Full Length Article
Towards an ecologically grounded functional practice in
Daniela Virgínia Vaz
, Paula Lanna Silva
, Marisa Cotta Mancini
, Claudia Carello
Departament of Physical Therapy, EEFFTO, Universidade Federal de Minas Gerais, Av. Pres. Antônio Carlos, 6627 Campus – Pampulha, Belo Horizonte, MG
CEP 31270-901, Brazil
Department of Psychology, McMicken College of Arts & Sciences, University of Cincinnati, P.O. Box 210376, 4150M Edwards 1 Bldg, Cincinnati, OH
45221-0376, United States
Department of Occupational Therapy, EEFFTO, Universidade Federal de Minas Gerais, Av. Pres. Antônio Carlos, 6627 Campus – Pampulha, Belo Horizonte,MG
CEP 31270-901, Brazil
Department of Psychology and Center for the Ecological Study of Perception and Action, University of Connecticut, 406 Babbidge Road, Unit 1020, Storrs, CT
06269-1020, United States
Center for the Ecological Study of Perception and Action, University of Connecticut, Doctor of Physical Therapy Program, Dept. of Kinesiology, Neag School
of Education, 358 Mansﬁeld Road, Unit 2101, Storrs, CT 06269-2101, United States
Received 3 June 2015
Revised 20 January 2017
Accepted 21 January 2017
According to the International Classiﬁcation of Functioning, Disability and Health, effective
rehabilitation requires interventions that go beyond minimizing pathological conditions
and associated symptoms. The scope of practice must include promoting an individual’s
activity within relevant contexts. We argue that best practice requires decisions that are
not only evidence-based but also theory-based. Perception and action theories are essential
for interpreting evidence and clinical phenomena as well as for developing new interven-
tions. It is our contention that rehabilitation goals can best be achieved if inspired by the
ecological approach to perception and action, an approach that focuses on the dynamics
of interacting constraints of performer, task and environment. This contrasts with
organism-limited motor control theories that have important inﬂuence in clinical practice.
Parallels between such theories and the medical model of care highlight their fundamental
inconsistency with the current understanding of functioning. We contend that incorporat-
ing ecological principles into rehabilitation research and practice can help advance our
understanding of the complexity of action and provide better grounding for the develop-
ment of effective functional practice. Implications and initial suggestions for an ecologi-
cally grounded functional practice are outlined.
Ó2017 Elsevier B.V. All rights reserved.
In 1996 Human Movement Science published a special issue on the relevance of dynamical and ecological approaches to
rehabilitation. The special issue aimed to bring dynamically and ecologically inspired research together and bridge the gap
0167-9457/Ó2017 Elsevier B.V. All rights reserved.
E-mail addresses: email@example.com (D.V. Vaz), firstname.lastname@example.org (P.L. Silva), email@example.com,firstname.lastname@example.org (M.C. Mancini),
email@example.com (C. Carello), firstname.lastname@example.org (J. Kinsella-Shaw).
Human Movement Science 52 (2017) 117–132
Contents lists available at ScienceDirect
Human Movement Science
journal homepage: www.elsevier.com/locate/humov
between these theoretical approaches and rehabilitation practice (Wagenaar & van Emmerik, 1996). By then, few attempts
had been made to link dynamical and ecological perspectives to rehabilitation. Accounts were young and caution seemed
needed. The state of the art then did not allow conclusions as to the fruitfulness of the approaches to clinical practice
(van Wieringen, 1994).
Today, after 20 years, theoretical and applied clinical research based on dynamical and ecological approaches has ﬂour-
ished. The ﬁeld of rehabilitation has also matured in its understanding of human functioning and disability, as is reﬂected by
the development and wide recognition of the International Classiﬁcation of Functioning, Disability and Health (World Health
Organization, 2001, 2007). According to the ICF, effective rehabilitation requires going beyond minimization of pathological
conditions and associated symptoms. It requires promotion of an individual’s activity within relevant contexts.
As researchers and instructors in rehabilitation clinical courses, we contend, however, that the changes in clinical practice
in the face of these developments have been modest and insufﬁcient. ICF pushes an understanding of functioning that lies at
the interface of an individual with his or her environmental context. It is our view that a great barrier to the reform of clinical
practice demanded by the ICF is the continued credence in organism-limited theories of perception and action and motor
control. ICF-inspired clinical change would have to draw on theories that recognize the fundamental constitutive role of indi-
vidual x environment interactions in the explanation of perceptual-motor processes supporting task performance. The Eco-
logical Approach to Perception and action is one such theory. In this paper, we aim to bring to light the deep conceptual
connections between ecological theory and the ICF. We contend that knowledge of how principles of perception and action
relate to human functioning can effectively translate to basic and applied research that will set the stage for evolution in
In this effort, we are indebted to the pioneering work of Burton & Davis (Burton & Davis, 1992, 1996; Davis & Burton,
1991). Originally directed to adapted physical education, their model of practice called ‘‘Ecological Task Analysis” provided
the inspiration for many of the applications of ecological and dynamical theories to rehabilitation.
2. The need for functional therapeutics
Joseph, age 13, has hemiplegic cerebral palsy; his rehabilitation program focused on training repetitive discrete move-
ments of his affected hand and on maintaining ﬁngers’ range of motion, but has not resulted in better performance in
his favorite video game.
The realization that rehabilitation interventions all too frequently fail at helping clients achieve their functional goals pro-
moted a shift in the understanding of functioning and disability summarized in the ICF (World Health Organization, 2001,
2007). As exempliﬁed by the rehabilitation case of Joseph, improvements at one level of functioning (e.g., discrete move-
ments and range of motion) might not transfer immediately to other levels (e.g., the concrete activity of playing video-
games). The ICF encourages researchers and clinicians to develop interventions that are more effective in promoting
improvements across levels of human functioning. We will call a therapeutic model that focuses on such promotion ‘‘func-
tional therapeutics”. Its main aim is to improve engagement in functional tasks, and such aim cannot be achieved by con-
sidering the individual or the organism in isolation from its context. A growing body of evidence indicates that
traditional treatment approaches grounded in neurophysiologic (individual/organism-limited) theories are not effective in
improving function and urge clinicians to move towards activity-based therapy (Damiano, 2007; Dobren, 1994; Durand &
Vachon, 2003; Kollen et al., 2009; Kwakkel, Kollen, & Wagenaar, 1999; Macedo & Maher, 2009; Mayston, 2008; Van der
Lee et al., 1999; Van Peppen et al., 2004).
The move towards functional therapeutics can be fostered by perception-action theory. The ecological approach to percep-
tion and action pioneered by James J. Gibson (Gibson, 1960, 1979; Michaels & Carello, 1981; Shaw, Turvey, & Mace, 1982;
Turvey & Shaw, 1995, 1999; Turvey, Shaw, Reed, & Mace, 1981) is inherently consistent with the current conceptions of func-
tioning and disablement processes underwritten by ICF. One fundamental principle of the ecological approach is that of the
organism-environment mutuality. According to this principle, organisms (e.g., individual patients) and environments are not
separate or logically distinct entities—the organism-environment system (not just the organism) is the proper, irreducible
unit of analysis for understanding functional (or dysfunctional) behavior (Gibson, 1979; Holt, Wagenaar, & Saltzman,
2010; Michaels & Carello, 1981; Turvey & Shaw, 1995, 1999) (see Fig. 1).
