Motion Control and Consciousness
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This note suggests that physical processes supporting the capabilities necessary for efficient independent movement are sufficient to generate at least a rudimentary form of consciousness.
Most of us seem more inclined to attribute consciousness to dogs than to rosebushes. This intuition indicates consciousness in an entity may relate to its capacity for independent movement. Careful thinkers (Cotterill, 1996, 1997, 2000; Humphrey, 2000; Hurley, 1998; Llinas, 2001; Panksepp, 2001; Sheets-Johnstone, 2001 and Tye, 1997) have come to similar conclusions. This note specifically argues that the physical processes providing the capabilities necessary for an entity to execute efficient independent movements are sufficient to generate at least a rudimentary form of consciousness. "Independently moving entities" are defined as entities that can move from place to place by using coordinated movements of directly connected and differentiated sub-components, under internal power and direction, to obtain energy and avoid destruction. This definition excludes things like windblown seeds, waterborne eggs, remote controlled entities, plants, schools of fish, flocks of birds, colonies of unicellular organisms, ant colonies, or termite colonies (Humphrey and Dennett, 1989).
Motion control system requirements
From an engineering standpoint, successful control of actions of independently moving entities in a dynamic environment requires:
· Internal motion control. An independently moving entity must have a self-contained internal motion control system. The motion control system must be capable of choosing just one movement sequence out of the many possible movement sequences in any given situation.
· Sensing. Sensing is necessary to tell the motion control system about the entity's internal conditions, and environmental conditions affecting the survival of the entity. Sensing systems provide information needed for the motion control system to decide whether the entity should move and, if so, how and where. Sensory inputs identifying internal conditions must be separated from sensory inputs identifying external conditions. This enables the entity to move by acting on its surroundings.
· Memory. Some type of time-ordered memory of internal and external events is needed, so the entity need not repeatedly re-invent previously useful motion sequences in recurring situations.
Regardless of the details of the physical processes providing these capabilities, they seem sufficient to generate consciousness in independently moving entities, in the sense described below.
Aspects of consciousness
Cotterill (1997) says "the dictionary consensus…defines consciousness as an awareness of the surrounding world, of the self, and of one's thoughts and feelings." A distinction is often made between first person and third person aspects of consciousness (Block, 1995; Chalmers, 1995; Nagel, 1974; Tye, 1997). Third person descriptions of consciousness are of the form "A conscious entity does this and that," and first person descriptions are of the form "I experience this and that."
Dennett (1995) says we should consider "what entities…can do" to decide whether those entities "are conscious, and if so, why, and of what." However, Chalmers (1995) calls such externally detectable third person aspects of consciousness the "easy problems of consciousness", and includes among them such things as
· "the ability to discriminate, categorize, and react to environmental stimuli;
· the integration of information by a cognitive system;
· the reportability of mental states;
· the ability of a system to access its own internal states;
· the focus of attention;
· the deliberate control of behavior;
· the difference between wakefulness and sleep."
First person aspects of consciousness involve the arguably more difficult problem of explaining the phenomena of experience (qualia). Tye (1997) defines qualia as "the introspectively accessible phenomenal aspects of mental life." Chalmers (1995) claims "an organism is conscious if there is something it is like to be that organism", and identifies the "hard problem of consciousness" as that of explaining the first person phenomena of experience (qualia). Two questions must be addressed: "What are qualia?" and "Why do qualia occur?"
There is a fundamental disagreement in the study of consciousness between those who think first person consciousness can be explained directly in terms of physical processes and those who think something else will be needed. The first group includes Dennett (1996), who claims an explanation of the "easy" problems of consciousness will also explain the "hard problem." The second group includes Chalmers (1995), who says
For any physical process we specify there will be an unanswered question: Why should this process give rise to experience? Given any such process, it is conceptually coherent that it could be instantiated in the absence of experience. It follows that no mere account of the physical process will tell us why experience arises.
So, the explanation of first person consciousness set forth below is unlikely to satisfy the second group.
Consciousness from motion control
A motion control system with the previously listed capabilities enables an entity to
· distinguish itself from its surroundings, and
· use its historical record of its internal status, environmental conditions, and its actions in the environment
to select and execute movement sequences that may increase its chances of survival. In so doing, such entities necessarily discriminate, categorize, and react to environmental stimuli; integrate information; access their internal states; focus attention; and control their own behavior (Chalmers, 1995). An independently moving entity's internal historical record can provide "the 'story line' known as the stream of consciousness" (Cotterill, 1997). The entity's history of choices of specific sets of movements provides at least the illusion of free will (Aleksander, 1998). Entities that move from place to place to acquire energy and avoid destruction "behave as if they had intentionality" [Dennett, 1994]. In other words, such independently moving entities act as if they had "ideas" or "beliefs" about things useful to them and places to be avoided. So, it seems third person aspects of consciousness can be explained in terms of the structure and function of the motion control systems in independently moving entities.
