Take a moment and look around. Are you inside? Then you might come across books, a pile of mail, your computer and television. Or maybe your outside carrying your mobile device, and checking your appointments. The world we live in is surrounded by ubiquitous information. Information that is visual, audible, and tactile. It it meant to inform, to entertain, to instruct, and to warn.
Because we are constantly bombarded with this information in our daily lives, we must quickly collect, filter, and process which of it is important to use for specific tasks.
Consider, a busy intersection, you are trying to cross. You are surrounded by the sights and sounds of pedestrians conversing, cars and trucks honking, birds flying, signage on billboards, etc. Our minds have an amazing ability to focus on the task at hand, filter the surrounding "noise", process, store, and act on relevant information.
The crosswalk signal changes to "Walk" we identify the sign, interpret it's meaning, determine an action to move our body forward, carry out our actions by walking until you've crossed the street achieving your goal.
Understanding how we process and filter visual information, or data, will help us design effective displays of information on mobile devices. Let’s first explore the types of information.
Types of visual information
Humans more or less have the same visual processing system. However, without a standardized way of explaining and notating our perceptions, our communication of this information becomes arbitrary and not effective when designing mobile interactions.
Bertin (1977) organized visual information into two forms: data values and data forms. Ware (2000) introduces a more modern way of dividing data into entities and relationships. Entities are the objects that can be visualized such as people, buildings, signs. Relations, or relationships, define the structures and patterns that entities share with each other. Relationships can be structural and physical, conceptual, causal, and temporal. These entities and relationships can be further described using attributes. Attributes are properties of either the entity and relationship and they cannot be thought of independently. Some attribute examples are: specific color of an object, duration of a specific trip, texture of a specific surface, weight of a particular vector line, the size of a particular font.
In addition to creating descriptions of our perceptions, we have also standardized a classifying way to organize them. Common classifying schemes that we use are:
Nominal - using labels and names to categorize data. Ordinal- using numbers to order things in sequence. Ratio- a fixed relationship between one object compared to another using a zero value as a reference. Interval- the gap between two data values is measurable. Alphabetical- using the order of the alphabet to organize nominal data. Geographical-using location, such as city, state, country, to organize data. Topical- organizing data by topic or subject. Task- organizing data based on processes, tasks, functions and goals. Audience- organizing data by user type, such as interests, demographics, knowledge and experience levels, needs and goals. Social- A collaboration of organizing data by users who share the same interests. Such as tagging, adding to a wiki, and creating and following twitter feeds. Metaphor- organizing data based on a familiar mental model to the user. Such as organizing computer files with folders, trash, and recycle bin.
Organizing Information with Information Architecture
Now that we are able to describe the data that we perceive, we must understand how this information should be structured, organized, labeled, and identified on mobile user interfaces.
One of the most common organization structures humans have used through time is a hierarchy. A hierarchy organizes information based on divisions and parent-child relationships. When using heirarchies to organize information, Peter Morville explains rules to consider (Morville, 2006): Categories should be mutually exclusive to limit ambiguity. Consider the balance between breadth and depth. When determining the number of categories regarding breath, you must consider the user's ability to visually scan the page as well as the amount of real estate on the screen. When considering depth, limit the scope to two to three levels down. Recognize the danger of providing users with too many options.
Understanding how we visual perceive information
Our visual perception model is complex.
Our human mind is like a leaky bucket. It holds plenty of information, but can easily let information slip away and spill out. If we can understand how our mind works, and it’s limits, we can create visual information displays that limit our information loss and mental load during decision making processes.
Basically, information processing involves these major processes. 1. Sensation 2. Perceptual Processing 3. Memory: Sensory Memory, Short-term or working memory, and Long term Memory. 4. Intellection 5. Movement Control
Sensation is a process referring to the capture and transformation of information required for the process of perception to begin (Bailey 1996). Each of our sensors (eyes, ears, nose, skin, mouth) collects information, or stimuli, uniquely but all will transform the stimulus energy into a form the brain can process.
All of these senses respond selectively to certain types of stimuli. There are four types of stimuli our bodies can sense: Electromagnetic, Mechanical, Thermal, and Chemical. Each of these stimuli can be collected through different senses. Electromagnetic stimuli can be collected through vision. Mechanical stimuli can be collected by hearing, touch, pain, vestibular, and kinesthetic. Thermal by cold and warmth. Chemical by taste and smell (Ellingstad, 1972).
Our sensory processing has limits. For example, we can only see wavelengths between 400 and 700 nanometers. Our thermal sensors respond only to infrared wavelengths. Our skin temperature is about 91.4 degrees F and stimuli at this temperature do not cause a noticeable thermal sensation. However, below 60 degrees F, the skin will transmit a cold feeling and above 105 degrees, the skin will transmit a hot feeling.