Our contention is that a conception of organism-environment mutuality is, in fact, entailed by the ICF. In the following
section, a brief historical overview of the development of the current ICF model is provided and its congruence with ecolog-
ical principles is highlighted.
3. An evolving understanding of human functioning—from ‘‘mechanism to ‘‘system
Over the years, models of human disablement and functioning have evolved from a mechanistic to a systemic view.
Accounts of both physiological and psychological function from the 18th through the mid-20th centuries were largely indif-
ferent to the role of the environment and thus assumed that explanations of typical or altered behavior could be legitimately
attributed to the workings of body structures or to their malfunctioning due to pathology. The absence of pathology (or
injury) affecting organs, tissues, cells or molecular processes within the body could thus be equated with normal functioning
at the level of behavior. Analogously, abnormal functioning (or disablement) at the level of behavior was attributed solely to
118 D.V. Vaz et al./ Human Movement Science 52 (2017) 117–132
pathology (or injury) that disturbed organs, tissues, cells or molecular processes. The ﬁrst formal model of human disability
proposed by Saad Nagi in the 1950’s inherited such mechanical causal logic (Nagi, 1965; Verbrugge & Jette, 1994). Nagi’s
model included four components: active pathology,impairment, such as physical or mental abnormality or loss; functional
limitation in task performance; and disability, including limitation on social participation. For Nagi, the relationships among
these components was unidirectional—from the micro-level of biological functions to the macro-level of behavior—and lin-
ear—beginning with the disease and ending with social limitation (see Fig. 2). The unidirectional and linear relationships
between components reﬂect the assumption of a mechanical causal chain in which the presence of pathology unleashes
the disabling process with its stepwise negative consequences (Gray & Hendershot, 2000). The nature of Nagi’s model is both
mechanistic, in seeking a responsible patho-physiological component, and organism-limited, in seeking that responsible
component within the organism. Fundamentally, the model lacks constructs to identify the role played by the environment
in the disabling process.
The Möbius strip represents the organism-environment
system as the irreducible unit of analysis.
Fig. 1. Mutuality principle. The Möbius strip represents the organism-environment system as the irreducible unit of analysis.
The Nagi’s Model of Disability (1964)*
The WHO ICIDH Model of Disability (1980)**
*Adapted from: Appendix A: Disability Concepts Revisited: Implications for Prevention ."Disability in America: Toward a National Agenda
for Prevention” . Washington, DC: The National Academies Press, 1991.
** Adapted from: World Health Organization (WHO). International Classiication of Impairments, Disabilities, and Handicaps: A manual of
classiication rating to the consequences of diseases. WHO, Geneva, 1980.
efforts of the
organism to regain
abnormalities or loss
performance at the
level of the whole
organism or or
roles and tasks in a
Changes in the
functioning of the
Any loss or
activities within the
fulilment of a
Fig. 2. The Nagi and ICIDH Models of Disability.
Adapted from: Appendix A: Disability Concepts Revisited: Implications for Prevention .‘‘Disability in
America: Toward a National Agenda for Prevention”.Washington, DC: The National Academies Press, 1991.
Adapted from: World Health Organization
(WHO). International Classiﬁcation of Impairments, Disabilities, and Handicaps: A manual of classiﬁcation rating to the consequences of diseases. WHO, Geneva,
D.V. Vaz et al./ Human Movement Science 52 (2017) 117–132 119
In 1980, the World Health Organization (WHO) proposed a modiﬁed version of Nagi’s disability model, the International
Classiﬁcation of Impairments, Disability and Handicap, or ICIDH (Verbrugge & Jette, 1994; World Health Organization, 1980).
It also included four components that are slight variations on Nagi’s: disease; impairment (again, physical or mental abnor-
mality or loss); disability, now labeling limitations in performing tasks; and handicap referring to limits in fulﬁlling social
roles. Clearly, the ICIDH proposed mainly a change in terminology, retaining the same mechanistic, linear causal structure
from disease to social limitations (Gray & Hendershot, 2000), and without the possibility of identifying explicit environmen-
tal contributions to the disablement process (see Fig. 2). Both the Nagi and ICIDH models, presume that human disablement
at the macroscopic levels of behavior result from the additive contributions of the related microscopic level of physiological
processes. Any environmental inﬂuence, therefore, is reducible to its effects on the particular physiological processes that
triggered the limitations in task performance and social participation. The focus of these models remained on the disease
and its negative consequences for structures and processes internal to the individual.
A major source of criticism of the mechanistic view of disablement reﬂected in Nagi and in the ICIDH models was that
they lacked constructs to identify the role of the environment in a disabling process. Interventions that improve functional
outcomes by modifying environments in which people with disability live (Brush, Meehan, & Calkins, 2002; Hanft &
Pilkington, 2000; Henderson, Skelton, & Rosenbaum, 2008; Jette, Keysor, Coster, Ni, & Haley, 2005; Saegert, Klitzman,
Freudenberg, Cooperman-Mroczek, & Nassar, 2003; Schneidert, Hurst, Miller, & Üstün, 2003) bring the inadequacies of
the Nagi and ICIDH models into sharp relief. As an alternative, a systemic view of disabling and functioning processes ought
to include constructs that capture the interactive dependency between an individual and her or his environment, as well as
the possibility that an individual with a disease can engage in and experience functioning (however that functioning has
been transformed). In 2001, the WHO incorporated these constructs and approved the ICF (World Health Organization,
2001). The ICF reﬂects a biopsychosocial approach to human functioning; it considers the contribution of biological, individ-
ual, and social factors. In the ICF model, disability and functioning are viewed as processes underwritten by bidirectional
relations and non-linear interactions between health conditions (diseases, disorders, and injuries) and contextual factors
(both personal and environmental). The ICF and its version for children and youth (World Health Organization, 2007)
(Fig. 3) proposes three levels of human functioning: body structure and function, the level of body or body parts; activity,
the level of the whole person; and participation, the whole person in a social context. Disability involves malfunctioning
at one or more of these levels, manifested as impairments in body functions and structures, activity limitations and/or par-
ticipation restrictions (see Fig. 3).
According to the conceptual structure of the ICF, the contextual level refers to external environmental factors that include
social attitudes, architectural characteristics, legal and social structures, climate, terrain, assistive technologies and so forth;
and internal personal factors, such as gender, age, coping styles, social background, education, profession, past and current
experience, behavioral pattern, character and other factors that inﬂuence how disability is experienced by the individual
(World Health Organization, 2001, 2007). The interactive and bidirectional conceptual structure of ICF constitutes a signif-
icant departure from the linearity of the previous models. Each dimension is the result of dynamical (and non-linear) inter-
actions between factors intrinsic to the individual and factors intrinsic to the environment (see Fig. 3). The ICF counters the
view that people’s disability is a natural consequence of a disease. Rather, it describes an individual’s level of health and
functioning in its own right, that is, irrespective of the presence of a risk factor, health condition, disease or pathological pro-
cess. It provides health care practitioners with a function-enablement perspective, supporting a comprehensive and positive
view of an individual’s performance in various contexts (Goldstein, Cohn, & Coster, 2004; Jette, 2006).
