Mental simulation refers to the cognitive process by which the brain generates, manipulates, and evaluates internal scenarios that may or may not match current reality. In everyday language, people often describe these generated scenarios as “characters,” “worlds,” or “stories,” but clinically relevant constructs map to underlying mechanisms in perception, memory, imagination, and self-referential thought. The same system that supports planning and empathy also enables vivid internal experiences that can feel autonomous or remarkably lifelike.
At the neurocognitive level, mental simulation relies on coordinated networks rather than a single center. The default mode network (DMN), typically active during internally focused cognition, supports autobiographical memory retrieval and future-oriented thinking. The hippocampus and medial temporal lobe structures contribute pattern completion, contextual binding, and flexible recombination of stored information. The prefrontal cortex contributes goal-directed control, suppression of irrelevant material, and selection among competing interpretations. Temporal and parietal regions support semantic richness and perspective taking. Together, these systems allow a person to create plausible “characters” within a simulated “world,” including the motivations, histories, and predicted reactions of those imagined entities.
From a psychological perspective, simulation supports several adaptive functions. First, it improves planning by allowing rehearsal of outcomes (“if I do X, then Y may happen”). Second, it supports social cognition: to understand others, people simulate what others might know, want, and believe. Third, it enables coping by generating alternative appraisals that reduce uncertainty and help integrate threatening experiences. These processes are normal when they remain flexible, reality-based, and proportionate to context.
The clinical question is not whether mental simulation occurs—everyone simulates—but how it is regulated. Difficulties can emerge when simulation becomes intrusive, rigid, or strongly dissociated from sensory evidence. For example, rumination in anxiety and depression involves repetitive, self-referential simulations focused on threat or loss. In obsessive-compulsive disorder, intrusive thoughts can function like unwanted “characters” that capture attention despite the person’s intention to disengage. In psychotic-spectrum conditions, simulations may be misattributed as external reality, leading to hallucination-like experiences or delusional interpretations.
A useful framework is metacognition: the capacity to monitor one’s own thoughts and assign appropriate confidence. Healthy metacognition helps a person label internal events as internal. When monitoring weakens, internal simulations can be experienced as more real, more certain, or more externally sourced. This does not imply that all vivid imagination is pathological; clinicians emphasize that distress and impairment are key determinants. Risk increases when experiences cause significant functional decline, significant distress, or persistent inability to correct misinterpretations.
Mental simulation is also tightly linked to memory reconsolidation. When the brain retrieves a memory, it can be updated, modified, and reconsolidated. This means that internally generated scenarios can, over time, influence future recall, biases, and expectations. In trauma-related disorders, simulation may skew toward threat detection and safety behaviors, reinforcing a cycle of hypervigilance. In post-traumatic stress disorder, intrusive re-experiencing can be understood as maladaptive reactivation of sensory-laden simulations tied to the traumatic event.
Importantly, simulation is not inherently “delusional.” Many therapeutic approaches harness imagination and guided simulation. Cognitive-behavioral therapy (CBT) uses imagery rescripting to change the emotional meaning of distressing memories. Exposure-based therapies include imaginal exposure, gradually reducing fear through controlled confrontation with simulated cues. In some contexts, mindfulness improves the ability to observe thoughts as mental events rather than facts.
Medication may be considered when mental simulation is embedded in broader psychopathology such as major depression, generalized anxiety disorder, OCD, or psychotic disorders. For anxiety and depression, selective serotonin reuptake inhibitors and other agents can reduce the frequency and emotional intensity of intrusive simulations. In OCD, serotonergic modulation can reduce obsessions and compulsions. In psychotic-spectrum disorders, antipsychotic medications can improve reality testing and reduce the conviction of internal experiences that are misattributed.
Overall, the phenomenon of “characters” populating “worlds” maps onto mental simulation and its regulation. Adaptive simulation supports planning, empathy, and problem-solving, whereas maladaptive patterns involve impaired monitoring, intrusive persistence, heightened conviction, and functional harm. If a person experiences intrusive internal scenarios that feel uncontrollable, distressing, or detached from reality, clinical evaluation is warranted to clarify underlying conditions and to select evidence-based interventions.
Source: @vtellis
Viren: @pixelfondue Because you have worlds being created so easily, but there’s nothing populating those worlds. Characters is a natural next step. Not for every world, but many of them.. #breaking
— @vtellis May 1, 2026
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