nterest is a feeling or emotion that causes attention to focus on an object, event, or process. In contemporary psychology of interest, the term is used as a general concept that may encompass other more specific psychological terms, such as curiosity and to a much lesser degree surprise.
The emotion of interest does have its own facial expression, of which the most prominent component is having dilated pupils.
Applications in computer assisted communication and B-C interface
In a 2016 article, an entirely new communication device and brain-computer interface was developed, requiring no visual fixation or eye movement at all, that is based on covert interest in (i.e. without fixing eyes on) chosen letter on a virtual keyboard with letters each having its own (background) circle that is micro-oscillating in brightness in different time transitions, where the letter selection is based on best fit between, on one hand, unintentional pupil-size oscillation pattern, and, on the other hand, the circle-in-background's brightness oscillation pattern. Accuracy is additionally improved by user's mental rehearsing the words 'bright' and 'dark' in synchrony with the brightness transitions of the circle/letter.
Measurement of sexual interest
In social science measurement methodology, when the intensity of (sexual) interest needs to be measured, the changes in pupil size – despite its weaker, but still consistent, correlations with other measures such as self-reported measures of sexual interest's orientation – have been proposed as its appropriate measure.