The ICF is currently the most widely accepted model of functioning and disability. Its introduction marked a clear tran-
sition of rehabilitation professions from a medical model to a functional model. The medical model emphasizes the disease
Fig. 3. The International Classiﬁcation of Functioning, Disability and Health (CIF). Adapted from: World Health Organization (WHO). International
Classiﬁcation of Functioning, Disability and Health (ICF). Geneva, 2001. In bold are the components of functioning and in Italic are the components of
120 D.V. Vaz et al./ Human Movement Science 52 (2017) 117–132
and pathological processes and their impact on body parts and corresponding functions as the fundamental unit of analysis
(Engel, 1977). This model prioritizes the understanding of etiological factors leading to a pathological process, and its phys-
ical and/or psychological symptoms. The clinical reasoning supporting this model is based on relating pathological processes
and associated symptoms to the malfunctioning body parts and then identifying and treating its causes. Medical manage-
ment, therefore, focuses on successfully ameliorating or curing pathology. Such focus does not ensure the restoration of func-
tion in daily life, as it does not address the task and context-speciﬁc constraints on the activities performed by an individual.
Put simply, arresting a disease process or reducing its symptoms may improve functioning—for example, due to reduction of
pain—but this goal, though laudable, may leave function unchanged. Intervention at the level of the disease or its symptoms
does not impart skills to a patient within a task-speciﬁc context. Medical therapeutics may in fact, at times, introduce new
constraints on function. For example, a lower limb amputation can save a life but forever alters ambulation.
Improvements in functioning require task-speciﬁc, contextualized therapeutic intervention (Fetters & Ellis, 2006;
Ketelaar, Vermeer, Hart, van Petegem-van Beek, & Helders, 2001; Rensink, Schuurmans, Lindeman, & Hafsteinsdottir,
2009; Trombly & Wu, 1999; Weel, Meer, & Lee, 1991; Wu, Trombly, Lin, & Tickle-Degnen, 1998). The Functional model rests
on this rationale. It emphasizes processes supporting context sensitive task performance to guarantee goal satisfaction (Carr
& Shepherd, 2011; Holt et al., 2010; Mathiowetz, Gillen, & Burkhardt, 2004; Preissner, 2010; Radomski & Trombly, 2007;
Shumway-Cook & Woollacott, 2000; Wu et al., 1998). Its fundamental unit of analysis is the individual in a task-speciﬁc con-
text, intentionally engaged in an activity under the dual constraints provided by the properties of the environment and the
individual’s abilities. Returning to Joseph’s case, the failure to conduct clinical assessment and plan intervention according to
this fundamental unit of analysis limits real functional improvement in an important activity of daily living for him, namely,
playing his favorite video-game.
In the functional model, assessments, clinical reasoning and intervention processes must be explicitly distinct from those
used in the medical model, since a functional perspective emphasizes engagement in relevant tasks. Such emphasis requires
the individual and environment not to be taken as separate entities. The functional model underwritten by the ICF is thus
ecological at heart, as it commits to the mutuality principle: The organism-environment system (as opposed to just the
organism) must be the proper, irreducible unit of analysis (see Fig. 4). What are the implications of this commitment?
The ICF amounts to a declaration that the full complexity of behavior cannot be ascribed to the workings of anatomical
structures or physiological mechanisms of the body. As such, it requires a shift in clinical and research reasoning in rehabil-
itation beginning with a change of focus from the organism to the organism-environment system (Holt et al., 2010). The nec-
essary tuning of clinical practice to the understanding of functioning and disability conceived by ICF, therefore, cannot be
supported by organism-limited theories of perception and action and motor control. An account of functional behavior
(and likewise any intervention aimed at improving functional behavior) must be sought at the interface between an individ-
ual’s set of capabilities—or effectivities—and the opportunities offered by the environment for realization of his or her goals—
affordances, in ecological theory. Uncovering the underpinnings of successful functional performance, therefore, requires
uncovering the processes that facilitate a given affordance-effectivity ﬁt, as will be elaborated later in this paper (see
Fig. 5)(Michaels & Carello, 1981; Turvey, 1992; Turvey et al., 1981). We argue that ecological theory is particularly appro-
priate to support the shift required by the ICF. But why is a theory of perception and action essential to this process?
4. Best practice: the role of evidence and theory
Rehabilitation professionals are faced with pressures for accountability from both health-care payers and better-informed
patients. As a consequence, current ‘‘gold standard” guidelines for clinical practice emphasize the need for evidence-based
practice (EBP). The aim of EBP is to make use of the best available scientiﬁc evidence, moderated by patient circumstances
and preferences, to improve the quality of clinical judgments and facilitate cost-effective care. EBP has increased the prox-
imity of clinicians with the applied research literature and must be welcomed and promoted (e.g. Holm, 2000; Sackett,
Strauss, & Richardson, 2000).
The accumulation of empirical evidence on the efﬁcacy of clinical procedures, however, is of limited value to the practi-
tioner unless accompanied by underlying theory to ground wise application. Said differently, evidence is always viewed through
the prism of theory, whether the theory is private, implicit, and unarticulated, or public, explicit, and clearly articulated. An
articulated theoretical framework is preferred because the explanatory and predictive features of theory are essential to the
judicious design and selection of assessments and interventions. The challenges are many. As examples, how should a ther-
apist manage a conﬂict between patient preferences and available evidence of efﬁcacy of different interventions? How do
practitioners select and predict effects of multidimensional interventions if randomized clinical trials can only test a limited
number of combined interventions? How can it be determined if an intervention has worked, given the particular values and
expectations of a patient? How might new interventions be developed? How can an appropriate course of action be deter-
mined for issues where there is no ﬁrm evidence base? Finally, how might a general treatment philosophy, coherent with
ICF’s model, take advantage of local and fragmented empirical facts? The rehabilitation professional needs to be able to draw
on theory, research and practice in order to address such questions (Harper, Mulvey, & Robinson, 2013; Holt et al., 2010).
To illustrate the importance of theory, consider the roles (or lack thereof) played by constructs such as ‘‘information”, ‘‘re-
ﬂex”, ‘‘positional lesion”, ‘‘mobilization”, and ‘‘synergy” in various approaches to therapy. The meanings of all these terms,
and even of a seemingly benign and concrete term like ‘‘spasticity” have evolved as our understanding of neurology and
D.V. Vaz et al./ Human Movement Science 52 (2017) 117–132 121
motor control have changed (Carr & Shepherd, 2011; Landau, 1974; Sheean, 2002). Spasticity, for instance, was once con-
founded with the entire motor neuron syndrome, including motor performance disability as well as reﬂex release
(Landau, 1974). Currently, due to advances in conceptualization, it is more narrowly deﬁned as a velocity-dependent tonic
reﬂex contraction response to muscle stretch, distinct and independent from other positive and negative upper motor neu-
ron syndrome phenomena such as spasms, states of constant involuntary contraction, weakness and loss of dexterity
How, then, should evidence of the effects of therapies on spasticity be interpreted? Any interpretation will be directed by
the underlying theory one brings to the analysis. Moreover, to bring the example to the context of human functioning, what
should we expect the role of (interventions for) spasticity in function to be, given the understanding of function embodied in
the ICF? For example, should we expect Joseph’s ability to play video games to improve if we decreased the reﬂex contraction
levels of his wrist and ﬁnger ﬂexors in response to passive stretch? Reliance on evidence collected in accord with rigorous
scientiﬁc methodology is a necessary ﬁrst step towards clinical efﬁcacy but is not sufﬁcient to ensure best practice. Applica-
tion of evidence to the particular context of a patient’s goals and needs cannot be simply about using the evidence of the
effects of available interventions as local decision criteria; it must also emphasize the understanding of how the focus
and methods of a given intervention are consistent or at variance with the theoretical developments in the understanding
Ecological view of behavior and ICF’s view of functionality: several shapes and positions of the Möbius strip represent transformations over
time of an irreducible system of individual - environment interactions. Consistent with ICF’s view of function, the ecological view of behavior is
defined at multiple, nested levels of individual x environment interactions, from body to social. As noted by Withagen & Michaels (2005),
behavior is “…intrinsically functional. Behavior, even a reflex, constitutes a mode by which a functional relationship with the environment is
established”. Functional relationships at the levels of Body structures and functions, Activity and participation emerge from the mutual
influences between environmental and personal factors.
