PAD Ready State

EEG-gated pre/post speech capture — an Epoc X physiological anchor for the Pleasure dimension of the PAD framework.

Two channels of frontal alpha asymmetry. Four channels of frontal theta. A three-phase capture protocol. A live readout, an offline CSV importer with Cooley–Tukey FFT, and a session log you can export to disk.

This walkthrough explains what the station measures, how it computes each metric, and what the deltas can — and cannot — tell you. The actual capture tool runs on slide 6.

Research instrument Not diagnostic Single-subject
Will Carbone  |  FluentPlay Technologies LLC  |  April 2026  |  Provisional Patent Pending

The 14 channels on your head

The Emotiv Epoc X places 14 saline electrodes against the scalp at standard 10-20 system positions. Names encode location: F = frontal, T = temporal, P = parietal, O = occipital. Odd numbers = left hemisphere, even = right. AF = anterior-frontal (closer to the forehead).

What this station uses

Of those 14, only four drive the readout: F3, F4, AF3, AF4. They sit over left and right prefrontal cortex, the region where the affective-asymmetry literature has the most signal. The other ten channels are recorded but not scored.

Why frontal

Davidson's approach/withdrawal model holds that relatively greater left-frontal activity tracks approach motivation, and relatively greater right-frontal activity tracks withdrawal. That asymmetry shows up most cleanly in alpha-band power at F3 and F4. Frontal theta over the same region indexes cognitive control load.

For people who stutter

Speech-onset moments often carry an anticipatory threat response. The pre/post protocol asks: did the speech act push the speaker toward approach (positive Δ alpha asymmetry) or toward withdrawal (negative)? And how much cognitive load did it cost (Δ frontal theta)?

→Click any electrode to see its name and role.

Epoc X — top view (nose up)

Tap an electrode
Each circle is one of the 14 Epoc X channels. The four highlighted in teal are the ones this station scores.
— select to see usage —

Frontal Alpha Asymmetry — the Approach/Avoidance index

Take the alpha-band power (8–12 Hz) at the right frontal electrode F4. Take the alpha-band power at the left frontal electrode F3. Take the natural log of each. Subtract:

The formula

α-asym  =  ln(α F4) − ln(α F3)

Why this works

Alpha power is inversely correlated with cortical activation in that region. Less alpha = more activation. So a positive value here means the left frontal cortex was relatively more active than the right — which Davidson's model associates with approach motivation. Negative value = right-dominant = withdrawal/avoidance.

The clamp

The station clamps the value to [−1, +1]. Beyond that range the signal is dominated by noise or electrode contact issues, not real asymmetry.

The log

Power values are non-negative and span orders of magnitude. The log makes the difference between two power values into a meaningful ratio rather than an arbitrary scale-dependent number.

→Drag the two sliders. The asymmetry value rescores live.

α F3 vs α F4 — live computation

α F3 20.0
left frontal alpha power (μV²)
α F4 20.0
right frontal alpha power (μV²)
Frontal Alpha Asymmetry (ln α F4 − ln α F3) +0.000
−1.0 Avoidance0+1.0 Approach
Working through it

ln(20.0) − ln(20.0) = 0.000. The two hemispheres are balanced. No approach or avoidance signal.

Frontal Theta — cognitive load

Theta-band power (4–8 Hz) over frontal midline tracks cognitive control effort. The medial prefrontal/anterior cingulate generates theta oscillations whenever the system is performing executive monitoring — error detection, conflict resolution, attentional engagement.

The formula

θ-mean  =  (θ F3 + θ F4 + θ AF3 + θ AF4) / 4

Why average four

Single-channel theta is noisy. Averaging the four frontal channels (F3, F4, AF3, AF4) gives a more stable estimate of frontal cortical engagement than any one electrode alone, and it's a reasonable proxy for the deeper midline source we can't directly measure with surface EEG.

Reading it

Higher value = more cognitive load during the segment. A speaker who finds a phrase effortful will show elevated theta during TASK compared to PRE. A speaker for whom the phrase is automatic will show little change.

What the Δ tells you

Δθ between PRE and POST estimates whether the cognitive load persisted. A speaker who carries tension forward (rumination, residual arousal) shows positive Δθ; a speaker who recovers shows Δθ near zero or negative.

→Drag any of the four sliders — the dashed line is the running mean.

Per-channel theta → mean

θ F3 20.0
θ F4 20.0
θ AF3 20.0
θ AF4 20.0
F3
F4
AF3
AF4
mean 20.0

The capture protocol — PRE → TASK → POST

One session is three phases:

1. PRE — 60 s baseline

Speaker is at rest. EEG captures the baseline asymmetry and theta state before the speech act. Sets the reference point everything else is compared against.

2. TASK — speech

Speaker says the phrase out loud. The clock is open-ended — they take whatever time the phrase requires. EEG keeps recording continuously through the speech window, and frames captured during this phase are tagged task.

3. POST — 60 s recovery

Speaker is at rest again. Captures the asymmetry and theta state after, so the system can compute Δα-asym and Δθ between baseline and recovery.

Why this design

Single-trial EEG is too noisy to interpret moment-to-moment. But averaging across the 60-second baseline and 60-second recovery windows produces stable per-segment values, and the difference between them is what the protocol scores. The TASK segment is recorded for completeness but not used in the primary delta computation.

