Cat Pupil Stress Tracking
ISEF Category: Animal Sciences
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Subcategory: Physiology · Difficulty: Intermediate · Setup: Home Setup · Time: 1 to 2 Months
The Hook
A cat's pupils can change fast enough to miss by eye. That tiny shift can carry clues about light, alertness, and stress. If you measure it with video instead of guessing, you can turn a pet behavior question into real data.
What Is It?
Pupil dilation is the widening of the black center of the eye. Think of the pupil like a camera aperture. When a cat gets less light, or its sympathetic nervous system kicks in during stress or alertness, the pupil opens wider to let more light in.
That makes pupil size a possible stress biomarker, which means a measurable sign that can hint at what the body is doing. The catch is that light, motion, focus, and camera angle can all change the number you measure, so your project has to control those parts before you treat dilation as a stress signal.
Why This Is a Good Topic
This is a strong science fair topic because you can measure it with tools you already have, and you can test it without invasive steps. It connects to animal welfare, pet handling, and stress monitoring, which gives your results a real-world use. You can also learn video analysis, measurement error, and basic statistics in one project.
Research Questions
- How does ambient light level affect cat pupil diameter measured from smartphone video?
- What is the effect of a mild novel stimulus versus a neutral object on pupil dilation in domestic cats?
- Does pupil diameter change more during a familiar person's presence than during a stranger's presence?
- To what extent does time of day change baseline pupil size in the same cat?
- Which measurement method gives more repeatable results, manual tracing or OpenCV segmentation?
- How does pupil dilation compare with a simple behavior score such as ear position or retreat distance?
Basic Materials
- Smartphone with video recording.
- Tripod or stable phone stand.
- Plain matte backdrop or poster board.
- Adjustable indoor lamp with consistent lighting.
- Printed calibration card or ruler.
- Treats approved by the cat's owner.
- Notebook or spreadsheet for session notes.
Advanced Materials
- High-resolution camera with manual exposure controls.
- Diffuse LED light box or softbox.
- Calibration target with known dimensions.
- Computer with Python and OpenCV.
- ImageJ for manual cross-checking.
- Behavior scoring sheet and ethically approved observation space.
- Owner consent forms and a welfare checklist.
Software & Tools
- Python: Runs scripts to clean video frames and calculate pupil area.
- OpenCV: Finds the pupil boundary and tracks changes frame by frame.
- ImageJ: Lets you trace pupils by hand for a comparison method.
- Google Sheets: Stores trial notes and makes quick plots.
- Jupyter Notebook: Keeps your code, figures, and notes in one place.
Experiment Steps
- Define the exact stimulus types and the calm baseline you will compare.
- Standardize camera position, lighting, and background before you record any cat.
- Choose one measurement method, then plan a backup check against manual tracing.
- Set the controls that separate stress from light changes, motion, and time of day.
- Prewrite your analysis plan, including repeated trials, outlier rules, and your main comparison.
Common Pitfalls
- Changing room brightness between recordings, which makes pupils look larger or smaller for reasons that have nothing to do with stress.
- Filming from a new angle each session, which turns the pupil into an oval and breaks pixel measurements.
- Using a stimulus that gets the cat playful instead of stressed, which mixes arousal types in the same data.
- Measuring frames where the cat blinks, looks away, or moves fast, which hides the true pupil edge.
- Ignoring each cat's baseline pupil size, which makes between-cat comparisons unfair.
What Makes This Competitive
A strong version of this project does more than record bigger or smaller pupils. You compare the pupil signal against tight lighting controls, repeated trials, and a second stress cue, like posture or retreat distance. If you also check OpenCV output against manual tracing and use a model that handles repeated measures, your project starts to look like real biomarker research instead of a simple observation.
Project Variations
- Compare pupil changes during owner presence versus stranger presence in the same cat.
- Test whether different low-level sounds produce different dilation patterns while lighting stays fixed.
- Compare manual pupil tracing with OpenCV segmentation to see which method tracks stress-related change more consistently.
Learn More
- PubMed: Search review articles on feline stress, pupil physiology, and autonomic responses.
- Cornell Feline Health Center: Read free articles on cat behavior, stress signals, and welfare.
- Merck Veterinary Manual: Look up feline eye anatomy and stress-related behavior terms.
- OpenCV documentation: Learn the video tools used to find and measure the pupil in each frame.
- NCBI Bookshelf: Search physiology chapters on the sympathetic nervous system and pupillary control.