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HarmonEyes
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For developers

The Theia SDK

One SDK for Python and Unity. Runs on-device on any camera-based hardware (CPU-only, no calibration) and returns every validated model in real time. Download it, drop it in, read human state from the first frames.

SDKs

Ways to integrate.

Python SDK

        
Streaming & batch · Windows, Linux, macOS, Android
Unity SDK

        
Real-time XR · Meta Quest Pro & HTC Vive Focus Vision samples
Android SDK
Coming soon

A native Android SDK is in development, with the same validated models and outputs as the Python and Unity SDKs, running on-device at the edge. Public release and docs are on the way.

Native Android · availability coming soon
Docs coming soon
Quickstarts are illustrative. See the docs for the current API.
Validated models

Call a model. Get a result.

Every plan includes all validated models and capabilities. Each returns a real-time measurement and, where applicable, a prediction of when the state will change, with a confidence interval.

Cognitive Load

Cognitive Load refers to the amount of effort a person allocates to a task. It is recognized as an important factor in determining a person’s level of performance in a task and during daily life activities (Devos et al., 2020).

Eye tracking: Cognitive Load can be measured through physiological tools. Eye tracking is a sensitive, quantifiable, accurate real-time measure of cognitive effort via eye responses such as changes in the pupil (Fehringer, 2021), blinking (Chen, Epps, Ruiz, Chen, 2011), and other eye movements (Irwin & Thomas, 2010; Kramer, 1991; Van Orden, Limbert et al., 2001; Greef et al., 2009; Klinger, Tversky et al., 2010).

Current level
LowLow mental effort, significant cognitive reserve; if sustained for long periods, may lead to inattentiveness.
ModerateModerate mental effort: engaged, alert, attentive; some cognitive reserve, few performance effects.
HighHigh mental effort, low cognitive reserve; potential performance effects such as slow reactions and reduced decision-making capabilities.
When will the level change?

Assumes the same activity continues without intervention.

Predicted future level: Low, Moderate, or High

Time to reach the future state: seconds

Probability (%): for the current level and other levels

Confidence interval (0–1, low–high): for each output

Attention

Attention refers to how a person directs and distributes their focus during a task or activity (Nideffer, 1976). The width of a person’s attentional focus, from narrow to broad, plays a critical role in task performance. The ability to match attentional width to the demands of a situation is a key driver of success across a wide range of activities (Nideffer, 1990; Nideffer & Sagal, 2006; Wulf, 2013).

Eye tracking: Attention can be measured through eye movements. Eye tracking provides a real-time, objective window into how attention is being deployed, whether a person is locked onto a specific target or actively scanning a wide field. The HarmonEyes Attention solution captures attentional width through fixation patterns, saccade frequency and duration, and gaze distribution across the visual field.

Narrow-to-broad continuum
NarrowAttention is tightly focused on a specific, targeted object or cue. Well-suited for tasks requiring precision and concentration, such as reading or fine motor tasks. When applied to tasks requiring environmental awareness, performance can suffer.
Moderate-NarrowAttention is primarily focused but with some environmental scanning. Suited for tasks that require concentration with occasional situational awareness.
NeitherAttention is balanced between focused and distributed, neither strongly targeted nor broadly scanning. May indicate a transitional state or a task with mixed attentional demands.
Moderate-BroadAttention is largely distributed across the environment with some targeted focus. Suited for dynamic tasks that require awareness of multiple elements while maintaining some directed attention, such as driving in traffic.
BroadAttention is distributed widely across the environment. Supports rapid assessment of dynamic situations, such as monitoring a complex workspace, reconnaissance, medical triage, and physical security. When applied to tasks requiring focused concentration, performance can suffer.

Optimal performance depends on matching attentional width to the task at hand. Mismatches (a narrow focus during a high-awareness task, or a broad focus during a precision task) are associated with reduced accuracy, slower reactions, and increased error rates.

Mental Readiness

Mental Readiness is a real-time, session-level metric derived from cumulative cognitive load and grounded in the mental fatigue literature, which defines mental fatigue as a decrease in mental performance resulting from cognitive overload (due to task duration and/or workload), independent of sleepiness.