Fig. 4. Ecological and CIF perspectives. Ecological view of behavior and ICF’s view of functionality: several shapes and positions of the Möbius strip
represent transformations over time of an irreducible system of individual – environment interactions. Consistent with ICF’s view of function, the ecological
view of behavior is deﬁned at multiple, nested levels of individual x environment interactions, from body to social. As noted by Withagen & Michaels (2005),
behavior is ‘‘...intrinsically functional. Behavior, even a reﬂex, constitutes a mode by which a functional relationship with the environment is established”.
Functional relationships at the levels of Body structures and functions, Activity and participation emerge from the mutual inﬂuences between
environmental and personal factors.
122 D.V. Vaz et al./ Human Movement Science 52 (2017) 117–132
of human functioning. Best practice in rehabilitation requires, therefore, theory-based practice as much as it requires
evidence-based practice (Holt et al., 2010). For best practice in rehabilitation, theories of perception and action are funda-
mental. These theories set the stage for expectations and predictions of how human behavior should reorganize in the presence
of health conditions (and interventions).
In particular, a theory of perception and action that shares the principle of organism-environment mutuality with current
models of human functioning, as is the case of the ecological approach, can be the necessary catalyst for a deﬁnite, ICF-
inspired, transition of rehabilitation professions from the medical to the functional model. In Joseph’s case, this transition
would implicate assessments and interventions planned in reference to his performance in a task-speciﬁc context, namely,
intentionally engaged in playing his favorite video-game. These assessments would thus necessarily take into account the
complementary constraints provided by the properties of the environment and his capabilities. Interventions should pro-
mote the conditions for development and discovery of new affordances and effectivities. Within an ecological perspective,
expectations and predictions of behavioral reorganization would be made with reference to nothing less than this
individual-environment unit of analysis.
If rehabilitation goals demand a transition to a functional perspective, could such a transition be supported by the tradi-
tional theories that have been (and still are) foundational to mainstream rehabilitation practice? To answer this question, we
examine these theories in the next section.
5. Theoretical underpinnings of organism-limited therapeutic approaches
Physical rehabilitation clinicians have (implicitly or explicitly) drawn much of their practice from theories of motor con-
trol. Two features should be noted. First, as we emphasize in describing these theories below, they are classiﬁed as theories
of motor control because their focus is on human movement, not perception and action more generally. Second, they are
organism-limited. The central assumption of these theories is that functional movement can be reduced to the operation
of special elements of the movement system, taken to be context-independent units—speciﬁc to anatomical structures—that
are properly arranged to form complex movement patterns (Sechenov, 1935). The original notions of reﬂex, reciprocal inhi-
bition and motor commands that have dominated theories of movement instantiate such a rationale (Gallistel, 1982). For
example, a reﬂex arc was originally conceived as a stereotypical motor response resulting from the proper stimulation of
a receptor and its associated afferent path (Gallistel, 1982; Lloyd, 1943; Prochazka, Clarac, Loeb, Rothwell, & Wolpaw,
2000). Whole patterns of reciprocal inhibition of pairs of antagonistic muscle groups were attributed to hard-wired combi-
nation of these reﬂexes. Finally, the outﬂow signals from neurons in different locations in the motor strip (motor commands)
Affordances are opportunities for action offered by the environment that are
specific to an individual’s capabilities —his or her effectivities.
Changes in personal and changes contextual factors affect the fit between these
The focus of functional practice in Physical and Occupational Therapy should be in
uncovering the processes that facilitate a given affordance-effectivity fit for a patient.
two complimentary aspects of function.
Fig. 5. Affordance-Effectivity ﬁt. Affordances are opportunities for action offered by the environment that are speciﬁc to an individual’s capabilities—his or
her effectivities. Changes in personal and changes contextual factors affect the ﬁt between these two complimentary aspects of function. The focus of
functional practice in Physical and Occupational Therapy should be in uncovering the processes that facilitate a given affordance-effectivity ﬁt for a patient.
D.V. Vaz et al./ Human Movement Science 52 (2017) 117–132 123
were believed to directly modulate these patterns of activation and inhibition, generating the observed movement patterns
(Gallistel, 1982; Sherrington, 1961).
More current perspectives on motor control recognize that, due to context-conditioned variability, there is no one-to-one
mapping between a given pattern of neural or muscular activation and the resulting pattern of movement. This problem of
context-conditioned variability was ﬁrst articulated by Bernstein (Bernstein, 1967; Turvey, Fitch, & Tuller, 1982) and has dri-
ven important advances in theories of motor control ever since (Turvey, 1990). In particular, Bernstein cogently argued that
movement always takes place against a background (or context) of ongoing non-muscular forces that will necessarily inﬂu-
ence the end result of any pattern of muscle inhibition and excitation initiated by either a motor command or a reﬂex. The
implication is that motor commands, reﬂexes and inhibition do not result in predictable movement outcomes independently
of the context, that is, environmental constraints. In the face of the challenge of context-dependency, current theories try to
accommodate context-sensitive elements into their account of how the nervous system might produce coordinated move-
ment. Prominent modern accounts of this problem can take either a physiological (- e.g., Lambda Theory (Feldman, 2010;
Latash, 2008) or computational slant (- e.g., Optimal Control Theory, Todorov, 2004; Todorov & Jordan, 2002). These theories
nonetheless maintain a privileged focus on an anatomical component—the central nervous system—as a special source of
coordination, and are thus also organism-limited. These theories share the idea that movement coordination underlying
the execution of functional tasks is deﬁned as the combining, by a central controller, of behavioral units to yield task-
sensitive movement patterns. The ordered combination of these behavioral units for each type of movement is believed
to be realized by neural structures. In diverse theories, neural structures responsible for controlling movements have been
variously referred to as motor engrams, programs or schemas (Keele, 1968; Morris, Summers, Matyas, & Iansek, 1994;
Schmidt, 1975), forward and inverse models (Kawato, 1999). These concepts have had a great impact on the ﬁeld of physical
rehabilitation (Morris et al., 1994; Schmidt, 1988; Shea & Wulf, 2005; Shumway-Cook & Woollacott, 2000).
