What Can Biometric Data Tell Us
Before conducting a full test, it is necessary to understand the purpose of collecting data with the Cinematronic Biosignal. The CBP supports neurocinematics, a research initiative that merges neuroscience with film and media. This method aims to provide valuable insights in a more accessible and cost-effective manner compared to traditional tools. Although established industry tools used in neuroscience may offer more features, the CBP has been tailored through the KreaTech project to the specific needs of film and media producers.
For students in film and media, this represents a significant shift in how audience feedback can be understood. Traditionally, evaluation takes place after screenings through surveys, group discussions, or teacher observations. While valuable, these methods often overlook moment-to-moment responses that occur during viewing, such as a:
- sudden spike of surprise at a jump cut;
- the gradual build of tension across a sequence;
- the subtle drift of visual attention away from the intended subject on screen.
By capturing physiological responses in real time, the CBP makes these normally invisible processes observable and provides a new layer of evidence that can inform editorial and creative decisions without compromising artistic freedom.
At the same time, these signals must be interpreted with care. A spike in skin conductance shows that something provoked arousal, but it does not reveal whether the moment was enjoyed or disliked. A rise in heart rate may indicate building tension, but it might equally reflect confusion or unease. Eye tracking can indicate where the eyes were looking at, but this does not guarantee that the viewer consciously processed the element in question. Someone may appear to be looking at the screen, while their attention is elsewhere. For this reason, biosignals are most valuable when used with complementary evidence, such as annotations, questionnaires, and professional judgment.
In this lesson, we will examine the three primary data sources supported by the CBP: galvanic skin response (GSR/EDA), heart rate derived from photoplethysmography (PPG), and eye tracking. We will explain what each one measures, the timescale for which it is most useful, and how it can inform specific creative decisions without sacrificing artistic freedom.
What each source actually measures
When we test a cut or a scene using the Cinematronic Biosignal Platform, we rely on implicit physiological signals. These signals are automatic responses produced by the body without the need for verbal answers or self-report scales, and which cannot typically be faked or altered.
In creative testing, these quantitative signals are valuable because they capture reactions in real time with millisecond precision. For instance, Galvanic Skin Response (GSR), also known as Electrodermal Activity (EDA), measures the strength and timing of a person's physiological response. At the same time, eye tracking provides insights into where attention is focused and what may have attracted it. None of these signals directly indicates whether a moment was "good" or "bad"; instead, they reveal that something occurred and help to identify and describe that event.
In simple terms, the software can tell you when and where a reaction was captured, but it is up to you to investigate precisely why it happened.
Understanding Data though the Autonomic Nervous System
The signals recorded by the Cinematronic Biosignal Platform are shaped by the autonomic nervous system (ANS), the part of the body that regulates processes we do not consciously control, such as sweating, heart rate, and pupil dilation. The ANS has two complementary branches:
- The sympathetic system is responsible for preparing the body for action. It activates when we are alert, stressed, or excited, and is often described as the "fight or flight" system. Increased sympathetic activity results in higher skin conductance, a faster heart rate, and other signs of arousal.
- The parasympathetic system is responsible for recovery and balance. It dominates when we are calm, relaxed, or safe, and is sometimes referred to as the "rest and digest" system. Parasympathetic activation helps slow the heart rate and restore the body to baseline.
Creative testing with biosignals involves observing how the balance between the sympathetic and parasympathetic nervous systems shifts during a viewing experience. For instance, a jump scare or dramatic reveal activates the sympathetic branch, resulting in spikes in skin conductance and short-term changes in heart rate. On the other hand, a long release shot or resolution sequence allows the parasympathetic system to regain control, and these measures can return to baseline levels.
GSR / EDA (Galvanic Skin Response / Electrodermal Activity)
GSR measures subtle changes in skin conductance resulting from the activity of sweat glands, which are controlled by the sympathetic nervous system.
When we experience feelings of surprise, excitement, or suspense, certain glands in our body react. This reaction is measured through something called Galvanic Skin Response (GSR), which helps us understand how intense our arousal is, but does not tell us what specific emotion we are experiencing.
In film analysis, GSR is particularly useful because it provides instant feedback on how viewers respond to specific moments in a film. Over just a few seconds, we can see spikes in GSR that match important points in the movie, like a jump scare, a plot twist, a joke, or a sudden change in music. If viewers have a strong reaction immediately after these moments, and if those reaction align with the artistic goals of the director, it means the scene was effective.
