(A) The cognitive system as an open-loop dynamic. (B) The cognitive system as a closed-loop dynamic.
Open- versus Closed-loop Systems
Another very important distinction between how the dyadic and triadic frames for psychology have developed is that the dyadic frame tends to view the cognitive dynamic as an open-loop causal system. In this open-loop perspective, a causal sequence, akin to a sequence of dominos, is typically assumed:
stimuli --> sensations --> perception --> decision --> response.
In this framework, the key is to describe the internal computations (i.e., transfer functions) that translate input to output for each of the distinct stages of information processing. There is, at least an implication, that each of the distinct stages can be understood in isolation from the other stages (e.g., as modules within a computer program); and researchers typically identify with specific stages in this sequence (e.g., one might describe herself as a perceptual researcher, another might call himself a decision researcher, while another might be referred to as a motor control researcher).
In contrast, the triadic frame tends to view the cognitive dynamic as a closed-loop system. In the closed-loop system, the precedence relationships in time that have typically been used to differentiate causes (prior events) from effects (later events) are lost. For example, in the circular system responses can be both causes of stimuli (e.g., looking around) and the effects of stimuli (e.g., orienting to a sound). In a circular system, there is no sense in which any portion of the circle is logically prior to any other portion of the circle. Thus, causal explanations and parsings based on a domino model (based on sequence in time) make no sense for a closed-loop dynamic.
In a closed-loop dynamic there are constraints at the system level (stability) that determine relations that must be satisfied by the components. Thus, for the system to be stable (i.e., to survive) certain relations among the components must be satisfied. Thus, in contrast to the open-loop system where the behavior of the whole is determined by the behavior of the parts. The opposite is true of circular systems - the circular dynamics of the whole (i.e., the organization) creates constraints that the components must satisfy or the system will go out of existence.
For example, in the circular dynamic associated with prey-predator systems, it makes no sense to isolate either the prey or the predator as the cause of the pattern of population levels. Unless certain relations exist between the prey and predators (e.g., as described by a differential equation) the system will either converge on a stable population, oscillate, or collapse into extinction. It is important to emphasize that a differential equation expresses constraints over time associated with relations among the components. The equations describe the coupling of prey and predators. In the dynamic of cognition we are interested in the coupling of perception and action through an ecology.
Events in Time versus Constraint Over Time
In the open-loop dynamic, the focus tends to be on events in time and the challenge is to identify the aspects of prior effects that cause later events (e.g., find the root cause of an accident by tracing back in time to find the initiating fault). However, in dealing with closed-loop dynamics explanations tend to be better framed in terms of constraints over time. For example, the laws of motion are constraints over time that are typically expressed in the form of a differential equation. The constraints over time, do not determine events, but they set limits on the fields of possible events. For example, the laws of motion set constraints on the possible trajectories a body might take (e.g., aerodynamics). Similarly, a goal (e.g., to land safely at a specific airport) or value system (e.g., a desire to minimize energy consumption) will not determine the path of an aircraft. However, these constraints will limit the set of possible paths.
The term circular causality has typically been used to indicate that the logic of circular dynamics requires new ways to think about causality and explanation. However, this term does not identify the key distinction from typical causal reasoning. I prefer to say that when dealing with circular systems, it is necessary to dispense with the notion of causality all together and to replace it with the construct of constraint.
I think this shift has some similarities with the shift from particle based explanations to field based explanations in physics. Thus, rather than framing psychology in terms of discovering the causes of behavior, the focus shifts to understanding the dynamic constraints on behavior. In this context the terms affording, specifying, and satisfying refer to different sources of constraint on the cognitive dynamic. Affording refers to the constraints on action (e.g., laws of motion). Specifying refers to the constraints on information (e.g., laws of optics). Finally, satisfying refers to the constraints on value (e.g., principles of reinforcement and punishment).
The figure below suggests how these three sources of constraint map onto the triadic semiotic. Note that these are constraints over the components of the system, but that tend to be grounded in different components. Affording is grounded in the physics of the ecology (e.g., the nature of the gravitational field, the surfaces of support, vehicle dynamics, etc.). Specifying is grounded in the properties of the interface or representation (e.g., optical flow field, acoustic field, computer interface). Satisfying is grounded in the intentions and preferences of the cognitive agent.
Note that there tends to be a parallel structure in the way in which Rasmussen has framed Cognitive Systems Engineering (CSE). His Abstraction Hierarchy (AH) focuses on how the domain constraints shape the affordances (determine the field of possibilities) relative to the goals and capabilities of an agent. The SRK model tends to reflect the internal strategies and expectations of an agent in terms of Skills, Rules, and Knowledge relative to the problem constraints and the intentions of the agent. Finally, the Ecological Interface Design (EID) focuses on the design of interfaces that specify the field of possibilities in ways that are consistent with the capabilities of an agent. I will talk more about CSE in future blogs. For those interested in going into this deeper, I suggest you look at the link to Bennett & Flach's Interface Design book.