LESSON 8Sensual & Perceptual Theory

TOPICS COVEREDThe Sensual and Perceptual Theories of visual communication skills.Gestalt and Visaul Organisation.

OBJECTIVESBy the end of this chapter you should know:. The difference between visual sensation and visual perception.. The various components and uses for gestalt

There can be no words without images.

Aristotle

Psychologists, philosophers, and practitioners have devised several approaches that help explainthe way we see and process images. Knowing the four visual attributes the brain responds to-color, form, depth, and movement-is only part of the story for the visual communicator. The fourtheories we discuss in this chapter can be divided into two fundamental groups: sensual andperceptual. Those who advocate the sensual theories (gestalt and constructivism) maintain thatdirect or mediated images are composed of light objects that attract or repel us. The perceptualtheories (semiotics and cognitive) are concerned mainly with the meaning that humans associatewith the images they see.

To understand any of these approaches to visual communication, you must first know thedifference between visual sensation and visual perception. A visual sensation simply is astimulus from the outside world that activates nerve cells within your sense organs. Woodburning in a fireplace activates the cells in your ears because you can hear the logs cracking andhissing; in your nose because you can smell the rich aroma of the wood; in your hands and facebecause you can feel the warmth of the fire; and in your eyes as you watch the hypnotizing glowof the yellow flames. Sensations are lower order, physical responses to stimuli and alone conveyno meaning. Nerve cells in your ears, nose, hands, and eyes do not" have the capacity to makeintelligent thoughts. They are simply conveyors of information to the brain.

When stimuli reach the brain, it can make sense of all the sensual input. Conclusions based onthose data are almost instantaneous. Your brain interprets the noises, smells, temperatures, and

sights as a fire in a fireplace. Visual perception is the conclusion that is made by combining all ofthe information gathered by your sensual organs. Sensations are the raw data. Visual perceptionis the meaning concluded after visual sensual stimuli are received.

SENSUAL THEORIES OF VISUAL COMMUNICATION

Gestalt

The gestalt theory of visual perception emerged from a simple observation. German psychologistMax Wertheimer received his inspiration during a train trip in the summer of 1910. Wertheimerhappened to look out the window as the train moved through the sunny German countryside. Hesuddenly realized that he could see the outside scene even though the opaque wall of the trainand the window frame partially blocked his view. He left the train in Frankfurt, went to a toystore, and bought a popular children's toy of the day-a stroboscope or flipbook. The flipbook is asimple form of cartoon animation. On the first page of the book, a drawing, say, of a cartooncharacter in a running position is displayed on the left-hand side of the page. On each subsequentpage, the drawing of the figure is to the right of the previous drawing until the last page showsthe character at the right-hand side of the page. To see the effect of the character running fromthe left to the right side, the viewer simply flips the pages rapidly. Wertheimer's observationsduring the train trip and using the flipbook led to a famous laboratory experiment at the Univer-sity of Frankfurt.

Wertheimer concluded that the eye merely takes in all the visual stimuli and that the brainarranges the sensations into a coherent image. Without a brain that links individual sensualelements, the phenomenon of movement would not take place. His ideas led to the famousstatement:

The whole is different from the sum of its parts.

In other words, perception is a result of a combination of sensations and not of individual sensualelements.The word gestalt comes from the German noun that means form or shape. Gestalt psychologistsfurther refined the initial work by Wertheimer to conclude that visual perception was a result oforganizing sensual elements or forms into various groups. Discrete elements within a scene arecombined and understood by the brain through a series of four fundamental principles ofgrouping that are often called laws: similarity, proximity, continuation, and common fate.Similarity states that, given a choice by the brain, you will select the simplest and most stableform to concentrate on. This principle stresses the importance of basic shapes in the form ofsquares, circles, and triangles.

Similarity. Six tourists who rest on a bench at Versailles outside Paris come from a similarcultural group and are linked together in our minds. Because the woman to the right reads a bookand is from a different generation, she looks as if she does not belong, or is dissimilar.

Proximity states that the brain more closely associates objects close to each other than it doestwo objects that are far apart. Two friends standing close and holding hands will be viewed asbeing more closely related than a third person standing twenty yards from the couple .

Proximity. Three boys dressed in similar Mardi Gras costumes, but with dissimilar personalities, wait to bephotographed with the queen of a ball in New Orleans. One of the reasons the brain links the boys as a single unit isbecause they are sitting so close together.

Continuation rests on the principle, again assumed by gestalt psychologists, that the brain doesnot prefer sudden or unusual changes in the movement of a line. In other words, the brain seeksas much as possible a smooth continuation of a line. The line can be a line in the traditional senseof the word, as in a drawing, or several objects placed together that form a line. Objects viewedas belonging to a continuous line will be mentally separated from other objects that are not a partof that line. Continuation also refers to objects that are partially blocked by a foreground object.