The organism-limited theories of motor behavior whose principles were brieﬂy outlined above lead to a view of rehabil-
itation as a process of ‘‘relearning” or re-establishing the neural mechanisms or programs that were impaired by a health
condition. Applying this notion to the rehabilitation of a stroke patient, for instance, would mean developing an intervention
with the goal of re-establishing normal engrams, motor programs or schemas (Bobath, 1978; Brunnström, 1970). Classical
treatment approaches usually attempted to achieve this goal by facilitating normal and inhibiting abnormal muscle activity
(such as spasticity). One example is the Neuro-Developmental Treatment, initially proposed more than 50 years ago (Bobath,
1948) and adopted by thousands of clinicians in many countries around the world. Treatment was organized around reﬂex-
inhibiting postures and manual techniques to reduce tone in order to avoid reinforcing pathological synergies. The connec-
tion with organism-limited reﬂex-based theories of motor control is evident. Relatedly, in pediatric care, reﬂex-hierarchic
and neuromaturational approaches to development (Bobath, 1991; Gesell, 1945; McGraw, 1943) have stimulated the devel-
opment of interventions based on the idea that development progresses from primitive, reﬂex movements to controlled, vol-
untary actions, through a ﬁxed sequence and regular rhythm of acquisition of motor milestones as maturation of nervous
structures takes place. Traditional models of intervention for children with movement disorders like cerebral palsy thus,
incorporated recapitulation of the normal pre-programed sequence of development (Mayston, 2008). As a consequence,
for both adults and children, activities of daily life such as dressing up, eating or performing household chores and leisure
activities, which are commonly the main concern of patients and their families, have not been prioritized in these models
of intervention. As was pointed out before, the ineffectiveness of these therapies to improve functional activities have
prompted numerous publications urging clinicians to abandon them and move on to activity-based therapy (Damiano,
2007; Kollen et al., 2009; Mayston, 2008; Van Peppen et al., 2004).
More recent clinical research has used current cognitive neuroscience principles as their foundation. Neuroscience
assumes that ‘‘complex behavior can be described as a collection of simpler task processes ... implemented in specialized
brain systems” (p. 4S C, (Corbetta & Fitzpatrick, 2011). Accordingly, recent interventions proposals aim to improve speciﬁc
neural mechanisms, for example direct stimulation of the cortex to improve motor outﬂow, robot-assisted movement to
favor sensory feedback, motor imagery exercises to improve putative internal forward models (Corbetta & Fitzpatrick,
2011; Pomeroy & Aglioti, 2011). In a recently published consensus, a panel of experts in the ﬁeld argued for advancing
neuroscience-based rehabilitation according to a computational, anatomical and physiological (CAP) framework (Frey
et al., 2011). In spite of drawing from the most current ﬁndings and concepts of neuroscience, what the CAP framework offers
is an updated version of a still organism-limited perspective to movement organization.
In orthopedic rehabilitation, neuroscience-based interventions following the same logic of the previously described CAP
framework have been gradually increasing in popularity. This increase in popularity has been catalyzed by new models of
explanations for orthopedic dysfunctions, which were made prominent by Panjabi (1992) (Panjabi, 1992) and most recently
advocated by a number of researchers in the ﬁeld (e.g. Hodges & Moseley, 2003; Jull & Richardson, 2000). Their argument is
that the development of typical orthopedic conditions should not be simply attributed to impairments such as muscle
strength and range of motion (the traditional targets of orthopedic interventions). Rather, the onset and maintenance of such
conditions should be primarily attributed to impairments in neurophysiological mechanisms related to recruitment of the
muscular system during performance of functional tasks (cf. Hodges & Moseley, 2003 for a review in the context of low back
pain). Identiﬁed neurophysiological impairments include changes in excitability at the spinal or cortical level, changes in
proprioception or afferent mediated control, or speciﬁc cortical effects imparted by aspects of pain, stress or fear (Hodges
& Moseley, 2003). The proposed deﬁciency in neural mechanisms has been primarily indexed by the presence of altered tim-
ing and patterns of muscle recruitment in individuals with a number of orthopedic conditions such as low back pain (Hodges,
124 D.V. Vaz et al./ Human Movement Science 52 (2017) 117–132
2001), cervical pain (Szeto, Straker, & O’Sullivan, 2005), impingement syndrome (Lin et al., 2006), and patello-femoral syn-
drome (Cowan, Bennell, Hodges, Crossley, & McConnell, 2001). Intervention strategies inspired by these ﬁndings commonly
include exercises intended to restore ‘‘normal” patterns of muscular activation with the goal of reducing abnormal stresses
to the affected joint (Comerford & Mottram, 2001; Jull & Richardson, 2000; Van Vliet & Heneghan, 2006). In practice, the
training advocated in these approaches is on conscious control of the level of activation of impaired muscles, which should
ﬁrst be recruited in isolation and then in coordination with other muscles in the context of elemental movement patterns
(such as diagonal and spiral patterns). Adequate performance of more complex skills like reaching for an object, standing
up from a chair and walking would depend ﬁrst on the automatizing of these elemental patterns and later on their integra-
tion in a motor program speciﬁc to the class of activities in question (Costa et al., 2009; Jull, Falla, Vicenzino, & Hodges, 2009;
McMullen & Uhl, 2000). Interventions following this rationale give little consideration to the ﬁt between the capabilities of
the patient and the contextual constraints on daily tasks. Not surprisingly, evidence suggests neural-based interventions pro-
mote, at best, only modest reductions in disability and are no more effective than traditional interventions, e.g. manual ther-
apy or exercise (Macedo & Maher, 2009). A widening of the scope of rehabilitation theory, research and interventions is
needed if coherence with the ICF model of function is desired.
