use Boyle’s Law, PV = nRT (pressure P times volume V is a linear function of absolute temperature T ), even though there are no perfect gases that follow this relationship exactly. Similarly, we continue to teach the Lotka–Volterra equations in ecology, even though no ecologist today would defend them as precise or mechanistic descriptions of nature. Much has been written about the unified neutral theory (UNT) since my book appeared (Hubbell 2001), some of it critical, and there have been several major technical and conceptual advances in the theory since then (e.g. Volkov et al . 2003; Vallade & Houchmandzadeh 2003; Houchmandzadeh & Vallade 2003; McKane, Alonso & Sole 2004; Etienne & Olff 2004). However, my main focus for this forum on neutral theory will not be on the new developments in the theory or on the criticisms. Rather, I wish to highlight the empirical observations that led me to question my own long-held beliefs about the assembly rules for ecological communities in the first place, particularly in plant communities. Before discussing these observations, however, I should sketch out a few of the major milestones in the intellectual history of the classical paradigm of competitive niche assembly theory.

FUNCTIONAL CEREBELLAR ACTIVATION DURING NOVEL AND LEARNED EXECUTED AND IMAGINED SEQUENTIAL HAND MOVEMENTS

Neuroimaging studies have shown cerebellar activation during movement and motor imagery, supporting Jeannerod's (1994) functional equivalence hypothesis. Novel tasks were used in these studies, so the question remains whether equivalence persists with learned tasks. PURPOSE This study compared cerebellar activation during executed and imagined sequential hand movements in Novel and Learned conditions. METHODS Participants (n = 5) were asked to execute or imagine a self-paced sequential key press task at 4 Hz inside a magnetic resonance (MR) scanner during 30s epochs before(Novel) and after one week of physical practice (Learned). The blood oxygen level dependent (BOLD) response of the cerebellum during executed and imagined movements was compared for the Novel and Learned conditions. RESULTS The mean/sd key press rate during the execution phase was 2.7/.6 Hz in the Novel condition and increased to 4.4/1.2 in the Learned condition (t(4) = 4.99;p < .01). For Novel, maximal activation was centered in the ipsilateral intermediate zone for executed movements (x = 8,y = −66,z = −18;136 voxels;Z = 5.61;p < .001) and in the contralateral intermediate zone for imagined movements(x = −10,y = −74,z = −38;85 voxels; Z = 5.39; p < .001). For Learned, maximal activation was centered in the contralateral hemisphere during executed movements(x = −32,y = −66,z = −30; 42 voxels; Z = 6.94; p < .001) and bilaterally during imagined movements x = +/−44,y = −58,z = −34; 7 voxels; Z = 3.00; p < .01). CONCLUSION Functional activation was centered in motor output regions during executed and imagined movements in the Novel condition, though lateralization and activation extent were varied. Activation relocated to motor planning regions in the Learned condition for both execution and imagery, though intensity and extent were substantially less for imagery. The data support similar cerebellar activation between execution and imagery in a Novel task with an increasing dissociation in a Learned task. Supported by the Department of Veteran's Affairs, Veteran's Healthcare Administration, Rehabilitation Research and Development Service.

Event-related potentials as a function of movement parameter variations during motor imagery and isometric action

Neuroimaging and electrophysiological studies have shown that executed action and motor imagery activate common neuronal substrates, leading to the hypothesis that movement preparation and motor imagery are functionally equivalent processes. This study further tested the functional equivalence hypothesis by determining whether electrocortical patterns associated with variations in motor control parameters are similar during imagined and executed actions. Event-related potentials (ERPs) were recorded from the supplementary motor/premotor area (SMA/PMA; FCz site) and primary motor area (M1; C3, C4 sites) during an executed and an imagined, cued, discrete isometric contraction task while target force (TF; low, moderate) and rate of force development (RFD; slow, rapid) were varied. For M1, the correlation of ERPs between moderate- and low force-executions was near zero and N2 amplitude was greater for moderate than low force executions, indicating that M1 activity is related to TF. Rapid executions were greater in amplitude and longer in latency than slow executions and the ERPs for rapid- and slow-executions were negatively correlated, indicating that M1 activity is also related to RFD. There were no differences in N2 amplitude and a zero correlation between execution and imagined actions of similar TF and RFD, indicating that neither TF or RFD are represented in M1 activity during imagery. For SMA/PMA, there was a moderate correlation between moderate- and low force-executions and larger N2 amplitude for moderate- than for low force-executions, indicating that TF may be related to SMA/PMA electrocortical activity. ERP patterns were uncorrelated between rapid- and slow-execution at FCz, but N2 amplitude was the same, making it unclear whether the RFD parameter is represented in FCz activity. The correlational and N2 amplitude analyses demonstrate that patterns of electrocortical activity at SMA/PMA are nearly isomorphic during executed and imagined actions as TF and RFD are varied. These results provide evidence that patterns of electrocortical activity associated with variations in the parameters of executed action are similar during motor imagery at SMA/PMA but not at M1.

Synthetic peptide inhibitors of complement serine proteases—III. Significant increase in inhibitor potency provides further support for the functional equivalence hypothesis

Synthetic peptides based on functionally equivalent (as defined by similar patterns of chemically equivalent amino acids) serine protease inhibitor (serpin) C-terminal sequences inhibit both classical and alternative pathways of complement activation. Inhibition was also found with hybrid peptides consisting of the cleavage site of one serpin (antithrombin III, α-1-antitrypsin, or antichymotrypsin) attached to the short and long functionally equivalent protease binding cores of the other two serpins. A hybrid peptide composed of the sequence at the site of cleavage of C4 by C1s attached to the long binding core of antithrombin III was selective in inhibiting the classical pathway with no effect on the alternative pathway at a concn of 10 μM. Extension of the functional equivalence hypothesis has produced inhibitors of complement activation named generic and generic +, whose sequences differ by 77% or 87%, respectively, from those of all three serpin sequences. A hybrid peptide composed of the antithrombin III cleavage site attached to the generic peptide is an inhibitor of complement activation at 500 nM, the most potent inhibitor found in this study.

The Relationships of Selected Size and Structure Indicators in Economic Organizations

June 1976, volume 21 Interrelationships of size and structure variables in 153 farmer cooperatives are investigated in three stages of analysis. First, an extension of the functional equivalence hypothesis is presented and supported. Alternative indicators of size, other than the traditional one of number of employees, are found to be useful in the analysis. Second, size categories are used to determine if structural differences occur. Differences appear in the structural indicators to varying degrees. The third stage focuses on relationships of size and structure indicators in groups. Major differences are found between small and large fi rms.