Another principle of gestalt psychology is common fate. A viewer mentally groups five arrowsor five raised hands pointing to the sky because they all point in the same direction. An arrow ora hand pointed in the opposite direction will create tension, because the viewer will not see it aspart of the upwardly directed whole.One of the first uses of the gestalt principles was to explain the phenomenon of reversible figureand ground spatial patterns in painting and photography, called negative and positive space. Forfigure and ground patterns the crucial question was how do we know what is in the foregroundand what belongs in the background of an image? This question is related directly to theimportant need of the brain to label objects as near or far in order to judge their relativeimportance or danger.

In 1915, Edgar Rubin, a Danish gestalt psychologist, experimented with figure and groundpatterns by drawing an object that could be interpreted as either a face or vase. Sensually, both the face

and thevase images are stimulating photoreceptors in the retina. However, the brain cannot seeboth images at once-you must make a conscious decision whether to see a face or a vase in thedrawing.

Rubin also outlined the principle of camouflage in which there is little or no separation betweenthe foreground and the background. Understanding and manipulating this trait of visualperception led directly to military applications of merging the colors of uniforms and equipmentwith those of surrounding backgrounds in order to hide them. This principle also influenced thework of artists M. C. Escher and Paul Klee, both of whom were influenced by the writings andfindings of several gestalt psychologists.

Gestalt and Visual Communication

The strength of the gestalt theory of visual perception is its attention to the individual forms thatmake up a picture's content. Any analysis of an image should start by concentrating on thoseforms that naturally appear in any picture. Recall that color, form, depth, and movement all arebasic characteristics of an image that the brain notices. Gestalt teaches a visual communicator tocombine those basic elements into a meaningful whole. The approach also teaches the graphicartist to focus attention on certain elements by playing against the gestalt principles. Forexample, a company's logo (or trademark) will be noticed in an advertisement if it has adissimilar shape, size, or location in relation to the other elements in the layout.

The work of gestalt theorists clearly shows that the brain is a powerful organ that classifies visualmaterial in discrete groups. What we see when looking at a picture is modified by what we haveseen in the past and what we want to see

Gestalt Principles of Visual OrganizationIn discussing the 'selectivity' of perception I have alluded to foregrounding and backgrounding.We owe the concept of 'figure' and 'ground' in perception to the Gestalt psychologists: notablyMax Wertheimer (1880-1943), Wolfgang Köhler (1887-1967) and Kurt Koffka (1886-1941).Confronted by a visual image, we seem to need to separate a dominant shape (a 'figure' with adefinite contour) from what our current concerns relegate to 'background' (or 'ground'). Anillustration of this is the famous ambiguous figure devised by the Danish psychologist EdgarRubin.

Images such as this are ambiguous concerning figure and ground. Is the figure a white vase (orgoblet, or bird-bath) on a black background or silhouetted profiles on a white background?Perceptual set operates in such cases and we tend to favour one interpretation over the other(though altering the amount of black or white which is visible can create a bias towards one orthe other). When we have identified a figure, the contours seem to belong to it, and it appears tobe in front of the ground.

In addition to introducing the terms 'figure' and 'ground', the Gestalt psychologists outlined whatseemed to be several fundamental and universal principles (sometimes even called 'laws') ofperceptual organization. The main ones are as follows (some of the terms vary a little):proximity, similarity, good continuation, closure, smallness, surroundedness, symmetry.The principle of proximity can be demonstrated thus:

What you are likely to notice fairly quickly is that this is not just a square pattern of dots butrather is a series of columns of dots. The principle of proximity is that features which are closetogether are associated. Below is another example. Here we are likely to group the dots togetherin rows.

The principle also applies in the illustration below. We are more likely to associate the lineswhich are close together than those which are further apart. In this example we tend to see threepairs of lines which are fairly close together (and a lonely line on the far right) rather than threepairs of lines which are further apart (and a lonely line on the far left).

The significance of this principle on its own is likely to seem unclear initially; it is in theirinteraction that the principles become more apparent. So we will turn to a second major principleof perceptual organization - that of similarity. Look at the example below.

Here the little circles and squares are evenly spaced both horizontally and vertically so proximitydoes not come into play. However, we do tend to see alternating columns of circles and squares.This, the Gestalt psychologists would argue, is because of the principle of similarity - featureswhich look similar are associated. Without the two different recurrent features we would seeeither rows or columns or both...

A third principle of perceptual organization is that of good continuity. This principle is thatcontours based on smooth continuity are preferred to abrupt changes of direction. Here, forinstance, we are more likely to identify lines a-b and c-d crossing than to identify a-d and c-b ora-c and d-b as lines.

Closure is a fourth principle of perceptual organization: interpretations which produce 'closed'rather than 'open' figures are favoured.

Here we tend to see three broken rectangles (and a lonely shape on the far left) rather than three'girder' profiles (and a lonely shape on the right). In this case the principle of closure cuts across

the principle of proximity, since if we remove the bracket shapes, we return to an image usedearlier to illustrate proximity...