What these examples of research agendas and treatment approaches in neurological, pediatric and orthopedic rehabili-
tation have in common is their consistency with organism-limited motor control theories that assume the brain (or body
structures more generally) to have ultimate explanatory value in accounting for functional movement. They assume a direct
causal path from brain (or body structures more generally) to functional movement. Their rationale ﬁts in nicely with the
medical therapeutics model of care and early narrower models of human disablement that assumed a linear causal progres-
sion from pathology to impairments in body structures to disability, with no or limited regard to contextual factors and
potentially complex nonlinear interactions. They lack appreciation of the full implications of the context-dependency of
functional movement, that is, of the fact that functional movement is goal directed and cannot be understood without seri-
ous consideration of the task at hand. For example, the lawfulness of patterns of muscular activation and joint motions of a
person using a hammer to hit a nail can only be captured if the properties of the hammer, the nail and the precision require-
ments of the task are taken into consideration. In spite of the lack of a one-to-one relation between muscle activation pat-
terns and the movement end result (Bernstein, 1967; Turvey et al., 1982) individuals are typically successful in producing
coordinated movement to satisfy task goals. This implies that the context in which a task is performed is fully taken into
account in the control of their actions. For this to be possible individuals and context must form a strongly coupled system,
and observed behaviors emerge as properties only of this coupled system. Motor control theories derived from conventional
neuroscience avoid providing an account of the (perceptual) coupling by displacing the problem of coordination from the
level of the organism-environment system to intelligent structural organizations (internal models, programs, commands)
internal to the organism without ever giving any explanation for their origin, viability or necessity (Turvey, 1986; Turvey
& Carello, 1981). The strong individual-context coupling implicates, however, that causes cannot be simply ascribed to neu-
ral commands targeting the muscles (even if they are to be assembled based on some putatively context-sensitive elements
in modern approaches, e.g. Schmidt’s Generalized Motor Program approach (Shea & Wulf, 2005). This is because the princi-
ples underlying control and coordination certainly cannot reside in the neuromotor system, any more than they do in the
tasks to be performed and in the environments in which they are performed. Said differently, context has a constitutive role
in movement as much as any speciﬁc motor process, and credit for adaptive behavior cannot be assigned to any one piece of
a coupled organism-environment system (Chiel & Beer, 1997). Likewise, according to the ICF, functioning and disability can-
not be credited to either aspects of the body or to contextual aspects, for functioning and disability emerge from a dynamical
interaction between health conditions and (personal and environmental) contextual factors (see Fig. 4). The implication to
physical rehabilitation is that interventions based on either traditional or modern organism-limited theories of motor con-
trol fall short of addressing rehabilitation needs because they are oblivious to the full complexity of functioning. Failure to
recognize this is likely behind the limited effectiveness of traditional therapies to promote functional gains for patients, as
shown by clinical trials and systematic reviews (Butler & Darrah, 2001; Macedo & Maher, 2009; Paci, 2003; Van Peppen et al.,
6. Theoretical foundation for a function-based approach
A theory that recognizes the fundamental constitutive role of context in functional movement is duty-bound to provide
an account of how the individual-environment coupling is established—how perception informs and is informed by action.
Said differently, a theory of perception and action is at a privileged level of analysis to explain functional movement. Ecolog-
ical psychology has long emphasized a dynamical perspective on perception and action that capitalizes on organism-
environment mutuality. It recognizes that correlations between perception and action’s neural support (or any other sys-
tem’s support) and observed behavioral patterns are not causal or reductive; such correlations are, rather, complementary
(Warren, 2006). Thus, instead of investing the brain with unexplained intelligent structures to control movement, ecological
psychology has embraced self-organization as a principled grounding for the functional behavior of living systems. Activity is
shaped by the nonlinear dynamics of the performer as he or she interacts with a particular context to fulﬁll task demands
(Bernstein, 1967; Burton & Davis, 1996; Holt et al., 2010; Kelso, 1995; Newell, 1986; Thelen, 1995; Turvey et al., 1982).
The assumption is that organisms exploit the regularities of this dynamics in producing purposeful activity guided by per-
D.V. Vaz et al. / Human Movement Science 52 (2017) 117–132 125
ceptual information (available in the optic, acoustic, olfactory and haptic ﬁelds). Information is viewed as speciﬁc to state of
the animal-environment system and, consequently, can regulate action directly. Therefore, according to the ecological
approach, the behavioral outcome is a function of a number of factors within and outside the organism and is not arbitrarily
imposed by the nervous system (or any other organism system (Warren, 2006). Functional limitations therefore cannot, like-
wise, be accounted for by a restricted focus on neural (or any other body) impairments.
Note that this is not to say that impairments should not be addressed in therapy. Relatedly, there is no implication that
biomechanics, coordination dynamics, neurology, cardiology or other disciplines have reduced relevance in theoretical and
clinical investigation of functional performance, speciﬁc impairments and compensations. The point, instead, is that the ines-
capable context-dependency of activity makes the animal-environment system the irreducible unit of analysis guiding any
functional rehabilitation proposal.
Given 1) our current understanding of disablement and functioning under the ICF model, 2) the available theories of per-
ception and action, and 3) limited effectiveness of traditional organism-limited clinical approaches in rehabilitation to pro-
duce functional improvement for patients, the adoption of an ecological approach to therapy is wise and well justiﬁed. In
sum, the ecological approach to perception and action is congruent with the roles that rehabilitation professionals should
play in promoting human functioning. An examination of how ecological principles could guide the development of thera-
peutic interventions follows.
6.1. First steps for an ecologically inspired rehabilitation practice
The potential of ecological principles for improving rehabilitation interventions has been explored in previous publica-
tions (Ahl, Johansson, Granat, & Carlberg, 2005; Burton & Davis, 1996; Darrah et al., 2011; Fetters & Ellis, 2006; Gibson
et al., 2009; Handford, Davids, Bennett, & Button, 1997; Holt et al., 2010; Ketelaar et al., 2001; Mathiowetz & Haugen,
1994), but these principles have not yet reached mainstream research or clinical practice. We believe that the ecological per-
spective provides a principled basis for the design of activity-based therapies because of its conceptual consistency with the
ICF model. Therefore, in this ﬁnal section, we suggest ways to translate ecological principles into clinical practice and related
perceptual-motor research. Speciﬁcally, we offer examples from ﬁve domains of rehabilitation that could beneﬁt from an
adherence to ecological principles: (1) the content targeted by assessment tools, (2) the incorporation of meaningful context
into interventions, (3) the identiﬁcation of multiple task solutions, (4) capitalizing on performance variability, and (5) the
outcomes of interventions.
6.1.1. The content targeted by assessment tools
Any effort to apply ecological principles to therapeutic practice necessarily begins with a consideration of the tools of
assessment. Because what therapists assess must be coherent with what they intend to change (Trombly, 1993), the devel-
opment of appropriate tools will have to respect the individual-environment system as the appropriate unit of analysis. As
noted earlier, a central concept of ecological psychology is that behavior capitalizes on affordances (Fajen, 2007; Gibson,
1979; Michaels & Carello, 1981; Riccio & Stoffregen, 1988; Turvey, 1992; Turvey et al., 1981; Warren, 1984). Affordances
are opportunities for action offered by the environment that are speciﬁc to an individual’s capabilities—his or her effectivities.
From an ecological perspective then, the objective of rehabilitation is to restore or increase affordance-effectivity pairs for a
patient (Fig. 5). In contrast to current assessments that focus on the individual, ecologically-grounded tools will have to
include evaluation of the relevant local environmental properties, not just in general, but as they relate to patients’ capabil-
ities (Burton & Davis, 1996).
A starting point would be developing assessments based on intrinsic-scaled or action-scaled measures (Fetters & Ellis, 2006;
Warren, 1984). A classical example of this kind of measure in the ecological psychology literature relates to the task of climb-
ing stairs. Describing the riser height of a staircase in meters (that is, based on an extrinsic metric) is not useful for deter-
mining whether or not an individual will be able to climb it with little effort or to climb it at all. In contrast, measuring riser
height in (intrinsic) units of leg length—a property of the organism that relates to his or her ability to climb stairs—can pro-
vide such insight. For instance, Warren (1984) found that a riser height/leg length ratio of 0.26 speciﬁes a setting for climbing
stairs that demands the least oxygen consumption per meter ascended for typical adults. A ratio of .88 to 89, in turn, deﬁnes
an action boundary—a limit above which bipedal climbing is not possible for typical young adults. Interestingly, individuals
seem to be sensitive to information that speciﬁes such invariant relations. When asked to visually identify the riser height of
a staircase that would be optimal for climbing and the maximum (bipedal) climbing height, individuals selected the riser
height whose relation to their leg length was very close to .26 and .89. Elaboration of this seminal line of research highlighted
factors beyond the geometry of body size. For older adults, other action-related variables have been shown to be relevant to
optimal and boundary action-scaled ratios. As hip ﬂexibility and leg strength become signiﬁcant constraints to performance
in the older population, for example, they become critical determinants of the affordance-effectivity ﬁt (Cesari, Formenti, &
Olivato, 2003; Konczak, Meeuwsen, & Cress, 1992). Several other intrinsic or action-scaled descriptors have been investi-
gated in the ecological psychology literature on affordances: Individuals determine comfortable sitting height relative to
their eye height (Mark, 1987), control object grasping relative to their to hand span (Newell, McDonald, & Baillargeon,
1993), control passing through apertures relative to their shoulder width (Warren & Whang, 1987), control walking or run-
ning under a horizontal barrier relative to their eye-height and locomotor ability (van der Meer, 1997).