Our sense of touch (pressure) is experienced when an object contacts our skin. The skin within certain locations, can identify where the object is, it’s size and shape, and it’s movement. (**talk in detail about this in chapter of Navigation and Gesturing?**) For more information on sensory limits, refer to Chapter 3: Sensing and Responding (Bailey, 1996).
This chapter details patterns on Displaying information. Therefore, it is beneficial to discuss in greater detail the sense of vision, how it works, and it’s limits.
The human eye. Many people use the analogy that our eye works similar to a camera. Both eye and camera have a lens, an aperture (pupil), and film (retina). However, the similarity stops there. Because the image that is shown on the back of our retina does not resemble our perception of it.
How does the eye work?
The eye is an organ responsible for vision. It first collects, filters, and focuses light. Our eyes can only experience a narrow band of radiation in the electromagnetic spectrum.
The narrow range is approximately 400 nanometers (where we can perceive the violet color) to about 700 nanometers (where red is perceived). The focused beam of light is then projected onto the back part of our retina where it contacts photoreceptors, known as rods and cones. These receptors are light sensitive. The cones are used for seeing when there is bright light and are color sensitive. The rods are sensitive to dim lighting and are not color sensitive. These receptors convert light into electro-chemical signals which travel along the optic nerve to the brain for processing.
The eye is sensitive to stimuli in many ways at any moment, including the size of stimulus, its brightness and contrast, and the part of the retina that is stimulated.
As a designer, it’s important to understand how these stimuli can affect and influence our design decisions.******* The size of the stimulus is measured with visual angle. This is the angle formed at the eye by the viewed object. The visual angle can be calculated using the following formula: Visual Angle (minutes of arc) = (3438)(length of the object perpendicular to the line of sight)/distance from the front of the eye to the object. Visual angle is typically measured in degrees of arc where one degree=60’(minutes of arc), and 1 minute of arc=60”(seconds of arc). With an understanding of visual angle, we can determine the appropriate size of visual elements including character size viewed at specific distances. According to Human Factors Society (1988), the following visual angles are recommended for reading tasks: When reading speed is important, the minimum visual angle should not be less than 16 minutes of arc and not greater than 24 minutes of arc. When reading speed is not important, the visual angle can be as small as 10 minutes of arc. Characters should never be less than 10 minutes of arc or greater than 45 minutes of arc. So, let’s assume I’m designing a text that is to be read quickly on a mobile device with a viewing distance of 30 centimeters(11.8 inches). The equation would look like this: Length= 16 minutes of arc(30)/3438. The smallest acceptable character height would then = .14cm. or about 10 points. Now, other factors that need to be addressed when designing character size on mobile is 1: The distance changes all of the time, and 2: Glare and wobble affects legibility. This will be further addressed in another chapter*******
Visual Perception After our senses collect visual information, our brain begins to perceive and store the information. Perception involves taking information that was delivered from our senses and interacting it with our prior knowledge stored in memory. This process allows us to relate new experiences with old experiences. During this process of visualization of perception, our minds look to identify familiar patterns. Recognizing patterns is the essential for object perception. Once we have identified an object, it is much easier to identify the same object on a subsequent appearance anywhere in the visual field (Biederman and Cooper, 1992). The Gestalt School of Psychology in 1912, was founded to study how humans perceive form. They developed the Gestalt Laws. These principles can help designers create visual displays based on the way our minds perceive objects. The following are Gestalt principles: Proximity-states that objects that are close together are perceived as being related and grouped together. When designing graphical displays, having descriptive text close to an image will cause the viewer to relate the two objects together. This can be very effective when dual coding graphical icons. Similarity- Continuity- Symmetry- Closure- Relative Size- Figure and Ground-
Collecting Information Model of Perceptual Processing: Stage 1: Parallel Processing to Extract Low Level Properties of the Visual Sense. -Rapid Parallel Processing -Extraction of features, orientation, color, texture, and movement patterns. -Transitory nature of information, which is briefly held in an iconic store -Bottom-up, data driven model of processing
(Steps: Parallel processing or orientation, texture, color, and motion. Then Detection of 2D patterns, contours and regions. Then object identification, working memory.
Stage 2:Sequential Goal-Directed Processing -Slow Serial Processing -Involvement of both working and long-term memory -More emphasis on arbitrary aspects of symbols -Top-down processing -Different pathways for object recognition and visually guided motion
In addition to the understanding how we collect information, we also need to understand our information processing limits. After collecting information, it is stored in short-term, or working memory. This information is stored from a fraction of a second up to a minute or two.and continues onto long-term memory. The ability to store working memory into long term memory is affected by our limitations in memory capacity and time. Working memory's capacity is stored in three to seven chunks of information.
Why is this important to Displaying Information on Mobile Devices? The point here is that in order to effectively display information, we must understand how users process it. Gestault theory: Symbol Information Processing Patterns Relationships
Articulate Graphics ***** Easterby Task, Process and Display Design **** Environment Surface detection Visible Light Light interacting with surfaces Eye Visual Angle