How the Invention of the Pupilometer Is Changing the History of Neurology

Rather than “windows” into the soul, others have argued that the pupils are “gateways” to the mind. Observing the world around us, our eyes follow specific patterns. To perceive a situation clearly, the corneas and the tissue surrounding our eyes’ lenses shift. The amount of light entering our eyes may be influenced by the size of our pupils, but it is not the only thing that has an effect on this. Pupil dilation is influenced by how we see the world and how we feel it.

Pupillometer, is a device designed for measuring the size of a person’s pupils to learn more about how they perceive their environment. It was formerly thought that the pupil would only dilate in response to pleasant or attractive stimuli. However, psychologists have proven that positive and negative information may trigger this dilation too. Pupilometers can provide the minute details of these changes with accuracy.

Due to its demonstrated ability to quantify the expansion of a person’s pupil diameter in response to any emotionally charged stimulus (such as images, words, or sounds), it has been compared to the galvanic skin response (GSR; in which the intensity of an emotion can be uncovered, but not the direction).

Furthermore, research has indicated that pupillometry tests may be more accurate than GSR in predicting stress-related behaviors. However, the study’s weaknesses are detailed below.

There’s a lot more at play here.

Further research has revealed that pupils dilate in proportion to the amount of cognitive effort they are subjected to, with larger pupils linked to more cognitively demanding tasks. Examples of this may be seen in the Stroop test, which asks participants to read words in various colors (for example, the word “blue” is printed in a different color).

As your brain struggles to interpret emotions or pieces of information, your pupils become larger. Pupil dilation is a good predictor for evaluating mental functions at a deeper level because of fMRI scanning; scientists think that increases in brain function in different areas are strongly associated with pupil dilation.

For example, among people with depression, anxiety, Autism Spectrum Disorder (ASD), and Parkinson’s illness, abnormal pupillometry responses to stimuli have been identified. Generally speaking, pupillometry is a critical tool for determining how healthy people function and what happens within a sick person’s head.

This does not negate the fact that pupillary evaluation offers early insights into enhancing the short-term quality of life for people suffering from neurological illnesses. Pupilometry data may be used to predict the success of psychiatric treatment to some degree, according to researchers. Using this strategy may ensure that the patient receives the best possible treatment, which might improve recovery rates and the overall effectiveness of healthcare.

With the help of BCI (brain-computer interface), pupil dilation as a secondary signal may have a significant impact. Eye-tracking may be an accessible means of computer interaction for people with physical mobility limitations, which is a widespread use for BCI. An additional cognitive signal may be provided by incorporating a correct assessment of pupil size into the BCI process, boosting overall efficacy.

The combination of other biosensors and pupillometry could even further advance BCI: “In particular, if personal computers could perceive a user’s emotions through the use of physiological measures such as heart rate, galvanic skin response, EEG, pupil diameter, and so on, then it could intelligently alter a user’s experience,” Graur and Siegle write in their article (2013).

How is pupillometry performed?

With only a pupillometry system, a selected stimulus (or stimuli), and NeurOptics, anybody may begin exploring the fascinating world of pupillometry. Since it is a non-invasive treatment, setting it up and running is a breeze. Special pupillometry tools aren’t necessary with eye-trackers since they can usually do the job.

A pupillary assessment must take into account the amount of light that is illuminating the topic. To ensure that any pupil reflex is not solely a physiologic reaction to light intensity, the luminescence of the stimuli must be standardized.

Once this consideration has been made, the experiment may be started (together with the degree of illumination in the room). In addition to pupillometry data, the inclusion of other biosensors may enhance the study’s findings.

EEG signals may be used to identify specific measures of a person’s pupil reactivity. This data may be used to estimate the individual’s level of cognitive strain (among other metrics). Combining an EEG with pupillometry makes it feasible to detect whether increased pupil dilation is driven by cognitive load or other factors.

It is also possible to examine frontal asymmetry using EEG to see whether a participant is likely to approach or avoid a stimulus in the context of their study. With iMotions, this measurement is calculated automatically, making determining the root cause of pupil dilation easier.

Pupil evaluations might benefit from the addition of more physiological sensor combinations to better comprehend a person’s thoughts, feelings, and actions. A person’s emotional valence may be learned via face reading. As opposed to this, the other eye-tracking metrics let researchers determine what the individual is looking at, how it affects their mood or behavior, and how strong that mood or behavior is.

Conclusion

Ad testing, user experience testing, psychological testing, and more all benefit from the use of pupillometry, which measures the intensity of stimuli and pupil responsiveness in diverse circumstances. Before conducting a pupillometry experiment, it is essential to understand its limits. It’s still a vital resource for psychologists and other behavioral scientists because of the volume of information it provides, but it’ll be a long time before it becomes obsolete.