Modeling the Sunk Cost Effect: Perspective, State, and Action in Decision Dynamics

 This post introduces a cognitive-behavioral model for understanding the Sunk Cost Effect—the tendency to persist in a course of action due to prior investment, even when change may be more rational. The framework maps how different viewpoints (past investment vs. future vision) shape the perception of the present and influence whether individuals maintain the status quo or initiate change. It offers a structural lens for analyzing decision inertia and adaptive reasoning.

Modeling Based on 西剛志『結局、​どう​したら​伝わるのか？』

Entity Name	Description
Viewpoint	The cognitive stance from which the present is evaluated—either anchored in the past or projected from the future.
Past Investment	Resources, time, or effort already committed, often used as justification for continued action.
Future State Image	A vision of desired outcomes or goals that may challenge the relevance of past investments.
Current State	The present condition, interpreted either as a result of past investment or as a step toward future goals.
Current State from Past	The present viewed as a continuation or consequence of prior choices.
Current State from Future	The present evaluated in reverse from a desired future, often revealing misalignment.
Action	The behavioral decision—either to maintain the current trajectory or to initiate change.
Maintain Current State	Choosing to continue based on sunk costs, often driven by loss aversion or commitment bias.
Change	Choosing to pivot or adapt, often requiring detachment from past investment.

By modeling the sunk cost effect as a dynamic interplay between perspective, state, and action, this framework clarifies why individuals often resist change despite rational incentives. It encourages decision-makers to shift from retrospective justification to future-oriented evaluation.