It remains to relate motion control to first person aspects of consciousness involving "qualia" or "experience." The connection can be made by identifying experience with the continually shifting pattern of activity in the motion control system of an independently moving entity in a changing environment. The experience consisting of this changing pattern of motion control system activity is unique to (and only fully accessible by) that entity. If qualia are the time varying patterns of motion control system activity, they occur because they necessarily result from the action of the motion control system.
In this reductionist view, "what it is like to be a bat" (Nagel, 1974) is what it is like to have the motion control system of a particular bat, accessing the internal self-reports of shifting sensory inputs and motion control system activation in that bat's brain as it moves in a specific environmental situation. For effective motion control, the bat must make "judgements (of some inarticulate sort) in order to organize and modulate its language-free activities. Wherever these inarticulate judgement-like things happen is where we should look for the bat's privileged vantage point" (Dennett, 1995).
Qualia are essentially private because any attempt to observe the instantaneous status of an entity's motion control system activity from the outside will significantly modify that activity. In addition, the nature of the independently moving entity affects the nature of the qualia. A man would have to be an exact replica of his sister to know exactly what it is like to be that sister. Nevertheless, there is something it is like to be the man's sister, even if he cannot know exactly what it is.
The identification of experience with activity patterns in the motion control system of an entity with directly connected components implies there is nothing "it is like" to be a brick, a rosebush, a flock of birds, a school of fish, or a termite colony. However, there is something "it is like" to be an individual bird, a bat or a cockroach. Entities with simple motion control systems would be expected to have simple experiences and entities like your brother or sister, with elaborate motion control systems, would be expected to have rich and elaborate experiences.
The short-term working memory needed to execute movement sequences may engender the brief time span of present consciousness (Humphrey, 2000). This is consistent with the idea that "…the memory process directly involved in consciousness is of the very short…type which lasts a few seconds at most." (Cotterill, 1996).
Motion control system activation can be expected to be particularly intense in situations of great importance to an entity's survival. High activation of an entity's motion control system would correspond to particularly vivid qualia (experiences). Retaining memories of sensory inputs, motion control system activation, movement options and choices, and the resulting consequences in important situations confers a competitive advantage. So, vivid qualia might be associated with enhanced memory retention in situations where those memories could be particularly relevant to future situations.
Identifying qualia as the instantaneous status of motion control system activation is consistent with Dennett's (1996) position that an explanation of the "easy" problems of consciousness will explain the "hard problem." The idea that qualia, or a sense of experience, will arise in any independently moving entity is also consistent with Chalmers' (1995) "principle of organizational invariance." Chalmers' principle says "what matters for the emergence of experience is not the specific physical makeup of a system, but the abstract pattern of causal interaction between its components."
The dynamic view of qualia set forth above can be contrasted with Llinas' (2001) proposal that qualia can be identified with fixed action patterns in the sensory systems.
Suppose some moving entities are self-reproducing and evolve under selective pressure over millions of years. Then one might expect motion control system capabilities in some of these entities to become increasingly elaborate. We see the results of such selection here on earth, where Berthoz (2000) says "The brain is above all a biological machine for moving quickly while anticipating."
Some elaborated motion control system capabilities may result from "principles of good design…homed in on by self-designing systems" (Dennett, 1986) under selective pressure. Possible consequences for the consciousness of entities with more advanced motion control capabilities include the following:
· In dynamic environments, sources of energy or danger may not be stationary. Berthoz (2000) claims nearly all sensory receptors detect the derivatives of the variables that activate them, and says "Evolution obviously selected receptors capable of predicting the future." Entities with motion control systems that can predict movements of external objects and the consequences of the entity's own movements have a selective advantage (Dennett, 1984). A capability for predicting consequences of remembered movement sequences in alternative situations also provides a selective advantage (Llinas, 2001), and could be the beginning of thinking.
· Some entities might develop motion control systems with multiple motion control circuits, each suited for specific movement sequences useful in different situations. The dominant motion control circuits in any given situation should be those relevant to the highest levels of threat or reward in the environment. Other aspects of motion control (e.g., respiration, locomotion and circulation in animals) could be automatically accomplished in the background (Llinas, 2001). This directs energy to the most important problems at the moment, resulting in a shifting focus of attention. Activation of different motion control circuits, appropriate to different conditions, will change the entity's response characteristics in different situations. This is analogous to our sense that we are different persons in different circumstances.
