Perception & Action Lab

Affordances & Embodied Perception

Research on how individuals perceive what actions are possible in a given environment has, in recent times, focused on the concept of affordances (possibilities for action). In particular, this research has demonstrated how action or body-scaled information specifies possibilities for action, and how perceiving these possibilities can constrain the activities an individual engages in. In addition to examining the information that specifies affordances, our  research aims to highlight how perceiving an affordance, including its action boundaries, dynamically constrains and self-organizes the action system of multiple agents into functional organized units or synergies. We aim to show how individuals not only perceive and actualize affordances by recruiting other bodily degrees of freedom (e.g., go from lifting objects with 1-hand to lifting objects with 2-hands; or go from climbing up surfaces using only the legs to climbing up surfaces using both the legs and the arms), but also extend their perception-action capabilities with the use of environmental objects or tools, or by cooperating with other individuals (e.g., go from lifting objects alone to lifting objects together with another person; or go from climbing up surfaces alone to climbing up surfaces using a tool or another person).

Coordination Dynamics

Noise and Coordinated Movement: 

Many human movements are often performed rhythmically and in a coordinated or synchronized manner. Think of the leg and arm movements of an individual when walking. It is important to appreciate that such movements are not perfect and are always performed with a certain amount of variability. Much of this variability results from internal and external sources of noise that are continuously affecting the movement’s trajectory. Interestingly, this noise does not always have a negative effect on the stability of human movement and can sometimes operate to increase the stability of the movement. Thus, we are currently using dynamical modeling and analysis techniques to examine the role and structure of the noise influencing human movement. This includes examining different types and levels of noise and whether injecting low-level perceptual noise results in more adaptive movement patterns (stochastic resonance phenomena).

Interpersonal Coordination: 

Drawing from the belief that the most significant environmental interactions a human has are those that involve other individuals, this body of research seeks to combine work from the areas of coordination dynamics, perception, psycholinguistics, and social psychology in order to better understand coordinated social action. In particular, this research investigates interpersonal coordination as an instance of bi-directional actor-environment processes—from actor to environmental object (partner) and vice versa—and attempts to enhance our understanding of the informational and intentional constraints necessary to support this coordination. 

This research also examines whether the type of social interaction (e.g., cooperative, competitive) affects the amount of unintentional synchrony exhibited between two co-actors. Current research is also investigating the relationship between mimicry and synchrony using an interpersonal walking paradigm. Ideally, this latter research will help determine whether the same informational couplings cause mimicry and synchrony, and whether any observed differences between the two phenomena are simply differences in the temporal time course of behavior.

Behavior-environment coupling:  

Paralleling the work on interpersonal coordination is research that examines the degree to which an individual’s behavior is coupled to environmental stimuli and the effects of such environmental couplings on the stability of movement. Indeed, the occurrence of interpersonal coordination is evidence that human movements are often constrained by the perceptual pick-up of environmental information. To illustrate this, we are conducting research with R. C. Schmidt at the College of the Holy Cross that examines how the rhythmic movements of an individual unwittingly become coupled to an environment stimulus. Some findings have shown that the stability of both unintentional and intentional coordination becomes significantly stronger when a participant’s visual system is actively involved in the pick up of environmental information. This latter result indicates that environmental information constrains an individual’s perceptual-motor processes by providing a common frame of reference.

Downloadable Software & Applications:

Liberty 8 Capture - simple data capture program for Polhemus Liberty 8 magnetic tracking system (zipped windows .exe, dlls, and readme files).