Understanding Human Behavior – A Physiological Approach

As fantastically (and fanatically) self-aware organisms, we humans tend to ascribe great importance to our intellectual processes: We’re rational and reasoning creatures, we assert, capable of stepping back and assessing our own behavior through an analytical lens.

Like any other biological entity, however, we’re interacting with and responding to our environment in myriad ways well beyond the realm of our conscious perception. We usually take these nonconscious, autonomic aspects of our being for granted, but naturally, they’re fundamental to both our appreciation of the world around us and, critically, our day-to-day survival.

We don’t need to compel ourselves to shiver when the mercury drops; our hand recoils at the lick of the flame or the bite of the dog. Thankfully, we don’t have to think our way through the mechanics of walking in order to pull it off – start trying to, and you’re liable to beeline for the pavement.

The conscious and the nonconscious, the voluntary and the involuntary: When it comes to Homo sapiens, these processes aren’t either-or propositions. They’re thoroughly intertwined, influencing and echoing one another. In short, human beings (breaking news) are complicated systems, and the study of human behavior is a complex task. Parsing out behavioral and emotional nuances requires zoomed-in looks at the tempos and intensities of all kinds of physical and psychological networks – and a holistic, big-picture perspective of how those networks interface with one another.

Physiology and Human Behavior

Researchers interested in how humans respond to stimuli, therefore – whether it’s an Internet ad or an interpersonal encounter – can enhance their investigations by employing biosensors that document psychophysiological patterns. 

Self-assessment / self-reporting remains a powerful and useful tool for understanding the how and the why of human behavior but has some major limitations.


People aren’t always entirely honest when describing how something makes them feel – not necessarily because they’re trying to be duplicitous or crafty, but because they may feel pressured by the formal self-critical exercise to give what they think is the “right” answer (or the least embarrassing one).

Furthermore, it’s often exceedingly difficult to explain in coherent sentences our response to a piece of information, or our mood at a given moment. We may not know exactly why we favor one product over another, or why we’re feeling generally joyful or generally depressed (there are many techniques for honing a survey’s efficacy – you can learn more in one of our blog posts).

Meanwhile, physiological data – such as the rate of our heartbeat, the degree of our perspiration, and the direction and rhythm of our eye movements can shed light on behavioral phenomena our conscious minds may deny, distort, or completely fail to register.


The academic and commercial applications of the psychophysiological studies considering such data are virtually limitless, relevant to fields as diverse as neuroscience, psychotherapy, marketing, and design. 

Examples of Biosensor Research

What’s remarkable about such studies are the incredibly fine-scale insights into the human emotion that can be gleaned from the minute nonconscious or involuntary phenomena.

Consider galvanic skin response or GSR. This is a measure of electrodermal activity: the relative conductance of our skin from perspiration. Sweating is an utterly autonomic operation that, in addition to its role in thermoregulation, is a reaction to arousal, from general excitement to flat-out terror. By measuring sweat production via skin conductance, GSR can reveal evidence for a stimulated, agitated state of being that’s beyond a person’s deliberate control – including arousal too subtle to manifest on the self-aware spectrum.


Electrocardiography (ECG) registers the electrical signature of a heartbeat, revealing intricacies of their rate and variability that, like GSR, can demonstrate physiological, emotional, or psychological arousal.

Then there’s electroencephalography (EEG), which tracks brainwaves via scalp-affixed electrodes that measure the electrical pulses produced by mass neuron firings. An EEG readout indicates the moment-by-moment “geography” of brain activity – which cortex is excited when, basically – as well as the brain’s overall state at a given time.

eeg research

Eye tracking, meanwhile, quantifies when and where a subject’s gaze lingers, the rhythm of reading, and other optical minutiae, while facial expression analysis looks up-close at the configuration of the face’s musculature for clues to a person’s emotions.

eye tracking glasses supermarket

The information outputted by a single kind of biosensor can be intriguing and useful, but only to a point. For instance, GSR and ECG readings can suggest the condition of arousal, but not its valence, or emotional character. In other words, sweaty palms or a ramped-up heartbeat doesn’t reveal whether we’re dealing with a love-at-first-sight (i.e., a positive stimulus) sort of situation or a figure-looming-out-of-the-shadows (i.e., a negative stimulus) deal.

Integrate those electrodermal and cardiac data with EEG, facial expression analysis, eye tracking, and other analyses, and you’ve got a much more multifaceted picture. That’s what iMotions is all about.

Expanding Horizons

As we noted earlier, psychophysiological investigations have wide-ranging utility – whether it’s a company trying to gauge the appeal of a new product design to a prospective shopper, or it’s a therapist treating a patient with post-traumatic stress disorder.

As research into human behavior continues to expand – in concert with improvements in the technology and methodology for implementing that research – it goes without saying that its applications will as well.

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