Keynote Speaker

Keynote at the 20th European Congress of Psychology, ‘Psychology: Responding to the Challenges of Technology and Humanity’, Belgrade, Serbia, 7-10 September 2027

The sense of vision presents sighted organisms with detailed information about their environment, thus providing invaluable support for guiding their actions. The difficulty of this task is reflected in the fact that a substantial portion of the cerebral cortex is devoted to the processing of visual information. However, the experience of vision itself appears simple and straightforward: we only need to open our eyes to become instantly aware, in a seemingly direct and effortless fashion, of an astonishingly rich and intricate world of objects and events. However, the reason for this apparent and yet deceptive simplicity is that, similar as in well-designed software applications, the complexity of the background machinery is successfully hidden behind a user-friendly front interface.

I will illustrate some of the complexities of vision by first describing a number of challenges to the endeavor to extract reliable information about the surroundings from the structure of the light field registered by the eyes. For example, optical projections of three-dimensional scenes onto two-dimensional retinal surfaces typically involve considerable geometrical distortions. Nevertheless, we are generally hardly aware of these deformations and usually visual constancies obtain, that is, our perception of features such as sizes, shapes, distances etc. is generally approximately correct. On the other hand, there exists a large and bewildering variety of visual illusions, in which our apprehension of visual features deviates surprisingly and systematically from their physical values. Furthermore, vision can involve significant context effects, that is, the appearance of identical figures can be remarkably different when they are placed in different surrounds. The talk will be richly illustrated with numerous presentations of intriguing visual phenomena.

Vision science has witnessed remarkable progress over the years, but many issues still await generally accepted explanations. Better understanding of visual phenomena and mechanisms, besides being of intrinsic interest as well as useful in a number of applications (such as in various branches of psychology, and also in medicine, education, machine intelligence, advertising etc.) also raises philosophical issues concerning the scope and limits of our sensory based knowledge of external reality.