It reflects how much cognitive capacity a person has left in reserve, as shaped by their cognitive load over time. People rarely operate at a single, steady level of mental effort. Cognitive load naturally fluctuates, and periods of sustained high cognitive load gradually deplete available resources (Borragán et al., 2017; Hu & Lodewijks, 2020). When mental readiness runs low, the effects are tangible: attention narrows, decision-making slows, and errors become more likely. Tracking how much of a session is spent at high cognitive load is therefore a key indicator of sustained performance, resilience under pressure, and the likelihood of cognitive overload (Boksem & Tops, 2008; Chen et al., 2018).

What percentage of the session is high vs. low or moderate cognitive load?

A running percentage of time spent in each demand state, updated every second starting one minute into a session:

Low demandTime spent in low or moderate cognitive load, mentally engaged but with capacity to spare.
High demandTime spent in high cognitive load, operating near or at mental capacity. Research shows prolonged high-demand work depletes working memory resources and leads to impaired attention, planning, and decision-making (Boksem & Tops, 2008; Chen et al., 2018).

For example, a session showing 70% Low / 30% High indicates that most of the session was spent with meaningful cognitive reserve intact.

Fatigue

Fatigue is a state of increased situational sleepiness associated with reduced alertness, slower reactions, and a greater tendency to fall asleep (Hu and Lodewijks, 2020). It impairs focus and responsiveness, especially during prolonged or repetitive tasks. Fatigue is driven by a combination of sleep debt (how long it has been since a person last slept) and the body’s internal 24-hour clock. Sleep is the most effective way to relieve fatigue.

Eye tracking: Changes in blink behavior are especially indicative of increasing fatigue (Barbato et al., 1995; Caffier et al., 2003; Schleicher et al., 2008; Cori et al., 2019; Abe, 2023).

Current level
AlertHigh alertness and responsiveness. No meaningful sleep pressure. Cognitive and physical performance are unimpaired, with substantial reserve available for sustained or demanding tasks.
Somewhat FatiguedEarly signs of sleepiness. Reductions in alertness and responsiveness may be present. Increased effort is required to maintain focus, particularly during monotonous or sustained tasks.
FatiguedElevated sleepiness consistent with fatigue. Difficulty maintaining alertness, slowed reactions, and increased risk of attentional lapses. At higher levels, individuals may be fighting sleep or experiencing brief sleep intrusions, leading to significant performance impairment and increased safety risk.
When will the level change?

Predicted future level: Alert, Somewhat Fatigued, Fatigued

Time to reach the future state: seconds

Confidence interval (0–1, low–high): for each output

More capabilities on the roadmap →
Theia Dashboard

A ready-made front end for Theia output.

An optional display layer for teams who need a front end but don’t want to build one. Configurable widgets size to your canvas and render live capability output in real time. No UI work required.

Live display

Real-time Cognitive Load and Fatigue readouts, with discrete or continuous scales and configurable widget sizing on the canvas.

In-session controls

Thresholding, refining, baselining, annotation, and prompting, all available live during a session.

Replay & review

After a session, replay results with every interaction, add annotations, and track task type.

Export & resources

Save, upload, and download session data as CSV. Built-in access to tutorials, updates, and dashboard info.

Works with

Any camera, plus dedicated eye-tracking hardware.

Phones Tablets Laptops Webcams Smart glasses XR headsets Vehicles Aircraft
Technical specifications

Runs on the hardware you already have.

The Theia SDK turns standard eye-tracking hardware into human-state insight at a fixed per-frame compute cost. No GPU, no cloud round-trip, no calibration. Figures below reflect validated production targets.

Download the full spec sheet (PDF) →
Compute & performance
Per-frame inference budget & footprint
Compute requirement (GFLOPS)
~ 0.14
Compute requirement (TOPS)
1.37 × 10⁻⁵
Inference latency
100–200 ms
Output frequency
1 Hz (tunable)
Deterministic / real-time
Yes, fixed compute cost per frame, no cloud round-trip
SDK memory size
25 MB
SDK package size
20 MB
Processor & hardware support
Runs on devices people already use
CPU / NPU / GPU
Runs entirely on CPU (x86 and arm64), the primary validated target. No accelerator required.
Recommended CPU class
Arm64, Apple M1 or newer · x86-64, Intel 9th-gen / AMD Ryzen 3000 or newer
Supported architectures
x86-64, ARM64
Supported OS
Windows, Linux, macOS (Arm), Android, Unity
Eye-tracker input
Hardware-agnostic recommendations
Spatial (gaze) accuracy
Not required. Theia doesn’t depend on absolute gaze-point accuracy, so low-cost or uncalibrated trackers are fine.
Precision
< 2° of visual angle (recommended). Sample-to-sample precision matters; spatial accuracy does not.
Sampling rate
30 Hz minimum
Tracker type
Webcam, remote, smart glasses, XR, VR, RGB camera
Calibration
Not required. Supported to improve accuracy.
Input data format
Required: gaze coordinates, timestamp. Optional: pupil diameter, event streams.
Integration, privacy & licensing
Private at the edge
Deployment
On-device / edge, no internet connection required at inference time
Data privacy
All processing is local; no raw gaze or video data leaves the device by default
API / language bindings
Python, C++, Unity, Android
Releases

