© Jody Walker, 2007 22 understanding perspective visual illusion multiple viewpoints descriptive...

© Jody Walker, 2007 1

understanding perspective

visual illusion

multiple viewpoints

descriptive characteristics

pre-attentive processing

Gestault theory

eye tracking

Now that we understand more about the complexity of visual processing, let’s learn about some things that influence processing and the creation of meaning.

memory RECOGNITION and RECALL arousal high level and low level


We generally speak of two kinds of memory: short-term (recognition) and long-term (recall). The processing energy and/or speed (cognitive stress) for each of these is different.

Short-term or “working memory” (similar to CPU - RAM)Memory we need to complete a given taskTemporaryTransientEfficacy influenced by:

•Amount of information•Ordering (First and last most memorable)•Recognition = visual patterns, symbols

RECOGNITION

RECALL Long-term memory (similar to ROM)Analysis, history, memorization


recall

recognition

brain energy(cognitive stress)

Let’s use gray to represent minimal energy/activity in the brain, and fuchsia to represent maximum energy/activity in the brain.

But another factor has an impact on processing in attention and memory…the level of arousal.


low

high

recall

recognition

brain energy(cognitive stress)

Levelof

arousal

An example of high arousal is flashing lights and blaring sirens on an emergency vehicle. Our body responds instantly, heart rate goes up, we scan the environment and act quickly.

An example of low arousal is a sitting in a conference room where everything is beige, the wall color, the furniture, the carpet, and we are listening to a speaker who has a monotone voice droning on about statistical data from a meaningless project.


low

high

Levelof

arousal

An example of high arousal is flashing lights and blaring sirens on an emergency vehicle. Our body responds instantly (stress), heart rate goes up, we scan the environment and act quickly.

An example of low arousal is a sitting in a conference room where everything is beige, the wall color, the furniture, the carpet, and we are listening to a speaker who has a monotone voice droning on about statistical data from a meaningless project.


low

highrecall

recognition

brain energy(cognitive stress) Level

ofarousal

To pay attention, to remember, to think, to process information effectively is helped or hindered by the amount of cognitive stress and the level of arousal.

It’s important to address this whenever you design a functional and/or design element, particularly in a website environment. You don’t want people to waste valuable brain energy struggling to remember where something is located on your website, nor do you want them to be inundated with tons of bright colors, and animations. But you do want them to be interested/engaged, so the arousal level has to be “high enough.”


Another factor that impacts visual processing is how brain the brain creates meaning from (makes sense of) all the inputs it receives from the body.

What do we know about the creation of meaning?


“We seem as a species to be driven by a desire to make meaning…we are, above all, Homo significans - meaning makers.

This fundamental concern underlies the process of human visual perception. Faced even by ‘meaningless patterns’ the mind restlessly strives to make them meaningful.

Where an image seems to lend itself to a possible interpretation in 3D we seem to prefer this interpretation.

Most features of the general process of visual perception appear to be virtually universal rather than being culturally-specific.”Daniel Chandler, Visual Perception Lecture Series, University of

Wales, July 1997

Homo significans - meaning makers


descriptive characteristics

pre-attentive processing

Gestault theory

What are some of the ways the brain makes sense out of visual input?


These are some of the terms that we use in design to describe physical characteristics of objects.

Physical characteristics


Pre-attentive Processing

Pre-attentive processing refers to visual identification performed in a very short time lapse (typically between 200 and 250 milliseconds or less). The brain performs a series of identification and recognition operations in an "automatic" way without the need to focus our attention or even be conscious of them.

Proper use of the pre-attentive phenomena is fundamental for the generation of good user interfaces and graphics. There should always be a clear difference between the whole and the part.



ColorForm

MovementSpatial

Localization

According to Colin Ware in his book Information Visualization: Perception for Design, the list of features that are pre-attentively processed can be grouped into four basic categories:

Illumination is processed pre-attentively, so our sight identifies sentences in bold face, so that, when properly constructed, you can read the essentials of the text synthesized in a few lines.


Notice how quickly and effortlessly you differentiate the objects in the following examples of pre-attentive processing.