126 D.V. Vaz et al. / Human Movement Science 52 (2017) 117–132
What is the implication of a focus on the affordance-effectivity ﬁt for rehabilitation? The context in which activities take
place would be most usefully described with a metric that is directly related to an individual’s action capabilities in a task-
speciﬁc context (intrinsic-scaling). Pointedly, the metric is not neutral or absolute (which usually means independent of con-
text). When assessing a patient, rehabilitation professionals should therefore identify what individual-environment relations
need adjustments to guarantee performance of relevant tasks. If we return to Joseph’s example, a traditionally motivated
focus on range of motion and discrete movements would have come from statistical population norms. But their conse-
quences for a speciﬁc task—in Joseph’s case, performance in a favorite video game; in someone else’s case, control over
the paintbrush, coping saw, keyboard, and so on—are limited. Knowledge of what sort of individual-environment relation
is required for task performance (and not an extrinsic biological norm) should thus guide assessment and the design of inter-
ventions. There is no doubt that for most abilities addressed in rehabilitation, the relevant properties of the individual and
the environment that should enter in the constitution of action-scaled clinical measures still have to be investigated. For
example, the properties that will be used in these measures will certainly not be restricted to geometrical parameters (such
as leg length) and will likely include dynamic parameters such as muscle strength, ﬂexibility, energetic potential, and dex-
terity, among others. Clearly, discovering what relations matter most for the performance of each activity is a hard scientiﬁc
endeavor. Recognition that action-scaled clinical measures are needed, however, might steer the ﬂow of perceptual-motor
research in the direction that leads to the design of this class of measures. In Joseph’s case, determination of the relevant
variables for description of the affordance-effectivity ﬁt for controlled grasp and manipulation of the videogame joystick
would direct functional intervention. Therapeutic strategies then should be directed at scaling properties of the environment
and properties of the patient in order to provide the ‘‘just right level of challenge” during therapy, in an effort to achieve
relations that allow for optimal functioning in typical environments. Neither the patient nor his/her environment when con-
sidered in isolation would provide enough constraints for wise clinical decisions.
6.1.2. Meaningful context in interventions
A second issue in developing an ecologically inspired practice regards the need for meaningful context in interventions. In
opposition to training decontextualized movement primitives, rehabilitation should capitalize on the power of meaningful,
concrete goals. For example, studies show that children with cerebral palsy (Donker, Ledebt, Roerdink, Savelsbergh, & Beek,
2008; Volman, Wijnroks, & Vermeer, 2002; Weel et al., 1991), and individuals with stroke (Rensink et al., 2009; Trombly &
Wu, 1999; Wu, Trombly, Lin, & Tickle-Degnen, 2000) exhibit improved movement performance when tasks involve concrete
goals with real objects as opposed to abstract goals and simulated tasks. This evidence suggests that for Joseph, a focus on
repetitive discrete ﬁnger movements and range of motion exercises may be necessary but is probably insufﬁcient to reach
his preferred goals and his full potential.
The positive effects of meaningful concrete goals reﬂect the essential role of affordances in the organization actions, in
accordance with ecological psychology. Different lines of perceptuo-motor research could support clinical advances in this
direction. The ﬁrst evident connection is with affordance-based control research (Fajen, 2007). This line of research investi-
gates how people take the limits of their capabilities into account for online control of their movements, for example while
steering or braking a vehicle or intercepting a ball. How is this affordance-based control affected in clinical populations? It is
possible for instance that the risk of fall in individuals after stroke might be related to overestimation of reaching capabilities.
On the other hand, underestimation of capability limits might lead to unnecessary restrictions in activity that leads to decon-
ditioning and further disability.
The second line of research refers to attention. Superior motor performance and learning is observed when attention is
focused on environmental effects of an action (external focus) rather than on movement itself (internal focus). For example,
when reaching and grasping a can on a shelf to place it on a table, patients with hemiparesis demonstrated shorter move-
ment times and larger velocity peaks when they were instructed to focus their attention on the can rather than on their arm
movements (Fasoli, Trombly, Tickle-Degnen, & Verfaellie, 2002). Advantages of the external focus have been documented in
a large variety of tasks (reviewed in Wulf, 2013). This line of research is of considerable relevance to clinical practice, given
that instructions offered to patients typically refer to ideal or correct movement form or timing, thus inducing an internal
focus (Durham, Van Vliet, Badger, & Sackley, 2009). Proper movement form is important in several clinical situations, for
example, to correct or prevent abnormal mechanical stress related to injury. Is an external focus beneﬁcial even for tasks
where the goal is proper form? Some evidence indicates this is the case (Abdollahipour, Wulf, Psotta, & Palomo Nieto, 2015).
Lastly, adequate perceptual task manipulations could become a formidable tool to aid motor learning. When very difﬁcult
and complex movement patterns are represented by simpliﬁed visual feedback (such as a circle in an angle-angle plot on a
screen, to represent bimanual oscillation movements at 90°of phase shift) these movements can be performed stably after
very little training (Kovacs, Buchanan, & Shea, 2009, 2010; Mechsner, Kerzel, Knoblich, & Prinz, 2001). Note that these sim-
pliﬁed perceptual guides also induce a focus on the environmental effects of movement (attention is externally focused on
the plot) rather than on movement itself. Patients with stroke ﬁnd it difﬁcult to coordinate shoulder and elbow ﬂexion with
forearm pronation and wrist extension to bring a cup to their mouth. Would they beneﬁt form this kind of simpliﬁed per-
All these lines of evidence converge to the importance of affordances and idea that actions should be more effective if they
are planned and controlled in terms of their intended environmental outcome, rather than in terms of speciﬁc movement
patterns. We believe investigation of affordances and perceptual inﬂuences on movement for clinical populations is still
underdeveloped in research clinical practice. Hopefully, their potential to improve function will stimulate more interest.
