Braitenberg Vehicles

• Thought experiment by neuroscientist Valentino Braitenberg.

• Vehicles: Experiments in Synthetic Psychology, MIT Press, 1984

• 14 types of vehicles of increasing complexity.
  
  

  • Vehicle 1: single sensor-motor coupling

  • Sensor measures concentration of X (temperature, light, chemical gradient, food, noise, etc.)

  • Vehicle moves forward in response to amount of X

  • If X is temperature, vehicle will move fast in hot regions and slow in cold regions

  • Appears to "like" cold regions and "dislike" hot regions

  • Friction in environment results in more complicated behavior

    
    
    
    

  • Vehicle 2a, 2b: two sensors, positive connections

  • Each motor stimulated by one of the sensors

  • Vehicle 2a is a "coward" (it avoids X)

  • Vehicle 2b is "aggressive" (it approaches X and speeds up)

    
    
    
    

  • Vehicle 3a, 3b: two sensors, negative connections

  • Each motor inhibited by one of the sensors

  • Vehicle 3a "loves" X (it turns toward X and stays close by)

  • Vehicle 3b likes X too but keeps an eye out for other sources (it gradually moves away from X)

    
    
    
    

  • Vehicle 3c: multiple sensors and connections

  • Several types of sensors, tuned to different aspects of environment

  • Mixture of excitatory and inhibitory connections

    

  • Now we have really interesting behavior:

    • dislikes high temperature
    • turns away from hot places
    • hates light bulbs, since it turns toward them and destroys them
    • prefers well-oxygenated regions of environment with many organic molecules, since it spends much of its time in such places
    • may move elsewhere when supply of oxygen or organic matter is low

  • Vehicle 3c has a system of "values"

  • It "knows" what it likes and dislikes
    
    
    

  • Vehicle 4: non-linear sensory response curves

  • response to X is no longer simply linear

  • response may be continuous, discontinuous, or a combination of both

    

  • Vehicle 4 appears to "pondor" over its decisions (discontinuous thresholds)

  • Behavior is now even more interesting:

    • likes one sort of stimulus when it is weak but not when it is too strong
    • likes another the stronger it becomes
    • turns away from a weak smell and destroys the source of a strong one
    • visits in alternation a source of smell and a source of sound
    • turns away from both with a change in temperature
    • may respond suddenly when approached with a lure

  • We might be tempted to attribute "free will" to the vehicle
    
    
    

  • Vehicle 5: threshold logic units, neural networks

  • Vehicle 6: evolution

  • Vehicles 7-14: learning, more sophisticated cognitive abilities
    
    
    

• "Law of uphill analysis and downhill invention"

• Easy to implement vehicles 1-5 as mobile robots.