Substitution in real attempts to manage intrusive thoughts
In clinical and everyday settings, people rarely rely on a single strategy. Someone troubled by intrusive thoughts may try to stop thinking about a topic and, when that fails, deliberately turn attention to a substitute idea. Work on overcoming traumatic memories describes exactly this pattern, with intrusive thoughts being terminated by identifying a substitute [2]. The substitution feels more manageable than brute-force blocking, but the evidence does not show that it avoids the forgetting cost.
This matters for how we judge coping advice. A technique that feels easier and more sustainable is not necessarily free of side effects. If substitution engages the same control process as suppression, then recommending it as a gentler alternative may simply relocate the cost rather than remove it [2].
How firm is the case for substitution-driven forgetting?
The case rests on a small evidence base. The work on traumatic memories discusses both suppression and substitution and links them to Wegner's thought-suppression research, but it does not directly measure collateral forgetting as an outcome of substitution [2]. So the claim that substitution produces the same forgetting is an inference from a shared mechanism, not a directly demonstrated result. It is consistent with the evidence rather than proven by it.
Related work on suppression in artificial systems does not settle the question either. A method for inducing cognitive friction in large language models by applying concept suppression notes collateral consequences at the behavioral level, but it concerns model behavior rather than human memory and does not examine thought substitution or collateral forgetting in people [1]. It is a reminder that suppression has wider effects, not a test of the substitution question.
What this means if you are trying to stop thinking about something
The practical upshot is that neither direct suppression nor substitution should be treated as a clean fix. Both appear to engage a control process that can make related memories less accessible [2]. If the goal is to protect memory for surrounding material, switching from blocking to substituting may not help.
What remains genuinely open is how large the substitution effect is and whether it depends on how often or how forcefully the substitute is used. The current evidence supports expecting some collateral forgetting but does not pin down its size, and direct measurement of substitution-driven forgetting is still missing [2].
Sources used in this answer
Designing cognitive friction with concept suppression in large language models
The paper applies concept suppression to induce cognitive friction in large language models and notes collateral behavioral consequences, but it does not address collateral forgetting or thought substitution in human memory.
Overcoming traumatic memories
The paper discusses both thought suppression and thought substitution as strategies for managing intrusive thoughts, noting that intrusive thoughts can be terminated by identifying a substitute, though it does not directly measure collateral forgetting as an outcome of substitution.