However, if a particular scene doesn't elicit a strong response despite that being the intent, it suggests that the filmmakers might need to reconsider how they set it up, the timing, or how clear the scene is. Using GSR data helps creators improve their storytelling techniques by ensuring that key moments connect with the audience as intended.
Heart rate from PPG
Heart rate can be measured indirectly through photoplethysmography (PPG), which detects small changes in blood volume in the skin as blood pulses through the body. Unlike Galvanic Skin Response (GSR), which reacts quickly to brief moments of excitement, heart rate is affected by both parts of the autonomic nervous system. The sympathetic part of the nervous system speeds up the heart during excitement or mental effort, while the parasympathetic part slows it down to help restore balance. What we see at any moment is the combined effect of these two systems.
In practice, heart rate is less about individual events and more about the pattern over time. A gradual increase in heart rate throughout a sequence suggests that sympathetic activation is intensifying, signalling rising tension, anticipation, or cognitive load. On the other hand, a return to baseline heart rate reflects parasympathetic recovery and often aligns with moments of resolution, release, or calm within the narrative.
For editors and directors, heart rate serves as a valuable indicator of pacing and escalation. If a sequence designed to build suspense shows flat or declining trends in heart rate across multiple viewers, it indicates a plateau that fails to retain engagement. On the other hand, if the heart rate stays elevated without recovery, the audience may become fatigued, suggesting the need for a pause or a "breath beat" before the next escalation.
Eye tracking (via webcam + Beam).
Eye tracking measures what viewers focus on while watching a screen. The Cinematronic Biosignal Platform records gaze points, indicating whether attention is directed toward faces, objects, or actions that convey the story's meaning. Since gaze is sampled multiple times per second, eye tracking is the most precise of the three measurement methods.
Remember, however, that eye tracking does not directly reveal cognition. A viewer may appear to be looking directly at the intended area of the screen while their attention drifts, or they may glance at the focal subject without fully processing its meaning. This limitation means that gaze data should not be interpreted as proof of understanding, but rather as evidence of what has entered the viewer's visual focus.
Eye tracking is a valuable tool for verifying that important story elements are viewed at the right time and in the appropriate context. If viewers focus on faces, props, or text when it's most important, the framing is likely to work well. On the other hand, if their gaze drifts to background details or other actions, the main message may be lost for first-time viewers. Directors and crew often miss these issues because they are familiar with the script and tend to look where they expect.
Corrective strategies typically involve adjusting the setup of scenes, including blocking, framing, or visual hierarchy. For example, filmmakers might adjust lighting to highlight a face, hold back secondary movements until after the main action, or keep an insert shot on screen longer so viewers have enough time to read it. These changes can be subtle, and eye-tracking data helps filmmakers be sure that the audience is looking where they want them to.
Simple glossary
Arousal
Arousal refers to a general increase in the body's activation level, which is controlled by the autonomic nervous system. High arousal indicates that the body is reacting strongly. Still, it does not specify whether the reaction is positive (such as excitement or joy) or negative (such as fear or confusion). In CBP tests, arousal is measured using Galvanic Skin Response (GSR) and heart rate.
Baseline
The baseline is a brief, neutral recording taken before a test begins, typically lasting 1–2 minutes of calm without any stimulus. Because individuals exhibit a wide range of physiological variability, the baseline serves to anchor each participant's signals to their own "normal" starting point. Without establishing a baseline, comparisons between participants become unreliable.
Normalisation
Normalisation is the process of adjusting raw data so that it can be easily compared across participants. For example, one individual may naturally sweat more than another, but normalisation scales their responses to ensure that the shape of their signals can be compared fairly.
Peak / Spike
A peak or spike refers to a sudden, sharp increase in a signal (for instance, a GSR spike following a scare or reveal). Peaks indicate moments when something registered strongly with the body, but they do not reveal the reason for that reaction. Reliable peaks are those that appear consistently across multiple viewers.
Trend
A trend describes the overall direction of a signal over a longer period. For example, a heart rate that gradually increases during a chase sequence illustrates a trend. Trends can show the emotional arc of a scene, indicating whether tension is building, being sustained, or resolving.
Sympathetic System
The sympathetic system, often referred to as the "fight or flight" branch of the autonomic nervous system, increases heart rate, enhances skin conductance, and prepares the body for action. In film testing, sympathetic activation typically corresponds with moments of suspense, shock, or excitement.
Parasympathetic System
The parasympathetic system is known as the "rest and digest" branch of the autonomic nervous system. It slows down the heart rate and restores balance to the body. In film testing, parasympathetic activity is often observed when tension decreases or resolution occurs.
