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Notes on Braitenberg's Vehicles
Here are links to a couple of computer simulations of the Braitenberg vehicles. Vehicle 1: Alive Components: Sensor and motor. Principle: The more there is of the quality (e.g., heat) to which the sensor is tuned, the faster the motor goes. Description: alive, restless, doesn’t "like" heat
Vehicle 2a: Cowardly Components: 2 sensors, 2 motors, each sensor connected to the motor on the same side ("uncrossed") Principle: The more there is of the quality to which the sensor is tuned, the faster the motors go ("excitatory"). Description: dislikes source to which the sensor is tuned; occasionally "attacks" it
Vehicle 2b: Aggressive Components: 2 sensors, 2 motors, each sensor connected to the motor on the opposite side ("crossed") Principle: The more there is of the quality to which the sensor is tuned, the faster the motors go ("excitatory"). Description: dislikes source to which the sensor is tuned; "attacks" it
Vehicle 3a: Loving/Quietly Adoring Components: 2 sensors, 2 motors, each sensor connected to the motor on the same side ("uncrossed") Principle: The more there is of the quality to which the sensor is tuned, the slower the motors go ("inhibitory"). Description: loves the source, wants to be near it, comes to rest facing it
Vehicle 3b: Loving/Exploring Components: 2 sensors, 2 motors, each sensor connected to the motor on the opposite side ("crossed") Principle: The more there is of the quality to which the sensor is tuned, the slower the motors go ("inhibitory"). Description: likes the source, but easily attracted away
Vehicle 3c: Knowing, Valuing Components: 4 sensors, 4 motors, each tuned to different properties of the environment. Principle: one each of the four types so far:
Description: Cowardly toward areas of high temperature; Aggressive toward light sources; Loves organic material; leaves and seeks new source if environment is depleted; Restlessly seeks best source of oxygen. Vehicle 3c appears to know a great deal.
Vehicle 4a: Displaying Instincts, Specialization Components: sensors and motors Principle: connections both excitatory and inhibitory but non-monotonic Description: does everything 3c vehicles do, but with much less predictability.
Vehicle 4b: Making Decisions Components: sensors and motors, and threshold devices Principle: connections both excitatory and inhibitory but non-monotonic Description: does everything 3c vehicles do, but with much less predictability, and appears to ponder over its "decisions"; appears to will.
Vehicle 5: Reasoning Logically, Counting, Recognizing Individuals Components: sensors, motors, threshold devices, some networked, so they give output according to some numerical formula (e.g., one out for every three in). Principle: connections are both excitatory and inhibitory, monotonic and non-monotonic. Like a computer. Description: apparently recognizes individuals, counts, does logic, math calculations. Law of Uphill Analysis and Downhill Invention: machines are easy to understand if you’re creating them; much harder to understand "from the outside". Psychological consequence: if we don’t know the internal structure of a machine, we tend to overestimate its complexity.
Vehicle 6: Evolving Description (from the outside): "the [mistaken] feeling of a mysterious supernatural hand guiding the creation" (28)
Vehicle 7: Associating Ideas, Abstracting Concepts Components: sensors, motors, threshold devices, networks of threshold devices, and Mnemotrix wires between threshold devices. Principle: simultaneous activation of both ends of Mnemotrix temporarily lowers resistance to stimuli at either end; makes vehicle both more sensitive to this combination of environmental stimuli, and to the combined individuals alone. E.g., if aggressive predators are red in color, vehicle responds to other red things as if they were predators too. Description: Vehicle adjusts to new conditions, appears to derive concepts by abstraction from particular cases (e.g., danger, "smell of death") – a capacity non-sentient beings were thought not to have!
