Vehicle 4
Values and Special Tastes
By chapter four, Braitenberg has stopped changing the body and started changing the transfer function. Values, tastes, and aversions can all be made to appear by reshaping how the same signal turns into action.
9 min read
Drag the main warm source. This plate stays grounded in a literal Braitenberg body while the chapter moves toward values and preference.
DemonstrationEven with a simple body, a mixture of attraction and aversion starts to read as taste. The path itself becomes a visible preference ordering.
Vehicles 1 through 3 taught the basic trick: alter the coupling and the path changes enough to invite a new interpretation. Vehicle 4 makes the next move. Instead of asking which sensor drives which motor, it asks how much a given signal should matter at all.
The answer is a response curve. Some vehicles respond broadly. Some have a narrow preferred band. Some are drawn toward moderate intensity but avoid extremes. That is already enough to make them look as if they have values.
Key idea
A taste can be implemented as a curve before it is implemented as a symbol. If the same world produces different action because the transfer function is shaped differently, observers start talking about preference.
Taste lives in the curve
The same stimulus can excite one vehicle, leave another indifferent, and repel a third. Nothing about the world changed. The only change is the shape of the mapping between signal intensity and output.
This is important because it relocates value from high-level judgment to low-level response. The vehicle does not have to represent a rule like “prefer warmth but not too much warmth.” It only needs a curve that behaves that way.
Signal 0.62 produces output 0.99. In this chapter, taste lives in the shape of that curve.
Values can be narrow, local, and mechanical
Special tastes appear when the preferred zone becomes narrow. The vehicle is not generally attracted to a kind of input. It is attracted to a particular band. Outside that band it slows, ignores, or avoids.
That narrowness matters because it explains how behavior can look choosy without becoming abstract. Selectivity can emerge from a local tuning function long before it becomes an explicit category.
Signal 0.62 produces output 0.99. In this chapter, taste lives in the shape of that curve.
Modern translation
A large amount of what we call preference in software is really response shaping: thresholds, saturations, penalties, floor values, and preferred operating bands. The vocabulary becomes psychological only after the curve has already done its work.