Release notes

Every Theia SDK and Theia Dashboard release, newest first.

Version 2.4

August 2026 Latest
Theia SDK · Theia Dashboard
New

Fatigue model v2.4

An updated fatigue model reports on three levels instead of four. “Neither Alert nor Fatigued” and “Rather Fatigued” are consolidated into “Somewhat Fatigued.”

Alert
Performance unimpaired, with reserve for sustained or demanding tasks.
Somewhat Fatigued
Early sleepiness. Holding focus takes more effort, especially on monotonous tasks.
Fatigued
Difficulty staying alert, slowed reactions, and risk of attentional lapses.

Version 2.3

July 2026
Theia SDK · Theia Dashboard
New

Browser-based dashboard

The dashboard runs in a web browser with no desktop install. Every user gets a private session.

Improved
  • “Mental Workload” is now “Cognitive Load,” and “Drowsy” is now “Fatigued”
  • The Mental Readiness gauge tracks changes in load more closely
  • Webcam tracking: smoother live gaze with fewer gaps and more reliable camera startup on Windows
  • Scene and webcam recordings survive an unexpected stop, so footage is no longer lost
  • Restyled update notifications, with a single press to restart and apply
  • First-run license prompt, a clickable license status indicator, and automatic entitlement refresh on startup
  • Export session predictions to Excel (.xlsx), with a ledger of every recorded value
Fixed
  • macOS auto-update is architecture-aware; an Apple-Silicon install no longer updates to an Intel build, or vice versa
  • No more backend crash after very long session runtimes
  • Mental readiness no longer reports “No predictions” in the 1-minute window
  • Sessions survive a page refresh, and Start Session disables while starting to prevent double-starts

Version 1.1.0

May 2026
Theia SDK · Theia Dashboard
New

Mental readiness indicator

A real-time mental readiness widget, with a 1-minute, 1-hour, and all-time lookback.

Attention indicator

Real-time attention classification (focused vs. distributed).

Improved
  • More time window options for the cognitive load history
  • View is now its own top-level menu, separating widget visibility from configuration
  • Submenus open as right-flyouts and stay open until you click outside

Version 1.0.0

February 2026 Initial release
Theia Dashboard · Theia Python SDK

The first release: the Theia Dashboard for real-time cognitive load and drowsiness monitoring, and the Theia Python SDK for programmatic integration.

Predates the 2.3 rename: “Mental Workload” became “Cognitive Load,” “Drowsiness” became “Fatigue.” Original wording kept for the record.

Theia Dashboard
  • Live monitoring: real-time cognitive load from a generalized base model, plus four-level drowsiness detection (Alert, Neither Alert nor Drowsy, Rather Drowsy, Drowsy) on a color-coded bar
  • Cognitive load graph: discrete categorical levels or a continuous scale, over a 3, 5, or 10-minute window
  • Scene camera: live video from the connected eye tracker
  • Sessions: start and stop from the footer and annotate live
  • Layout & settings: resizable panels, per-panel visibility toggles, license management, and header status indicators
Theia Python SDK
  • Real-time streaming: start and stop sessions and view included solutions
  • Requirements: Python 3.12 and Pupil Labs Neon (PL) or the mock tracker (WT) for development

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HarmonEyes

Bringing human-state intelligence to 8 billion devices.

HarmonEyes technology is patented. Privacy statement: the HarmonEyes service does not record, collect or store any personal user data or eye-tracking data. Bethesda, Maryland, USA · sales@harmoneyes.com
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