· Recognizing that other moving entities might make choices, and successfully estimating what those choices might be in novel situations, provides a competitive advantage. Motion control systems with this capability are essentially recognizing the existence of "other minds."
· Entities that react appropriately to harm done to similar entities nearby, or increased activity of other entities in the presence of energy sources, will have a competitive advantage. This could lead to something analogous to empathetic behavior.
· Motion control is a demanding task. If the motion control system is also responsible for internal movements related to housekeeping and maintenance activities, some entities may develop the capacity to periodically shut down motion control circuits used to direct movement from place to place. This "sleeping" allows energy otherwise required for motion control to be devoted to internal housekeeping and maintenance chores. Sleeping would be most likely to occur when the entity is safe from external danger and has adequate stores of energy.
· An efficient motion control system must monitor the overall status of all of the moving entity's systems. Motion control circuits activated in a crisis can be more efficient if they only monitor the most critical system status indicators. That is, efficiency will improve if the motion control system responds primarily to the highest excitations of the sensory systems, focusing its attention in a crisis. Under benign conditions, a motion control system will receive a wide array of sensory inputs in an unstressed state. It can then evaluate, at leisure, a range of alternative motion strategies of potential adaptive value. Evaluation of alternate motion strategies in response to fluctuating sensory inputs in an unstressed system would result in randomly shifting conscious attention in unstressed conditions.
Relation to human consciousness
There is no need to assume a homunculus in a Cartesian theater within ourselves. Our motion control systems access a unique historical record of sensory inputs, movement alternatives evaluated, expected consequences of movement alternatives, movement sequences selected, and the consequences of actual movement sequences executed in the past. The record involves abstract metaphorical movements (such as those considered by lakoff in connection with language and thought) and seems to be the source of our sense of personal unity. A functioning motion control system accessing a historical record of sensory inputs and movement alternatives, choices and consequences is a reasonable candidate as the basis for our sense of self, because it is "a framework that remains largely stable across many different life situations" (Baars, 1996). This is "consistent with the neurological evidence that no particular cortical lesion abolishes the sense of 'self'" (Calvin, 1996). In this view, one would not expect the sense of self to be abolished unless all brain tissue necessary for independent movement were destroyed.
The idea that our motion control systems are the basis of consciousness certainly does not deny consciousness and a sense of self to persons paralyzed from birth. Such individuals have the same basic brain structure as people capable of a full range of movement. Their observation and memory of the movements of people and objects around them, and the consequences of those movements, should give them a consciousness and sense of self similar to people who are not paralyzed.
Each hemisphere of the human brain controls movements of the opposite side of the body. Severing the corpus callosum connecting the two hemispheres does not prevent coordinated movement on either side of the body, but may result in conflicting motions by the right and left side of the body. In "split-brain patients, where transfer of information between the two hemispheres is blocked, the left side can be shown to maintain a narrative account of its reality that can be quite different from the right side's story" (Baars, 1996). The hypothesis that consciousness is an outgrowth of the capabilities of independent motion control systems explains the twin consciousness in split brain patients, without the need to consider the neurological details invoked by Cotterill (1996).
Readiness potentials are electrical changes in the brain preceding human actions. These potentials can be detected before a person consciously decides to act (Libet et al., 1983). This is congruent with the idea that consciousness relates to motion control system activities. Although we may act freely, the part of us that actually initiates action may not be the conscious entity we perceive. We may decide to act subconsciously, with our consciousness only becoming aware of the decision later, when the decision is recorded in the short-term working memory needed to maintain movement sequences.
In self-reproducing entities that mate repeatedly, there is high motion control system activation in situations involving sex. This can lead to particularly vivid and attractive qualia. Sexually reproducing entities whose motion control circuits lead them to repeatedly seek sex and the associated rewarding experiences have a competitive advantage. This is one reason why population control will not be easy.
Most of us are well aware of the human capability for dissatisfaction, even in near ideal circumstances. The relation between motion control and consciousness might cast light on this unfortunate, but perhaps inescapable, capability. Soren Kierkegaard is reported to have said that comparison is the root of all unhappiness. However, independently moving entities use comparison as the basis of their survival strategy. Their motion control systems must continually evaluate whether or not the entity would be better off somewhere else. Shutting down this comparison capability would eliminate the advantages of movement. Even in the best circumstances, our motion control systems continually and restlessly compare the advantages of our present situation with the possible advantages of alternative situations we might reach by some movement sequence. So, perhaps our capacity for dissatisfaction is partially rooted in the survival strategies of moving entities.