We examined how child and adult bicyclists perceived the same temporal opportunities for crossing two lanes of continuous traffic when viewing those opportunities from the same direction or from opposite directions. Twelve-, 14-year-olds, and adults rode an instrumented bike through a virtual environment where they crossed two lanes of one-way or two-way traffic. Crossing opportunities consisted of aligned (far gap opens with or before near gap) or rolling (far gap opens after near gap) gap pairs. All age groups took gap pairs with significantly smaller overlaps and were significantly more selective in making gap pair choices (taking fewer gap pairs with smaller overlaps and more gap pairs with larger overlaps) when crossing rolling gap pairs in one-way than two-way traffic. In addition, 12-year-olds were more selective in making gap pair choices when crossing aligned gap pairs in one-way than two-way traffic. Twelve- and 14-year-olds also timed their entry into the near lane more tightly when crossing aligned gap pairs in the one-way than two-way condition. This work illustrates a new way to shift how people perceive and act on the same temporal affordances by engineering the perceptual information available and the looking behaviors required for perceiving complex temporal relations.
Learning a novel interceptive action involves picking up useful perceptual information for prospective control and learning to organize the degrees of freedom (DoF) within the movement system into novel coordinative structures. Existing literature has shown that interceptive actions are guided by perceptual information that continuously specifies the movement of the ongoing action. However, the use of prospective control at task level and the formation of a novel coordinative structure at DoF level has not been jointly evaluated in previous research. Using a virtual lateral interception task incorporating a body-machine interface with a novel redundant mapping, prospective control was examined through differences in end effector trajectories and the presence of a coordinative structure using the uncontrolled manifold analysis during Intercepted and Unintercepted trials. Prospective control reflected in Angle of Approach and movement initiation effects were present in Intercepted trials, whereas Unintercepted trials only showed movement initiation effects. Compensatory covariation in joint angles was higher than variability affecting task performance in both Intercepted and Unintercepted trials. These findings suggest the use of prospective control and formation of a stable coordinative structure in Intercepted trials, while signs of prospective control were also present during search for a new coordinative structure in Unintercepted trials.
Perception and action are unified by invariants in energy arrays that directly specify (are information about) lawful agent-environment relations or affordances. Invariants are defined by symmetry: relational structures that persist across transformations. Building on this ecological foundation that Turvey championed, we propose a framework for perception-action that uses continuous symmetry groups to formalize how energy arrays-optic, acoustic, and haptic-are structured via action. Using the special Euclidean group SE(3) as a working exemplar, we demonstrate how the six generators of this group directly map invariants (symmetries) in ambient energy arrays to the motor-generator subspaces that actualize affordances. We do this across canonical cases of locomotion, catching, climbing, and grasping. By situating Ecological Psychology within the scientific foundations of symmetry and continuous symmetry groups, this framework potentially clarifies and extends Turvey's legacy, providing a formal and generalizable language for the direct theory of perception-action.
In team sports, teammates form functional synergies to outperform the opposition. Evidence suggests that synchronization among defenders is linked to successful outcomes. This study aimed to explore what mediates the formation of interpersonal synergies in a football defensive unit during both successful and unsuccessful defensive plays. Using the Uncontrolled Manifold (UCM) hypothesis, we analyzed 60 successful and 34 unsuccessful defensive sequences from five competitive matches. We examined two performance variables: the defensive set's average position (Centroid) and its structure (Stretch Index). These variables were assumed to be stabilized by individual adjustments in players' running line velocities. Interestingly, successful defensive outcomes were associated with lower UCM values, indicating that players' velocity adjustments contributed less to stabilizing the defensive set's position or structure. This suggests that success may rely more on effectively managing velocity variability between players rather than minimizing it. Overall, defensive synergies were more often formed to maintain the structure (Stretch Index) than the geographical position (Centroid) of the unit. Additionally, when the defense succeeded, the synergy strength was lower than during unsuccessful attempts. This implies that successful defense may result from flexible coordination rather than rigid control.
Multifractal geometry has found growing support as the proper framework for mapping, stimulating, and scaffolding growth of neural structures. We predicted that multifractal structure reflecting nonlinear interactions across scales might moderate effects of stimulation on subsequent behavioral response. We reanalyzed Golgi/Cox stained slices of orbitofrontal cortex from rats injected with either saline or with corticosterone, a stress hormone whose effects can depend on reshaping neural morphology at the fine scale of dendritic spines. Following injection, the rats completed the elevated plus maze (EPM) and open field task (OFT), and their general activity and anxiety-related behaviors were observed. We used spatial multifractal analysis to estimate the multifractal spectrum of neurons at two objective magnifications, and we used surrogate comparison to calculate the degree of multifractal nonlinearity reflecting interactions across scales at each magnification. Regression modeling demonstrated that corticosterone and coarse-scale multifractal nonlinearity of neural tissue promoted anxiety-related behaviors. Meanwhile, multifractal nonlinearity at the finer scales was associated with reduced anxiety following corticosterone injection. For older rats, multifractality was itself sensitive to corticosterone but did not mediate its effects. Multifractal nonlinearity of neural tissues may thus provide constraints on the effects that chemical changes have on organism behavior.