D.V. Vaz et al. / Human Movement Science 52 (2017) 117–132 127
6.1.3. Multiple task solutions
A third lesson is that no assumption should be made that there is a single best solution for a particular task (Burton &
Davis, 1996;Darrah & Bartlett, 1995;Darrah et al., 2011; Harbourne & Stergiou, 2009; Holt et al., 2010;Stergiou &
Decker, 2011a, 2011b). Quite to the contrary, many solutions are available. These solutions are demanded by context-
conditioned variability and arise from the unique interaction of performer and varying environmental constraints with
the task goal, as anticipated in the discussion on affordance-based assessment. This view has a profound impact on how reha-
bilitation professionals conceptualize movement dysfunction. The research work initiated by Holt, Obusek, and Fonseca
(1996) is an example of this shift in understanding with respect to the atypical gait of children with cerebral palsy. In a num-
ber of studies (Fonseca, Holt, Fetters, & Saltzman, 2004; Fonseca, Holt, Saltzman, & Fetters, 2001; Holt, Fonseca, & LaFiandra,
2000; Holt et al., 1996) they showed that the observed coordination patterns may be driven by the underlying task dynamics
and the available dynamic resources. They argued that the observed movement patterns, though non-standard, are not nec-
essarily dysfunctional, and may actually represent the current optimal solution for a particular person-environment system
(Holt et al., 2010). It is the job of the therapist to analyze the cost, the risks and possible long-term impact of a given move-
ment solution. Based on this movement analysis, the therapist should decide whether to stimulate the current solution or to
promote speciﬁc changes in task dynamics and dynamic resources while encouraging further search of alternate solutions by
the patient. By implication, ‘‘normalization” of movement pattern (for example through neurotherapeutic techniques
(Bobath, 1991; Brunnström, 1970) may be a consequence of therapy, but should not be a primary goal (Darrah & Bartlett,
1995; Harbourne & Stergiou, 2009; Holt et al., 1996, 2010;Stergiou & Decker, 2011a, 2011b). For the case of Joseph, there-
fore, therapy goals should not be limited to what is considered normal grasping and manipulation patterns for typical chil-
dren; rather, therapy should explore alternative functional possibilities afforded by his unique characteristics.
In summary, the existence of different ways to complete a task means that therapists need to conduct a deeper investi-
gation of the organization of actions. They need to observe the degree of success in completing a task and the stability and
ﬂexibility in movement patterns as constraints of the performer and the environment are manipulated systematically. This
allows the identiﬁcation of the speciﬁc contexts in which a person can always accomplish the task, sometimes accomplish
the task, and never accomplish the task (illuminating the issue of transfer discussed above). In addition, the performer or
environmental variables which elicit change in movement form may indicate what performer-environment systems or sub-
systems may be limiting the person to certain movement forms which in turn may limit movement ﬂexibility (Burton &
Davis, 1996; Holt et al., 1996, 2010).
6.1.4. The role of variability
The implication of multiple task solutions brings us to an additional issue. Movement variability is essential for exploring
the regularities in the dynamics of the individual and her or his environment (Holt et al., 2010). Interestingly, research has
shown that ﬂexible, adaptive, healthy motor behavior is linked to optimal variability down to the ﬁne temporal structure of
movement details (see for example Donker et al., 2008; Harbourne & Stergiou, 2009;Stergiou & Decker, 2011a, 2011b). To
optimize performance ﬂexibility, therapists would be encouraged to translate research in differential learning (Frank,
Michelbrink, Beckmann, & Schöllhorn, 2008; Schöllhorn et al., 2006) into clinical programs. The aim of differential learning
is to support a subject in ﬁnding his or her individual, context-dependent performance repertoire in order to perform a com-
plex motor skill as successfully as possible. Importantly, the goal is to improve the ability of an individual to ﬁnd successful
behavioral patterns under permanently changing internal and environmental conditions, that is, attaining more ﬂexible and
versatile affordance-effectivity ﬁts. Note that the a priori deﬁned, idealized or prototypical performance patterns (the normal
synergy that traditional therapy strives for) are replaced by subject- and context-dependent ﬂuid movement solutions. Prac-
tice variability is especially designed to allow emergence of these solutions (Frank et al., 2008). In Joseph’s case, the path to
his full functional potential would involve exploring a great variety of alternate strategies to accomplish his goals.
6.1.5. The outcomes of intervention
Finally, in analyzing results of an ecologically inspired intervention, outcomes should be put in the light of the domains of
the ICF (World Health Organization, 2001). Outcomes at the level of Activity and Participation should be speciﬁcally valued,
in addition to those at the level of Body Structure and Functions, which have been prioritized by traditional models of inter-
vention. We believe that an ecologically grounded functional practice in rehabilitation would improve efﬁcacy of interven-
tion to produce positive outcomes in patients’ abilities to perform activities of daily life in varying contexts and fulﬁll the
roles to which they aspire. Such an orientation would narrow the gap between therapeutic practice and theoretical under-
standing of functioning and disability underlining the ICF, helping therapists move beyond the medical model of care.
7. Future directions
This paper was an attempt to highlight the conceptual consistency between the ICF model and the ecological approach to
perception and action. Arguments were developed to stimulate clinicians to apply ecological principles in their clinical rea-
soning. Connections with potentially relevant perceptual-motor research were also explored. We contend that adoption of
ecological principles can catalyze the reform of clinical practice encouraged by the ICF.
128 D.V. Vaz et al. / Human Movement Science 52 (2017) 117–132
As researchers and instructors in rehabilitation clinical courses we think it is our responsibility to work for advancements
in rehabilitation practices. We hope to promote an interest of the rehabilitation and perceptual-motor research community
on the incipient science of clinical affordance-effectivity ﬁts. We speculate that this research would provide the basis for the
development of an ‘‘affordance-detection therapy”. The hope would be to amplify functional repertoire by capitalizing on
affordance-effectivity cycles. Darrah et al. (Darrah et al., 2011) provide an example of how this cycle could work, for a child
who’s goal was to ﬁnger-feed himself Cheerios independently. With a clear focus on enabling function, the therapist exper-
imented with putting peanut butter on the ﬁngertips of the child so that the food could stick to it. A new affordance-
effectivity ﬁt was created, perceived and actualized: the child accomplished ﬁnger feeding in one intervention session, even
though he did not have a pincer grasp. The therapeutic choice was based on the assumption that further independent prac-
tice of the task would change the relationship between capabilities and possibilities, so that the child would eventually learn
to ﬁnger feed without the peanut butter.
In order to concretize contributions, we are currently working to build a theoretical and clinical research program con-
sistent with ecological insights to the current understanding of functioning and disability. This ‘‘ecological-ICF research pro-
gram” adheres to suggestions found in Davis & Burton’s seminal paper (Davis & Burton, 1991). Particular research questions
will be proposed within a more global structure of investigations of functional task performance of clinical populations and
particular individuals. In other words, the program will structure investigations on affordance-effectivity ﬁts for patients.
Functional task performance will be investigated with respect to:
a) the set of individual and environmental conditions that allows achievement of functional goals
b) the set of individual and environmental conditions that allow for the most efﬁcient functional task performance
c) the set of critical or boundary individual and environmental conditions for goal achievement
d) the degree of ﬂexibility in applying movement solutions
e) the consistency in applying movement solutions
Ultimately, we hope to promote change in clinical practice by incorporating knowledge produced in this framework into
the syllabi of courses offered to our physical therapists students.
Declarations of interest
The authors report no declarations of interest.
This research was supported by Grant 200676/2009-1 of the Brazilian Council of Scientiﬁc and Technological Develop-
ment (CNPq), awarded to the ﬁrst author.
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