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Abstract
Active Inference models biological agents as self-organizing
systems that maintain structural integrity by minimizing Variational
Free Energy (VFE). This paper explores the epistemological and
mechanical boundaries between physical ground-truth reality and an
agent’s internal subjective reconstruction. We implement an online
Predictive Coding Neural Network (PCNN) navigating an environment
containing dynamic target attractors and localized threat obstacles.
Critically, we examine the behavioral and affective
distortions—termed here "cognitive illusions"—that
arise when an agent's top-down generative weights are miscalibrated
or non-optimal.
Furthermore, we formalize an emotional mapping layer where
affective valence is modeled as the second-order rate of change of
VFE. Our empirical results, derived from continuous time-series
simulation logs across 2,480 iterations, reveal that mismatched
weights induce stable spatial tracking offsets that prematurely
paralyze the agent. When online synaptic plasticity is re-engaged via
gradient descent on the Neural Network VFE, the agent dynamically
re-calibrates its generative model. This structural learning process
reduces subjective free energy by over 99.5%, collapses the
perceptual divergence, triggers predictable transitions in emotional
states from anxiety to homeostatic motivation, and restores objective
goal tracking.
1. Introduction
A foundational premise of theoretical biology and computational
neuroscience is that living organisms must resist the natural
tendency toward thermodynamic decay and informational entropy. Active
Inference, formalized via the Free Energy Principle (FEP), posits
that agents achieve this existential imperative by executing actions
that minimize an upper bound on sensory surprise, known as
Variational Free Energy (VFE). Under this paradigm, the brain does
not passively register environmental impressions; instead, it
operates as a hierarchical prediction engine, constantly projecting
top-down hypotheses about the hidden causes of its sensory streams.
However, a deep conceptual vulnerability emerges when an agent's
internal map of the world—its generative model—diverges
structurally from the actual laws governing the environment—the
generative process. If the internal synaptic pathways that translate
beliefs into expected sensations are miscalibrated, the agent’s
perceptual apparatus will distort reality.
While existing literature frequently evaluates Active Inference
under idealized, perfectly matched models, this paper systematically
investigates the mechanics of model miscalibration. We decouple
physical ground-truth coordinates from internal network beliefs to
study three interconnected phenomena:
The temporal alignment between physical trajectories and
inferred beliefs under an asymmetric sensory integration
architecture.
The genesis of stable spatial "cognitive illusions"
driven by non-optimal generative weights.
The mathematical and empirical divergence between the true
analytical free energy of the environment and the subjective free
energy computed by the agent’s neural architecture.
The formal computational modeling of affective valence and
emotional states as a reflection of the second-order rate of change
of free energy over time.
By analyzing the comprehensive data profiles of an active
inference agent across 2,480 iterations of simulated environmental
interaction, we chart the exact journey of an uncalibrated mind
discovering, suffering from, and ultimately resolving its own
structural illusions through synaptic learning.
2. Mathematical Foundations & Generative
Architecture
To mathematically parse the boundary between objective nature and
subjective mind, we establish a rigid dual-space architecture.
2.1 The Generative Process (Physical Reality)
Let (1) define the absolute,
omniscient ground-truth coordinates of the physical agent in a
bounded two-dimensional arena. The agent
moves through space based on an applied physical velocity vector v actual (2).
The environment contains a static target attractor and a localized threat obstacle. The agent possesses no direct,
unmediated access to its ground-truth coordinates. It must observe itself through a
noisy sensory channel (3), where (4) represents high-frequency environmental and
sensory measurement noise.
2.2 The Generative Model (Subjective Neural
Network)
The agent possesses an internal network parameterized by internal
state beliefs (5) and top-down generative
weights (6). The network's sensory prediction is defined as (7)
When the agent can perceive environmental features (governed by
visibility thresholds), it computes sensory
prediction errors. The total spatial prediction error
(11) is divided into target-directed
attraction (9) and threat-directed repulsion (10) components, weighted by
their respective sensory precisions (8).