Line orientation Line length Line width

Line collinearitySize

Curvature Spatial grouping

Added marks

Numerosity

Form



Color

Hue Intensity

Direction of motion. An object moving against a still background or in relation with a homogeneously moving background in a different direction is detected immediately.

Flicker. An element that appears and disappears, the blinking of a car signal or the flashes of the anti collision lights of the planes are detected pre-attentively. For this reason they are used as safety elements in aviation, populating planes, antennas and potentially dangerous obstacles.

Movement



Stereoscopic depth the objects placed in a particular depth layer are pre-attentively identified respect the distractors placed in other depth layers.

Spatial Position

Concavity / convexity produced by the shading of objects.



Proximity occurs when elements are placed close together. They tend to be perceived as a group.

Gestalt Principles on visual processing include:

Closure occurs when an object is incomplete or a space is not completely enclosed. If enough of the shape is indicated, people perceive the whole by filling in the missing information.

When confusion in Figure-Ground happens, the stability of the image is diminished.

Gestalt Principles


Gestalt Principles

Similarity: similar objects will be counted as the same group.

Pragnanz (Good Form): A stimulus will be organized into as good a figure as possible.”

Continuation: the eye’s instinctive action to follow a direction derived from the visual field.


Unity/Harmony: relationships between objects when they exist within the same form.

Balance/Symmetry: symmetric or balanced objects are more readily perceived

Good continuity: smooth continuous lines are perceived more readily than contours that rapidly change direction. People perceive the entire picture of an object even if part is hidden

Common fate: objects connected by continuous contours are perceived as related

Common region: objects within an enclosed region of space are grouped

Connectedness: objects that move together are perceptually grouped

Gestalt Principles

ETC.


understanding perspective

visual illusion

multiple viewpoints

eye tracking

A few more concepts involved with the creation of meaning during visual processing…


Visual Illusions

“We know, above all, that the eye, as an extension of the brain into the world outside of us, is an interpreter of experience, that it is liable to illusion, and that it is also intelligent, continually solving enormously complex problems presented by the environment, apparently almost instantaneously.“ Ann Marie Barry. (1997) Visual Intelligence: Perception, Image, and

Manipulation In Visual Communication. Albany : SUNY


Some examples of two dimensional visual illusions.

Visual Illusions


What we see, to a large degree, is determined by our knowledge of what we should see, which is based on our previous experience.

Constructing Visual Reality

Théodore Gericault, Derby at Epsom (Musée du Louvre)


A much simplified sketch still captures many of the essential features of the painting. With only a few lines, it shows us familiar objects in well-known poses, which we recognize as running horses.

Consider how difficult it would be to design a computer program that would view the few lines in this sketch and arrive at the same conclusion as we humans do.

Robert L. Solso. (1994) Cognition and the Visual Arts. Cambridge, MA: MIT Press.


We are Comfortable with Multiple Viewpoints


Our eyes search rapidly to define our reality.

But what are we actually focusing on?

Our current understanding of eye movement (saccadic movement) began in 1878 when the French scientist, Emile Javal, observed that school children read text material by moving their eyes by small jumps (par saccades), then pause, then jump to another part of the text, pause, and so on.

While reading, the eye normally follows a linear track…sometimes we backtrack or fly ahead to salient words or phrases.

Eye movements are unconscious adjustments to the demands of attention during a visual experience


How do we look at faces?

Russian scientist Yarbus was one of the pioneers in the field of eye tracking and picture perception.

In 1967, he concluded “that a large amount of time is spent observing the eyes, mouth and general shape of the head. These features are the most salient for the observer; and the record of his eye movements and fixations alone tell us something of his thoughts. These activities are so universally shared that it is possible to guess the identity of the object (a face) by looking only at the record of eye movements.”


Tracking Eye Movements

searching for clues to answer question related to a painting

searching for informationon a web page

http://www.poynterextra.org/eyetrack2004/about.htm

http://www.infovis.net/index.php?lang=2




© Jody Walker, 2007 22 understanding perspective visual illusion multiple viewpoints descriptive...

Documents

Transcript of © Jody Walker, 2007 22 understanding perspective visual illusion multiple viewpoints descriptive...