A common observation in motor behavior is that humans demonstrate coordination patterns in their movements that can self-compensate to maintain a given action result - i.e. they demonstrate task synergies. The literature, based on traditional group-based analyses, postulates single and monotonic paths of change in how these synergies emerge from practice. Based on the search strategies approach literature, common paths of change in motor learning are rare given individuals start and change differently and the tasks are redundant. Thus, we explored if individuals demonstrate similar dynamics in synergy measures by reanalyzing the data of 15 individuals practicing a throwing task for five days. Our results failed to demonstrate the postulated dynamics. We discuss these findings considering how individuals use different strategies in interacting with the task and learning to perform task synergies. These outcomes invite further discussions and theorizing on motor learning dynamics.
Recently, we asked how ecological psychologists should conceptualise the environment in a time of ecological collapse. Appreciating the interdependency of life forms, our response was to describe the environment as an ecosystem replete with affordances. Accompanying this was a morality calling for change to what is a dominantly anthropocentric lifestyle. Upon reflection, however, morality may not be enough if we are to curb such anthropocentrism; there is need for an ethicality that brings an invitation to respond in ecocentric ways. Thus, the aim of this commentary is to introduce an ethic of response-ability, aligning it with our earlier environmental description. This ethic brings a practical acknowledgement that organisms are already implicated in the lives of others, often in unforeseen ways. Not only does this practical acknowledgement foreground an ecological scale of analysis, but it should function to educate attention towards affordances that our actions hold open, or close, with reference to the lifeways of others.
Michael Turvey's (2009) paper, 'On the Notion and Implications of Organism-Environment System', significantly clarified my understanding of the extended organism concept. Turvey's ecological approach underscored the symbiotic relationship between an organism and its environment. These insights allowed me to further conceptualize language as a model organism and extend its physiology, where communicative processes are seen as an extension of bodily functions. Similarly, this ontological vantage enabled a deeper understanding of dreams as extended inner speech, suggesting that dreaming is a form of cognitive processing that extends beyond waking consciousness.
Michael T. Turvey viewed perceptual facility with words as a nonlinear prestress of whole-body synergies, forming a multifractal tensegrity rather than a computational cognitive mechanism. This reanalysis of young adults completing an upright-postural Stroop-like conjunction search links three aspects of multifractal synergies to the cognitive processes involved in the visual word search. First, searching tightly constrained task space benefits from reducing multifractal postural variability. Visual search for incongruently colored words occurred with less multifractal nonlinearity in the postural center of pressure (CoP), particularly for targets within a narrow visual angle. Second, physical constraint or destabilization requires compensatory changes in multifractal variability elsewhere. Restraining stance led successful search to become associated with increased multifractal nonlinearity in movement fluctuations at the head and clavicle. Third, applying task constraints that narrow search in the visual field links search performance with multifractal variability higher up in the body, i.e. closer to the narrowed search. Searching for inverse-incongruent words (e.g. a red-colored "blue" instead of a blue-colored "red") benefited from the reduction of multifractal nonlinearity in clavicle rather than in CoP displacement. Multi-joint synergies of multifractal nonlinear interactions support visual-word search by responding to or imposing constraints and reorganizing in response to intentional shifts.
Michael T. Turvey will be known for his innovative scholarship and incisive thinking, but he also leaves a powerful legacy of community-building. The ecological community would not be what it is today without his leadership in carving out space for our field, his commitment to encouraging the next generation of scholars, and his earnest outreach to other disciplines. Reflecting on Turvey's legacy, we would like to encourage us all to pick up this mantle by intentionally committing to grow our community through new connections to the rest of cognitive science. Historically, our community has not been seen as inviting; even interested fellow travelers have felt rebuffed by seemingly rigid adherence to radical theory. Thanks in large part to Turvey, ecological scientists know that what we strive for is rigor, not rigidity-disciplined thinking, not unthinking allegiance. Following Turvey's example, we argue that openness and rigor can be complementary strengths that will promote even more vibrant ecological community in the coming decades. Turvey helped form our community and helped prove that we had a place in cognitive science; let's commit to taking the next steps in growing that place and becoming a community that many others can come to call home.
Movement control faces a problem of redundancy. In general, there are more degrees of freedom available to solve a task than the task requires. This ‘degrees of freedom’ problem has been reframed as a ‘motor abundance’ feature (Latash, 2012), where the redundancy enables crucial flexibility. The balance between flexibility and control has been proposed to depend on synergies, which are lower-dimensional organisations of movement dynamics into systems that solve the task at hand. There are now several movement analysis methods designed to search for the signatures of synergies (the uncontrolled manifold, Scholz & Schöner, 1999; tolerance-noise-covariation, Cohen & Sternad, 2009, and others) and a great deal of empirical evidence that synergies feature in movement control. However, while all of these analysis methods rely on notions of ‘task’ to constrain movement solutions, they do not come with a formal theory of what a task is or how tasks are perceived. This paper proposes the hypothesis that tasks should be formalised as task-dynamical affordances, and that perceiving these via specifying information is how they constrain synergy formation (effectivities). I lay out the hypothesis, and detail a research programme to investigate the hypothesis, with reference to existing work on throwing.