The system’s Variational Free Energy is mathematically
represented as the squared sum of these precision-weighted prediction
errors (12).
Action in Active Inference proceeds via the changing of states to
fulfill predictions. The motor velocity command executed by the
physical body is driven directly by the reflex-like minimization of
this error gradient (13).
3. Core Structural Analyses
3.1 Ground Truth Trajectory vs. Inferred Belief
State
A critical development in our model involves how the agent
integrates time. The agent updates its subjective position
belief by adding its internal inferred velocity command (14).
Our refined architecture enforces strict asymmetric sensory
integration. The internal states (5) are determined
strictly by filtering incoming observations. As demonstrated in the
empirical logs, the inferred belief trail binds tightly to the
ground-truth trajectory. The belief state hovers directly over the
physical agent, experiencing only a high-frequency jitter bounded
directly by the sensory noise variance (4).
Figure 1: Perceptual Trajectory Tracking Map
3.2 Cognitive Illusions Induced by Non-Optimal
Weights
When the generative weights are frozen away from unity, the network experiences a profound cognitive
distortion. We simulated this state by initializing weights at (15)
Under these non-optimal weights, the agent develops a structural
blind spot. As it approaches the target, its internal network
calculates that it has arrived at the correct position, because the
distorted top-down prediction perfectly cancels out the incoming
sensory observations (16). Subjectively, the agent
believes its free energy is minimized, causing its motor commands to
ramp down to zero. Objectively, however, the agent is paralyzed
several units away from the target star, frozen in space by an
uncorrected perceptual bias.
3.3 Analytical VFE vs. Neural Network VFE
Profiles
To map this discrepancy, we track two distinct energy metrics:
Analytical VFE: The
absolute error function calculated using omniscient ground-truth
coordinates.
Neural Network VFE: The
internal error calculated strictly through the agent's distorted
generative model (17).
When weights are static and non-optimal, Neural Network VFE drops to zero as the agent experiences its illusion of arrival, while Analytical VFE remains high. This divergence proves
that an agent can optimize its internal universe perfectly while
remaining completely uncalibrated with the physical world.
To bridge this gap, we re-engage synaptic plasticity by allowing
the prediction error to flow back into the weights via online
gradient descent (18), (19) e (20):
Under this
configuration, the lingering prediction error actively rewires the
network's parameters (as seen in Figure 1´s right graphic) as the agent sits for a moment in its illusion
zone, before converging to the target´s true position.
3.4 Mathematical Formalization of Affective
Valence (Emotional States)
Following the mathematical models of Smith, Friston, and Kirsch
(2019), we formalize the agent's emotional state as the second-order
rate of change of free energy over time. Let (21) define the
emotional valence metric:
We map three explicit computational thresholds based on the
dynamics of (21) and the presence of contextual precision
indicators:
Epistemic Exploration / Curiosity: Occurs when
VFE is flat or gently fluctuating near zero under low
contextual precision. The agent
experiences low error gradients and engages in unconstrained search.
Threat Repulsion / Anxiety: Characterized by highly
unpredictable, positive acceleration spikes in VFE paired with high-precision threat inputs. The agent registers a rapid
expansion of surprise, manifesting behaviorally as avoidant
repulsion.
Target Attractor Lock / Motivation: Initiated when VFE
begins dropping significantly faster than a baseline expectation. The rapid minimization of prediction error
yields positive emotional valence, driving sustained, focused motor
action until satiation homeostasis (VFE approaches 0, (21) approaches 0) is achieved.
4. Empirical Results & Data-Driven Discussion
The model was evaluated over a continuous run of 2,480 iterations. Telemetry logs captured the exact behavioral and
emotional state transitions of the agent, divided across three
distinct phases.
4.1 Phase 1: Epistemic Foraging (66.73% of
Lifetime)
For the first 1,655 steps, the agent was placed outside the
visibility horizon of both the target and the threat. Operating under
zero environmental information, the system engaged in epistemic
exploration. The physical coordinates moved via a bounded random
walk, search-foraging through the environment. The logs recorded this
baseline state as "Epistemic
Exploration. I am curious.". Because spatial prediction
errors were absent outside visibility zones, the weights remained
unchanged at their initial values.