Vehicle 8: Neighborhood, Thing-ness, Reality and Unreality, A priori concepts Components: all of above plus object detectors and movement/directionality detectors (connect threshold devices one-to-one with photo cells) – creating internal maps – plus lateral inhibition. Principle: lateral inhibition means an active threshold device automatically puts a brake on the activity of its neighbors, so the more it’s activated, the more its neighbors are inhibited. (Vehicle appears to concentrate, focus.) Description: Vehicle 8 behaves as though it understands the concept of space, e.g., will take the diagonal to go back to a place it likes, even if it didn’t arrive that way. Vehicle 8’s internal maps determine its concept of reality: e.g., since it can’t represent objects that are not physically contiguous in space through time, such objects can’t be real. Solids objects cast continuous and regular shadows; don’t change their shapes as they move, etc. Vehicle 8 "just knows" these things.
Vehicle 9: More a priori concepts; "Thou"; Confrontation; Properties of shapes Components: all of above plus bilateral symmetry, radial symmetry, periodicity detectors. Principle: A bilateral or radial symmetry detector is an array of threshold devices activated just when the vehicle is presented with a bilaterally or radially symmetrical object. Descriptions: Vehicle 9 appears able to "con-front" others; has concept of the Other, which affects its behavior; has concept of being the focus of someone else’s attention.
Vehicle 10: Getting More Complicated Ideas by Association Components: Mnemotrix devices with all features of Vehicle 9. These devices have been around awhile and have accumulated a lot of connections. Principle: Vehicle sees same string of stimuli many times, learns to associate all the elements of the string by process of association as in Vehicle 7. Description: Vehicle 10 behaves as though it has foresight, thinks.
Vehicle 11: Sequential Reasoning; Causes and Effects; Signals Components: all of above plus Ergotrix connections. Principle: Ergotrix conducts in one direction only and "has an increased conductance when it is interposed between elements that are active in succession within a brief period of time" (57). New rule: whenever Ergotrix connections are strengthened, the Mnemotrix wires within the groups also strengthened. Mnemotrix suited for acquiring descriptive knowledge. Ergotrix suited for acquiring dynamic knowledge. Both kinds of knowledge are essential to each other: reliable knowledge about interaction depends on good description; and vice-versa. Example: "Hear the lion’s roar associated with see the lion" becomes "lion’s roar caused by nearby lion". "Hear lion roar" becomes signal to run away.
Vehicle 12: Trains of Thought; Free Will Components: all of above plus "epilepsy inhibitor" – a threshold control device. Principle: A global negative feedback loop, that simultaneously raises or lowers all thresholds at once. Raising threshold of outside stimuli --> more attention can be directed "inward" --> possibility of "trains of thought". For any fairly large brain, each configuration of active elements will be unpredictable based on the previous configuration; i.e., the vehicle’s thoughts can surprise itself as well as predators (evolutionary advantage).
Vehicle 13: Genuine Foresight; Intentionality, Individuation Components: all the above plus splitting brain into two halves (predictor and sensor). Principle: Compare expectations (formed by Ergotrix and Mnemotrix) with sensory input. Incorporate rule: When in doubt, believe sensors. Make the Predictor more and more accurate by a new component, faster Ergotrix (short-term memory), which can serve as a "mental echo", and note Darwinian survival knowledge (the "Darwinian evaluator" mechanism D). "Whenever the Darwinian evaluator D signals an unpleasant turn in the real course of events, or a very pleasant one, the predicting half-brain P is disconnected from the input it normally receives from the realistic (sensory) half-brain, R. Instead the predicting half-brain receives its input from the short-term memory two steps back. So it will go again through the two instants preceding the important happening. At the same time its output is connected to the input of the short-term memory. So it will receive over and over again via the short-term memory the succession of the two events, a and b, until the Darwinian evaluator D has calmed down and everything has switched back to normal. The net effect is that strings of events leading to strongly emotional consequences are incorporated strongly into the Mnemotrix-Ergotrix system even if they occur only rarely." (78) Description: Vehicles of type 13 appear individuated – they will be quite different one from another because they’ve had different experiences.
Vehicle 14: Egoism and Optimism Components: all the above, plus incorporate a new principle that favors optimism. Principle (new): When choosing among several equally likely next brain states, choose the most pleasant one. Description: Vehicles of type 14 "dream", and "run after their dreams". "They move through their world with consistent determination," guided by a chain of optimistic predictions, which often turn out to make the state of the world a "more favorable" one. |