What gets logged

Per-frame: timestamp, phase tag, raw α F3/F4, raw θ F3/F4/AF3/AF4, computed α-asym, computed θ-mean. Per session: PRE mean, POST mean, Δ for both metrics. Everything exports as CSV.

→Hit play — watch a simulated three-phase session run.
PRE — 60 s
TASK — speech
POST — 60 s
0.0 s

Try a scenario

A fluent speaker. Alpha asymmetry stays near zero throughout. Theta rises modestly during speech and returns to baseline. Δα-asym ≈ 0, Δθ ≈ 0.

Try the delta interpretation yourself

Drag the PRE and POST sliders. The interpretation matches the station's actual analyzer thresholds (±0.05).

PRE α-asym
−0.10
→
POST α-asym
+0.15
=
Δα-asym
+0.25
Shift toward approach

PAD Ready State — Capture Tool

Connect to the Epoc X via Cortex, or import an EmotivPRO CSV. Research instrument — not diagnostic.

Disconnected

Cortex Settings

Capture

Export

Frontal Alpha Asymmetry (ln α F4 − ln α F3) 0.000
−1.0 Avoidance0+1.0 Approach
Frontal Theta Mean (F3, F4, AF3, AF4) 0.000
0max
1
PRE — Baseline
60-second resting capture before speech
60
2
TASK — Speech
Speak your phrase. EEG records in background.
—
3
POST — Recovery
60-second resting capture after speech
60

Session Log

TimePhrase Pre α-AsymPost α-AsymΔ α-Asym Pre θPost θΔ θ
No sessions captured yet. Connect to Cortex and start a PRE capture to begin.
PRE segment TASK segment POST segment —

PRE (Baseline)

m:ss
m:ss

TASK (Speech)

m:ss
m:ss

POST (Recovery)

m:ss
m:ss

Analysis Results

Pre α-Asym
—
Post α-Asym
—
Δ α-Asym
—
Interpretation
—
Pre θ Mean
—
Post θ Mean
—
Δ θ
—
Windows analyzed
—

Offline Session Log

FilePhrase Pre α-AsymPost α-AsymΔ α-Asym Pre θPost θΔ θ
Import a CSV and set segment markers to analyze.

Methods & limitations

PAD Ready State is a single-subject research instrument. It is not a clinical diagnostic device. Read this slide before drawing any conclusion from a session.

Methods

Acquisition

Hardware: Emotiv Epoc X, 14 channels, saline electrodes, sampled at 128 Hz. Live mode streams via the Cortex API over wss://localhost:6868 using the pow stream (Cortex-computed band powers).

Offline pipeline

EmotivPRO CSV import. Cooley–Tukey radix-2 FFT with Hanning window. Window size selectable (128 / 256 / 512 samples) at 50% overlap. Sample rate auto-detected from timestamp deltas.

Bands

  • Alpha — 8 to 12 Hz, computed at F3 and F4
  • Theta — 4 to 8 Hz, computed at F3, F4, AF3, AF4

Derived metrics

  • α-asymmetry = ln(α F4) − ln(α F3), clamped to [−1, +1]
  • θ-mean = average of θ at F3, F4, AF3, AF4
  • Δ = POST mean − PRE mean

Interpretation thresholds

Δα-asym > +0.05 → "shift toward approach". Δα-asym < −0.05 → "shift toward avoidance". Within ±0.05 → "minimal asymmetry change". These are display labels, not significance tests.

Limitations

What this is not

This is not a diagnostic device. It cannot be used to identify, classify, or treat any condition. It does not produce evidence of effect for any specific person.

Single-trial variability

EEG band power on any single 60-second segment is noisy. A meaningful conclusion about any individual speaker requires repeated sessions across days and conditions, not one session.

Individual baselines vary

The "approach/avoidance" sign of α-asym is meaningful at the group level in published research. The absolute value for any one person depends on skull thickness, electrode placement, and trait baseline. Within-subject Δ is more interpretable than absolute level.

Cortex POW stream limits

In Live mode the station consumes Cortex's pre-computed band powers, not raw EEG. The exact filtering Cortex applies is not fully documented. For publishable analyses, use the offline CSV pipeline against EmotivPRO raw export — that path is fully reproducible.

Speech artifact

Frames captured during the TASK phase contain jaw, tongue, and breath EMG riding on top of EEG. The protocol logs them but excludes them from the primary delta. Treat any TASK-phase number as exploratory.

Generalization

Frontal alpha asymmetry literature derives from non-stuttering populations. Its applicability to people who stutter, and to the specific moment of speech onset in stuttering, is an open empirical question — not an established result.

Selected references. Davidson, R. J. (1992). Anterior cerebral asymmetry and the nature of emotion. Brain and Cognition, 20(1), 125–151.  |  Allen, J. J. B., & Reznik, S. J. (2015). Frontal EEG asymmetry as a promising marker of depression vulnerability. Current Opinion in Psychology, 4, 93–97.  |  Cavanagh, J. F., & Frank, M. J. (2014). Frontal theta as a mechanism for cognitive control. Trends in Cognitive Sciences, 18(8), 414–421.  |  Smith, E. E., Reznik, S. J., Stewart, J. L., & Allen, J. J. B. (2017). Assessing and conceptualizing frontal EEG asymmetry. International Journal of Psychophysiology, 111, 98–114.

Will Carbone  |  FluentPlay Technologies LLC  |  Somerville, MA  |  April 2026  |  Provisional Patent Pending

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