4.2 Phase 2: Threat Repulsion and Anxiety (18.27%
of Lifetime)
During its random walk, the agent repeatedly breached the
perimeter of the threat zone. Entering this
sector triggered an immediate spike in precision-weighted threat
prediction errors, causing the free energy to rise sharply.
The system logged this state as "Threat
Repulsion. I am anxious.". This computational anxiety
generated a powerful repulsive motor command vector that
successfully drove the agent out of harm's way, illustrating how
affective valences function as rapid protective mechanisms in
cybernetic systems.
4.3 Phase 3: Attractor Lock and Plasticity
Convergence (15.00% of Lifetime)
At iteration 2,108, the agent crossed the visibility threshold
of the target. It moved
forward but halted prematurely due to its weight-induced illusion. At
step 2,108, the weights stood heavily biased, causing an internal network loss of 1.9858 .
As the agent stagnated, online synaptic plasticity began resolving
the mismatch. The prediction errors actively re-tuned the synaptic
paths over the remaining 372 steps of the simulation.
Simulation Step
|
Weight X
|
Weight Y
|
Neural Net VFE
|
Physical X
|
Physical Y
|
Affective Mood State
|
2,108 (Target Encounter)
|
1.2615
|
0.8135
|
1.9858
|
1.5933
|
6.2920
|
Target Lock. I feel motivated.
|
2,115 (Learning Intercept)
|
1.2793
|
0.8430
|
0.6771
|
2.1104
|
6.8410
|
Target Lock. I feel motivated.
|
2,470 (Near Convergence)
|
1.0001
|
1.0008
|
0.0174
|
8.0095
|
7.9972
|
Target Lock. I feel motivated.
|
2,479 (Satiation Homeostasis)
|
1.0006
|
1.0008
|
0.0102
|
8.0053
|
8.0012
|
Target Lock. I feel motivated.
|
As shown in the data table, the gradient descent update pulled
both weights back to near-unity. As
the internal structural map aligned with reality, the internal
network loss plummeted by 99.48%, dropping from 1.9858 to a
baseline of 0.0102 .
Because the free energy was dropping consistently faster than the
baseline expectations, the system sustained its
high-motivation valence ("Target
Attractor Lock. I feel motivated."). With its perceptual
illusion dissolved, the agent resumed its trajectory, executing
accurate motor commands that brought its physical body to rest
directly on the true target coordinates, achieving
full homeostatic stability and emotional satiation.
Figure 2: Synaptic Weight and Free Energy
Convergence Profile
Caption: Figure 2: Multi-panel time-series analysis
of the phase-three learning intercept. The top panel illustrates the
dynamic adaptation of generative weights as they converge toward unity (1.0) upon encountering the
target at iteration 2,108. The bottom panel displays the matching
exponential decay of Variational Free Energy, which drops by over
99.5% as the structural illusion dissolves, maintaining a positive
affective motivation state.
5. Conclusion
This paper demonstrates that Active Inference loops are highly
vulnerable to systematic spatial offsets and behavioral stagnation
when their top-down generative components are miscalibrated. An agent
can optimize its internal neural network parameters to experience a
subjective illusion of target arrival, while remaining objectively
stranded short of its physical destination.
By separating the system into a dual-space architecture—objective
physical truth versus subjective inferred belief—we successfully
tracked this divergence. Furthermore, by framing emotional states as
the second-order rate of change of free energy, we show how cognitive
illusions and threats project distinct affective signatures onto the
agent's internal state.
Crucially, our results show that introducing online synaptic
plasticity driven by prediction errors allows the agent to break its
own perceptual illusions. Over time, the network updates its
generative weights, aligns its subjective free energy with absolute
environmental free energy, and guides the physical chassis to its
true target destination.