The Psychology of Visual Art Eye, Brain and Art

Introduction

Assume, as we did at the beginning of the previous chapter, that the aim of the artist is to create a representational painting, which is as close as possible to the light distribution that would be sent to the viewer by the scene itself; a window onto a virtual scene. Even though the artist may be able to use detailed knowledge of perspective projection and optical devices such as the camera obscura, in every case the painting will fall short of an exact facsimile. Instead, it will be a resemblance or approximation to the scene itself. The viewer is almost always aware of the perceptual characteristics of the picture as a flat surface in itself, such as its shape, size and position. The information carried in a picture is also lacking in several important respects, even when the picture is a photograph captured by the highest resolution camera available today or a painting faithfully copied from such a photograph. Natural objects and surfaces have an inherent spatial scale, which we apprehend when we view real scenes. Redwood trees appear massively tall, while the intricate pattern of lichen growing on a rock surface appears tiny. Pictures of objects and surfaces, on the other hand, can be any size; information about absolute scale is lost. In a closely cropped photograph, it may be impossible to distinguish between small ripples in sand, as seen at one’s feet when standing on a beach, and massive sandbanks viewed from an aeroplane. We are able to appreciate absolute scale in real scenes because they have three spatial dimensions (width, height and depth), which carry information about absolute distance. When one’s gaze shifts between real objects, the lens of the eye adjusts its focus to maintain a sharp image (accommodation, described in Chapter 2) and the two eyes alter their convergence angle so that both are directed at the same object. Changes in focus and convergence angle are brought about by muscles inside the eye itself (which control focus) or those attaching the eye to its socket (which control convergence). Sensory information about the state of tension in these muscles provides the visual system with information about absolute depth, which can be used in judgements of absolute size.