The early Colony model began with needs because needs produce motion. Hunger, danger and discomfort can make an otherwise inert agent do something. But a pressure is not yet a personality. Two agents can experience the same need and still behave differently.
This is why naming matters. Calling a behavioural pressure “courage” quietly turns an action tendency into a moral judgement. An agent that advances is not necessarily brave; an agent that retreats is not necessarily cowardly. What differs first is agency: how readily perception and internal pressure become action.
The need asks for change. Character shapes the route taken toward it.
Working distinction
Pressure — something has become difficult to ignore.
Perception — what the agent believes is happening.
Disposition — stable biases in how evidence, attachment and agency are weighted.
Response — behaviour produced by those quantities in this situation.
A compact architecture can therefore be layered rather than enlarged. Primitive pressures remain close to the body: sustenance, safety and comfort. Higher social and reflective behaviour can be derived from a small set of attuned values rather than represented as dozens of unrelated personality sliders.
Virtue and vice can then appear as imbalance rather than separate inventories. Pride may emerge when agency greatly outruns truth and attachment. Sentimentality can appear when attachment overwhelms evidence and agency. Dogmatism can appear when commitment to perceived truth is insufficiently tempered by compassion or revision.
The exact equations are less important than conservation of meaning. A variable should describe one thing well enough that derived behaviour remains interpretable. If one value simultaneously means moral bravery, willingness to act, tolerance of danger and motivation to finish a task, the model may generate numbers but those numbers stop explaining the agent.
Character should bias behaviour without dictating it. Strong circumstance can force an atypical response; weak pressure gives disposition more room to show. Those departures are useful because the agent exists inside a world rather than inside a personality test.
A practical Colony experiment follows: give several agents identical immediate needs and observations, vary only a small number of dispositions, and record not merely which action wins but why. Repeat while increasing one environmental pressure. A useful model should show recognisable tendencies followed by understandable departures as circumstance becomes dominant.
The target is not psychological completeness. It is explanatory compression: enough internal structure that complex behaviour can be traced back to a few comprehensible causes.
Design principle / Keep pressures primitive. Let character bend them. Interpret the resulting action in the context of the world.